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 closed the office which kept an accounting of damage from climate-change disasters. 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
1st, 2nd, 3rd, 4th
and 5th 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.
