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Tuesday, December 12, 2017

Corporate Taxes and the 2017 Republican Tax Reform Plan

The Republican-controlled Congress is in the final stages of writing the most sweeping tax changes in forty years.  The Senate version of the tax bill is 487 pages, which is hardly the sweeping simplification promised by Republicans, and too long to easily summarize in this paragraph.  Business taxes are affected far more than individual taxes. Specifics of the tax bill are summarized at the end of this article.

The main focus of the tax reform is lower taxes for corporations.  The pretext is that lower taxes on corporations will result in economic growth, but the real goal is to lower taxes on unearned income.  Profits saved through lower taxes will flow through corporations to shareholders, including Republican Party donors.  The expectation of higher dividends and capital gains has driven the stock market by more than 25% since the election.

Most, if not all, serious economic reviews of the tax plan do not support the expectation of higher economic growth.  The Congressional Joint Committee on Taxation concluded that the bill would only add marginally to economic growth, while adding one trillion dollars to the US Federal debt, even after accounting for the additional tax revenue resulting from growth.  And both private and JCT analyses conclude that tax benefits will accrue to the wealthiest Americans, with poorer Americans losing money.
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Justification for 2017 Corporate Tax Cut
The rationale for the deep cut in corporate taxes is based on the idea that higher after-tax profits for corporations will result in a higher rate of economic growth.  Also, the argument is that a higher rate of growth will be shared by wage-earners in the form of higher take-home pay.
Let’s look at that idea.

United States Corporate Taxes Compared to the OECD
In justifying the corporate tax cut, both of Alaska's Senators have said that American corporate taxes are "among the highest in the world".  They believe those high taxes render our corporations noncompetitive in global markets. As this blog has previously noted, a quick trip to the OECD database shows that idea is simply false.  Although US nominal corporate taxes are comparatively high, the corporate tax actually paid in the United States is less than the average for the OECD.   
GDP Growth, Corporate Taxes, After-Tax Profits and Wages
The premise that higher after-tax corporate profits lead to higher economic growth and higher wages is false.  American economic growth has been declining since World War II.
This is especially evident when we look at non-recessionary periods.  This chart has deleted all quarters with negative GDP growth.
Wages have declined since World War II, as a share of gross domestic income, GDI (or similarly, GDP).
Let's look at Corporate After-Tax Profits.  We can see that profits have soared since the 1980s as a share of GDP.  Higher corporate profits since 2004 (excepting the recession year) have not produced higher GDP growth, or higher wages.
Corporate taxes have also fallen as a percent of GDP, coincident with a falling rate of growth.
But the rise in After-Tax Profits has not resulted in a higher rate of economic growth, or higher wages for workers.  The argument that lower taxes will result in higher economic growth appears to be void.
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Tax Cuts and the Reagan Economy
The final argument for tax cuts is that tax cuts worked in the past.  The basis for that claim is generally in the mythology surrounding tax cuts enacted in 1981 and 1987 during the Reagan administration.  Close examination proves that economic growth during the Reagan administration was not extraordinary, and the growth that did occur was largely due to other factors. The actual performance of those tax cuts is complicated by eleven tax hikes that were also passed during the Reagan years, for the purpose of restoring lost revenues.

Let’s look at the Reagan economy.
First, the “economic boom” of the Reagan years looks less spectacular when viewed in the context of the total post-war economy.  American economic growth has been falling steadily since World War II, part of a general structural problem in the U.S. economy, reflected in GDP growth, wages as a share of the economy, and the time required for recovery after recessions.  [That should be the topic of another blog post.]  There were really only two years during the Reagan administration that had economic growth above the long-term, non-recessionary trend (1983 and 1984). 
Still, the Reagan administration was marked by a period of fairly persistent and strong growth.  There are three reasons for that growth. 
1)      Interest Rates
I believe that the main reason for sustained growth during the Reagan years was falling interest rates.  Interest rates reached a singular, extraordinary peak in 1981 (see chart).  The Volcker Federal reserve had largely quelled inflation by 1981, and began to let interest rates fall.  The extraordinarily high interest rates at the peak probably caused the multiple recessions of 1980 – 1982.  As interest rates fell, economic growth which had been bottled up by high rates was released.  I believe the influence of falling rates far exceeded the influence of lower taxes.
2)      Serendipity
Secondly, there is simply the matter of good timing.  The Reagan administration was faced with recessions in 1981 and 1982, but afterwards enjoyed the benefit of the typical eight-to-ten year business cycle.  There is no particular policy which can be attributed to this aspect of success, except luck.  [See previous chart, with indicated recessions.
3)      Tax Cuts
Tax cuts do provide stimulus to the economy, and the Reagan tax cuts of 1981 were appropriately given during an economic recession.  Ultimately, though, tax cuts are literally borrowing against the future, and must someday be paid back in terms of later economic growth.  I believe that it is best to run budgetary surpluses when there is strength in the economy, to allow the government the ability to incur deficits when the economy is weak, without fear of destabilizing the economy.  The Reagan administration never fully funded the government to pay for the deficits it incurred.

The 2017 Republican Tax Reform Plan
The Republican Tax Plan passed by the House and the Senate must now be reconciled into a single bill.  The bills are very similar in scope, and the process should not result in significant changes to the plans, except where major errors are discovered in the assumptions and provisions of the bill. 

