by Timothy Lane 5/24/14
Alarmist watermelons (green on the outside, red on the inside) use climate as their favorite means of scaring the public. Go back a few decades and their concern was global cooling (which in fact remained a concern well into the 1980s, as I know from a book I bought then), but already global warming was mostly beginning to replace it as a major concern. This became especially popular in the 1990s even though the evidence didn’t really support it; one thing I noticed is that the alarmists would proclaim the case settled, then a few years later would admit that it hadn’t been settled before but was now, and then a few years later . . . It doesn’t take many such backtracks to sacrifice credibility, at least to those who are paying attention.
As one who had been studying environmental concerns since I was in college, I picked up books on the subject, and even moderated panels at the World SF convention in Winnipeg in 1994 on global warming and ozone-layer depletion. But then came the El Nino of 1998, and since then there has been no significant net warming. Several years ago the alarmists decided to change their buzzword from “global warming” to “climate change” because of this. The problem is that climate is always changing, and over time more and more people came to realize that “stopping climate change” (as the zealots called for) was akin to Canute stopping the waves. (One version of this is that Canute was trying to teach his sycophantic court a lesson, in which case he was far more sensible than modern environmentalists.)[pullquote]Several years ago the alarmists decided to change their buzzword from “global warming” to “climate change” because of this. The problem is that climate is always changing, and over time more and more people came to realize that “stopping climate change” (as the zealots called for) was akin to Canute stopping the waves.[/pullquote]
As it happens, several years ago I wrote a quartet of articles, 3 of which are related to this subject, for The Encyclopedia of Environmental Issues from Salem Press. I’ve mentioned these occasionally in commenting on the subject in various blog posts, and it occurred to me that I could include them here (not precisely due to copyright restrictions – even if Salem Press is no longer around, unfortunately). So I will include here my article on Global Warming, with additional material from my articles on Climate Change and Human Health and Climate Models. I had wanted to do the article on Climate Change Skeptics, and was especially concerned that an alarmist would get the topic and use it to smear skeptics, but instead that article was written by a skeptic with excellent credentials, Professor C. R. de Freitas.) So here goes:
Scientific findings on global warming are extremely important for policy-makers. Harmful consequences may result if the catastrophic anthropogenic global warming (CAGW) theory is correct and policy-makers don’t take the actions necessary to address the problem. Conversely, harmful consequences may result if the CAGW theory is not correct and policy-makers make decisions based on the belief that it is.
According to the IPCC, overall global temperature increased by about 1 degree Celsius during the 20th Century. This involved an increase of about 0.5 degrees from 1910 to 1945 and a similar increase from 1975 to 2000 (actually peaking in 1998), with a very slight decrease in the intervening years. These figures are approximate because of uncertainty of data and yearly fluctuations (which can be as large as 0.25 degrees up or down), as well as the complexity of adjusting the raw temperature data. Explaining these increases and projecting future trends and their consequences are the key issues addressed by the scientists who examine global warming.
Two basic theories have been posited regarding the source of the warming, both of which could be partially correct. Some see the warming as basically natural (as many scientists agree was probably the case for the pre-1945 warming that predates most of the increase in atmospheric carbon dioxide). Short-term natural causes have definitely occurred, such as volcanic eruptions (the Mount Pinatubo eruption of 1991 led to a strong temperature down-spike in 1992) and the El Nino/La Nina cycle (the very strong 1998 El Nino led to a very large temperature up-spike that year). In addition, some long-term fluctuations, such as the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation, affect global as well as local temperatures. Also, solar energy isn’t constant; there are cyclical variations correlated with sunspot activity. These don’t seem sufficient to explain the post-1975 warming; Patrick J. Michaels and Robert Balling in Climate of Extremes: Global Warming Science They Don’t Want You to Know (2009), estimate that natural causes explain only 25% of the post-1975 warming as compared to 75% of the earlier warming. Some scientists think the rest can be explained naturally (such as by the effect of solar activity on cosmic rays reaching Earth, and the cosmic rays’ effect on cloud formation).
These scientists think the current warming is natural, part of a large cycle in which the Medieval Warm Period was followed by the Little Ice Age, which was then followed (after about 1850) by the Modern Warm Period. A wide array of historical temperature proxies show a roughly 1500-year cycle, with shorter heating and warming subcycles. Unstoppable Global Warming: Every 1,500 Years by S. Fred Singer and Dennis T. Avery (2008) uses ice cores dating back hundreds of thousands of years, 6000 boreholes from all continents, seabed and lake-bed sediment cores, tree rings and tree lines, cave stalagmite cores, peat bogs, and historical records (such as a Japanese monastery’s report on the yearly freezing of a nearby lake). These show remarkable shifts, such as global temperature increasing about 1 degree Celsius for about a decade at the end of the Younger Dryas (11,500 years ago) for reasons still unknown (there was an increase in greenhouse gases after the rise).
