Top Skeptic, Prominent Scientist Agree on Likely Global Warming Scenario by 2050

NASA’s James Hansen widely is credited as “the father” of the global warming issue because of his 1988 congressional testimony concerning his detection of a human influence on world climate. His work with a General Circulation Model developed at the Goddard Institute for Space Studies led him to that conclusion, just as GCMs subsequently led others to the offer up “scary scenarios” of our climate future. It is remarkable, then, when Hansen writes in the March 2004 edition of Scientific American (PDF) that the climate change scenarios put forth in the Intergovernmental Panel on Climate Change’s (IPCC) 2001 Third Assessment Report “may be unduly pessimistic” and that the IPCC extreme scenarios are “implausible.”

In “Defusing the Global Warming Time Bomb” Hansen argues that the observed trends in atmospheric carbon dioxide and methane concentrations for the past several years fall below all IPCC scenarios. As a consequence, he concludes, future temperature rise will most likely be about 0.75ºC over the next fifty years.

In reaching this conclusion, Hansen relies on simple empirical evidence he considers more precise and reliable than model results “because it includes all the processes operating in the real world, even those we have not yet been smart enough to include in the models.” As a consequence, he and the University of Virginia’s Patrick Michaels, a climatologist characterized by many as representing the opposite pole of scientific opinion on this issue, find themselves in agreement.

Michaels, like Hansen, believes the IPCC scenarios in large part overestimate the potential temperature rise in the coming century. And like Hansen, Michaels relies on observations for his insight into future climate behavior. In his 2002 Climate Research paper “Revised 21st century temperature projections,” Michaels writes, “[Observations] are the perfect integrators of all processes that are currently active” and thus avoid the “varying degrees of uncertainties surrounding every aspect of the models.”

Michaels used observations of the rate of the observed buildup of carbon dioxide in the atmosphere, along with observations of the global temperature change during the past twenty-five years or so, to determine, “Our adjustments of the projected temperature trends for the 21st century all produce warming trends that cluster in the lower portion of the IPCC TAR range.” Michaels concludes the warming during the next fifty years will be somewhere near 0.75ºC — precisely the conclusion at which Hansen arrived two years later. Sadly, this is where most of the agreement between the two climate researchers ends. Note from the poster: this is double the rate of warming in the 20th century.

Hansen says it is imperative that we undertake concerted and organized efforts to lower this warming rate even further in order to avoid what he describes as “dangerous human interference” with the climate system (thereby echoing the words of the 1989 United Nations Framework Convention on Climate Change, a/k/a the “Rio Treaty”). He declares the “emphasis should be on mitigating the changes rather than just adapting to them.”

Michaels argues such a likely and modest temperature rise is one to which earth and its inhabitants can readily adapt. He contends it may even offer great advantages — longer growing seasons, reduced heating costs, enhanced global vegetation, and so forth. Because the rate of climate change is manageable, Michaels believes, it isn’t necessary to induce changes in the global energy structure. He advocates allowing market forces to dictate change because fossil fuels are finite and mankind will have to develop alternative energy sources.

How can two scientists who base their conclusion upon a collection of empirical evidence end up so at odds?

Hansen says his biggest concern is the potential for a large rise in sea-level. Yet empirical evidence shows that the rate of sea-level rise over the course of the 20th century (during which there was about 0.75ºC of warming) was about 1.8 mm per year. Therefore the cumulative rise over the past 100 years has been about 7 inches. Double that rate, as implied by a continued steady rise in temperature, and in most places there are no problems that cannot be controlled or adapted to. **see note below in comment

Other lines of evidence demonstrate the potential for positive impacts. Research by Ramakrishna Nemani and colleagues (who studied variations in global vegetation patterns based upon data collected from satellites) shows a remarkable enhancement of the growth of global vegetation. They attribute the growth to two decades of change in the climate and to the increased atmospheric concentration of carbon dioxide, which acts as a plant fertilizer.

The litany of dire consequences that could result from global warming generally is in step with the magnitude of the warming. In the IPCC’s Third Assessment Report the range of potential warming manifest by 2100 is presented as being between 1.4ºC and 5.8ºC. The IPCC does not indicate which value is more likely. However claims of drastic future consequences are based upon the possibility of temperatures ending up on high end of the IPCC range (for instance see the claims made by the environmental organization The Bluewater Network which are reportedly behind some recent climate actions by Senators John McCain (R-AZ) and Ernest Hollings (D-SC), http://www.co2andclimate.org/wca/2004/wca_14c).

If one looks at actual evidence (rather than modeled responses), as do Hansen and Michaels, it is the lower end of the range that is more likely. The impacts associated with warming at the low end of the IPCC TAR range are far less dramatic and infinitely more manageable than those that accompany high-end warming.

It seems about time to dispense with the notion that future warming will be catastrophic and begin to focus on the implications of a modest warming where benefits are likely to outweigh costs.

The IPCC is a joke and a fraud. Here is a little reality check:

Word from the IPCC (Intergovernmental Panel on Climate Change) meeting in Shanghai is that the upper range of temperature rise during the next 100 years is nearly 11°F. "This adds impetus for governments of the world to find ways to live up to their commitments . . . to reduce emissions of greenhouse gases," Robert Watson, chairman of the IPCC and former Clinton science advisor, is quoted as saying.
The January 23 edition of The Washington Post put this particular global warming story above the fold on its front page! The play could have been bigger only were it in the upper left-hand corner rather than the right.
Neither the Post nor Watson mentions that this forecast of extreme warming is the result of a computer model. And not just any model, either. It is a product of the most extreme climate model run under the most extreme set of future emission scenarios. In other words, it's not a model based upon present trends; it's a model of a model! Putting a fine point on it, this particular result was produced by one (that's right, one) of 245 models the modelers ran.
From Patrick J. Michaels Ph.D. More info on bad modeling at the link.