My main objections to the plan are as follows:
1)      Debt
The plan runs large federal deficits, at a time when the total Federal debt is approaching 100% of annual GDP, and interest payments are starting to become a significant part of annual spending.
2)      Timing
The plan cuts taxes at a time of full employment, when fiscal policy should be to run surpluses.  
3)      Corporate Taxes
The plan awards long-term tax relief to corporations, at a time when corporate taxes are already low; corporate earnings are already soaring, and no gains in GDP have been observed.  
4)      Lack of Middle-Class Tax Relief/Benefits for Unearned Income
Individual tax relief in the plan will accrue mostly to high income families, particularly those with unearned income.  The corporate tax reduction will flow through to investors, much more directly than to wage-earners.  The plan will not result in long-term tax relief for wage-earners, whose share of gross domestic income has been falling for 47 years.
5)      Abolishes ACA Individual Mandate
The tax plan eliminates the individual mandate aspect of the Affordable Care Act.  It is considered an important facet of the act, in encouraging younger people to participate in the insurance pool.  

Conclusion
The Republican tax plan is based on false ideas:  that American corporate taxes are higher than other countries; that higher corporate taxes produce higher economic growth and higher wages; that general tax cuts during the Reagan administration produced extraordinary growth.  All of these ideas can be demonstrated to be false, using economic data that is available to anyone.

Lower corporate taxes increased profits, not wages.

The Republican tax plan will probably become law.  I expect that it is unlikely to survive the next administration and Congress.  But the debts incurred before it is overturned will last for a generation.

A copy of this post is available on my political blog, http://debatablypolitical.blogspot.com/.
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Appendix
Summary of Important Changes in the Republican Tax Reform Bill
Business Tax Changes
1) Drops the nominal corporate income tax rate from 35% to 20%.  The current Senate bill, perhaps through an oversight, keeps the minimum corporate tax at 20%, eliminating exemptions by default.  It is expected that the reconciliation bill will restore those exemptions, dropping the actual corporate rate below 20%.
2) The tax rate for “pass-through” small businesses is reduced, excepting service businesses such as lawyers, accountants, and doctors.  The amount of the reduction is to be determined in reconciliation.
3)  Rules for expensing, rather than capitalizing, spending are relaxed, allowing quicker realization of tax benefits from business investment.
4)  Repatriated profits from foreign operations would be taxed at a much lower rate than US profits.  Cash assets would be taxed at 10% (Senate) or 14% (House), while non-cash assets would be taxed at 5% (Senate) or 7.5% (House). 

Individual Tax Changes
5) All classes of individual taxpayers will see a tax reduction in the near term, but those reductions will expire in ten years.  On the other hand, business tax reductions will be permanent.
6) The standard deduction is doubled, but personal exemptions are eliminated.  Child tax credits are increased, but the full value is only available to those with higher income to offset taxes.  For large families, the child tax credit may not fully offset the loss of personal exemptions.
7)  State & local tax deductions are eliminated; casualty loss deductions are eliminated.  The mortgage interest deduction is retained for all but the largest mortgages.
8) The estate tax may be eliminated, or the minimum threshold for the estate tax may be doubled.
9)  The individual mandate tax of the ACA is repealed.  Some fear that this will destabilize the insurance markets, by removing a large number of younger, healthy individuals from the insurance pool.
10) The fate of the Alternative Minimum Tax will be determined in reconciliation.
11) Waived tuition, common for graduate students, will now be taxed.  Colleges with very large endowments will have some earnings taxed.

Other
12) Drilling will be allowed in the Arctic National Wildlife Refuge Area 1002, which was originally set aside for consideration for oil development.
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Appendix 2

As this blog has previously noted, American Federal taxes are among the lowest in the world, in direct contrast to Republican claims that American taxes are among the highest in the world.  Here is data from OECD and the World Bank, showing the relative ranking of American Federal taxes compared to other countries.  

United States Federal taxes as a share of GDP, compared to 34 OECD countries.
United States Federal taxes compared to 123 other countries; data from World Bank.
Countries with lower Federal taxes than the United States are Ethiopia, Pakistan, India, Afghanistan, Bangladesh, Central African Republic, West Bank and Gaza, Lithuania, Oman, Nigeria, Bahrain, Estonia, United Arab Emirates.
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References
Summaries of the Republican Tax Plan
Washington Post
Forbes
CNN

Economic Reviews of the Tax Plan
Tax Policy Center – the plan will ultimately raise taxes on more than half of Americans.
University of Chicago Survey – only one out of 42 economists believes that the plan will significantly grow the economy. 
University of Pennsylvanian/Wharton review – the tax plan will add about $1.3 trillion to the national debt.

This article attempts to put lipstick on a pig.  The article acknowledges that economic growth from the tax plan will be small, “but significant”.  The article recognizes that slower growth has occurred in the past two decades, when progressively slower growth has actually been going on for seven decades.  The article gives no explanation for why growth is slower now than in the past, or why tax cuts at a time of full employment will help. 

A Federal tax expert says that the tax plan is stupid.

Historical Data
OECD tax on corporate profits
US corporate tax among the lowest in the OECD

Corporate Tax as share of GDP

Source of federal revenue

FRED

Monday, November 13, 2017

Computer Sentience

The great ethical debate in the year 2100 will be about the civil rights of sentient machines. 
The great ethical debate in the year 2200 will be about the civil rights of sentient humans.  
OK, that’s supposed to be a joke.  But let’s think a bit about the possibility of sentient machines.

