Extreme Precipitation and the July 4h Texas Hill Country Flood

Central Texas recently experienced a storm with extreme rainfall, leading to flash-flooding in a number of rivers, particularly the Guadalupe River, a popular recreational river.  The storm happened over the July 4th holiday, when the campgrounds and RV parks near the river were crowded with families out for the holiday, and hundreds of children were enjoying summer camp beside the river.  The flood was sudden and savage, sweeping down the river at 4 am, with the river level rising 26 vertical feet in 45 minutes, sweeping away buildings, cabins, RVs, cars, and people.  At the last count, different sources indicate that between 135 and 145 people are confirmed to be dead.  Preliminary estimates of property damage are around $20 billion.  

I don’t want to talk about the emergency planning, the lack of an effective notification system, the lack of an evacuation order, or delays in the search and rescue emergency response.  I want to talk about the rain.  

Within days of the central Texas floods, there were unrelated flooding events in New Mexico, North Carolina, New Jersey, Illinois and New York.  There were fatalities due to flooding in New Mexico, North Carolina and New Jersey.  Property damage is extensive.  The floods in parts of New Mexico, North Carolina and Illinois were considered 1000-year flood events.  All of the floods were due to extreme rainfall events.  

Climate Report Warnings
There have been six international and five U.S. major climate reports in the past 35 years.  We have been warned repeatedly – human CO2 emissions cause more frequent and severe  extreme rainfall events, due to high temperatures of the air and ocean surface.  Twenty-five years ago, the 1st National Climate Assessment said this:

“Droughts and flash floods are likely to become more frequent and intense….It is very likely that more rain will come in heavy downpours, increasing the risk of flash floods….Floods, especially those related to flash floods from intense short-duration heavy rains, are likely to increase in magnitude or frequency in many regions….Future climate scenarios show likely increases in the frequency of extreme precipitation events, including precipitation during hurricanes.”

The 2017 5th National Climate Assessment is more strident in delivering that warning, adding detail about what regions are most at risk, notably  in the Appalachians and Texas Hill Country.  When global warming reaches 2.0 C above pre-industrial levels, the Appalachians and Hill Country will see increases between 25% and 50% in the heaviest rainfalls.  In a recent article, the commercial weather service Accuweather put it plainly:  “Climate change from fossil fuel pollution is amplifying the conditions that make flash floods more likely and more severe.”

In 2025, global air and sea temperatures are clearly higher than twenty-five years ago.  Global humidity has increased, and heavy rainfall events have already increased in frequency and severity.  Sea surface temperatures are particularly important in causing extreme rainfall events.  Global sea surface temperatures are about 2 degrees F (1 degree C) warmer than the 20th century average, and about 1 degree F warmer than the average for 1971 – 2000.  Tropical systems now carry more moisture, due to higher sea and air temperatures.  When those systems move inland, more severe rainfall and flooding occur.  It’s worth noting that the 2025 central Texas flooding developed out of the remnants of tropical storm Barry, and 2025 flooding in North Carolina was from tropical storm Chantal.  Other recent catastrophic floods include 2024 flooding in Asheville, N.C. from Hurricane Helene (>107 deaths, $60 billion in damages) and the 2017 flooding in Houston from Hurricane Harvey (103 deaths and $125 billion in damages related to inland flooding).  Coastal areas are most at risk, with repeated flooding events from ocean-born humidity in Texas, Louisiana, Florida, and the Carolinas.  But areas far inland are also subject to extreme rains from the remnants of tropical storms, such as the 2016 flooding in Utah and the 2024 flooding in Tennessee. 

Attribution Studies
It’s difficult to attribute the cause of any specific weather event.  Attribution studies require months of study and have ranges of uncertainty in the results.  Undoubtedly, there will be studies of the July 4th flooding in Texas, but results may not be available for a year.  However, we already know that atmospheric water content was 7% higher than any previous, similar storm.  It seems certain that climate change played a role in the severity of the rainfall and flooding.

In 2016, a year before Hurricane Harvey flooded Houston, the Associated Press reported that extreme downpours had doubled in frequency in the preceding three decades, and that Houston already ranked badly in every category of repeated flood losses.  Houston’s flood-control infrastructure was built decades earlier, for less severe flood conditions.  When the flooding from Harvey occurred in 2017, the volume of water exceeded the flood control capacity by about 30%.   Attribution studies after the disaster concluded that between 15% and 38% of the flood volume was attributable to climate change, with 30% as the most likely volume.  In short, climate change was responsible for the >100 deaths and $125 billion dollars in damages from Hurricane Harvey.  

Similarly, attribution studies of Hurricane Helene show that climate change increased the volume of the  record rainfall, and greatly increased the likelihood of the extreme rainfall.  NOAA modeling shows that the regions most likely to see increased rainfall in coming decades are in Appalachia and the Texas Hill Country.  (See figures at the end of the article.)  Both areas are already prone to flash-flooding, due to topography.  

Between 2001 and 2019, Houston experienced four storms that exceeded the 100-year flood threshold derived from prior rainfall statistics.  Two of those storms exceeded the 1000-year flood threshold.  

Following Hurricane Harvey, FEMA and NOAA increased the 100-year, 24 hour rainfall amount for Houston, revising the 100-year flood plains.  Today, nearly a decade later, those estimates may already be obsolete, and will need to be revised upward again.

Global Impact
Flooding is now a pervasive fact of life in the United States and around the world.  Rainfall records studied by the non-profit group Climate Central show that hourly rainfall rates have grown heavier in nearly 90% of large US cities since 1970.  A few days ago Accuweather published a warning that 33 states are at risk of localized flooding this week, with 21 states at “greatest risk” for flooding.  There is currently flooding in the UK and Italy; ten European countries were impacted by flooding in 2024.  India, Pakistan, Bangladesh, China, Nepal, South Korea and Indonesia have all recently experienced severe flooding.  A quick Google search shows reports of record flooding in Africa, with over 100 fatalities in South Africa last month, and catastrophic flooding in Argentina and Brazil. 

In 2025, the National Weather Service has issued a record-setting 3050 flash-flood warnings through July 15th, with 706 warnings issued in the first two weeks of July.  Yesterday, a friend posted a go-fund-me request to benefit a young man in New Jersey, who lost everything he owned in recent flooding.  And an hour ago, my son in Maryland sent me a video of a flooding river near his home, flowing over a pedestrian bridge we’ve often used.

Trump Administration Approach to Climate Change
The Trump administration is in denial about climate change.  The administration closed down the Office of Global Change, created by Congress in 1990 to study and deliver reports on climate change.  The administration also removed all of the climate reports from government servers, reneging on a pledge made just a few weeks ago to keep those documents available.  The administration terminated development of a NOAA forecasting tool which would take changing climate into consideration in forecasting heavy rain and flooding.  The administration ended support for a variety of programs to develop alternatives to CO2 emissions, and implemented policies to make low-carbon solar and wind energy development more difficult.  In view of the decades of climate warnings, and the increasing frequency and severity of climate-change driven disasters, the actions of the Trump administration are completely irresponsible.

Conclusion
I spent my career finding oil and natural gas, which were needed to fuel our economy.  But like buggy-whip manufacturers of the past, times change.  The climate damage from fossil fuels is increasing, and we need to adopt alternatives to mitigate future disasters.

Global air and sea temperatures will continue to rise until we reach zero greenhouse gas emissions.  Realistically, that will not happen in my lifetime, or possibly in my children’s lifetimes.  We are already at 1.5 degrees C above pre-industrial levels.  (It was the target of the initial 2017 Paris agreement to keep temperatures below that threshold.)  We are almost certain to exceed 2.0 degrees C, and likely to approach 3.0 degrees C before reaching zero greenhouse gas emissions.  Extreme flooding and other climate disasters are certain to become worse as temperatures rise.  

The only question is how many children’s lives, adult lives, and how much property damage must occur before we seriously begin to address climate change.  Jim Blackburn is a Rice University scholar and author of three reports on Houston’s readiness for extreme flooding, following on the impact of Hurricane Harvey.  Blackburn writes, ““For too many years we debated whether climate change was happening. We now accept it but face great challenges in countering this local and global threat. We have wasted enough time.”

