Skip to comments.Global Warming, Too Hot or Not?
Posted on 09/06/2006 5:53:02 PM PDT by Coleus
The theory of global warming proposes that man's activities are causing the Earth to heat up, but there is compelling scientific evidence that does not support this conclusion. Very few people have heard of the Larsen B ice shelf. For thousands of years in the Antarctic, the place was a desolate frozen wasteland, crisscrossed by crevasses and swept by powerful ice and snowstorms. Beginning in 2002, satellite imagery began to show instability in the Larsen B ice shelf. According to research published by the journal Nature, much of the more than 4,600 square mile ice shelf collapsed. Since then, icebergs have continued to be formed from the formerly stable ice shelf and from glaciers that are now flowing more quickly from the ice-bound continent. The cause of the Larsen B breakup, according to many, is global warming. Moreover, Larsen B is not the only strange and extreme geological or weather event to be blamed on global warming. In Europe, the famous Matterhorn, reportedly, is falling apart as the glaciers that once held it together retreat. "All the rock fractures generally held together by the ice, which acts as a glue, give way because the ice melts, leading to a situation of instability," global-warming scientist Michelle Comi told ANSA, the Italian news agency. "Geologically speaking, the process is normal. What isn't normal is the acceleration of these phenomena."
Other scientists, working in other regions, claim to be witnessing similar changes. A team of scientists from the University of Texas at Austin noted in August, for instance, that the Greenland ice sheet is melting faster than anticipated. Led by Jianli Chen, the UT team asserted that Greenland is now losing 57 cubic miles of ice each year. "This is a good indication of global warming, that it's there," Jianli Chen told the Houston Chronicle. "At least, it's happening in the Arctic." According to most media reports, a substantial consensus exists among scientists that global warming is real, that it is of human origin, and that it poses an unprecedented threat. Though this is how the media reports it, there is, in fact, a great deal of debate about the situation. Many climate scientists disagree with the anthropogenic that is, human-caused global-warming hypothesis. The UN's Intergovernmental Panel on Climate Change (IPCC), however, represents the alleged consensus. The IPPC argues: "Greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise." According to Science, the journal of the American Association of the Advancement of Science, other major scientific bodies agree with the IPCC assessment. "The American Meteorological Society, the American Geophysical Union, and the American Association for the Advancement of Science (AAAS) all have issued statements in recent years concluding that the evidence for human modification of climate is compelling," wrote Naomi Oreskes of the University of California at San Diego.
Such apparent agreement among scientists suggests that the science behind global warming is robust and persuasive. However, though the evidence, they say, seems to indicate that the Earth is warming, how much, how quickly, and what exactly is responsible remain matters of debate.
The Human Factor
The leading theory on global warming the one that gets all the press, is debated in Congress, and shows up on popular science programs on cable TV holds that the planet is getting warmer because human industrial activity over the last century is filling the atmosphere with carbon dioxide (CO2), a greenhouse gas. According to this theory, carbon dioxide in the atmosphere prevents heat from escaping into space. The retained heat causes an increase in temperatures. The retention of heat in the atmosphere is in fact a natural phenomenon known as the greenhouse effect. Without it, the planet would be far too cold to permit life as we know it. The standard model of global warming holds that this essential natural process is being supercharged by greenhouse gases released by human activities, allegedly causing the Earth to retain more heat than it would normally. This, say some scientists, then causes natural processes to release even more greenhouse gases into the atmosphere, causing a further acceleration of warming. "We are underestimating the magnitude of warming because we are ignoring the extra carbon dioxide dumped into the atmosphere because of warming," said John Harte, UC Berkeley professor of energy and resources and of environmental science, policy, and management. "Warming gets an extra kick from CO2 feedback."
The result of all this CO2 is a warmer climate, according to this model of climate change. A graph developed in 1998 and 1999 by climatologist Michael Mann, now of the University of Pennsylvania, purported to show the recent rise in temperatures against historical temperature levels estimated from the study of "proxies" such as tree rings. The resulting chart has since been called the "hockey stick" because of the sharp spike displayed for the last century in comparison to the relatively flat trend line for the preceding centuries. The hockey-stick graph shows a rise in northern hemisphere temperatures of almost 1 degree Centigrade since 1900. Though the graph has come under fire, on June 22 the National Academy of Sciences (NAS) released a report that was generally supportive of the "hockey stick" findings. "We roughly agree with the substance of their findings," says Gerald North, the NAS committee's chair and a climate scientist at Texas A&M. North continued, emphasizing that the committee has "a high level of confidence" that the last few decades were substantially warmer than the previous four centuries.
