Posted on 05/11/2004 7:56:43 AM PDT by cogitator
Observations Not Models
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.
(click on article link for references)
So what.
One large meteor strike, one large volcanic eruption, one large solar flareup, etc, will have more influence on our atmosphere, than a thousand years of man's influence.
This global warming bloviation is all about trying to restrict OUR private property rights. Do you believe the U.S. should sign the Kyoto treaty, restrict property rights, or regulate the type of vehicle (IE SUV's) we can drive, etc, in the name of "saving the planet"?
IMO, we have far more important things in life than worrying about the planets temperature changes.
I spend a lot of time in the ocean, friend, and I've seen temp changes of 10 degrees from one day to the next, just because of up welling. I get a little tired of chicken little scientists who have an agenda of obtaining more govt. funding, and in the process, lining their own pockets with these taxpayer funded studies. Hey; if we humans can't affect atmospheric conditions......than who needs the study? See the agenda?
You science guys that look at this planet as if it were some little biosphere bubble, are so narrowly focused, that you can't see the forest for the trees.
-> Which, btw, we have more of today than anytime in history, thanks to modern firefighting techniques.
Regards
We can't do anything about circumstances and events that are out of our control. If we got hit by a meteor large enough to cause global climate change, climate change would be the least of our problems. As for volcanoes, change your adjective "large" (Kuwai, Tambora, Krakatoa, Katmai and Pinatubo were "large") to "supermassive" and then you can talk about effects lasting more than a couple of years. Solar flares cause problems; there would have to be a significant change in the total luminosity of the Sun to have a major climate impact. (On that note, you might look up the science fiction story "Inconstant Moon" by Larry Niven.)
This global warming bloviation is all about trying to restrict OUR private property rights. Do you believe the U.S. should sign the Kyoto treaty, restrict property rights, or regulate the type of vehicle (IE SUV's) we can drive, etc, in the name of "saving the planet"?
No.
I believe we should respond appropriately.
Appropriately means first recognizing that there is a situation requiring a response. I believe that the scientific understanding of the climate changes occurring now is at that stage. The second step is formulating appropriate response strategies. In my opinion, that is what we -- the United States, other countries -- should be doing now. As more data is gathered, as the science continues to improve, selection of the final set of response strategies to implement will be facilitated. Implementation is the third step. Evaluation of the implementation effectiveness is the fourth step; modifications to the iniitial implementation would be the fifth step. And so on.
Have you ever seen a coral bleaching event?
Coral Bleaching and Mass Bleaching Events
Do you think that we should be concerned about these events? The increasing incidence of such events? The possible cause of this increasing incidence? The rapid decline of many of the world's coral reef areas?
If you think there is reason for concern here, then we may agree about a lot more than you think we do.
If they are deliberately skewing their models by introducing spurious factors, there will be an outcry in the scientific community sooner or later. It would be a huge scandal comparable to the N-ray scandal.
They are always enthusiastically trying to trip each other up. There is one rule in this game: you must be able to defend your assertion.
And I'm suppoised to enter into a serious discussion with this one, eh?
No thanks my friend, but don't let that stop you.
...sounds like you've time to kill. :o)
I agree with your statement. Glad you liked the article.
I am wondering what is the source of Hansen's information. The most detailed report I've read on sea level change have concluded that a significant measurement of sea level change will not be obtained until 2030. Previous reports of sea level changes did not account for changes in land elevation due to tectonics, and were complicated by sea level changes due to such effects as El Nino.
That would depend on what you mean by "spurious". The IPCC has described its modeling procedure pretty well; the upper-range estimates have been obtained by taking out some negative feedback factors in some models. They evaluate a range of models to come up with a range of climate scenarios, and then the evaluate the consequences of those possibilities.
The media alarmists tend to glom onto the worst-case scenarios and present them as if they were the likeliest scenarios -- which isn't the case. But "moderate changes" don't make stories that lots of people will read. So there really isn't a scandal here (nor is there a deliberate attempt to skew the science) -- the name of the IPCC game is to evaluate the broadest possible set of circumstances, and then propose various ways to address different sets of circumstances.
Of course, members of the IPCC community have seized upon particular aspects of the reports and used them to push their own agendas. Not much can be done about that.
"The main issue is: How fast will ice sheets respond to global warming? The IPCC calculates only a slight change in the ice sheets in 100 years; however, the IPCC calculations include only the gradual effects of changes in snowfall, evaporation and melting. In the real world, ice-sheet disintegration is driven by highly nonlinear processes and feedbacks. The peak rate of deglaciation following the last ice age was a sustained rate of melting of more than 14,000 cubic kilometers a year—about one meter of sea-level rise every 20 years, which was maintained for several centuries. This period of most rapid melt coincided, as well as can be measured, with the time of most rapid warming. Given the present unusual global warming rate on an already warm planet, we can anticipate that areas with summer melt and rain will expand over larger areas of Greenland and fringes of Antarctica. Rising sea level itself tends to lift marine ice shelves that buttress land ice, unhinging them from anchor points. As ice shelves break up, this accelerates movement of land ice to the ocean. Although building of glaciers is slow, once an ice sheet begins to collapse, its demise can be spectacularly rapid. . . . These considerations do not mean that we should expect large sea-level change in the next few years. Preconditioning of ice sheets for accelerated breakup may require a long time, perhaps many centuries."
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