Water vapor in the atmosphere has risen measurably in recent decades, as predicted in climate reports since 1990.  Higher levels of atmospheric moisture increase the likelihood and severity of extreme rainfall events, and consequent flooding.

Atmospheric temperature have risen steadily since the 1970s, due to increasing concentrations of greenhouse gases, primarily CO2.

Sea surface temperatures have risen dramatically in recent years, adding to atmospheric moisture content.

Sea surface temperatures have risen dramatically in recent years, adding to atmospheric moisture content.

Forecast of increased frequency of heavy rain at 2 degrees C above pre-industrial temperatures, relative to a baseline of the years 1991 - 2000.  We are currently at 1.5 degrees C above pre-industrial levels. Note that Appalachia and the Texas Hill Country, already prone to flash-flooding due to topography, will experience some of the largest increases in heavy precipitation in coming decades, due to rising temperatures.  This figure is found on page 2 - 25 of the 5th National Climate Assessment, which is no longer available on the GlobalChange.gov website.  The Office of Global Change, in the US State Department, was created in 1989, and closed on the order of Donald Trump in 2025.

 

References
1^st, 2^nd, 3^rd, 4^th and 5^th National Climate Assessments – These documents have been removed from public access on GlobalChange.gov by the Trump administration.  The administration pledged to keep these reports available on the NASA website, but reneged on that pledge.  Some, but not all, of the documents may still be available by searching the NOAA archives. 

 

NCA1,2000, Report Overview, Climate Change Impacts on the United States; The Potential Consequences of Climate Variability and Change
P. 4
…all climate models suggest that the climate is going to get warmer, the heat index is going to rise, and precipitation is more likely to come in heavy and extreme events. This consistency lends confidence to these results.
P. 7
Over the 20th century, the average annual US temperature has risen by almost 1°F (0.6°C) and precipitation has increased nationally by 5 to 10%,mostly due to increases in heavy downpours.  These trends are most apparent over the past few decades. The science indicates that the warming in the 21st century will be significantly larger than in the 20th century…. This [temperature] rise is very likely to be associated with more extreme precipitation and faster evaporation of water, leading to greater frequency of both very wet and very dry conditions.
P. 10
Heavy and extreme precipitation events are likely to become more frequent, yet some regions will get drier.
p. 11
It is also very likely that there will be more precipitation overall, with more of it coming in heavy downpours. In spite of this, some areas are likely to get drier as increased evaporation due to higher temperatures outpaces increased precipitation.  Droughts and flash floods are likely to become more frequent and intense.
P. 13
As the Earth warms, more water evaporates from the oceans and lakes, eventually to fall as rain or snow.  During the 20th century, annual precipitation has increased about 10% in the mid- and high-latitudes.
P. 22
In both the Hadley and Canadian models, most regions are projected to experience an increase in the frequency of heavy precipitation events.
P. 39
Warmer and moister air will very likely lead to more intense rainfall events, increasing the potential for flash floods.
P. 54
the projected increase in very heavy precipitation events will likely lead to increased flash flooding and worsen agricultural and other non-point source pollution as more frequent heavy rains wash pollutants into rivers and lakes.

NCA1, 2001, Full Report, Climate Change Impacts on the United States; The Potential Consequences of Climate Variability and Change
P. 10 
Droughts and flash floods are likely to become more frequent and intense.
P. 11
It is very likely that more rain will come in heavy downpours, increasing the risk of flash floods.
P 423 
Floods, especially those related to flash floods from intense short-duration heavy rains, are likely to increase in magnitude or frequency in many regions.
P. 445
Future climate scenarios show likely increases in the frequency of extreme precipitation events, including precipitation during hurricanes.

 

NCA5, 2017, Fifth National Climate Assessment
Overview 1-16
As the world’s climate has shifted toward warmer conditions….Many other extremes, including heavy precipitation,…flooding…are becoming more frequent and/or more severe, with a cascade of effects in every part of the country.
Overview 1-23
More frequent and intense heavy precipitation events are already evident, particularly in the Northeast and Midwest.
Overview 1-24
Heavy rain and more frequent storms damage crops and property and contaminate water supplies.
Overview 1-41
…more rain falls during the most extreme precipitation events. 
2-5
heavier precipitation and increased flood risk across much of the US are linked to rising temperatures.  Scientists cannot rule out the possibility of still more dramatic shifts if certain tipping elements trigger rapid and irreversible changes….Put simply, communities across the country are built for a climate that no longer exists.
2-10
Global average temperatures over the past decade (2012-2021) were close to 2F (1.1C) warmer than the preindustrial period (1850-1899).  This warming has been accompanied by several large-scale changes:…increases in atmospheric humidity, shifting rainfall patters and more frequent heavy precipitation….
2-11
The Characteristics of Precipitation Are Changing
2-18
Rainfall is Becoming More Extreme
Since the 1950s, there has been an upward trend in heavy precipitation across the contiguous US (Figure 2.8)  This increase is driven largely by more frequent precipitation extremes, with relatively smaller changes in their intensity.
There is robust evidence that human-caused warming has contributed to increases in the frequency and severity of the heaviest precipitation events across nearly 70% of the U.S.  
2-19
Maps show observed changes in three measures of extreme precipitation: (a) total precipitation falling on the heaviest 1% of days, (b) daily maximum precipitation in a 5-year period, and (c) the annual heaviest daily precipitation amount over 1958-2021.
2-20
The complexes of thunderstorms that bring substantial precipitation to the central United States during the warm season have become more frequent and longer-lasting over the past two decades.
2-24
The Frequency and Severity of Heavy Precipitation Increases with the Global Warming Level
Extreme precipitation-producing weather systems ranging from tropical cyclones to atmospheric rivers are very likely to produce heavier precipitation at higher global warming levels.  Recent increases in the frequency, severity and amount of extreme precipitation are expected to continue across the U.S. even if global warming is limited to Paris Agreement targets.  
2-25
Note: In the U.S., the largest changes to precipitation falling on the heaviest 1% of days at a global warming level of 2C will occur in the Appalachians and the Texas Hill Country, with increases of 25% to 50% compared to the period 1991 to 2020.  
2-26
Even in regions that experience an overall decrease in precipitation, atmospheric rivers are projected to become stronger and wider, increasing the risk of downpours and floods across the Western United States.
It is likely that the frequency of weather environments that give rise to severe thunderstorms in the United States during spring and fall will increase under stronger warming scenarios.  These changes are likely to lengthen the severe thunderstorm season as the world warms, especially in the Midwest and Southeast during cool-season months. 
2-35
Long-term changes have been observed in many other aspects of the climate system.  Seasonal average and extreme precipitation changes are widely documented using observations, and changes are consistent with our physical understanding.

https://www.ipcc.ch/reports/
IPCC climate assessment reports #1 through #6 can still be found on the IPCC website.

https://en.wikipedia.org/wiki/Hurricane_Helene
Hurricane Helene

https://en.wikipedia.org/wiki/Hurricane_Harvey
Hurricane Harvey

https://en.wikipedia.org/wiki/July_2025_Central_Texas_floods
Texas Hill Country July 4^th, 2025 flooding

https://web.archive.org/web/20170910032838/https://apnews.com/5b28b342061344d7ad6e7395a56e7cce/climate-change-runaway-development-worsen-houston-floods
Warning that heavy rainfall events had doubled, published a year before Hurricane Harvey.

https://www.accuweather.com/en/severe-weather/is-the-us-seeing-worse-flooding-this-summer-heres-whats-happening/1793836
Accuweather notes that extreme rainfall and flash-flooding events have occurred this month in five states, with deaths occurring in four of those states.  Two states experienced 1:1000 probability rainfall events.  Accuweather plainly says that climate change due to fossil-fuel emissions cause warmer air to hold more water, causing extreme rainfall.
 “Climate change from fossil fuel pollution is amplifying the conditions that make flash floods more likely and more severe.”