In addition to all of this none repeat none of the computer models currently in use can accurately predict the heating that has already occurred when past data is used. In other words if you put in all of the data available up to say 1980 you can not accurately predict the weather as it occurred in 2000.

Your bias is showing. The article said:

It seems about time to dispense with the notion that future warming will be catastrophic and begin to focus on the implications of a modest warming where benefits are likely to outweigh costs.

Then you said,

I.e., if it warms to the point that large-scale melting of glaciers and ice sheet commences, we're going to be in trouble.

Give it up. If humans made a maximum effort to reduce production of carbon dioxide, the consequent reduction in heating is so small as to be virtually unmeasurable. Worse, our economic ability to fund the means to accommodate climate variation will have been seriously curtailed. Both humans and nature would be better off if we expend our efforts learning to manage habitat wisely on microscopic bases.

Reams of valuable info on this topic available at Envirotruth.org

THE ENVIROTRUTH: The modern global warming debate was ignited in 1989 when NASA climatologist Dr. James Hansen testified before a joint U.S. House and Senate committee that there was "a strong cause and effect relationship between the current climate" - then a blistering drought - "and human alteration of the atmosphere." His computer models predicted an average global temperature rise of 0.45°C between 1988 and 1997 and 8°C by 2050 due to greenhouse gas build-up. Despite enormous uncertainties in his simulations, it wasn't long before the politically correct view of the future included a global warming catastrophe.

Yet today, Hansen admits that his computer simulations were wrong and that current climate change models are unreliable (see related article by climatologist Dr. Patrick Michaels of the University of Virginia). After the U.S. spent $10 billion on this issue, Hansen wrote in the Proceedings of the National Academy of Sciences, "The forces that drive long-term climate changes are not known with an accuracy sufficient to define future climate changes." As more and more variables have been incorporated into the models, the amount of predicted change has decreased. Renowned Columbia University oceanographer/climatologist Dr. Wallace Broecker believes that more than one million variables influence climate change. Although not all are required to reasonably model climate, this fact underlines why contemporary computer simulations are not very accurate.

The problem is also due to the fact that, even though water vapor is the major greenhouse gas, it is essentially ignored by climate models. These simulations are so primitive that they are even unable to determine today's climate when starting with known past temperatures and rates of CO2 level rise.

Dr. Tim Patterson, professor of earth sciences (Paleoclimatology) at Carleton University, explains that, despite these obvious flaws, much of the current debate on global warming has been hijacked by theorists, relying primarily on these inaccurate models but working with little actual data. With the support of biologists, who generally lack a proper understanding of long-term climate dynamics, mass media and government have treated the more extreme of these theoretical scenarios as credible indicators of future environmental change, which they clearly are not.

Dr. Michaels puts the controversy into perspective: “Temperatures measured by surface thermometers have risen about 0.7°C in the last 100 years, but about half of that warming occurred before most changes in atmospheric carbon dioxide. The other half, which has occurred in the last three decades, is often attributed to human causation."

“If this is true, then we have a very good idea of future warming,” says Dr. Michaels. “While global climate models are incapable of predicting the distribution of regional and vertical climate change, they generally agree that once human-induced warming begins, it takes place at a constant (not increasing) rate. This is because the response of temperature to carbon dioxide becomes damped at higher concentrations, while it is generally assumed that the carbon dioxide increase itself is exponential, along with population. The mathematical combination of the two is a straight line.”

Dr. Michaels concludes that the resultant warming predicted by these computer models works out to approximately 1.6°C in the next 100 years. "Half of this amount, in the last 100 years, saw a doubling of life span and a quintupling of crop yields where economic freedom reigned," he says. "There is no reason to expect a sudden turnaround; rather, continued adaptation and prosperity are much more likely."

Dr. Roger Pocklington of the Bedford Institute of Oceanography says, "Professional doomsayers always pick the least likely, upper extremity, of the temperature range for their polemics, never the average." They also never explain that most of the computer models forecast much lower temperatures and that the average of these models is more in the range cited by Dr. Michaels.

Dr. Michaels concludes, "Changes in atmospheric carbon dioxide [the primary driver of temperature change in the computer models] have been much slower than anticipated by virtually all scientists 25 years ago. The increases are so small that they may not even be exponential. This predicts a damping of the already-small warming rate in coming decades."

A good illustration of how poorly today's Global Climate Models (GCMs) perform is obtained by comparing the rise in global average temperatures actually measured over the past two decades with how the GCMs used by the IPCC 'predict' they should have increased. As evident in the following graph (where measured temperature rise is indicated as an averaged trend) even the most conservative of the models used by the IPCC 'predict' significantly greater temperature rises than what actually occurred. How can we put any faith in the IPCC's predictions for the future when their forecasts are based solely on such inaccurate GCMs?

What forced the climate changes on both ends of the Ice Age???

Changes in solar insolation due to variability in Earth's orbit, inclination, and axial tilt, combined with ocean currents and plate tectonics changing the location of the continents.

Those changes took place over longer time-frames than the Industrial Age (mid 1800s to present) that is the time-frame of concern now.

It is only a man's vanity to believe that he can affect global temperatures one way or another. It is caused by ocean currents, volcanic activity, etc.

While those are certainly important, so is the composition of the atmosphere (which we are changing) and land surface cover. Some recent research indicates that land surface changes dating back to the beginning of agriculture, a couple thousand years ago, may have significantly affected climate.

Incidentaly, one of the largest contributors to greenhouse gas (methane) is termites. What does Mr Hansen sugest we do about that? Call Terminex?

What he suggests is that we don't have to worry about methane emissions right now, because they have declined so substantially in the past five years.

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