Predictions of Disaster
According to the IPCC's Third Assessment Report (2001), "Climate models result in an increase in globally averaged surface temperature of 1.4 to 5.8°C over the period 1990 to 2100. This is about two to 10 times larger than the central value of observed warming over the 20th century and the projected rate of warming is very likely to be without precedent during at least the last 10,000 years, based on paleoclimate data." As a result, the IPCC has warned of a number of potential negative outcomes. These include "increased incidence of death and serious illness"; "increased risk of damage to a number of crops"; and "more intense precipitation events (very likely, over many areas)," causing "increased flood, landslide, avalanche, and mudslide damage." The IPCC also predicts an increased frequency and intensity of drought-causing "decreased water resource quantity and quality," and "increased risk of forest fire," among other things. There are no shortages of other predictions of disaster. Among those most worried about the potential impact of global warming is former Vice President Al Gore. In An Inconvenient Truth, his documentary on global warming (see review page 31), Gore warns that global-warming disasters are like "a nature hike through the Book of Revelations." In particular, he is worried about an increase in the frequency and intensity of hurricanes, the potential for coastal flooding as Greenland's ice cap melts, and the possibility that an influx of cold, fresh water might shut down the ocean currents of the Gulf Stream, the so-called Atlantic conveyor belt. Other gloomy predictions are more frightening still. According to reports in the New Zealand Herald and elsewhere, the giant Amazon basin is drying. "The Amazon now appears to be entering its second successive year of drought, raising the possibility it could start dying next year," wrote correspondent Geoffrey Lean in the Herald in July. "The immense forest contains 90 billion tons of carbon, enough in itself to increase the rate of global warming by 50 percent."
Much of the New Zealand Herald report that originally appeared in the Independent of London was based on experimental work in the Amazon funded by the Woods Hole Research Center. Daniel Nepstad, the senior scientist involved with the research, subsequently released a statement criticizing the news reports about his research. "This alarmist article involved no interview, and it contains many statements that I do not support," Nepstad said. "To clarify, our results do not show that the rainforest 'could become a desert.' In the third paragraph, the piece implies that I support the position that drought in the Amazon will lead to drought that would spread to Britain, with the world spinning out of control, becoming uninhabitable. That is simply not true." Other observers claim that global warming will lead to wars over scarce water and agricultural resources. Some are already saying that the war in the Sudan's Darfur region, between the government-supported Janjaweed militia and indigenous farmers, is just such a war. One of these is British Home Secretary John Reid. In June, Reid pointed to global warming as the cause of the conflict. "[Environmental] changes make the emergence of violent conflict more rather than less likely," Reid said. "The blunt truth is that the lack of water and agricultural land is a significant contributory factor to the tragic conflict we see unfolding in Darfur. We should see this as a warning sign."
With the news filled with reports like these, the public can be forgiven for being convinced that global warming is about to cause an unprecedented disaster. Nevertheless, there are important contrary views and findings on the subject.
Perhaps the most important consideration is one of perspective. Is it warmer now, as is alleged, than ever before in human history? The "hockey stick" graph says it is. In fact, it is not at all clear that it is warmer now than ever before. The Earth has been warming, more or less, since the beginning of the current Holocene Epoch, when the planet shook off the cold of the last ice age. The overall increase in temperatures has been punctuated by periodic short-term changes. The Medieval Warm Period, a time of temperatures warmer than average beginning in about 800 A.D. and lasting until about 1300 A.D., was followed by the Little Ice Age, a period of several centuries of colder-than-normal temperatures. It was during the Medieval Warm Period that the Vikings discovered Greenland and made their other remarkable voyages of exploration in the North Atlantic. According to Jared Diamond, professor of geography at the University of California, "Between A.D. 800 and 1300, ice cores tell us that the climate in Greenland was relatively mild, similar to Greenland's weather today or even slightly warmer.... Thus, the Norse reached Greenland during a period good for growing hay and pasturing animals." The mild climatic conditions may have helped Eric the Red, Greenland's discoverer, to market the area to potential settlers. The Grnlendinga Saga records that Eric "called the land, that he had found, Greenland, for he said, that might attract men thither, when the land had a fine name." According to Dr. Philip Stott, professor emeritus of bio-geography at the University of London, "During the Medieval Warm Period, the world was warmer even than today, and history shows that it was a wonderful period of plenty for everyone."