https://www.accuweather.com/en/weather-forecasts/flash-flood-dangers-far-from-over-as-storms-reload-across-us/1795199
Accuweather says that 33 states are for localized flooding this week; with 21 states at “greatest risk” for for flooding.

https://www.propublica.org/article/texas-flash-flood-camp-mystic-climate-change-trump-noaa-fema
The Texas Flash Flood Is a Preview of the Chaos to Come

https://www.cnn.com/2025/07/18/weather/flash-flooding-west-gulf-east-climate
“Hourly rainfall rates have grown heavier in nearly 90% of large US cities since 1970, according to a study from the nonprofit research group Climate Central.”

https://www.eea.europa.eu/en/topics/in-depth/extreme-weather-floods-droughts-and-heatwaves
Europe extreme weather

https://disasterphilanthropy.org/disasters/2024-central-and-eastern-europe-floods/
Central and Eastern Europe Flooding

https://wmo.int/news/media-centre/extreme-weather-and-climate-impacts-bite-latin-america-and-caribbean
Latin American extreme weather

https://www.epa.gov/climate-indicators/climate-change-indicators-sea-surface-temperature
Sea Surface Temperature

https://ourworldindata.org/grapher/sea-surface-temperature-anomaly
Global Average Sea Surface Temperature

https://climate.copernicus.eu/global-sea-surface-temperature-reaches-record-high
Global Average Sea Surface Temperature

https://www.climate.gov/maps-data/dataset/global-temperature-anomalies-graphing-tool
Links to a variety of climate data and maps.

https://www.rmets.org/metmatters/world-exceeds-15degc-threshold-entire-year-first-time
Atmospheric Temperature Chart

https://www.bakerinstitute.org/sites/default/files/2018-08/import/bi-pub-blackburnharveyanniv-081018.pdf
Houston a Year After Harvey: Where We Are and Where We Need to Be

https://www.bakerinstitute.org/research/houston-flooding-35-years-after-harvey
Houston Flooding 3.5 Years After Harvey

https://www.bakerinstitute.org/research/assessing-houstons-flood-vulnerability-6-years-after-harvey
Assessing Houston’s Flood Vulnerability 6 Years After Harvey 

Curiosity Rover on Mars Drills Hole, Strikes Oil!!!

Oil Discovered On Mars
I recently wrote a post on Facebook about a discovery recently announced by NASA and JPL.  The Mars Curiosity rover drilled a hole in a mudstone in Gale Crater and analyzed the sample with its chemical instruments.  The analysis showed trace amounts of C10, C11 and C12 hydrogen-saturated carbon chains.  Oil.  Black Gold.  Texas Tea.

Cumberland mudstone drill-site.  I should write headlines for supermarket tabloids.

The Curiosity Rover is exploring a former lakeshore in Gale Crater, located near the Martian equator.  The crater formed between 3.8 and 3.5 billion years ago, and was periodically filled with water from the time of its formation until about 2 billion years ago.  Scientists studying the spectra of minerals from Mars orbit identified the crater as a likely location to find shoreline deposits and evidence of former life. 

Artist's impression of Gale Crater.  Image credit Kevin Gill; references below.

After I posted my note, a Facebook friend immediately asked the most important question, “For real? Doesn’t that mean there was life?”  I gave a waffling answer which probably left Tom unsatisfied.  Certainly, on Earth, oil is the product of thermal alteration of biological materials, primarily algae, leading to the formation of crude oil.  But there are non-biological processes in some hydrothermal environments that can lead to the formation of these molecules.

Curiosity drilled this sample in 2013, and the immediate results showed small carbon molecules.  The rover stored portions of the sample for later analysis.  Since then, NASA/JPL conducted experiments trying to replicate the origin and detection of these molecules.  NASA scientists developed a new procedure to test for larger carbon molecules, and reconfigured the equipment on the rover to test the stored sample.  (A third sample exists on the rover for future testing.)  The recent test with reconfigured equipment showed the presence of the large carbon molecules.  NASA/JPL now think that the large carbon molecules were produced from fatty acids in the original sample, which were altered to carbon chains during heating for the chemical analysis.  It is possible to produce fatty acids in hydrothermal environments in earth environments, so the finding is not yet diagnostic of life.  

To be clear, the concentration of the long-chain carbon molecules is very small; on the order of one part to ten parts in 100 billion.  (The concentration given in the press release is given as tens of pico-moles.)  But this is within the sensitivity of the rover’s instrumentation.  

It’s hard to generate carbon chains from water and carbon dioxide using non-biologic processes.  Long carbon chains are even more difficult.  That’s why large and complex carbon molecules are considered diagnostic of life, termed biosignatures.  Lipids, carbohydrates, nucleic acids and proteins are considered biosignatures, among others.  These would be considered proof of former life.

Intriguingly, the detection of C12 is at the upper limit of the capability of the instrumentation on Curiosity.  It’s possible that longer chains existed in the sample.  Also, JPL scientists note that non-biological processes usually produce shorter fatty acids than 12 carbon atoms, but that the C12 molecule detected in the Martian sample was more abundant than C10 or C11.  

Proof
We use different standards of proof depending on what we are trying to prove and why.  In civil cases, we use the standard of preponderance of evidence; more than 50% of evidence is considered sufficient proof.  In criminal cases, we require a higher standard, termed reasonable certainty.  Reasonable certainty is not well defined, but is generally understood and used by juries.  In science, the standard of proof is usually held to be an unequivocal finding, meaning that all evidence-based alternatives have been examined and refuted.  Mathematical proof is a higher standard, with a demonstration that it is not possible for the assertion to be false.  

For the Mars samples, I would say that the preponderance of evidence is that Curiosity has discovered chemical proof of extraterrestrial life.  The sample was taken on an ancient lakeshore, which is a likely place for algal growth.  There is little evidence of local hydrothermal activity, which would be the only alternative explanation for the occurrence of long-carbon chain molecules.  (Although the rover has discovered elemental sulfur nearby, of unknown origin.)  Other chemicals found nearby are consistent with life, including chlorinated and sulfur-containing carbon compounds, carbon-ring compounds (aromatics) including benzoic acid, nitrates and elemental sulfur.  The relative abundance of C12 also points towards a biologic origin for the molecules.

But the finding is slightly less than reasonable certainty, and is not yet unequivocal.  Additional sampling and testing are needed to prove the existence of more complex carbon molecules, or to disprove the possibility of non-biologic generation of long-chain carbon molecules.  

Astronomer Carl Sagan was preoccupied with the planet Mars and alien life from a young age, something that led to his stunning career.  Sagan also coined the aphorism, “Extraordinary claims require extraordinary evidence.”  So, what is an extraordinary claim?  An extraordinary claim may be: 1)  something that violates known scientific knowledge or processes, 2)  something that is within the realm of scientific possibility, but with an extremely low likelihood of occurrence,  or 3) something that is outside the envelope of prior experience.  The possibility of ancient life on Mars is in the third category of extraordinary claim.   This would be the first discovery of extraterrestrial life, and therefore requires extraordinary evidence, stronger than what has been discovered to date by Curiosity’s instruments.  

In the official press release announcing the discovery of large carbon chain molecules, NASA described the molecules as “pre-biotic”.  I think that ultimately, further research will prove the existence of ancient primitive life on Mars.  Given the evidence, I would be surprised if the discovered chemistry is not the result of self-replicating processes sufficient to be considered life.  It’s a thought worthy of contemplation, that primitive life may have lived on Mars simultaneously with cyanobacteria or algae on earth.  But on Mars, through planetary bad luck, the atmosphere and oceans were stripped away by the solar wind, while Earth was protected by its magnetic field.  And so, we, the descendants of cyanobacteria on Earth, are sending interplanetary probes to Mars, instead of the other way around.
 