Singer has estimated that the Medieval Warming Period exceeded the current warming (so far). Others dispute this. Michael E. Mann argued (using a limited number of historical proxies, and then current temperature estimates without comparing them to more recent proxy results) that global temperatures barely changed until the 20th Century.
One possible anthropogenic influence on climate is land use. These effects are important, but mostly local. Cropland is warmer than forest, and urban areas as much warmer than cropland (the urban heat island effect). Overgrazing can lead to desertification, which also makes the land warmer.
The strongest anthropogenic effect comes from the production of greenhouse gases such as carbon dioxide. Water vapor is actually the most important greenhouse gas overall, and methane is far more powerful than carbon dioxide, but a trend toward increasing atmospheric methane halted in the mid-1990s. Carbon dioxide has been the greenhouse gas causing the greatest concern. Since the beginning of the 20th Century, carbon dioxide in the atmosphere has increased from 290 ppm to almost 380 (as of when I originally wrote this). The increase in the greenhouse effect is far smaller than the increase in greenhouse gases, particularly in areas with high humidity, due to the climatic equivalent of the Law of Diminishing Returns (water vapor and carbon dioxide block the same infrared wavelengths). Greenhouse gas warming is highest at night and therefore in winter (especially in upper latitudes), and in the atmosphere it leads to a warmer troposphere and a cooler stratosphere.
Computerized climate models can be used for historical research as well as future projections. The key models in climate research are general circulation models. An ideal GCM would take every climate factor into account, but in practice some factors are ignored or simplified. Among these factors are volcanic eruptions, solar radiation, natural weather oscillations (lasting from a few years to several decades), the water cycle (evaporation, condensation into low-level clouds, and precipitation all move heat between the surface and troposphere), atmospheric content (including greenhouse gases such as water vapor and carbon dioxide as well as pollutants such as sulfur dioxide), ocean currents, wind patterns, and land use. None of these is entirely predictable, and some are random in occurrence. Local events can have global effect; for example, El Nino conditions in the southern Pacific lead to weaker Atlantic hurricanes (due to wind shear) and changes in precipitation in many areas.
Very complex GCM provide information on how either natural or greenhouse gas warming is likely to affect climate all over the globe and into the atmosphere, and these projections can be tested against observational data. Such testing is as necessary for the predictions made by computer models as for those produced by any other scientific theory; results must be shown to be replicable by others and the results must be available for examination by other (which is why the refusal of the Hadley Research Unit to provide its data to skeptics was a serious violation of proper scientific practice). One problem with the testing of climate models is that observational data is often too recent (satellite tracking of hurricanes only began in 1970 and satellite measurement of Arctic sea ice in 1979, for example) to allow scientists to determine reliably whether any changes represent coincidental long-term oscillations or result from the warming trend.
The models used by the IPCC generally project a temperature increase of 2 to 3 degrees Celsius by the year 2100. Part of this is expected to come from natural causes, part from increased atmospheric greenhouse gases, and part from positive feedback effects such as increased humidity from evaporation and increased summer slow melt (bare ground absorbs more heat). All of these are speculative numbers. In reality, temperature rise since 1975 was far less than projected. Part of this may result from the cooling effect of sulfate aerosols (another speculative number), but part may also result from negative feedback effects such as the water cycle (especially cloud formation, usually ignored in climate models). Scientists continue to disagree about the effect of global warming on cyclones and other severe storms; there’s no observational evidence so far that warming leads to more storms or more severe ones. Climate models also make predictions about regional conditions (such as increased drought in the southwest United States) that are unverifiable so far.
Early models greatly exaggerated the warming and couldn’t match the previous history. More recent models that added in sulfate aerosols are more accurate, but failed to predict the absence of net warming since 1998 or the lack of warming in the Southern Hemisphere with its lower sulfate aerosol levels (they basically used on unknown to check another). Climate models predict different results from natural and greenhouse gas warming, and many observations (such as the greatly increased Arctic warming) support the latter, but not entirely (such warming has not been reported in Antarctica). The models predict that greenhouse-gas warming will lead to a cooler stratosphere (which is happening) but a warmer middle troposphere (which has in fact warmed less than the surface).