This judgment flies in the face of the National Academy of Sciences finding that the "hockey stick" graph, which, again, shows that until recently temperatures have remained stable over time, is largely correct. There are other dissenting voices on that matter as well, most notably Canadian researchers Ross McKitrick, a professor of economics at Canada's University of Guelph, and Stephen McIntyre. They argue that the hockey-stick graph is based on a flawed statistical method, and their highly technical rebuttal was published in Geophysical Research Letters, the same journal that originally published the hockey-stick interpretation. Incredibly, they found that the same set of data could be interpreted to show a gradual cooling during the 20th century. Summarizing their work in a presentation to the National Academy of Sciences, they noted: "If a group of proxies is selected because they are sensitive to temperature, the simplest way to characterize their dominant pattern is to standardize the scale and calculate the mean." If that is done, they continued, "One notes that the 20th century is unexceptional and, for what it is worth, that there is a downward trend over the 20th century."
Nevertheless, McKitrick and McIntyre did find, in fact, that there has been some warming since 1900. But, importantly, they confirmed that the Medieval Warm Period was at least as warm as today, if not warmer. Such findings cast doubt on the claim that only human induced warming could have raised temperatures to their present levels.
Indeed, if the Medieval Warm Period was just as warm or warmer than today, something other than anthropogenic (human-caused) greenhouse gases must drive climate. In fact, some scientists maintain that increases in atmospheric carbon dioxide occur after the increases in temperature. Scientists Arthur Robinson, Sallie Baliunas, Willie Soon, and Zachary Robinson note in their paper Environmental Effects of Increased Carbon Dioxide: "Indeed, recent carbon dioxide rises have shown a tendency to follow rather than lead global temperature increases." This conclusion follows research published in the journal Nature in 1990 by Cynthia Kuo, Craig Lindberg, and David J. Thompson that noted: "Changes in carbon dioxide content lag those in temperature by five months." Far more striking was a report entitled Ozone & Global Warming: Are the Problems Real?, in which physicist Baliunas noted: "Most of the temperature rise of the last 100 years occurred before the greenhouse gases from human activities existed in the atmosphere. So the buildup of greenhouse gases cannot be the cause of most of the 0.5°C warming that occurred between 1880 and 1930."
Other global warming suppositions have also come into question recently. One of these is the idea that fresh water from the melting of Greenland and the Arctic will shut down the ocean currents of the Atlantic conveyor, plunging Europe into the deep freeze. According to this theory, warm water in the Gulf Stream flows northward where it gradually gives up its heat, moderating Europe's climate. As it cools it becomes dense and sinks to the bottom of the ocean, flowing south where it again warms and rises, repeating the cycle. As Greenland melts, the theory goes, the less-dense meltwater interferes with the sinking of the formerly warm Gulf Stream water, and the circulation shuts down. The doomsday scenario was ably described in a March 2004 NASA news bulletin. "The thawing of sea ice covering the Arctic could disturb or even halt large currents in the Atlantic Ocean," wrote NASA's Patrick L. Barry. "Without the vast heat that these ocean currents deliver comparable to the power generation of a million nuclear power plants Europe's average temperature would likely drop 5 to 10°C (9 to 18°F), and parts of eastern North America would be chilled somewhat less. Such a dip in temperature would be similar to global average temperatures toward the end of the last ice age roughly 20,000 years ago."
Europe's moderate climate, however, may not be based on the warm waters of the Gulf Stream. Climate scientist Richard Seager of Columbia University, writing in the July-August issue of American Scientist, noted instead that Europe, especially the westernmost parts of Europe, enjoy a maritime climate because the ocean warms and cools slowly, moderating temperatures of nearby landmasses. "Because sea-surface temperatures vary less through the seasonal cycle than do land-surface temperatures, any place where the wind blows from off the ocean will have relatively mild winters and cool summers," writes Seager. "Both the British Isles and the Pacific Northwest enjoy such 'maritime' climates. Central Asia, the northern Great Plains and Canadian Prairies are classic examples of 'continental' climates, which do not benefit from this moderating effect and thus experience bitterly cold winters and blazingly hot summers. The northeastern United States and eastern Canada fall somewhere in between. But because they are under the influence of prevailing winds that blow from west to east, their climate is considerably more continental than maritime." As a result, according to Seager, a slowdown or halt of the Atlantic thermohaline circulation (the conveyor) would not lead to climate catastrophe. Instead, "a slowdown in thermohaline circulation would serve to mitigate the expected anthropogenic [human-caused] warming!"