Life is immaterial and ephemeral.   One moment after death, a being has all of the same solids and fluids, all of the same atoms and molecules as at a moment before death.   But something mysterious has departed.  Life exists as a collection of electrical impulses and chemical changes.  The idea of a living, immaterial, non-physical spirit is a powerful one, and most people throughout history subscribe to the idea that all living creatures are endowed with such a spirit.   But no such spirit has ever been reliably observed.  On a scientific basis, we must presume that life consists solely of the electrical and chemical interactions that animate our muscles and minds.

Consciousness, too, must be a matter of electrical and chemical physical properties.  It should not be a surprise. We can influence consciousness with as chemicals diverse as caffeine, TCP, or LSD; and we can stimulate memories with electrical impulses to the brain.  Is there any reason, then, why machines using complicated patterns of electrical connections could not become as conscious and aware as humans? 

Examples from Science Fiction
Science fiction and science fiction authors have proved to be remarkably prescient about future technology and social issue, and there are innumerable examples of computer consciousness in science fiction.   Considering the remarkable consensus of science fiction authors about the possibility of computer consciousness, I am inclined to believe that it is a real possibility.   I think it is time to consider in what form it may occur, and what implications it will have for mankind.

Here are a few sentient machines from some of my favorite science fiction stories.

Character            Type                  Book or Show                                              Author
Mycroft              Mainframe           The Moon is a Harsh Mistress                     Robert Heinlein
Daneel Olivaw   Android                The Caves of Steel                                       Isaac Asimov
Colossus             Mainframe           The Forbin Project                                        Michael Crichton
Data                    Android                Star Trek, Next Generation                          Various
Samantha           AI Program          Her                                                               Spike Jonze
Marvin                Robot                    Life, the Universe and Everything              Douglas Adams
Bender                Robot                   Futurama                                                     Matt Groening
Jay Score            Robot                   Jay Score                                                      Eric Russell
Einstein               AI Program          Beyond the Blue Event Horizon                  Fredrick Pohl
Tardis                  Time-Ship            Dr. Who Series                                             Various

There are dozens of other examples in science fiction. What makes these stories interesting is the range of thoughts and behaviors exhibited by the sentient machines.  And in a way, the stories are explorations of what it means to be human and sentient.  In some of the stories, machines threaten mankind; in some stories they save mankind.  Sometimes they bond as friends with human characters; sometimes they question their own lack of humanity.  But as drawn by the authors, they are unquestionably alive.
Image from the film "I, Robot", screenplay by J. Vintar and A. Goldsman, 
after a collection of stories by Isaac Asimove. 

Today, artificial intelligence is one of the fastest developing fields of technology.  Artificial Intelligence is expected to understand our spoken speech, speak meaningfully in response, act as clerks or servants, interpret our instructions from gestures, render judgments and decisions in complex fields such as medicine, recognize and appropriately classify images and scenes, drive our cars, work in our factories.  Ultimately, artificial intelligence may design and improve its own replacements.  At this time, there are no known limits to what artificial intelligence can do.

But all of this is less than what we see in science fiction.  Few computer specialists would believe that today’s artificial intelligence is anything living.  AI programs execute instructions from programmers, and in some cases, can adapt that programming based on input from the external environment.  But even then, the program is simply performing as it was designed, without motivation or will.  It isn’t alive.

Sentience
What, then, would be the hallmarks of a sentient machine?  What qualities would it have that differ from today’s artificial intelligence?  Would we recognize a sentient machine if we saw one?

Here is a list of the qualities that I think are necessary to the definition of sentience.
Consciousness – Awareness of the surrounding environment.
Self-awareness – The ability to say “I am”, without being asked.
Personal Memory – The ability to remember former analyses (thoughts) and actions.
Thought -- the ability to think in processes, make forecasts and predictions based on processes, rather than pattern recognition.
Will – The deliberate decision to perform or not perform an action according to self-determined reasons.
Empathy – The ability to recognize other beings as sentient.

Consciousness
Consciousness is hard to define.  In the biological world, I think that consciousness is a gradational quality, rather than a discrete property.  No one would suggest that a virus is conscious, and yet it has some property of life which is greater than that of a piece of rock.   But most would agree that a worm is more conscious than a virus, and a dog is more conscious than a clam.   And perhaps a colony of bees is more conscious than an individual bee. 

Both computer programs and flatworms can respond to external stimuli.  Flatworms can be trained to avoid stimuli associated with pain, and seek stimuli associate with food.  Perhaps these actions demonstrate the emotions of fear and pleasure.  But it is unclear if the responses of either flatworms or computers are aware and knowing responses, or simply the results of chemical and physical programming.

Definitions of consciousness include awareness of exterior and/or interior things.  But the definition and observation of awareness is difficult, even in humans who have suffered brain damage.  The identification of consciousness, separate from the qualities of self-awareness and free will, will be very difficult to recognize in computer intelligence. 

Personal Memory
Personal memory is a critical part of human personality.  I define personal memory as the memory of prior thoughts (analyses) and actions.  Personal memory is distinctly different than computer memory which is used to hold data for processing.  It is the memory of performing previous processes, and the memory of those results.  This kind of memory allows people to learn, and to develop preferences which reflect personality.  Without personal memory, a machine could never develop self-awareness or will.

When we wake up in the morning, personal memory is what allows us to know that we are the same person who went to bed the night before.  Or more directly, personal memory informs us that we are the same person from moment to moment. 

