J.C. Moore Online

Current Events from a Science Perspective

We must switch to renewable energy for health reasons, economic reasons, and environmental reasons.

Health reasons: The American Lung Association estimates that there are 26,000 deaths and 1.5 million cases of acute bronchitis and aggravated asthma caused by small particulates, much of it emitted from coal-fired power plants and from coal ash disposal. They estimate the economic benefits of reduced exposure to particulates alone could reach as much as $281 billion annually. Recently, fine particles have been implicated as a cause of Alzheimer’s and Parkinson’s disease and new research has revealed a troubling link between mental illness and air pollution that seems to particularly effect children.

Economic reasons: Besides reducing health care costs, a switch to renewable energy will help keep our future electric rates low. Wind and solar are falling in cost and are now competitive with energy from coal-fired power plants. Recently AEP/PSO in Oklahoma purchased 800 MW of wind energy saying the cost was now less than building new coal fired plants, and that the purchase will save an estimated $53 million in the first year and even more thereafter. Kansas currently has 27,000 jobs in the clean energy sector. Of those jobs 75% are in wind energy, and are growing at a rate of 2.3% per year.  By the end of 2016, 32% of Westar’s retail electricity will come from the wind.

Environmental reasons: Coal is 65 to 95 % carbon. What about the rest? Burning coal releases mercury, chromium, lead, cadmium, arsenic, sulfur oxides, nitrogen oxides, carbon dioxide,  particulates, and radioactive isotopes. Burning  coal releases millions of tons of pollutants into the air and leaves several hundred million tons behind in the coal ash. Some pollutants stay in the air and others eventually find their way into the water, the food chain, and into us. For comparison, mercury is 100 times as toxic as cyanide, arsenic is 20 times as toxic, and chromium(VI) is 4 times as toxic. These three are also are carcinogenic and accumulate in tissue. Even exposure below the allowed levels increases the chance of cancer over time. The sulfur, nitrogen oxides, and carbon dioxide released by coal combustion harm plants, produce acid rain, and increase the greenhouse gas concentrations. Switching to renewable energy would greatly reduce these  pollutants and help preserve the environment for future generations.

Summary: Investing in clean energy protects the environment, reduces death and disease from air pollution, and creates good, local jobs. We must develop policies to encourage the development of renewable energy investments and energy conservation. Our energy needs will best be served by a mixture of traditional and alternate energy sources, and we must be proactive in developing our renewable energy resources.

(c) 2016 J.C. Moore

 “All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be….  ”  – Trenberth

 

Kevin Trenberth, senior scientist at the National Center for Atmospheric Research, explains that asking for proof that global warming causes severe weather, is asking the wrong question. “All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be. The main way climate change is perceived is through changes in extremes because those are outside the bounds of previous weather. The average anthropogenic climate change effect is not negligible, but nor is it large, although a small shift in the mean can lead to very large percentage changes in extremes. Anthropogenic global warming inherently has decadal time scales and can be readily masked by natural variability on short time scales.”

Scientists  have been very cautious about linking severe weather events to global warming, but the link is getting stronger each year. The Earth has warmed an average of 0.82 over the last century, which doesn’t sound like much, but it means that some places have warmed much more than in the past. Since the amount of moisture the air can hold depends on the temperature, the air can now hold about 6% more moisture. Before 2010, scientists would cautiously point out that higher temperatures lead to the likelihood of drought, and that more energy and moisture in the atmosphere was a recipe for severe weather. But how is it possible to establish that weather events were becoming more extreme?

There are many reports like the interim report by the Climate Council in Australia which found that, in the period between 1971 and 2008,  heatwaves in Australia were becoming more frequent, increasing in intensity and are lasting longer. The report said climate change was  having a key influence on a trend that has seen the number of hot days in Australia double and the duration and frequency of heatwaves increase. Reports like that were not good enough for the skeptics. By 2011 a good case was established that global warming was causing heat waves and droughts in the U.S., but the case was not strong enough to overcome the Skeptics objection, even when in 2012, a definite probability link  was established for  extreme temperatures and droughts. 

To understand whether a weather event is extreme, it must be compared to the norm. This can most easily be done for temperatures, as we have over a century of temperature records from almost all parts of the world.