Michael E. Mann and Lee R. Kump in their study of the 2007 IPCC report (Dire Predictions: Understanding Global Warming) praised James Hansen of NASA’s Goddard Institute for Space Studies and his presentation of 3 projections in his 1988 testimony to Congress on global warming. The most severe scenario projected an increase of just over 1 degree in the next 30 years, comparable to the high-end projection of 3 degrees in a century, but started to diverge from reality within a couple of years. The middle scenario projected an increase of less than a degree, roughly comparable to an increase of 2 degrees over a century; the lower scenario projected an increase of 0.25 degrees in 30 years, or about 1 degree or less over a century. (They didn’t explain the difference, but I’ve seen reports since that Hansen was basing his different estimates on carbon dioxide levels, which would put the expected increase between the first 2 scenarios.) The last 2 tracked closely with each other until about 2005, but the continued warming pause since then show that the lowest scenario has so far been the most accurate.
Global warming may have many effects. The Medieval Warm Period was beneficial to European and Arctic agriculture but often led to droughts elsewhere (including the drought believed to have caused the collapse of the Anasazi culture). Similar effects can be seen today, such as the decline in the snowpack on Mount Kilimanjaro (which seems to result primarily from local aridity rather than warming).
Warming also leads to a sea-level rise of 1-2 cm per decade, which could increase if the Greenland and/or Antarctic ice packs (but not ocean ice shelves) melt significantly, which could also seriously alter ocean currents. Also with warming, warm-weather crops can be grown further north, and warm-weather habitats can invade cold-weather habitats. Direct deaths from warm weather would increase, but deaths from cold weather (which are much higher in temperate zones) would decrease. (In Europe, annual deaths amount to about 1.5 million from cold weather and 200,00 from heat; the warmer United States had about twice as many deaths from cold as from heat between 1979 and 1997.) Even the severe August 2003 heat wave that led to 35,000 deaths in Europe (half in France, many because the doctors were all on vacation) led to only a modest increase in heat deaths that year.
Drought in many places can make obtaining water supplies more difficult even as population continues to grown in some of them (such as sub-Saharan Africa). This can force people to labor more to acquire water that is often tainted, leading to increases in diseases such as dysentery, typhoid fever, and cholera as well as aquatic parasites such as guinea worms. Scarcer water also causes cleaning and sanitation to suffer; unclean bodies (especially hands) help spread diseases, and unclean clothes can carry and spread parasites such as lice. Warmer weather, particularly if it’s also wetter, can increase the number of insects; mild winters can be important in spreading insects vulnerable to freezing weather. Many of these insects are disease vectors for serious diseases such as malaria, dengue fever, yellow fever, typhus, and plague. They can spread to larger areas and higher elevations (such as a 1997 malaria outbreak at 2100 meters in Papua New Guinea), and for longer periods during the year. On the other hand, warming may reduce the range of schistosomiasis and the ticks that carry diseases such as Rocky Mountain spotted fever.
Wetter weather can lead to increases in hay fever and asthma, and flooding can drive rodents such as rats from their burrows, which can increase the incidence of diseases such as plague. Carbon dioxide increases lead to improved crop yields, but also increased allergenic pollens such as ragweed.
Many skeptics, such as Barry Beaty of Colorado State University, argue that the spread of diseases such as malaria seen during the warming period since 1975 result primarily from non-climatic factors, such as resistance to drugs and pesticides and a collapse in public health measures in some areas. (More than 80% of the world’s population is theoretically vulnerable to malaria even without global warming.
Suggested approaches to addressing global warming include adapting to the heat and its effects when it occurs (and meanwhile devoting resources to dealing with other major problems, as recommended by Bjorn Lomborg in Cool It: The Skeptical Environmentalist’s Guide to Global Warming in 2007), as well as trying to reduce the increased in warming. The latter can have no effect on the natural component and will be unnecessary if the increase is small.
Some proposed solutions for reducing greenhouse gas emissions are dubious. For example, the substitution of ethanol for fossil fuels can decrease food production or replace forest with cropland (and has proven to be of no value in terms of reducing greenhouse gas emissions). The severe changes that would be necessary to cause a significant reduction in greenhouse gas emissions would involve serious economic dislocations (and would also lead to the migration of energy-intensive industries to countries that don’t impose such limits, which thus would minimize the emission reductions). Per capita carbon dioxide emissions have declined slightly since 1979; if this trend continues, they will level off when global population does (around 2050). • (2984 views)