Image of a city on Edgar Rice Burrough's Barsoom (Mars).  Image credit Woodrow Edgar Nichols, Jr.
--
Afterword
NASA’s Opportunity rover landed on Mars in 2004.  At the time, I was working as an international exploration petroleum geologist for a major oil company.  I had previously studied images of Mars taken from NASA orbiters, and noted clear signs of water channels, and I was quite interested in the new mission.  Opportunity landed in Eagle crater, and its first photos showed an outcrop of a likely fluvial sandstone.  I was gob-smacked.  I printed a photo and taped it to my office door, without explanation.  The Vice-President of exploration wandered down the hallway, and curious, asked me where the photo was from.  I told him it was Mars.  We agreed that the photo looked like sandstone, and I joked that maybe someday we would find oil on Mars.  He didn't seem amused.  But twenty years later, here we are.  

An outcrop of fluvial sandstone in Eagle Crater on Mars, viewed from the Opportunity Rover landing place.  Higher resolution photos were available in 2004.

References
https://www.jpl.nasa.gov/news/nasas-curiosity-rover-detects-largest-organic-molecules-found-on-mars/
https://www.pnas.org/doi/abs/10.1073/pnas.2420580122
https://www.sci.news/space/long-chain-alkanes-mars-13778.html
https://earthsky.org/upl/2025/01/lake-Gale-crater-Mars-artist-illustration-Kevin-GillDecember-10-2014.jpg
https://www.flickr.com/photos/kevinmgill/15369584444/
https://www.erbzine.com/mag33/3307.html

Current Topography of Gale Crater, with shading suggesting former lake level.  Image credit Ryan Anderson.

Ukraine, Independence, Yorktown and France

 President Trump, Vice-President Vance, and prime minister without portfolio Elon Musk have all said, in one way or another, that President Zelenskiy of Ukraine does not want peace.

Of course not.  That’s why they are fighting.  The victim of aggression can usually have peace, of a kind, by surrender.  But Ukraine is fighting for other values that Americans hold dear: independence, freedom, democracy and prosperity.  As a sovereign nation, Ukraine has a right to pursue trade associations and political alliances of its own choice, not the choice of its larger neighbor to the east.  This is true regardless of the historical ties (and historical conflicts) between Russia and Ukraine.  In 1991, Ukraine voted for independence by a 92% to 8% margin, in an election with 84% turnout.  Those numbers put most American elections to shame.  At that time, Ukraine became a sovereign and independent state.  In 1994, Ukraine agreed to give up its Soviet-era nuclear weapons in an agreement with Russia, the United States and the United Kingdom.  In exchange, the other parties agreed to respect Ukraine’s 1991 borders, to seek redress in the UN Security Council if Ukraine’s borders were violated, and to refrain from economic coercion of Ukraine.  

From 1991 until 2014, there was extensive meddling by Russia in Ukrainian affairs, including elections.  My company maintained an office in Kiev for about a decade, working with Ukrainian authorities to establish a legal framework for oil and gas production in Ukraine, without success.  Our company representative told me that these efforts were sabotaged in the Ukrainian parliament by Russian interference, as Russia wanted to keep Ukraine dependent on Russian energy exports.

The crisis between Russia and Ukraine developed after Ukraine signed a free trade and association agreement with the European Union, in 2013.  The agreement came after two decades of rapprochement with the EU, and a year of detailed negotiations.  The agreement was overwhelming approved in the Ukraine parliament, but pro-Russian President Yanukovych refused to sign the deal.  President Yanukovych was deposed by the parliament in the ensuing crisis.  Russia invaded the bordering provinces and Crimea the following year.  European negotiators expressed complete shock that the Russians reacted as they did to the free trade agreement.  The time since the original Russian invasion has been marked by cease-fire agreements, each later broken by Russia with new military action.  

Ukraine has been a vassal state to Russian since Tsarist times.  It was robbed and starved in the Holodmor famine of the 1930s.  Its independent energy development was stifled in the 1970s, following the discovery of natural gas in the Donbass, and again through Russian political meddling after independence.  

Before peace, Ukraine wants independence, freedom, and the opportunity for prosperity through independent association with Europe.  After these are secured, then Ukraine will be ready for peace, with Western guarantees of security.  These are the same things that a fledgling United States wanted in 1776.  

In 1781, after five years of grinding war with Britain, George Washington was marching his army south to confront General Cornwallis in South Carolina.  At Philadelphia, the entire army threatened to desert, unless they were paid in coin, instead of Continental paper money.  The French representative paid the American soldiers in gold coin, using half of his monetary reserve.  The French also provided 10,800 foot soldiers, a larger force than the American army.  A fleet of 29 warships fought and defeated the British fleet, and blocked reinforcement of Cornwallis’ army.  After a month-long siege, General Cornwallis surrendered to Washington, and the Revolutionary War was over.  

Without the assistance of the French, there would have been no Revolutionary War victory.  There would be no July 4th, no Star-Spangled Banner, no American government.  No one can say what the future would have been, but we would not have achieved independence on our own.  

Let there be no doubt that Russia is a tyrannical country.  Russia is a country where investigative journalists and opposition politicians are brazenly murdered with the apparent complicity of the secret police.  Russia is a country where high-level business executives are flung from high-rise windows, or hacked to death with axes, along with their wives and children.  Russia is a country where children are separated from their parents because a child expresses a desire for peace at school.  Russia is a country where perceived enemies are hunted down in exile and murdered.  Russia is a country where other politicians are poisoned, imprisoned or murdered in prison.  Russia is a country where lawyers are imprisoned for simply representing an opposition or anti-corruption client, or suffer fractured skulls during police interrogation.  Russia is a country without free media, where all messaging is controlled by the government, and where alternative sources of information on the Internet are banned.  Russia is a country without a right to free speech, where even carrying a blank sign can result in a prison term.  Russia is a country whose closest allies are North Korea, Iran, China, Cuba and Venezuela, all of whom are antithetical to American values and American interests.  

Ukraine is in a similar fight for its independence, freedom, territorial integrity and sovereignty.  Ukraine has a sovereign right to choose between freedom, democracy, free speech and free and fair markets, or to submit to Russian tyranny.  We owe it to the people of Ukraine to help them defend their lands, their people, and their independence from Russian tyranny, just as France assisted the newborn United States gain our independence from Britain.  

Fighting Disease Overseas So We Don't Fight Disease Here

  My uncle, Lewis Robbins, had a long career with the U.S. Public Health Service.  His career spanned three phases - foreign epidemiology, cancer research, and preventative medicine.  In the 1940s and 50s, he was assigned to fight diseases in foreign countries.  The idea was to fight and defeat diseases overseas, so we didn’t have to fight them here.  Uncle Lewis’ house was filled with souvenirs from his early assignments – fighting sleeping sickness in Africa, malaria in Vietnam, an epidemic of blindness in Tibet.  His alma mater, Johns Hopkins University, has his biography on its webpage as a public health hero, and a large collection of his papers and notes in its library.

 

His second contribution was as head of cancer research for the USPHS.  He was lead author on a groundbreaking paper in 1959 identifying cigarette smoking a primary cause of lung cancer.  That work led to the Surgeon General’s warning placed on cigarette packages in 1963, allowing smokers to make an informed decision on whether to smoke.  His third major contribution was to develop a statistical system relating lifestyle choices (such as diet, exercise, safety and habits) to health outcomes, with the goal of keeping people healthy rather than trying to fix people after they are sick.

My niece also earned her doctorate at Johns Hopkins, and is working for the World Health Organization in France.  She is continuing my uncle’s work in the field of cancer epidemiology.

The World Health Organization plays a vital role in world health in both research and action.  WHO played a key role in ending the Ebola epidemic in West Africa, which grew at an exponential rate before being contained by courageous doctors from WHO.  WHO is also active in fighting cardiovascular diseases, cancer, diabetes, emerging respiratory diseases, Covid, HIV, tuberculosis, malaria, dengue fever, and health emergencies due to natural disasters.  WHO collaborated with the US CDC in identifying the disease vector for the Zika virus, which causes babies to be born with severe brain damage.  Thanks to their efforts, the Zika virus has been kept away from the US, despite a brief outbreak in Florida.

In the new president’s first full day in office, he ordered that the United States withdraw from WHO.  The US currently provides 18% of the WHO budget, a trivial amount compared to most of our other categories of spending.  This is one way in which selfishness and isolation will only hurt us in the long run.
https://publichealth.jhu.edu/about/history/heroes-of-public-health/lewis-robbins-md-mph

The Federal Debt Crisis

This is the first part of a two-part post about the U.S. Federal debt and fair taxation.  I will try to keep this part brief.  