Machine learning algorithms must have some kind of personal memory, recording and comparing previous analyses to new ones.  The type of memory probably depends on the type of machine learning algorithm.  Some kind of personal memory, perhaps developed from machine learning, will be a necessity for a sentient machine. 

Self-awareness
My son gave me the simplest definition of self-awareness: The ability to say “I am”, without being asked.  But perhaps this is a little too glib.  Like consciousness, living creatures span the range from clearly not self-aware, to fully aware. 

A test performed with some creatures uses a mirror.  A parakeet can be kept company by a mirror, never realizing that the parakeet in the mirror is not a companion.  A cat is initially mystified by a mirror, but may eventually realize that the cat in the mirror is not another cat.  A great ape will almost immediately realize that the image in the mirror is itself. 

It seems to me that for a digital entity, self-awareness implies a recognition of external reality and the separation of the self from that reality. 

How could self-awareness be recognized?  In biology, creatures have reward systems, seeking food and sex.  Rewarding oneself is a demonstration of self-awareness.  Self-aware creatures also pass the mirror test, recognizing a patch of paint visible only in the mirror.  If a computer could be observed treating itself differently than external reality, it might demonstrate self-awareness.  Perhaps a self-diagnosis problem might show that the computer would treat an internal problem differently than an external problem.  But computers lack inborn desires, fears or survival instinct.  It might be difficult to observe self-awareness in a computer, even when it exists.

Will
Will is the ability to perform independent actions.  This will be easier to recognize than consciousness or self-awareness.  Actions independent of programming would be evidence of some measure of sentience in a computer.  Nevertheless, machine-learning algorithms allow computers to make independent judgments and perform actions.  Machines can play chess, diagnose medical conditions, connect electronic traffic in efficient ways, answer questions, and perform many functions similar to humans.  But at what point does a computer exhibit free will?  How can we tell? 

Computer AIs do unexpected things all the time.  Chatbots are a good example, offering spectacularly bad examples of conversations, based on some learning algorithm applied to real human conversations.   Microsoft’s experimental chatbot “Tay” became notorious after only a few hours of exposure to interaction with real humans.  Of course, a number of users were deliberately trolling Tay, and succeeding in turning the na├»ve chatbot into a bigoted and sexually aggressive delinquent.  Within 16 hours, the chatbot’s personality was hopelessly corrupted, and Microsoft took Tay offline, ending the experiment.  In a second, accidental public release of the chatbot, the bot became stuck in a repetitive and poignant loop, tweeting “You are too fast, please take a rest” several times a second to 200,000 followers. 

It is still unclear how we could recognize free will in a machine, as opposed to an apparent malfunction.  (Once again, I recall episodes of Star Trek which explored that very dilemma.)  Perhaps behaviors that were clearly in the best interest of the machine would be noticed, but how could we expect such behaviors, when machines have not evolved to pursue their own best interest?  Once again, recognition of sentience seems difficult or impossible.

Thought
It seems to me that thought is a property of sentience.  I believe that the empirical learning performed by AI programs is not thought.  (I have similar views about empiricism in science, e.g., http://dougrobbins.blogspot.com/2016/12/the-scientific-method-redefined.html.)  Actual thought involves something more than the correlation of previous patterns.  Thought requires the recognition of processes which change reality (even a digital reality).  When an AI program can recognize causation, rather than correlation, I would acknowledge that the machine is thinking.  And thinking is one component of sentience.

There might be a test which could reveal how a computer was solving problems, whether by empirical correlation, or by understanding processes (thought).  Understanding processes allows something that physicist David Deutsch calls “reach”.  Processes can be extrapolated to situations which are far beyond the range of input data.  For example, a computer might draw empirical data on how apples fall from many trees, and describe how other apples fall from trees.  But understanding the process of Newtonian gravity allows the computer to describe the orbits of planets, far beyond the bounds of what could be achieved by any empirical program.

Empathy
My wife suggested that empathy should be a component of sentience, and I agree.  A sentient machine must have the qualities already discussed: Consciousness, Self-awareness, Will, and Thought.  But just as self-awareness requires the recognition of external things (which are “not-self”), full sentience requires the recognition of other sentient beings. 

Forms of Computer Sentience
As I would define sentience, it consists of several components: Consciousness, Personal Memory, Self-awareness, Will, Thought and Empathy.  If sentience does emerge in machines, I expect it will be gradual, and will not appear as the full-blown sentient beings of science fiction.  Recognition of sentience may be very difficult, particularly in machines which are already performing independent machine learning. 

In the biological world, four billion years of evolution has been necessary for the development of sentience.  Computers lack that evolutionary background.  Computers have no innate instinct for survival or self-interest.  Computers, even if they have the glimmerings of consciousness and self-awareness, may not demonstrate self-oriented behavior that would reveal their progress toward sentience.  Some period of evolution, by design or by accident, will probably be necessary for computers to develop sentience.  

I am not sure what form computer sentience might take when it appears.  It seems to me that sentience could appear in many different guises, and may surprise us by the form that it takes.   It may be a single machine, running specialized machine learning programs, and designed to develop sentience.  It may be a network of computers, or it may be the entire Internet.  The latter would echo an old story by Arthur C. Clarke, in which a global telephone system developed sentience.  Sentience may develop out of computer viruses, which have considerable evolutionary pressure placed upon them already.  Sentience may exist as software, jumping from device to device as new hosts.  In most science fiction stories, sentience develops in a single, unique machine, but it may not happen that way.  My daughter suggested that each of many small devices – cell phones, smart TVs, home security systems – may become sentient at the same time.  Alternatively, it is worth remembering that the human brain (as well as the human body) is a colony of smaller cells, each capable of performing some of the basic functions of life independently.  Cells in the brain each perform some analytical function, but it is only the total network of the brain that we consider sentient. 