Example of a Normal Distribution – Click to Enlarge

There is enough temperature data that normal distributions can be graphed, which allows us to quantify  the probability of a temperature event. In the example at the right, the maximum in the curve is the mean of the data. The probability of the occurrence of an event can be measured by the number of standard deviations, sigma(σ), a particular value is from the mean. The values within 2σ of the mean, blue, are considered to be in a mostly normal range. Those from 2 to 3σ, yellow, are considered to be exceptional events, and those beyond 3σ, red, are considered to be extreme. Those yearly events that fall in the yellow range are considered to be 100 year events while those that fall in the red are 1000 year event.

As an example, the normal distribution graph to the right is for the temperatures in Moscow since 1950.  The maximum in the curve is the average temperature, which is set to zero, and the temperature for other other year is described as a temperature anomaly, i.e., how far it is above or below the average value. The curve approximates a normal distribution so the standard deviation of the temperature anomalies can be used to decide whether an event is extreme. The temperatures for 1972  and 2001 fall in the hundred year event range, while  that for 2010 would only be likely to occur only once in every hundred thousand years, unlikely, but still possible.

The Skeptics would still not be convinced, claiming that the link to global warming climate change causes severe weather was not proven, but proof is not necessary when probabilities for a large number of events are involved. For instance, you have only a 50% chance of calling a coin toss correctly, but you can likely guess the number of heads on 1000 flips with less than 1% error. Small differences in probabilities lead to big outcomes. The rules of blackjack give the house a 50.5% to 49.5% advantage, and though some players may win thousands on a lucky streak, considering all the bets placed, the house will make millions from that small difference in probability. And, probabilities are useful for predictions. A 0.270 hitter may get the game winning hit at his next bat while a 0.300 pinch hitter may strike out, but with the game on the line, the coach will likely pinch hit. If trying to predict the future, it is better to go with the probabilities. Though  it is not possible to prove that any one weather event is caused by global warming , scientists have observed a change in probabilities of severe weather events over long periods of time. With the thousands of weather events that occur on the Earth each year,  a small change in probability can cause an definite change in the number of severe weather events.  

An even more convincing argument can be made that global warming causes severe temperatures if the normal distribution is examined as a function of time. Research by James Hansen has established the link by showing that the normal distribution has changed since 1951. The curves show that beginning in about 1970, the mean begins to move to the right and the the curves flatten, showing that the probability of extreme temperatures increase greatly from 1950 to 2011.  His work shows that the probability of extreme temperatures is 10 times as great as for the 198o to 2010 years.

It should also be noted that the left side of the graph flattens, but that the probability of extremely cold temperatures is not zero. There is still a significant likelihood of cold temperatures -and a cold winter now and then does not disprove global warming.

The Skeptics are still claiming that is not proof enough, and that the data says nothing about droughts and wildfires.  There are still some Skeptics who argue that this does not mean  heat waves necessarily related to droughts or that the droughts are causing the increase in wildfires we have experienced, but their arguments seem to be improbable. It should be clear by now that no amount of evidence will convince Skeptics who wish to ignore probabilities.

(C) 2014  J.C. Moore

This is a letter I sent to Congressman Frank Lucas (R – OK) on August 5, 2013. I asked him at his town hall meeting on November 7, 2013 if he had received it, and he could not recall it. It was a 15 page letter which contained anecdotal evidence plus the latest evidence from climate research in full color pictures and graphs. In case he misplaced it, I have reproduced the letter here in hopes he might run across it while looking for my write-up on his town hall meeting. It would seem that this information would be of vital interest to him as he is Chairperson of the Agriculture Committee, charged with the security of our food supply. 

Dear Congressman Lucas,

I’m sure you’re aware of the Pearson drought index which shows that most of Oklahoma, much of the Southwest United States, and much of the Earth’s land area where food is grown  is under moderate to severe drought conditions. It seems that lately the coastal areas of continents have been receiving more rainfall while the interiors have been experiencing more drought. I’ve lived in Oklahoma most of my 70 years and in my recollection, it seems that we are now seeing heavier rains in the spring and longer and more frequent droughts in the summer.

  My family has lived in Oklahoma since statehood and I have a number of anecdotes about how the climate is changing. Our Thanksgiving family photo in 1998 was taken in front of one of my Dad’s apple trees, which still had green leaves. He remarked at the time that he had never seen frost come so late, and he was 88 at the time. A few years ago our plant hardiness gardening zone was changed from a 6 to a 7, acknowledging later frosts and warmer winters. Armadillos are now abundant in Oklahoma, though there were none here when I was growing up.