Like a slow-moving train wreck, the United States is in a government debt crisis.   The debt crisis has been developing since the Reagan administration of the 1980s.  Federal debt as a percentage of GDP ranged between 30% and 40% from 1970 to about 1985.  Debt increased from 1985 to 1992 before settling in a range between 50% and 70% of GDP.  A sharp increase occurred in 2009-2010 after the banking crisis of 2009, establishing another plateau about 105% of GDP from 2010 to 2019.  Following the Covid pandemic, debt/GDP increased again to a new plateau of about 125% of GDP. 

Image Credit: CDCData.com

The reasons for the increasing debt are clear.  Debt began rising during the Reagan administration due to deliberate policy choices regarding taxation.  Under Reagan, Republicans enacted a series of tax cuts intended to limit the size of government by limiting government funding.  The strategy was called “starve the beast”.  By the end of Reagan’s presidency, however, deficit spending resumed its upward trajectory, driven by higher military spending and lower taxes.  President G.H.W. Bush negotiated a plan with Democratic congressional leaders to restore a balanced Federal budget, but was stymied by members of his own party, led by Newt Gingrich.  During the Clinton administration, moderate tax increases briefly reversed the trend of increasing debt, but were in turn reversed by more tax cuts during the G.W. Bush administration.  Still, overall, increasing debt was roughly matched to increasing GDP until the financial crisis of 2009.  The government then embarked on a massive spending program to avoid economic collapse, driving debt/GDP to over 100%.  A relative plateau of about 105% debt/GDP continued, despite a new Republican tax cut in 2017.  In 2020, the Covid pandemic caused another major economic disruption, and the government launched more spending to mitigate the economic consequences of the disaster.  The Payroll Protection Program enacted under President Trump, largely a handout to businesses and employers, was nearly one trillion dollars alone.  Debt/GDP took another step change, to about 125%.  Stimulus spending under President Trump in the CARES Act and the PPP totaled about $3.1 trillion.  Early in his presidency, President Biden followed with the family-oriented American Rescue Plan Act, which added $1.9 trillion in non-productive spending.  Unlike the later Infrastructure Act or climate-oriented Inflation Reduction Act, there was no increased productivity associated with CARES, PPP and ARPA.  The stimulus spending prevented a deeper recession by increasing liquidity in the economy, but contributed to inflation and worsened the debt-to-GDP ratio.

Measures of Government Debt
There are two different measures of Federal debt, and economists are divided in terms of which figure is more significant.  The Treasury Department reports Debt Held by the Public in 2024 at $28.2 trillion (T), exactly equal to forecast GDP for the year.  Treasury also reports Intragovernmental Debt of $7.1 T, for a Total Public Debt of $35.3 T, or 125% of GDP.  (Intragovernmental Debt largely consists of holdings in the Social Security Trust Fund which have been loaned to the Treasury and spent.)  The chart above, from ceicdata.com, uses the broader measure of government debt.  By contrast, in an opinion piece, Penn-Wharton Business School uses Debt Held by the Public as its measure of federal debt, disregarding Intragovernmental Debt.  I’m skeptical of this approach, because intragovernmental debt has very real obligations attached to it, and defaulting on intragovernmental debt would necessarily default on those obligations (i.e., social security payments).  That’s politically untenable, and isn’t going to happen.

Another element of government debt is debt issued by state and local governments.  This debt is generally ignored in discussions of government debt, but it also has an impact on the economy.  In the United States, many government functions are performed by the states rather than the federal government.  This is in contrast to the majority of other developed countries.  The difference can be seen in taxation statistics from the OECD, where the United States is an outlier in terms of Federal taxation.  US Federal taxation is about 50% of the OECD average.  Federal-level taxation is not directly comparable between the USA and other OECD countries, because in the USA, a number of government functions and the associated taxation are performed by the states.  But when looking at total taxation, the United States is still low, at about 75% of the OECD average, and among the lowest-taxed of the 38 OECD countries.  

So, in the United States, figures for government debt should include debt issued by state governments.  The most recent estimate of state & local debt I could find was for 2021, at $3.3 T.  In total, then, including intragovernmental debt and state debt, government in the United States has issued about $38.6 T in debt obligations.  This places the US debt/GDP ratio at about 135%.  

Why Does Debt/GDP Matter?
A higher debt/GDP ratio increases the cost of running the government, increases the risk of default, and impairs the economy.  Interest payments add to the cost of providing government services, and high payments may be difficult to maintain in the event of an economic crisis.  

At high levels of debt to GDP,  government borrowing consumes capital available for private lending.  This limits investment in business opportunities, home-buying and personal consumption.  High levels of debt impair economic activity and growth.  An economic model by the World Bank identified a debt-to-GDP ratio of 77% as a tipping point, with progressive impairment to economic growth for debt above that level.  According to the model, at debt/GDP of 100%, U.S. GDP growth is already impaired by 0.4%.  

For about a century, US government debt has been generally regarded as the safest in the world, although that perception is gradually changing.  Thirty years ago, US government bonds were presumed to be a “zero-risk” investment for the purpose of theoretical calculations of investment risk and return.  But in 2011, investment rating companies began gradually cutting the debt rating and outlook on US Treasury obligations.  All rating agencies now attribute risk to US bonds.  Egan-Jones, Standard & Poor and Fitch currently rate US Treasuries below a triple-A rating, while Moody’s and Dominion have a negative outlook on their ratings.

A lower debt rating means paying higher interest rates.  For decades, U.S. taxpayers have benefited from borrowing money at minimal interest rates, allowing the government to build infrastructure, pay for defense, improve social programs, and make society better without raising taxes.  But as the debt rises, interest rates will rise as well, compounding the problem of repayment for future taxpayers.

Rising debt implies rising interest payments, placing pressure on the Federal budget.  The Treasury reports, “As of August 2024 it costs $1049 billion to maintain the debt, which is 17% of the total federal spending in fiscal year 2024.”  A large debt increases the burden on taxpayers without providing additional government services.  We are teetering on a point where paying down the debt may become difficult or impossible without invoking inflation or some other means of reducing debt by cheating the bond-holders.  

Future Outlook
Our current budget trajectory is unsustainable, which is not seriously recognized by either political party.  A 2023 article on the Wharton Business School  website states: “We estimate that the U.S. debt held by the public cannot exceed about 200 percent of GDP…Under current policy, the United States has about 20 years for corrective action after which no amount of future tax increases or spending cuts could avoid the government defaulting on its debt whether explicitly or implicitly (i.e., debt monetization producing significant inflation).”  The 2024 budget deficit is $1.8 trillion; the CBO estimates that under current policies, the deficit will increase to $2.9 trillion in a decade.   The Wharton article contains tables showing expected future debt-to-GDP ratios under a range of interest rate assumption.  In all cases, the U.S. debt-to-GDP ratio exceeds 200% within twenty years.

President Trump, in his second term, has asked Elon Musk and Vivek Ramaswamy to develop plans to improve government efficiency and lower government spending.  It remains to be seen how much spending can be reduced, and how much Congress will resist spending cuts to currently approved programs.  My suspicion is that actual reductions in spending will be trivial compared to the size of the deficit.  Further, Donald Trump has promised to lower taxes, and cancel the resumption of taxes scheduled under the Tax Reduction Act of 2017.  These tax cuts will only increase the economic damage due to our high debt level, increase the risk of default and accelerate the date on which the debt produces an American economic collapse.  