Evolution of Sentience and Computer Viruses
My son asked how computer viruses could develop sentience.  I'm thinking about viruses which are sophisticated enough to evolve, which may require human initiative to get started.

As far as evolution, I'm thinking about a virus which is deliberately programmed to introduce variants in subsequent generations, or steal bits of code from other programs.  As in ordinary evolution, most of the variants will be irrelevant or harmful.  But given enough cycles, some of the variants may improve the virus' ability to survive. 

As for sentience, the virus itself would not be sentient, any more than human DNA is sentient.  But I can imagine a program sophisticated enough to take over a host machine. The virus might run in the background, undetected, and issue the commands that produce sentience in the machine; and then send its “DNA” to another machine to reproduce and evolve further.  If some aspects of sentience had evolutionary value (awareness of surroundings, self-awareness, will, thought), then those traits would be enhanced in subsequent generations.

Fear of Computer Sentience
Science fiction is full of evil machines, perhaps with good reason.  A number of futurists, including Elon Musk and Stephen Hawking, have spoken strongly about the risks that artificial intelligence (whether sentient or not) poses to mankind.  I would not presume to contradict them.  When artificial intelligence reaches the point that it becomes self-designing, producing improved replicas without human design, it will exceed our capacity to understand or predict the capabilities of those machines.  But I nevertheless think that the development of sentient machines will occur.  

Inevitability of Computer Sentience
If I am correct that human sentience is strictly a matter of physical chemistry and electricity, then I believe that machine sentience is ultimately inevitable, provided that humanity survives long enough.  When it happens, it will challenge our place in the world, the meaning of our goals, and the meaning of humanity.  It may be the most important thing that has happened to mankind since the emergence of our own species as sentient beings.

Thursday, October 12, 2017

Seven Ways Climate Change Makes Hurricanes Worse

As I’m writing this post, Hurricane Ophelia is forecast to hit Ireland, the first full-strength hurricane to hit the island since 1961, and the tenth consecutive storm this season to reach hurricane strength.  The year 2017 has already been a tragic and record-setting Atlantic hurricane season.  Hurricane Harvey hit Texas as a 1000-year rainstorm, dropping about 11 cubic miles of rain on Houston with enough weight to depress the earth’s crust by a measured 2 centimeters.  And within a period of two weeks, Hurricanes Irma and Maria struck the Caribbean Islands as category 5 hurricanes – the strongest measure on the Saffir-Simpson scale, setting a record for the duration of category 5 storms in one season. 

The obvious question is whether climate change is causing an increase in the frequency or intensity of these storms. 
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Hurricanes and Climate Change
A hurricane is a convection engine.  Warm tropical waters convey heat and humidity to the air over the water.  The warm, humid air is light, and begins to rise at random spots over the ocean.  The warm air cools as it rises, dropping below the dew point.  Water vapor condenses to form clouds and rain.  The condensation of water vapor reduces air pressure, further lowering the air density.  The low-pressure center draws warm air from the ocean surface toward itself, which feeds the rising convection column.

The converging air currents are affected by the Coriolis force, and begin to spin as they approach the growing low-pressure center.  As the storm develops structure, a downward current of air forms as the eye in the center of the storm, returning dry air from high altitude.  The hurricane eyewall of clouds, rain and ferocious winds spins around the central eye.  Surrounding the eye, spiral rain bands develop as subsidiary convection systems, with upward air flow in the rain bands and downward flow between those bands. 

The strength of a hurricane is often limited by high-level winds blowing across the top of the hurricane.  Strong high-level winds effectively decapitate a hurricane by blowing the top off of the convection column.  Hurricanes tend to drift westward in equatorial waters, as the globe spins eastward beneath them; and to drift toward the poles in temperate latitudes.  Areas of surrounding high and low pressure form steering currents, which modify the path of the hurricane as it drifts across the globe.

Climate change is expected to increase the intensity of hurricanes in a number of ways. Here are seven ways in which climate change is expected to make hurricanes worse.
Modified after image by Thompson Higher Education.

Temperature
1)  Average surface air temperature has risen around the globe by about one degree Celsius since 1980.  The particular warming is variable at different times and places, and may be greater over tropical waters at times.  Warmer surface air creates a greater tendency to form thermal convection currents.
Average annual global surface temperature, 1880 - 2016.  Image credit NASA.

2)  Average temperature in the upper 100 meters of the ocean has risen by ½ degree Celsius since 1980.  As with air, temperatures in the ocean vary seasonally and in complex patterns of time and space.  At times, tropical waters will be warmer by more than the average ½ degree Celsius global average.  A warmer ocean surface contributes more heat and humidity to a hurricane.

Average water temperature, 0-100 meters, 1955-2017.  Image credit NOAA.