 Anecdotes do not serve as proof, but they do raise questions about what the theories and evidence is saying. The greenhouse gas theory is solidly based upon the laws of physics. Though greenhouse gases comprise only 1 to 3% of the atmosphere, depending on the humidity, they are responsible for the Earth being about 33°C warmer than its would be without them. It seems reasonable that an increase in the greenhouse gases would cause the Earth to warm. Though water is by far the most abundant greenhouse gas, its concentration in the air is limited by its saturated vapor pressure. Carbon dioxide, though less abundant, absorbs strongly in the infrared and is not restricted in concentration as water is. Studies of the ice ages have identified carbon dioxide and changing solar irradiance as being the main factors in determining the Earth’s temperature.

 We are now putting about 30 billion tons of carbon dioxide into the air each year and measurements show that the concentration in the air is increasing. The increasing partial pressure of CO2 is causing more to dissolve in the oceans, decreasing their pH by about 0.1 pH unit.  That doesn’t sound like much, but the oceans are a carbonate buffer system and that translates into the oceans now being more than 20% acidic, threatening, shellfish, corals, and the plankton which convert much of the ocean’s carbon dioxide back to oxygen.

Biologists have observed that some species are migrating northward and to higher altitudes. There is evidence that glaciers are receding and that ice at the poles is declining. The declining extent of sea ice in the Arctic seems to be affecting the jet stream, which greatly affects our weather patterns. Though it is not possible to prove that global warming is the cause of any one weather event, it likely has an effect on most of the weather events that do occur, since the amount of energy and moisture in the air are the main determinants in weather events.

 There are always uncertainties in scientific measurements, and even greater uncertainties in predictions about the future. It is always possible to dispute any one piece of evidence based upon those uncertainties, but when a large number of independent measurements lead to a similar conclusion, the confidence level increases – but never reaches 100%.  I hope you will examine the evidence presented in the rest of this letter and agree that the preponderance of the evidence shows that we should take some action to address climate change.

 Republicans have a history of being strong advocates for science, environmental responsibility, and sound fiscal policy. Nixon created the EPA, Reagan signed the Montréal protocol limiting fluorocarbons and used cap-and-trade to reduce greenhouse gas emissions blowing into Canada, and archconservative Barry Goldwater once said that, ” The persistent myth that conservation and environmental protection are liberal causes continues to be perpetuated by the media, liberals and many self-professed ‘conservatives’. The truth is that conservation and environmental stewardship are core conservative values”.

 I hope you will examine the evidence presented in the rest of this letter and consider taking a leadership role in addressing the climate change issue in a manner that is consistent with Republican principles. In many ways, the world’s food supply is at risk.

The rest of the letter contained the images and descriptions from this article: http://jcmooreonline.com/2011/08/31/bits-and-pieces-10-global-warming-in-pictures/.

(c) 2013 J.C. Moore

A large body of scientific evidence, going back to the middle of the 19th century, links the concentration of atmospheric carbon dioxide,  the temperature of the Earth, and the Earth’s climate. Those who study the Earth and its ecosystems have found ample evidence that the climate is changing. The USDA recently acknowledge that fact by shifting the plant hardiness zones for gardeners northward, acknowledging that frosts occur later in the fall and the last freeze in spring occurs earlier. However many people still doubt climate change and point to weather events as evidence.

Theory: Climate scientists would like to clearly establish the link between climate change and extreme weather events, but that is difficult because of the natural variability of the weather.  The link between global warming, heat waves and droughts would seem unquestionable, but it is difficult to prove. Global warming has increased the energy and moisture in the atmosphere, making conditions for severe storms and floods more likely.  In the last century, the Earth’s average temperature has increased by about 0.8°C, increasing the amount of water the air can hold by about 7%.  It is a reasonable conclusion that when it rains, it will rain more and when it snows, it will snow more. So strangely enough, global warming could actually lead to greater snowfall.  (1) However, it has been very difficult to prove, and certainly even more difficult to convince skeptics that that might be the case.