It is worth noting that both Federal and total U.S. taxes, as a percentage of GDP, are among the lowest in the industrialized world.  Benchmarking according to other western industrialized countries, our inability to balance taxation and spending in the Federal budget is primarily a result of low taxes, not excessive spending.  We already tax payrolls, personal income and corporate income, but there is a category of economic activity which is entirely untaxed – unrealized capital gains.  Enacting a tax on unrealized capital gains would help greatly to balance our spending and revenue.  That will be the subject of my next post on Federal debt and taxation.
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References
https://fiscaldata.treasury.gov/americas-finance-guide/national-debt/
https://en.wikipedia.org/wiki/United_States_federal_government_credit-rating_downgrades
https://tradingeconomics.com/united-states/rating
https://en.wikipedia.org/wiki/Debt-to-GDP_ratio

https://www.pandemicoversight.gov/data-interactive-tools/data-stories/6.4-billion-in-pandemic-funding-was-received-by-recipients-in-foreign-countries-See-the-details

Total pandemic spending  $5 T
https://www.usaspending.gov/disaster/covid-19

Total pandemic spending $4.6 T
https://www.pandemicoversight.gov/about-us/pandemic-relief-program-laws

Trump Pandemic Spending
Total pandemic spending under President Trump was about $3.0 trillion.
Coronavirus Preparedness and Response Supplemental Appropriations Act,
March 2020;  $8.3 B
https://en.wikipedia.org/wiki/Coronavirus_Preparedness_and_Response_Supplemental_Appropriations_Act,_2020
Families First Coronavirus Response Act;  April 2020
https://en.wikipedia.org/wiki/Families_First_Coronavirus_Response_Act
https://www.kff.org/coronavirus-covid-19/issue-brief/the-families-first-coronavirus-response-act-summary-of-key-provisions/   $3.471 B
https://www.pandemicoversight.gov/about-us/pandemic-relief-program-laws  $15.4 B
https://www.cms.gov/files/document/accounting-federal-covid-expenditures-national-health-expenditure-accounts.pdf   $192 M
The CARES Act, passed under President Trump in March 2020 cost  $2.2 trillion. 
https://en.wikipedia.org/wiki/CARES_Act
Estimates for spending reported for the Payroll Protection Program and Health Care Act (April 2020) vary widely, from $484 billion to $953 billion.  Presumably the higher figures represent later estimates and better represent the full cost.
https://en.wikipedia.org/wiki/Paycheck_Protection_Program_and_Health_Care_Enhancement_Act
PPP $484 B
https://www.aeaweb.org/articles?id=10.1257/jep.36.2.55
PPP  April 2020     $800 B
https://en.wikipedia.org/wiki/Paycheck_Protection_Program
PPP     $953 B

Biden Pandemic Spending
The American Rescue Plan, passed under Biden, cost about $1.9 trillion.
https://en.wikipedia.org/wiki/American_Rescue_Plan_Act_of_2021

https://fiscaldata.treasury.gov/americas-finance-guide/federal-spending/
Federal spending in 2023 was $6.1 T, compared to $4.4 T in tax revenue, for a deficit of $1.7 T, or 38% of tax revenues.
https://www.cbo.gov/topics/taxes
https://www.whitehouse.gov/wp-content/uploads/2023/03/ap_17_receipts_fy2024.pdf
Federal tax revenue for 2024 are forecast to be $5.0 T (White House) or $4.85 T (CBO).
https://www.cbo.gov/publication/59946
Federal spending for 2024 is estimated at $6.5 T, for a deficit of $1.5 T. 

https://budgetmodel.wharton.upenn.edu/issues/2023/10/6/when-does-federal-debt-reach-unsustainable-levels
Penn-Wharton Business School, U. of Penn., Budget Model website, Jagadeesh Gokhale and Kent Smetters. Mariko Paulson, 2023
“We estimate that the U.S. debt held by the public cannot exceed about 200 percent of GDP.”
“Under current policy, the United States has about 20 years for corrective action after which no amount of future tax increases or spending cuts could avoid the government defaulting on its debt whether explicitly or implicitly (i.e., debt monetization producing significant inflation).”
“What is important is that a large broad-based future corrective change in fiscal policy happens in any form to stabilize the debt-GDP ratio, and that such a correction action is anticipated by financial markets. Otherwise, forward-looking financial markets would unravel much sooner…to cause a sovereign debt crisis.”
Penn-Wharton uses debt held by the public as its measure of federal debt, disregarding intragovernmental debt.  I’m skeptical of this approach, because intragovernmental debt has very real obligations attached to it, and defaulting on intragovernmental debt would necessarily default on those obligations (i.e., social security payments). 

https://www.stlouisfed.org/open-vault/2020/october/debt-gdp-ratio-how-high-too-high-it-depends
This St. Louis Fed blog article uses total Federal debt to GDP as its measure of indebtedness, but doesn’t specify any measures of when debt is too high.  The answer seems to be “it depends” on various institutions.  Alternatives to hard default are presented, but each of these cause other economic disruption.

https://www.investopedia.com/terms/d/debtgdpratio.asp
“World Population Review has reported that countries whose debt-to-GDP ratios exceed 77% for prolonged periods experience significant slowdowns in economic growth.”
The U.S. has had a debt-to-GDP of more than 77% since Q1 2009. The U.S.’s highest debt-to-GDP ratio before that year was 106% in 1946 at the end of World War II.”

https://www.thebalancemoney.com/current-u-s-federal-budget-deficit-3305783
“For every percentage point of debt that exceeds the 77% tipping point, the annual real GDP growth rate of a developed economy will be reduced by .017 percentage points for each 1% the debt-to-GDP ratio exceeds the tipping point.”
Reference:  World Bank Group. "Finding the Tipping Point - When Sovereign Debt Turns Bad."

https://fiscaldata.treasury.gov/datasets/debt-to-the-penny/debt-to-the-penny
Debt held by the public -- $28.2 T
Intragovernmental debt -- $7.1 T
Total Public Debt – $35.3 T

https://tradingeconomics.com/united-states/gdp
US 2023 GDP -- $27.4 T

https://www.statista.com/statistics/216985/forecast-of-us-gross-domestic-product/
US forecast 2024 GDP -- $28.2T

https://www.ceicdata.com/en/indicator/united-states/government-debt--of-nominal-gdp
chart of Federal Debt as percent of GDP

https://www2.census.gov/programs-surveys/gov-finances/tables/2021/2021alfinsummarybrief.pdf
State and Local debt was $3.3 T in 2021.

https://www.statista.com/statistics/312660/us-state-and-local-government-debt-outstanding-by-state/

https://www.statista.com/statistics/217500/revenues-from-social-insurance-tax-and-forecast-in-the-us/
Revenue from payroll taxes in the United States amounted to about 1.61 trillion U.S. dollars in 2023.  Payroll taxes are increasing at about 4% per year.

https://www.statista.com/statistics/216928/us-government-revenues-by-category/
Individual income taxes $2.176 trillion; payroll taxes $1.614 trillion; corporate income taxes 0.420 trillion; other 0.229 trillion.    Total 4.44 trillion in federal revenue.

https://fiscaldata.treasury.gov/americas-finance-guide/federal-spending/
In fiscal year (FY) 2023, the government spent $6.13 trillion, which was more than it collected (revenue), resulting in a deficit.

https://www.oecd-ilibrary.org/taxation/data/revenue-statistics/comparative-tables_data-00262-en?parent=http%3A%2F%2Finstance.metastore.ingenta.com%2Fcontent%2Fcollection%2Ftax-data-en
https://data-explorer.oecd.org/vis
OECD data tables.

https://fiscaldata.treasury.gov/datasets/debt-to-the-penny/debt-to-the-penny
Federal debt held by the public is $28.3 trillion; total Federal debt, including intragovernmental debt, is $35.3 trillion.

https://www.statista.com/statistics/188105/annual-gdp-of-the-united-states-since-1990/
2023 US GDP is $27.4 trillion.

Global Warming: How It Works

 I have a small collection on the bottom shelf of my bookcase of important books.  The books are: How Things Work (4 volumes), Roger Segalat, translated from German; The Way It Works, Robin Kerrod, 1980; The Way Things Work, translated from Italian, 1989; The Way Things Work, David McCauley, 1988; and two massive volumes on the history of science.  That’s what people do – we figure out how things work, and use that knowledge to understand and manipulate the world around us.  