3)  The average temperature of the ocean water at depth has also risen.  The average temperature of waters from the surface to 700 meters has risen by 1/10 of a degree Celsius since 1980.  Waters from 100 to 200 meters have warmed nearly as much as surface waters.  Hurricane waves churn up deeper water, bringing cooler water to the surface.  In the past, this stirring of deeper water cooled the ocean surface, and acted as a buffer on the intensity of a hurricane.  But now that deeper waters are also warmer, there is less tendency for wave action to moderate the strength of a hurricane. 
Average water temperature, 0 - 700 meters, 1955 - 2107.  Image credit NOAA.

Humidity
The principles of physics mean that higher air temperatures and higher water temperatures mean that more humidity is carried in tropical air before the formation of a tropical storm.  Warmer air raises the water-carrying capacity according to the principle of relative humidity, and higher water temperatures raise the humidity of the air according to the Clausius-Clapeyron equation.  Higher humidity acts in three ways to increase the intensity of a hurricane.

4)  Higher humidity lowers the density of the air, because the water molecule is lighter than the average molecular weight of air.  Intuitively, we tend to think that moist air is “heavy”, perhaps because liquid water seems heavy.  But the molecular weight of water is 20, while the molecular weight of nitrogen is 28, and oxygen is 32, giving dry air a molecular weight of about 29.  Molecules of water vapor occupy just as much space as gaseous molecules of nitrogen or oxygen, thus lowering the density of air.  [If we had a bucket of liquid water and a bucket of liquid air, the liquid air would be heavier.]   Lighter air contributes to stronger convection, which strengthens the hurricane.

5) Air with higher humidity has more moisture to condense, causing a stronger drop in air pressure.  This can lead to stronger winds and more rapid intensification of a hurricane.

6) Higher humidity raises the water-carrying capacity of the hurricane, and contributes to higher volumes of rainfall and flooding when a hurricane makes landfall.  The unusual volumes of rainfall associated with hurricanes Harvey and Maria probably reflect higher humidity caused by climate change.

Winds
7) Finally, it is possible that climate change has reduced the strength of high-level winds, reducing the tendency for these winds to blow the tops off of hurricanes.  Some scientists have observed a decline in the strength of high-level winds in recent years, and tentatively suggest that this may be a result of climate change.  However, the mechanisms by which climate change would affect these winds is unclear, and the proposal is still controversial. 

Quantification
I wrote to “Ask a Climate Scientist” on Facebook, and asked whether satellite data from NASA’s GOES satellites documented higher humidity over the Atlantic since the 1980s, either in actual hurricanes or in general background humidity.  I wanted to know if the data supported the idea that climate change is making hurricanes worse.  Here’s the answer I received:

"The GOES imager series involve technology upgrades and are not well calibrated, and so are not well suited for measuring changes in water vapour over time. 
However, the HIRS instrument aboard the NOAA polar orbiter series which began about the same time is fairly well calibrated, and does show increases in humidity. 
More recently the microwave radiometers on board the AMSU series of satellites also show the increases, as does the global radiosonde and surface-observing networks.  The increases are in line with expectations from thermodynamic principles (the Clausius-Clapeyron equation) and climate models. 
We are pretty confident that these increases are indeed causing a storm to dump more rain now than it would have a few decades ago, all other things being equal.”
Professor Steve Sherwood, Climate Change Research Center, UNSW Australia

I made a brief attempt to quantify changes in the hurricane system in the Gulf of Mexico that are due to climate change.  Assuming a 1.5 degree rise in sea surface temperature, humidity will rise by about 5 percent, from about 75% relative humidity to 80%, at an average daily temperature of 80 degrees F.  Along with rising humidity, air temperatures have risen by about 2 degrees F (global average).  Air density will fall, but not very much, only about ½ of one percent.  This will result in stronger convective activity, but I do not have the knowledge or modeling ability to translate that change into hurricane intensity. 

When water vapor in the air is converted to rain, air pressure drops.  Higher initial humidity will lower air pressure in the center of the hurricane.  This means stronger rotation and stronger winds.  Hurricanes are incredibly efficient at removing humidity from the air.  Almost all of the surface humidity in a hurricane is converted to rain, as convection drops the temperature of the air from 80 degrees Fahrenheit at the surface to minus 130 degrees F at the cloud tops.  But the initial saturation pressure of water in air is fairly small.  At 86 degrees F and 80 percent humidity, air contains only 3.3 percent water vapor.  Although climate change has raised the humidity by 5 percent, this means that the surface air in a hurricane now contains 3.5 percent water vapor.  When the vapor is converted to rain, the difference in air pressure is 0.2 percent. 

So, temperature and humidity reduce the air density in a hurricane by 0.5%; additional rain reduces the air pressure by another 0.2 %, for a total climate-change reduction in air pressure of 0.7%. 

Conclusion
Climate change produces higher temperature and humidity.  Those changes push the physical processes of a hurricane toward stronger convection, more rapid intensification, higher wind speeds, and greater rainfall. 

Quantifying those changes is difficult.  Without sophisticated modeling, it is impossible to say whether the small changes in air density and water vapor can result in a major change to a storm system.  But it is important to note that hurricanes are feedback systems.  Hurricanes start as a mild swirl of air over the water, or a rain squall no different than any other rain squall.  But like the proverbial “butterfly effect”, a small change in the initial conditions of the hurricane may result in profound changes in the ultimate intensity of the storm.  Feedback mechanisms in the convection system create the hurricane; it would not be surprising if those same feedback mechanisms amplify the small changes due to climate change to create monster storms. 