Climate Models: Another approach to linking extreme weather events to global warming has been through the use of climate models. The models take into account the factors that influence climate and weather, and are often used by meteorologists for “future casting” the weather for 10 day forecasts, which is about as long as normal weather patterns last. However, the models may also be used to examine the effect of global warming on the weather events. The models are used to compare the prediction for a weather event assuming that there is no global warming with a prediction of the weather event that includes global warming. In many cases, it can be shown that the weather and rainfall will be more extreme under the global warming conditions. The results are often challenged by climate Skeptics, who claim that the models do not accurately represent the data, or that the models are “falling apart”. The models were developed to fit a century’s worth of the weather and climate data, and there is little evidence to support the Skeptics claims. However climate scientists would like to show a definite link between global warming and weather events to silence those criticisms.

Statistical Evidence: A recent NOAA report, edited by Petersen, et al. (2) , examined 6 extreme weather events that occurred in 2011 and found that there was a link between climate change and the extreme weather event. One of the most interesting reports (3) ,  found that the 2011 heat wave and drought in Texas were 20 times more likely to happen than they would have been in the 1950’s. How did they arrive at that conclusion? A recent paper by Hansen et al.  (4), shows that extreme temperatures are much more likely to occur worldwide than in the 1950’s, and over 10 times as likely to occur as in 1980. As Hansen puts it, the extreme temperatures “which covered much less than 1% of Earth in 1950, now typically covers about 10% of the land area. It follows that we can state, with a high degree of confidence, that extreme anomalies such as those in Texas and Oklahoma in 2011 and Moscow in 2010 were a consequence of global warming because their likelihood in the absence of global warming was exceedingly small.”

Those two papers are important as they have been able to establish a quantitative link between the probabilities of weather events and global warming. More importantly, the link does not depend on theory or on climate models, and relies only on a straight forward statistical analysis of the data. The method depends on computing the normal distribution of the Earth’s temperature anomalies for each decade and then comparing how the distribution of extreme weather events change with time.

Normal distributions:  Before examining how the method works for weather events, it might be useful to examine how it works with something more familiar, like the height of American men. How could we show whether the number of extremely tall men was increasing as time went by?  This could be done by taking a representative sample of men and examining a graph of the normal distribution. We could find the average, μ , and then repeat the process every 10 years to see how the average changed with time. An increase in the average height might indicate that there would be more extremely tall men, but that is not the full story.

Another piece of information that needs to be considered is the variance, or how widely the height of men vary about the mean. The variance is usually measured by the standard deviation , σ, which can be easily calculated from the measurements done to compute the mean. A  graph of the normal distribution  is shown at the right.  “Normal” means that the data has been divided by the total number of men in sample, so that the area under the entire curve represents 100%. That feature is very useful for comparing heights, and it also allows us to associate an area under the curve with  probabilities.

The average height, μ on the graph, is 5’10”, and the standard deviation, σ, is 3 inches. About 95% of the sample falls within 2 standard deviations of the mean, which also says that the probability is 95% that a man selected at random would fall between 5’4″ and 6’4″. Those over 2σ  from the mean, or 6’4″, make up about 2% of the sample and are considered very tall. Finally, those over 3σ  from the mean , over 6’7″, are considered extremely tall and make up only 0.15 %. Michael Jordan and a host of other National Basketball Association players fall into that 3σ category.

How would it be possible to tell whether the incidence of extremely tall men is increasing? One way would be to take height data collected every 10 years, plot the normal distribution, and see how the area of the graphs out past 3σ change. We could not only tell whether there were more extremely tall men, but we could calculate how the probability of finding an extremely tall man changed, just by comparing areas on the graph.

Weather events. Enough data and computing power is now available to calculate normal distributions of temperature data every 10 years for many decades. Having the normal distribution of the temperature data by decade can be used to find whether the probability of extreme temperatures is increasing or decreasing. The Earth’s temperature was fairly stable from about 1950 to 1980, making it a convenient standard for comparing changes. Rather than using temperatures, the graph uses temperature anomalies, which measure how far a temperature reading was above or below average. 

The procedure is similar to the one described for examining the height of men. Hansen, et al. used the Earth’s temperature data to graph normal distributions of the Earth’s temperature anomalies by decade, from 1950 to the present. They found that the distribution of temperature anomalies approximate a normal distribution. 