A friend recently asked me, “What is the best argument that a lot of current climate change is caused by humans, through fossil fuel CO2, methane, and other green house gases?  What are the best data and arguments?”   The most important point about climate science is that we know how it works.  It isn’t speculation or correlation.  We simply know how it works.  Since the 1860s or before, people have known that glass bottles filled with CO2 heat up faster than bottles filled with air.  In 1896, the brilliant Swedish chemist Arrhenius calculated how much the earth would warm if CO2 concentration was doubled.  This happened in the same decade that we invented the manual transmission and radio transmission of Morse code, and about a decade after Edison’s electric lightbulb.  Scientific research has continued since Arrhenius, and we know how the CO2 greenhouse effect works just as well as we know how an AM radio, manual transmission, or incandescent lightbulb works.  

We’ve observed and measured the processes that trap heat in the atmosphere and we’ve made predictions of future warming and related events.  To confirm or deny the theory of global warming, scientists set up a system of instrumentation across the planet and in orbit, beginning about 30 years ago.  The data are clear – oceans are warming from the surface downwards, ice is melting in every setting on the planet, and atmospheric temperatures are rising.  We’ve seen the primary predictions of global warming and second-order climate changes robustly confirmed.  Objections and challenges to the data and interpretation have been evaluated and refuted.

How It Works
The entire spectrum of electromagnetic radiation includes gamma rays, x-rays, ultraviolet, visible light, infrared, microwaves and radio waves.  The high-energy end of the spectrum consists of very short wavelengths, including gamma rays and x-rays through visible light, while the low-energy end of the spectrum has longer wavelengths, from infrared through radio waves.  

Everything radiates electro-magnetic radiation at some wavelength.  It’s called by several names –Planck radiation, black-body radiation, or thermal infrared radiation.  The kind of radiation emitted by objects depends on temperature.  Hot objects emit high energy radiation with short wavelengths, and cool objects emit low energy radiation with long wavelengths.  The sun primarily emits energy in the visible spectrum, because it is very hot.  Atmospheric gases are transparent to the visible spectrum, so most of the sun’s energy passes through our atmosphere to reach the ground.  Visible light strikes the earth’s surface and is converted to heat.  The warmed earth also emits radiation, but at a longer wavelength (infrared) because it is cool. The earth’s infrared radiation mostly escapes back into space.  Carbon dioxide, water vapor and methane, however, are partly opaque to infrared radiation, depending on the specific wavelength.  These gases trap heat in the atmosphere, warming the air, the oceans and the ground.  The phenomenon is called the greenhouse effect, because glass will do exactly the same thing, keeping a greenhouse warm – visible light goes in, but infrared radiation is trapped inside.  

Image credit: Science News.  The yellow lines are actual IR readings from space, compared to the theoretical Planck radiation from the ocean surface shown in dark blue.  Depressions and divots in the yellow lines represent absorption of upgoing IR radiation by various greenhouse gases, notably CO2.  Differences between the yellow lines represent clear and cloudy skies, with cloud tops having cooler temperatures and a different baseline Planck profile.

The natural amount of CO2 and water vapor in the air keeps the earth at a temperature to which we’ve  become adapted.  If the earth’s atmosphere had absolutely no CO2 or H2O, the earth’s average temperature would be about 33 C colder, causing freezing conditions over the entire planet.

Of the sun’s incoming radiation (341 W/m2), about 29% (100 W/m2) is directly reflected back into space, mostly by clouds.  The remaining 241 W/m2 is absorbed by the ground and atmosphere, warming the Earth.  The Earth radiates energy back into space at a wavelength in the infrared spectrum, balancing the energy input from the sun to create a stable climate for the past 6000 years.  But the addition of greenhouse gases to the atmosphere is currently trapping 0.94% (3.2 W/m2) of the sun’s energy reaching the surface.  That heat is ultimately redistributed to the oceans, ice, and air, warming the earth.

This figure simplifies many heat transfers within the atmosphere before energy is either retained on earth or returned to space.  The heat retained by greenhouse gases is given the awkward technical term "radiative forcing".

[Technical note: The sun's radiation, measured in space, has an intensity of 1364 W/m2.  There is a range of reported figures from 1361 W/m2 to 1368 W/m2, depending on the choice of instrument calibration.  The earth receives sunlight according to its cross-sectional area, equal to one-quarter of its surface area.  The earth emits radiation from its entire surface area.  So for a simplified energy budget as shown below, we have to choose a convention of adapting numbers for the cross-sectional area or the surface area of the earth.  Most displays adopt the convention of the whole earth surface area as I've done above.  This requires dividing the sun's input radiation by four, yielding 341 W/m2 to represent the average energy input across the entire earth.]

Under natural conditions, a balance develops between the incoming and outgoing radiation, which keeps the earth’s temperature stable, unless disturbed by other factors such as orbital variation.  The earth’s orbit varies over cycles of 40,000 years and 100,000 years, which triggers feedback mechanisms (including CO2 concentration and reflective ice) producing ice ages. 

Climate-change deniers are fond of saying "The climate has always been changing."  But since the last ice age, for the past 6,000 years, the climate has been stable, as proven by geological studies of sea-level, temperature-sensitive isotopes, and ice-sheet deposits.  This is the entire period of the written record of humanity.  The pre-industrial level of CO2 created a “Goldilocks” climate in which humans and nature thrived.

For the past 150 years, we have burned increasing quantities of fossil fuels – coal, oil and natural gas, and cleared or burned forests to create new farmland.

The CO2 emitted from these human activities has markedly changed the concentration of CO2 in the atmosphere, from the pre-industrial level of about 280 parts per million (ppm) of CO2, to the current level of 420 ppm CO2.  Because CO2 is such a potent greenhouse gas, this small change in atmospheric composition has a marked change in retained infrared radiation. 

You might not think that 400 parts per million is enough to change the retention of radiation in the atmosphere.  I’d like to propose a small thought experiment.  Four hundred parts per million is equivalent to four parts in ten thousand, or one part in 2,500.   One ounce of water contains about 600 drops.  Four and 1/6 ounces of water, about a half-cup, contains 2,500 drops.  Imagine, for a moment (or really try) putting one drop of opaque India ink or dark food coloring into a half-cup of water.  The ink noticeably reduces the visible light transmitted through the otherwise transparent water.  It’s the same with CO2 in the atmosphere.  

Climate Feedbacks
There are further processes known as feedback mechanisms affecting the earth’s heat budget.  Feedbacks are processes that are triggered by changes in Earth’s temperature, which either amplify (positive) or diminish (negative) the primary changes.  The strongest feedback effect is the Planck effect, a negative feedback.  As the Earth’s temperature rises, it radiates energy more strongly, counteracting the influence of greenhouse gases.  The balance between the sun’s incoming energy and the Planck effect is what caused the Earth to settle at a stable temperature.  The second strongest feedback is water vapor.  As the ocean surface becomes warmer, the equilibrium humidity in the air rises.  Also, warmer air can hold more humidity, keeping additional water vapor in the air.  Higher humidity is a positive feedback mechanism, because water vapor is itself a powerful greenhouse gas.  So as the planet warms, more heat is retained by water vapor.  As Arctic snow and ice melt, the surface reflectivity diminishes, causing positive feedback.  Climate change increases cloudiness, causing feedback effects.  Clouds are complex as a feedback mechanism, with both positive and negative impacts.  Depending on the type of cloud, the primary impact may be to reflect sunlight, or may be to retain infrared emissions from earth.  Overall, clouds are considered to be a positive feedback.  There are more complex feedbacks involving biochemistry and methane, and fast versus slow feedbacks, but these are generally an order of magnitude less significant than the physical feedbacks.  This is an area of active climate research.

The Planck effect dominates all other feedback mechanisms, and the total impact of all feedback effects is negative.  This is very good, because a simple modeling exercise shows that the global climate would soon irreversibly blow up if the total feedback were positive.  Nevertheless, there are number of authoritative sources on climate feedbacks (notably Wikipedia and Andrew Dessler’s Modern Climate Change) that neglect to mention the Planck effect among climate feedbacks and assert that the net climate feedback is positive.  This is incorrect.