Expect the Unexpected
The diversity of opinions on issues related to global warming points to one unassailable fact: we simply do not know enough about the geophysical processes of the planet to make useful predictions about climate change. In fact, new climate surprises spring up all the time. The most recent concerns the temperature of the oceans.
According to the standard global-warming model, trapping extra heat via greenhouse gases should cause the oceans to warm. The National Oceanic and Atmospheric Administration noted this in the past. In 2000, the agency reported: "Scientists at NOAA have discovered that the world ocean has warmed significantly during the past 40 years. The largest warming has occurred in the upper 300 meters of the world ocean on average by 0.56 degrees Fahrenheit. The water in the upper 3000 meters of the world ocean warmed on average by 0.11 degrees Fahrenheit." New research, though, points out that the oceans have cooled over the last few years. In a study to be published by Geophysical Research Letters, researchers John M. Lyman, Josh K. Willis, and Gregory C. Johnson report: "The cooling ... is distributed over the water column with most depths experiencing some cooling. A small amount of cooling is observed at the surface, although much less than the cooling at depth." The lost heat, they write, does not appear to have been retained anywhere on the planet. "These findings suggest that the observed decrease in upper ocean heat content from 2003 to 2005 could be the result of a net loss of heat from the Earth to space." This seems an unlikely result if greenhouse gases were causing the planet to retain increasing amounts of energy in the form of heat.
So what can be said for the controversy over global warming? One fact that is not often reported in the popular press is the number of scientists who dissent from the global warming consensus. Among the most notable of these is William Gray of the University of Colorado, a scientist widely acknowledged to be the world's leading expert on hurricanes. In an interview in the September 2005 issue of Discover magazine, Gray explained that if global warming is causing climate change, "it is causing such a small part that it is negligible. I'm not disputing that there has been global warming. There was a lot of global warming in the 1930s and '40s, and then there was a slight global cooling from the middle '40s to the early '70s. And there has been warming since the middle '70s, especially in the last 10 years. But this is natural, due to ocean circulation changes and other factors. It is not human induced."
Another prominent critic of the anthropogenic global warming hypothesis is meteorologist Richard Lindzen of MIT. Writing in the Wall Street Journal in 2001 about a National Academy of Sciences report on global warming, Lindzen observed, "that there is no consensus, unanimous or otherwise, about long-term climate trends and what causes them." Also in 2001, in testimony before the Senate Environment and Public Works Committee Lindzen noted: "Climate change is a complex issue where simplification tends to lead to confusion, and where understanding requires thought and effort." The broad range of conflicting information on the subject of global warming demonstrates that, collectively, the issue of climate change still requires a lot more thought and effort.
Which begs the question: should we, as Al Gore and others suggest, undertake draconian measures like the Kyoto Accords or other, similar efforts to curb a phantom menace that may not exist, especially when such efforts would prove to have disastrous economic consequences? With the science of climate change still uncertain, the answer is "no."
The miocene era had CO2 levels that were 10 times what we have now and it was one of the coldest era's in earths history. The correlation of global warming and CO2 levels has not been proven.
That's one way to characterize it. Another way would be to negate any relevance to findings going back more than 400 years; to say that the findings between 150 years ago and 400 are shaky but not worthless; and that the claim that recent decades were the warmest in the last millenium is downgraded from "likely" to "plausible" - all while bending over backwards to be polite to Mann et al.
"We roughly agree with the substance of their findings," says Gerald North, the NAS committee's chair and a climate scientist at Texas A&M.
...This based upon support from other studies...which the committee didn't review.
North continued, emphasizing that the committee has "a high level of confidence" that the last few decades were substantially warmer than the previous four centuries.
Which is to be expected since four centures ago we were in the Little Ice Age.
Just to clear up this section.