I am generally critical of strictly empirical reasoning in science.  Science is about providing explanations, identifying, observing and measuring processes which change the world.  But empirical evidence can support scientific reasoning, and give a clue that an explanation is on the right track.  Currently, the remarkable 2017 hurricane season is supporting the notion that Climate Change is producing stronger, more frequent storms, with more rapid intensification and heavier rain.
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References:
Temperature of cloud tops -90 degrees C.

Chart showing mass of water contained in air at 50% and 100% humidity, as a function of temperature.
Air with 80% humidity at 86 degrees Fahrenheit contains about 21 grams of water per kilogram of air.

Tells us there is a roughly 3 percent increase in average atmospheric moisture content for each 0.5 degrees Celsius of warming

Air density calculator

Average annual humidity for places in Texas.

Average annual humidity for places in Florida.

Temperature change for mid-Gulf surface waters, 1975 to the present.  Average temperatures have increased by 1.5 degrees F; high temperatures have increased by about 3 degrees F.

Average Gulf of Mexico air temperatures, by month.

Mass of water in air at 50% and 100% humidity, as a function of temperature.

Hurricane facts. 

Cloud top temperatures for hurricane Ingrid, 2013.

Partial pressure of water in saturated air, as a function of temperature.

Standard Air Pressure
14.70 psi
1013.25 millibars
Air Density @ 80 F & 75% humidity:  1.166 kg/m3
Air Density @ 82 F & 80% humidity:   1.16 kg/m3

Personal Communication from Profesoor Steve Sherwood, Climate Change Research Center, UNSW, Australia:
"The GOES imager series involve technology upgrades and are not well calibrated, and so are not well suited for measuring changes in water vapour over time.  

However, the HIRS instrument aboard the NOAA polar orbiter series which began about the same time is fairly well calibrated, and does show increases in humidity. 

More recently the microwave radiometers on board the AMSU series of satellites also show the increases, as does the global radiosonde and surface-observing networks.  The increases are in line with expectations from thermodynamic principles (the Clausius-Clapeyron equation, https://en.wikipedia.org/wiki/Clausius%E2%80%93Clapeyron_relation) and climate models. 

We are pretty confident that these increases are indeed causing a storm to dump more rain now than it would have a few decades ago, all other things being equal."

Real time and archived statistics on global cyclone energy.

Friday, September 22, 2017

Flooding in Houston: Hurricane Harvey and Climate Change

September 2017 has been an active and violent hurricane season in the Atlantic tropical zone.  Most of this post was written following Hurricane Harvey, and before Hurricanes Irma and Maria.  Hurricane Harvey dumped record-setting volumes of rain on the south Texas coast.  Hurricanes Irma and Maria, occurring in a two-week period, were the strongest hurricanes on record in the open Atlantic Ocean.  For many years, researchers have warned that climate change would produce stronger hurricanes -- it seems that the future has arrived.

In the simplest analysis, I would ask the following question.  Is it more likely that Hurricane Harvey was a completely natural, unlikely event with a probability of 1:1000, or is it more likely that the storm was made worse by climate change, according to well-understood physical principles and predicted by scientists for over two decades? 

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In August 2017, Houston Texas became the face of climate change.   More than 20 inches of rain fell over an area of 28,949 square miles; > 30 inches over 11,492 square miles; and > 40 inches over 3643 square miles.  The maximum rainfall of 52 inches broke the record for rainfall from a single storm in the contiguous United States.  The intensely flooded area received 11 ½ cubic miles of water.  Within a few days, over 300,000 people had already filed claims for federal disaster assistance, and many more are likely to require assistance in the future.  The immediate death toll from the storm was 82, and illnesses relating to the storm are expected to persist for years.
Total Rainfall from Hurricane Harvey, August 30, 2017 

Climate change is often represented in terms of polar bear on melting ice; of changing migration patterns for wildlife; of seemingly trivial changes in long-term average temperatures; of higher sea level in the next century.  All of those are true and real.  But for many Americans, these issues do not impact their lives.  None of this matters in terms of day-to-day living. 

Hurricane Harvey is different.  It has been called a 1000-year flood by scientists.  This is an expression of the probability of an event of this magnitude in a given year, based on statistics of smaller events.  The storm dropped an awe-inspiring quantity of water on the earth, and America’s fourth-largest city was totally disrupted.  There was certainly no economic productivity from the city for a week, and the damages are considerable.  When floodwaters threatened to destroy Houston's earthen flood-control dams, emergency managers opened the floodgates, deliberately flooding neighborhoods downstream of the dams, to save other neighborhoods in a kind of triage.  An estimated 100,000 homes were flooded or damaged by the storm.  Many of them will be totally destroyed after sitting in flood waters for a month.  The human toll in lives and economic loss is huge. 

The damage is personal to me; two of my three former houses in Houston almost certainly flooded. Old friends and former neighbors are dealing with the loss of their homes, cars, and lifelong possessions. A number of deaths occurred in familiar neighborhoods
Image credit Joe Raedle/Getty Images
Image credit: David J. Phillip, AP
Image Credit: T.B. Shea, AFP/Getty
Image credit: AP

Climate Change: Prediction and Consequences

The Intergovernmental Panel on Climate Change (IPCC) 2014 Report includes this statement: “It is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions.”

On August 27, 2017, the National Weather Service tweeted this statement regarding Hurricane Harvey: “This event is unprecedented & all impacts are unknown & beyond anything experienced. Follow orders from officials to ensure safety.  #Harvey”.   [Emphasis mine.] 

These statements are not unrelated. 