The results of their work for the summer months show that beginning in about 1970, the mean begins to move to the right toward higher temperatures. It can also be seen that the variance of the data increased and shifted to the right, showing that the probability of extreme temperatures increase greatly from 1950 to 2011.  It can be seen that the number of extreme temperatures, those out past 3 ( meaning 3σ), almost nonexistent in the 1950s, have grown significantly larger in each decade after 1980. A similar graph, using  σ for the last 30 year period (not shown), found the probability of temperatures past 3 sigma is 10 times as great as for the 198o2 to 2010 years.

It should also be noted that the left side of the graph flattens, but that the probability of extremely cool temperatures is not zero. Though  hot temperatures became more probable, that there was still a significant likelihood of cooler temperatures.

Climate Skeptics often argue that an extremely cold weather event disproves global warming. The normal distributions by decade for the winter months is given at the right.  The graph shows the average winter temperatures have increased significantly during the last 30 years and the variance in the temperature has become greater as time progressed. However, the left side of the graph shows there is still a significant probability of extremely cold weather even though global warming is occurring. This means that the skeptics argument is baseless. It is also sometimes argued that extreme snowfalls disprove global warming, but that is also a baseless argument. Extremely cold air can hold little moisture, and it is warmer air, slightly below freezing, that produces the greatest amount of snow. The Inuit know that a warm spell brings a much greater chance of snow.

So there we have it. Climate physics predicts that global warming should cause higher incidences of extreme weather. Climate models find that global warming makes increased rainfall and storms more probable. A straightforward statistical analysis of temperature data not only shows that extreme temperatures are more likely, but has allow climate scientists to calculate how global warming affects the probability of extreme temperatures. A definite link between global warming and extreme weather has been established by the research.

 (1) http://jcmooreonline.com/2011/03/22/the-case-of-global-warming-and-extreme-weather/ 

(2) http://www1.ncdc.noaa.gov/pub/data/cmb/bams-sotc/2011-peterson-et-al.pdf 

(3) http://usnews.nbcnews.com/_news/2012/07/10/12665235-2011-texas-drought-was-20-times-more-likely-due-to-warming-study-says?

4) http://www.pnas.org/content/early/2012/07/30/1205276109.full.pdf+html

(C) 2012 J.C. Moore

Science is about using observation and reason to understand the physical world. Some people are suspicious of computer models and theories; so here is some of the the basic data in pictures and graphs.

Ice Ages: In the past, the Earth’s temperature has varied from the Ice Ages to the much warmer temperatures of the interglacial periods.  Ice core data gives a good picture of what has happened to the Earth’s temperature in the last half million years, as shown by the blue line. The changing temperatures are attributed to the  Milankovitch cycles,  small variations in the Earth’s orbit that cause the Earth to receive different amounts of sunlight. The Earth becomes slowly warmer during the periods where the solar energy increases. As the Earth begins to be warmed by sunlight, CO2 becomes less soluble in the ocean and the CO2 concentration in the atmosphere increases, which further amplifies the warming since CO2 is a greenhouse gas.  The CO2 did not rise above 300 ppm in any of the the warmer interglacial periods but it is now 398 ppm and rising.

  CO2: Man is now putting about 30 billion tons of carbon dioxide into the air each year. About half of it dissolves in the ocean, making them 20% more acidic, and the rest increases the concentration in the air.

Temperature: CO2 is one of the greenhouse gases that warm the Earth, and NASA’s graph shows how its increase is changing the Earth’s temperature:

.                            NASA GISS Data.

The Sun: The current global warming is often wrongly attributed to an increase in intensity of the sun. The sunspot activity does not show up above the noise in the temperature record above – and the solar irradiance increased slightly until 1960 and has declined slightly since then.

Arctic Ice: Many of the changes in the Earth are subtle but this NASA picture clearly shows  how the Earth is changing:

Arctic ice:  The next two graphs show quantitatively how both the extent and the volume of the Arctic ice is changing.

Arctic ice volume at each years minimum.

Antarctica: Research by Steig and by O’Donnell  show that Antarctica is warming. The warmer oceans result in more snowfall which increases the inland glacier mass, but the erosion of ice by the warmer oceans is causing an overall loss of ice mass.

Antarctic ice mass from GRACE satellite data.

Greenland: The Greenland ice sheets are also beginning to decline.