Global temperature change since pre-industrial times is about 1.1 C, so the current total feedback is -1.3 W/m2.  Combining the greenhouse gas effect with total feedback leaves a positive (warming) climate influence of 1.9 W/m2.  

Validation
Climate science predicts that the earth should be warming, due to heating resulting from the buildup of greenhouse gases.  These greenhouse gases, particularly CO2, are unquestionably from human activities (see my blog post, https://dougrobbins.blogspot.com/2019/12/understanding-source-of-rising.html).  We have detailed temperature records for much of the world for the past 150 year or so, and we have plentiful temperature measurements of the oceans beginning in about 1950.  However, early climate data have a few issues with data quality and coverage.

Starting around 1990, scientists put in place a comprehensive set of instrumentation specifically designed to detect and measure global warming.  These systems have corrected some of the issues of data collection from early research, and provide unprecedented coverage of our planet.  The results are unequivocal.  The oceans are warming from the surface downwards; the air is warming over the oceans; the air is warming more rapidly over land; the Arctic is warming faster than the rest of the planet; and continental glaciers, Arctic sea ice, and the Greenland and Antarctic ice caps are melting.  Other, second order effects of the heat are well-proven also, including an acceleration of rising sea level and seasonal changes in physical and biological systems.

There is simply no point to denying that global warming and resulting climate changes are happening due to human emissions of greenhouse gases.  These changes are observed to be accelerating, as expected, due to higher concentrations of greenhouse gases.  Previous predictions about climate change have been highly accurate.  There is no reason to doubt further predictions of serious to catastrophic harm from future climate change unless we greatly curtail emissions of greenhouse gases.

Appendices
Appendix 1
Climate change indicators and sources
Air Temperature Over Land and Oceans
https://data.giss.nasa.gov/gistemp/graphs_v4/

Temperature Anomaly Map, 2016-2022 vs. 1951-1980
Note Arctic warming is more intense than the rest of the planet, as predicted by the Macdonald report in 1979.  Also note that air over land is warming faster than air over oceans.
https://data.giss.nasa.gov/gistemp/maps/

Ocean Heat Content and Temperature
Note that the ocean is warming from the surface downwards.
https://www.ncei.noaa.gov/access/global-ocean-heat-content/index3.html
https://www.ncei.noaa.gov/access/global-ocean-heat-content/index.html

Continental Glaciers, World Glacier Monitoring Service
https://wgms.ch/global-glacier-state/

Arctic Sea Ice Extent (July)
http://nsidc.org/arcticseaicenews/

Antarctic and Greenland Ice Sheets
https://climate.nasa.gov/vital-signs/ice-sheets/

Sea Level Rise
https://climate.nasa.gov/vital-signs/sea-level/

Appendix 2, Comparison of Descriptions of Greenhouse Gas Heating
Arrhenius, 1896
“The selective absorption of the atmosphere is…of a wholly different kind [than diffusion of ultraviolet radiation]. It is not exerted by the chief mass of the air, but in a high degree by aqueous vapour and carbonic acid [CO2], which are present in the air in small quantities.  Further, this absorption is not continuous over the whole spectrum, but nearly insensible in the light part of it, and chiefly limited to the long-waved part, where it manifests itself in very well-defined absorption-bands, which fall off rapidly on both sides.  The influence of this absorption is comparatively small on the heat from the sun, but must be of great importance in the transmission of rays [thermal infrared, or long-wave radiation] from the earth.” 
Arrhenius then describes the debate over whether water vapor or CO2 has the greater influence as a greenhouse gas. 

Asimov, 1959
"The light rays of the Sun hit the air, pass through a hundred miles of it, hit the surface of the Earth, and are absorbed. The Earth heats up.  The heated Earth radiates energy at night back into space, in the form of the far less energetic infra-red.  This also passes through the atmosphere.  The warmer Earth grows, the more heat is radiated away at night.  At some particular equilibrium temperature, the net loss of radiation by Earth at night equals that gained by day so that, once the temperature (whatever it is) is reached, the Earth as a whole neither warms nor cools with time.
Carbon dioxide, however, introduces a complication.  It lets light rays through as easily as do oxygen and nitrogen, but it absorbs infra-red rather strongly.  This means that Earth’s nighttime radiation finds the atmosphere partially opaque, and some doesn’t get through.  The result is that the equilibrium temperature must rise a few degrees to reach the point where enough infra-red is forced out into space to balance the Solar input.  The Earth is warmer (on the whole) than it would be if there were no carbon dioxide at all in the atmosphere.  The warming effect of carbon dioxide is called the “greenhouse effect”.
…A recent set of calculations indicate that if the present carbon dioxide level should double, the overall temperature of the Earth would rise by 3.6 C."
Asimov was reporting on the work of G.N. Plass, published in 1958. 

Ramaswamy, 2019
“Interactions of the incoming solar radiation and outgoing longwave radiation with Earth’s surface and atmosphere affect the planetary heat balance and therefore impact the climate system.”

Also see:
Ramaswamy, Radiative Forcing of Climate Change, 2001

Ramaswamy, Radiative Forcing of Climate: The Historical Evolution of the Radiative Forcing Concept, the Forcing Agents and their Quantification, and Applications, 2019

R. J. Bantges & H. E. Brindley, On the Detection of Robust Multidecadal Changes in Earth’s Outgoing Longwave Radiation Spectrum, 2016

A. Dessler, Modern Climate Change, Third Edition, 2022

IPCC Reports, Technical Summaries, various dates.

Appendix 3, Discussion of Climate Feedback Discrepencies
Wikipedia asserts that there is a net positive feedback to warming.  However, a check of the referenced IPCC Technical Summary for AR5 (2014) is less clear and does not explicitly mention Planck radiation, the strongest negative feedback.  Andrew Dessler’s Modern Climate Change also concludes that total feedbacks are positive.  Dessler also does not mention Plack radiation as a feedback parameter.  [Dessler quantifies the total feedback relative to radiative forcing, rather than temperature change, which makes direct comparison of the feedback numbers a little more difficult.]  On the other hand, Global Climate Models, by D.L. Hartman, clearly identifies each feedback component, including Planck radiation.  Hartman states “the best estimate of the total feedback is about −1.2 ± 0.6 W m−2 K−1, but it is uncertain by about ±50%.”   The IPCC AR6 preliminary Technical Summary also concludes that total physical feedbacks are negative, with a best value of about -1.2 ± 0.7 W m−2 K−1.  I think that the value of -1.2 W m−2 K−1 is likely to be the best estimate.

References:
Svante Arrhenius, On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground, 1896.
https://www.rsc.org/images/Arrhenius1896_tcm18-173546.pdf

Isaac Asimov, "No More Ice Ages?", 1959
In Fact and Fancy, 1972

Ocean heat content, NOAA
https://www.ncei.noaa.gov/access/global-ocean-heat-content/ 

ARGO Ocean Temperature Program Homepage
https://argo.ucsd.edu/ 

NOAA Annual Greenhouse Gas Index
https://gml.noaa.gov/aggi/aggi.html 

Lambeck et al, Sea level and global ice volumes from the Last Glacial Maximum to the Holocene, 2014
https://www.pnas.org/doi/10.1073/pnas.1411762111

Doug Robbins, atmospheric CO2 and related charts, 2022.
http://dougrobbins.blogspot.com/2022/04/charts-of-atmospheric-co2-carbon.html 

NASA GISS Annual Mean Temperature over Land and over Oceans
https://data.giss.nasa.gov/gistemp/graphs_v3/

G. Macdonald, JASONs presidential science advisory report, excerpt, 1979.
https://climatestate.com/2019/07/10/the-jason-report-the-long-term-impact-of-carbon-dioxide-on-climate-1979/
Whole report:
https://irp.fas.org/agency/dod/jason/co2.pdf 

Dennis Hartmann, Global Climate Models, 2016 (feedback chart)
https://www.sciencedirect.com/topics/earth-and-planetary-sciences/climate-feedback
IPCC AR6 Technical Summary (feedback chart, pg. 96)
https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_TS.pdf

Andrew Dessler, Introduction to Modern Climate Change, Third Edition, 2022