Scientific Analysis
The full scientific analysis of Hurricane Harvey will not be known for a long time, probably years.  And uncertainties will remain after the full analysis of all available data.  There are a number of known factors relating to climate change which will increase hurricane severity – it is simply physics.  These factors include higher temperatures at the ocean surface, higher temperatures in the upper 200 meters of the ocean, and higher humidity.  The factors are well-established -- the changing temperature of ocean waters have been observed by NOAA’s ARGO system of buoys since 2004, and by satellite since the 1980s.  Some scientists have also suggested that climate change is reducing the strength of upper level winds, though this proposal is not yet considered proved.

Higher temperatures at the ocean surface are believed to have caused a rapid, late intensification of the storm from category 2 to category 4 immediately before landfall. 

Higher temperatures in the water column are believed to have reduced the tendency of wave action to bring cooler water to the surface, weakening the hurricane.  

Higher humidity, relating to higher water temperatures and higher air temperatures, allowed the storm to carry more water than other storms.  Higher humidity and higher temperatures also lower air density, contributing to the strength of convection and wind speed.

At this time, it is unknown how much wind systems have changed due to climate change, or how much these changes might have affected Hurricane Harvey.  Hurricane Harvey stalled after moving onshore, caught between stationary high-pressure systems.   High-level winds, which sometimes reduce convection through wind shear, were also weak through the hurricane.  Quantifying these impacts using new observations and modeling is the job ahead for scientists. 

The specific magnitude of these changes is unknown, but the known factors contributing to the severity of the hurricane are clear.  According to one preliminary estimate, factors relating to climate change increased the volume of rainfall from Hurricane Harvey by 30%.   While this may seem to be only a moderate increment, thirty percent of extra water is what exceeded the capacity of flood-control reservoirs, caused neighborhoods to flood, and caused a number of deaths.

Conclusion
The earliest warning that climate change could result in more frequent and severe hurricanes was published in 1992, and incorporated into the IPCC Second Assessment Report.  At that time, there was sparse statistical evidence that hurricanes were becoming worse.  In 2017, statistical evidence is still weak.  However, science is not all about empiricism.  Explanations matter.  We understand the physical processes of hurricane convection, the Coriolis effect, and the importance of water temperature, air temperature, humidity and air density.  We have observed that these factors are changing due to accumulating greenhouse heat, and will increase the frequency and intensity of hurricanes.

At this time, we do not know the specific amount that climate change contributed to the Hurricane Harvey disaster.  But there is a simple, shortcut analysis that we can do now.  Simply consider which possibility is more likely: whether Hurricane Harvey was an extreme event with a probability of 1:1000, or whether climate change intensified an ordinary storm, as predicted by scientists for over twenty years?


 Graphical Representation of 1:1000 Probability Event
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References
http://www.npr.org/2017/09/01/547598676/at-least-100-000-homes-were-affected-by-harvey-moving-back-in-wont-be-easy

Long-term temperature is about one degree higher than a few decades ago.    Local conditions were 2.7 degrees to 7.2 degrees F higher than usual.   Humidity rises at about 3 percent per degree C., so humidity during Harvey was 3% to 5% higher than usual.
High level winds that typically steer tropical storms collapsed in 2010.  Although a meteorologist expects the winds to return in a few years, long-term climate modeling suggests that collapse of steering currents may become more common.    

Speech by Mike Pence


Immediately prior to landfall, and during the time of intensification to category 4, Harvey over water 4 degrees F warmer than average.

Waters off South Texas were 5 degrees warmer than usual during Hurricane Harvey.

Warm water extended deeper into the water column.

Atlantic Decadal Oscillation is trending to cooler temperatures, which may bring cooler waters to the tropics and weaken storms in coming years.   Another researcher suggests that GHG warming may keep the ADO positive for the coming decade.

Background conditions were about 2 degrees warmer than average, and then warmed further by an eddy of the Gulf Stream Loop Current.

“The human contribution can be up to 30 percent or so of the total rainfall coming out of the storm”.  Hurricane waves usually bring cooler water to the surface, which acts as a buffer to moderate the strength of the storm.  But Hurricane Harvey churned up water 100 m to 200 m below the ocean surface, but this water was still warm. 

Graphics representing 27 trillion gallons (about 25 cubic miles) of water. 

Probability of Hurricane Harvey, based on historical statistics, is 1:1000.


Immediate death toll from Hurricane Harvey was 82.  A number of serious health effects could persist for years. 

Daniel Huber, Jay Gulledge, Center for Climate and Energy Solutions, Extreme Weather and Climate Change, 2011.
“There is a physical basis for expecting hurricanes to have stronger winds and produce more rainfall due to global warming, and models with enhanced greenhouse gas levels show an increase in the number of such storms….However, observational evidence is insufficient to confirm that such a response has already begun.”

IPCC Second Assessment Report, 1995.
"Direct impacts on infrastructure would most likely occur as a result of changes in the frequency and intensity of extreme events. These include coastal storm surges, floods and landslides induced by local downpours, windstorms, rapid snowmelt, tropical cyclones and hurricanes, and forest and brush fires made possible in part by more intense or lengthier droughts."
“It is presently uncertain whether the frequency and severity of tropical cyclones will increase due to climate change.”

O'Brien, S.T., B.P Hayden, and H.H. Shugart, 1992: Global climatic change, hurricanes, and a tropical forest. Climatic Change , 22 , 1750-1790.