Ocean Level Rise: The melting ice sheets, melting glaciers, and thermal expansion are causing the oceans to rise by about 3 mm per year which, though it seems small, amounts to an increase in ocean volume of 1190 cubic kilometers/yr.

Rise in Sea Level.

Severe Weather: Warmer temperatures increase both the rate of evaporation and the energy and moisture in the air. This has doubled the incidence of severe weather, floods, droughts, and wildfires.

Permission Courtesy of Munich Re.

Economic Costs: Large insurance companies such as Suisse Re now consider global warming a risk factor as there has been a fivefold increase in billion-dollar weather events in the last 30 years.

Droughts: The Palmer Drought Index below includes most of the continental areas used for food production. Zero represents average rainfall and -4 represents extreme drought. Since 1980, drought conditions have grown worse worldwide, and no one disputes the effect of droughts on food production.

Note : This was posted on 08/31/2011 and  updated on 04/03/2012,08/11/2012, and o2/12/2013.

(c) 2011  J.C. Moore

2011 Wildfire Terlton OK

In 1998, the US refused to ratify the Kyoto Treat which would have limited the release of greenhouse gases, primarily CO2, into the atmosphere. The refusal was based mainly on the highly inflated financial costs, without adequately considering the costs of inaction. On a per capita basis the US emits six times as much CO2 as any other country. Without our participation and leadership, the world has failed to stem the release of CO2 into the air, and scientists tell us that this is leading to a warmer Earth, more extreme weather, crop failure, droughts, and wildfires. We have  certainly experienced many of those things recently and it should make us think about what our failure to ratify the Kyoto Treaty may mean to us.

Three weeks ago the local Cleveland American’s front-page story was about the heat wave and the drought. Channel 6 Weather reported that this year Oklahoma set a record for highest temperatures of any state, ever. Recently, NASA reported this has been the hottest decade since records began in 1880, with 2010 and 2005 tied for the hottest years. A recent poll of climate scientists found that 97% of those active in research agree that the Earth is getting warmer and the main factor is man’s release of carbon dioxide into the air. The other 3% of the scientists get enough publicity to keep the public confused, especially since the climate scientists cannot claim certainty in their predictions, but only increased chances.

A recent paper from the University of Colorado predicted that global warming would cause higher probabilities of extreme weather, heat waves, droughts, crop failure, and wildfires. We’ve certainly seen all that happen this year. Last week, the Cleveland American’s front page story was on the devastating wildfires in the surrounding Pawnee County. Around 15,000 acres of our county burned, 40 homes when up in flames, one person died, and many were injured.  It stretched the resources of our emergency services to the limit and had it not been for the heroic efforts of our firefighters, many of them volunteers, the devastation would have been much worse.

Skeptical scientists, and many of our politicians, dispute the scientific evidence and claim there is not really a problem. They say that efforts to stop global warming will cause us too much inconvenience and expense. We might want to think about how inconvenient and expensive it is for us to lose our crops, homes, and in some cases our loved ones?

“We know who the culprit is, we just can’t prove it – yet.”  Detective Dick Tracy

The Case. That statement could have been uttered by climate scientists. They know global warming is the cause of the more extreme weather events we are experiencing, but it is hard to prove it.  Global warming has increased the energy and moisture in the atmosphere, and that combination makes conditions ripe for severe storms and floods. Certainly, hurricanes occur and intensify over low-pressure areas fed by moisture and warmer oceans. To be accurate, however, climate scientists could only say, “When weather events occur, global warming is likely to make them more extreme.”  However, the case against global warming is growing stronger. A number of recent research papers have shown global warming is the cause of extreme weather events, and the business community, particularly insurers, are beginning to take notice. (1)

The Link. The vapor pressure of water is one of the most important factors in determining weather. Water will evaporate from the surface until the air above it reaches its saturated vapor pressure. The saturated vapor pressure depends only on the temperature, which makes temperature the determining factor controlling the amount of moisture that the air can hold. (2) If a mass of air saturated with moisture moves to higher altitudes or encounters a cold front and is cooled, the air becomes supersaturated, which leads to precipitation. Over the last century, the Earth’s average temperature has increased by about 0.8°C, which translates into an increase in the saturated vapor pressure of water of about 7%. When precipitation occurs, on the average, 7% more moisture is available. It is a reasonable conclusion that when it rains, it will rain more and when it snows, it will snow more. So strangely enough, global warming could actually lead to greater snowfall. However, it has been very difficult to prove, and certainly even more difficult to convince skeptics that that might be the case.