Of course not. You have to understand that global warming doesn't necessarily mean that everything gets warmer. Some places get warmer, some places colder. Some places dry out, others are wetter. Or, returning to your question, if you believe global warming both more hurricanes and fewer hurricanes are proof of global warming. Don't you see? It's such a wonderful theory! It explains everything and everything is consistent with global warming.
Of course, since everything is consistent with global warming, it is completely useless as a theory since it can neither be proved right or wrong.
"Many specific findings of the NAS panel show that they did not endorse the work behind the hockey stick. The NAS report stated that the Mann et al decentered principal components methodology should not be used; that temperature reconstructions should avoid the use of strip-bark bristlecones and foxtail proxies; that the Mann et al reconstruction was strongly dependent on these problematic proxies; that their reconstruction failed important verification tests; and that they had incorrectly estimated uncertainties in their reconstruction.
"At the press conference, panel chairman North said that he agreed with the substance of the Mann et al reconstruction. However, this language is nowhere used in the report itself, where the panel expressly referred to the reconstruction merely as plausible and specifically withheld any attribution of confidence intervals for the period before 1600. "
The above site, is run for Stephen McIntyre of the abovementioned Ross McKitrick and Stephen McIntyre.
If you are against CO2 in the atmosphere you are against the planet being green.
If...if correlation were cause. Life's a journey, enjoy the ride.
In the late60s to early 70swe were being warned of the coming ice age, now we're worried about global warming!!!!!
I wish the chicken littles would make up thier minds!!
I've noticed much more frequent, intensely good weather this Spring and Summer. More proof of global warming!
I've known quite a few scientists who debate different theories in a variety of fields, and respect the people who hold opposite viewpoints. When it comes to the climate sciences however, these same scientists will dismiss those in the 'human impact is non existent or trival' camp as lone nuts or zealots. This is what makes me think that, for them, global warming is much more a 'faith based' issue rather than a scientific one.
That's one of the reasons that the bristlecone pine proxies that Mann used are considered "divergent"...modern levels of CO2 obviously greatly increase ring size. The thing going back in time is that they can't readily distinguish between wet and cool, nor do they collect environmental data year-round. The study Mann used for data to do his 98 and 99 studies even points out the trees are unreliable proxies for these reasons.
Read a paper that corrects a previous study: Included in it will almost invariably be a statement of faith on how despite this, clearly there is anthropogenic global warming and it is predominent - even though the paper itself doesn't address such a thing.
She earth plenty angry.
No like iron horse SUV. Puffing wheel machine heat earth.
Penguin gods, him heap upset that polar bears melt maybe and big wind god eat many house in big shrimp water where buses float. Must sacrifice virgin or ice spirit tell Nannaboojoo eat white man. Bad, bad white man.
Corn god, him like ethanol. Him need government subsidy. Him go to bad moon god and make heap big war. Corn god, him eat moon maiden, stop heat earth with government subsidy.
Big wind god, him go Hyannis stop hot earth. Kennedy god, him no like wind god. We ride with Kennedy god on short pier and pow-wow...
There's a reason for that. Solar insolation decreased over Antarctica at approximately the same time that atmospheric CO2 concentrations were decreasing. Changes in ocean circulation led to the climatic isolation of the Antarctic continent, and this set up essentially a new climate system. The change was most notably a shift in the Milankovitch forcing. Formerly the obliquity variable was the most important; during the Miocene the eccentricity variable became more dominant than the obliquity variable.
And actually your statement isn't entirely accurate. The Miocene marks a period of major ice sheet expansion on Antarctica, but the Plicene and the Pleistocene were colder.
IN the chart below (reduced in size; click on it for the big full-resolution chart), the oxygen-18 isotopes are a proxy for temperature. Essentially the Miocene was the beginning of a colder era in Earth's climate history, "setting the stage" for the continental glaciations in the Pleistocene.
(This is a nice chart, as it shows major tectonic shifts in paleoclimate history, a factor that is often overlooked. Until the closing the Central American isthmus, ocean circulation was much different than present, so direct comparisons to past climate states prior to the Pliocene are problematic.)
Also note in this chart the relatively brief Paleocene-Eocene Thermal Maximum, caused by a major release of methane which was oxidized to CO2 in the atmosphere, causing a short, radiatively-forced global warming episode.)
See post 18 for a more detailed view of the Cenozoic.
Yes, I agree. I'm going to bookmark it. It's very nicely detailed.