Floods. Two recent research papers have established a link between global warming, increased rainfall, and flooding. A recent paper in Nature (3) reported that the observed increase in rainfall in the Northern Hemisphere in the past 50 years and climate change are linked. The researchers analyzed the rainfall data in areas prone to flood and found that the rainfall has increased due to the warmer temperatures of the Earth. Their results “were based on a comparison of observed and multi-model simulated changes in extreme precipitation over the latter half of the twentieth century analyzed with an optimal fingerprinting technique.” They also found that the models seem to underestimate the observed increase in heavy precipitation with warming temperatures. Extreme precipitation in the future may be even more severe than now predicted.

The second paper, also published in Nature (4), has linked the increasing floods in England and Wales and global warming. The researchers generated several thousand climate model simulations of the autumn 2000 weather by using actual conditions and also by assuming conditions as they would have been had no greenhouse gas emissions or global warming occurred. They concluded that “the precise magnitude of the anthropogenic contribution remains uncertain, but in nine out of ten cases our model results indicate that twentieth-century anthropogenic greenhouse gas emissions increased the risk of floods occurring in England and Wales in autumn 2000 by more than 20%, and in two out of three cases by more than 90%.

Rivers in the Sky. Normally, when an air mass saturated with water moves ashore and is forced upward, it  cools and precipitation falls until the clouds are no longer over-saturated. However, that is not the case for “rivers in the sky, weather patterns that carry a stream of air saturated with water into coastal regions  continually for days. These  “rivers in the sky”,  cause flooding rains in coastal and inland mountains causing untold costs in property damage and human lives. One such river produced more than 40 inches of rainfall in the mountains of southern California in only four days in early January 2005. It caused widespread flooding and massive mudslides such as the one in La Conchita, California, which took 10 lives. The researchers say these “rivers in the sky” will become more common as global temperatures rise since warmer air means that the atmosphere can hold more water vapor. That is, unless global warming changes the weather patterns that produce them. (5)

Droughts. The link between global warming and droughts has not been yet established by research. Areas that receive little moisture from the oceans would not benefit from the fact that the air can hold more water. Though higher temperatures mean that more water evaporates into the air, it also means that the air can hold more moisture before becoming saturated. Areas that normally experience droughts are much more likely to have less rainfall in the future. This past year has seen droughts in Russia, China, and South America that have limited the production of grain and increased the chances that some species may become extinct. The heat waves in Europe in 2003 and 2010, that caused widespread crop failure and wildfires, may have been the worst in 500 years. Certainly, more frequent and extensive droughts may occur in a warming world. (6)

The Smart Money. The widespread damage caused by weather events related to global warming has caught the attention of the business community, particularly those who pay out insurance claims or invest large sums of money. Insurance companies ranked 2010 among worst years ever for climate disasters. Climate change is the culprit in many of the catastrophic natural disasters in 2010, according to insurance company Munich Re, one of the largest global insurance carriers. It added that trends are pointing to more frequent and riskier events in the future. (7) Recently, a group of International investors, responsible for more than $15 trillion in assets, issued a global warming warning. (8) They called for the world’s nations, particularly the United States, to move decisively to combat climate change or face the possibility of economic disruptions even worse than the global recession of the last two years. They also pointed out that “The economic opportunities are enormous for nations with the foresight to seize them while the risks of inaction are potentially catastrophic.”

(1) http://www.smartplanet.com/business/blog/intelligent-energy/studies-prove-link-between-human-activity-and-extreme-weather-events/4835/

(2)  http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/relhum.html#c3

(3) http://www.nature.com/nature/journal/v470/n7334/full/nature09763.html

(4) http://www.nature.com/nature/journal/v470/n7334/full/nature09762.html

(5)  http://www.noaanews.noaa.gov/stories2005/s2529.htm

(6) http://www.sciencedaily.com/releases/2011/03/110318091141.htm

(7) http://www.scientificamerican.com/article.cfm?id=insurance-ranks-2010-worst-for-climate-disasters&page=2

(8)  http://www.latimes.com/business/la-fi-climate-financiers-20101117,0,6204171.story

(C) 2011 J.C. Moore

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