Global Climate Change: is it worth brushing off?

The Oregon Petition, sponsored by the OISM, was circulated in April 1998 in a bulk mailing to tens of thousands of U.S. scientists. In addition to the petition, the mailing included what appeared to be a reprint of a scientific paper. Authored by OISM's Arthur B. Robinson, Sallie L. Baliunas, Willie Soon, and Zachary W. Robinson, the paper was titled "Environmental Effects of Increased Atmospheric Carbon Dioxide" and was printed in the same typeface and format as the official Proceedings of the National Academy of Sciences. Also included was a reprint of a December 1997, Wall Street Journal editorial, "Science Has Spoken: Global Warming Is a Myth", by Arthur and Zachary Robinson. A cover note signed "Frederick Seitz/Past President, National Academy of Sciences, U.S.A./President Emeritus, Rockefeller University", may have given some persons the impression that Robinson's paper was an official publication of the academy's peer-reviewed journal. The blatant editorializing in the pseudopaper, however, was uncharacteristic of scientific papers.

Robinson's paper claimed to show that pumping carbon dioxide into the atmosphere is actually a good thing. "As atmospheric CO₂ increases," it stated, "plant growth rates increase. Also, leaves lose less water as CO₂ increases, so that plants are able to grow under drier conditions. Animal life, which depends upon plant life for food, increases proportionally." As a result, Robinson concluded, industrial activities can be counted on to encourage greater species biodiversity and a greener planet:

As coal, oil, and natural gas are used to feed and lift from poverty vast numbers of people across the globe, more CO₂ will be released into the atmosphere. This will help to maintain and improve the health, longevity, prosperity, and productivity of all people.

Human activities are believed to be responsible for the rise in CO₂ level of the atmosphere. Mankind is moving the carbon in coal, oil, and natural gas from below ground to the atmosphere and surface, where it is available for conversion into living things. We are living in an increasingly lush environment of plants and animals as a result of the CO₂ increase. Our children will enjoy an Earth with far more plant and animal life as [sic] that with which we now are blessed. This is a wonderful and unexpected gift from the Industrial Revolution.

In reality, neither Robinson's paper nor OISM's petition drive had anything to do with the National Academy of Sciences, which first heard about the petition when its members began calling to ask if the NAS had taken a stand against the Kyoto treaty. Robinson was not even a climate scientist. He was a biochemist with no published research in the field of climatology, and his paper had never been subjected to peer review by anyone with training in the field. In fact, the paper had never been accepted for publication anywhere, let alone in the NAS Proceedings. It was self-published by Robinson, who did the typesetting himself on his own computer. (It was subsequently published as a "review" in Climate Research, which contributed to an editorial scandal at that publication.)

None of the coauthors of "Environmental Effects of Atmospheric Carbon Dioxide" had any more standing than Robinson himself as a climate change researcher. They included Robinson's 22-year-old son, Zachary, along with astrophysicists Sallie L. Baliunas and Willie Soon. Both Baliunas and Soon worked with Frederick Seitz at the George C. Marshall Institute, a Washington, D.C., think tank where Seitz served as executive director. Funded by a number of right-wing foundations, including Scaife and Bradley, the George C. Marshall Institute does not conduct any original research. It is a conservative think tank that was initially founded during the years of the Reagan administration to advocate funding for Reagan's Strategic Defense Initiative--the "Star Wars" weapons program. Today, the Marshall Institute is still a big fan of high-tech weapons. In 1999, its website gave prominent placement to an essay by Col. Simon P. Worden titled "Why We Need the Air-Borne Laser," along with an essay titled "Missile Defense for Populations--What Does It Take? Why Are We Not Doing It?" Following the collapse of the Soviet Union, however, the Marshall Institute has adapted to the times by devoting much of its firepower to the war against environmentalism, and in particular against the "scaremongers" who raise warnings about global warming.

"The mailing is clearly designed to be deceptive by giving people the impression that the article, which is full of half-truths, is a reprint and has passed peer review," complained Raymond Pierrehumbert, a meteorlogist at the University of Chicago. NAS foreign secretary F. Sherwood Rowland, an atmospheric chemist, said researchers "are wondering if someone is trying to hoodwink them." NAS council member Ralph J. Cicerone, dean of the School of Physical Sciences at the University of California at Irvine, was particularly offended that Seitz described himself in the cover letter as a "past president" of the NAS. Although Seitz had indeed held that title in the 1960s, Cicerone hoped that scientists who received the petition mailing would not be misled into believing that he "still has a role in governing the organization."

The NAS issued an unusually blunt formal response to the petition drive. "The NAS Council would like to make it clear that this petition has nothing to do with the National Academy of Sciences and that the manuscript was not published in the Proceedings of the National Academy of Sciences or in any other peer-reviewed journal," it stated in a news release. "The petition does not reflect the conclusions of expert reports of the Academy." In fact, it pointed out, its own prior published study had shown that "even given the considerable uncertainties in our knowledge of the relevant phenomena, greenhouse warming poses a potential threat sufficient to merit prompt responses. Investment in mitigation measures acts as insurance protection against the great uncertainties and the possibility of dramatic surprises."

Notwithstanding this rebuke, the Oregon Petition managed to garner 15,000 signatures within a month's time. S. Fred Singer called the petition "the latest and largest effort by rank-and-file scientists to express their opposition to schemes that subvert science for the sake of a political agenda."

Nebraska senator Chuck Hagel called it an "extraordinary response" and cited it as his basis for continuing to oppose a global warming treaty. "Nearly all of these 15,000 scientists have technical training suitable for evaluating climate research data," Hagel said. Columns citing the Seitz petition and the Robinson paper as credible sources of scientific expertise on the global warming issue have appeared in publications ranging from Newsday', the Los Angeles Times and Washington Post to the Austin-American Statesman, Denver Post, and Wyoming Tribune-Eagle.

In addition to the bulk mailing, OISM's website enables people to add their names to the petition over the Internet, and by June 2000 it claimed to have recruited more than 19,000 scientists. The institute is so lax about screening names, however, that virtually anyone can sign, including for example Al Caruba, a pesticide-industry PR man and conservative ideologue who runs his own website called the "National Anxiety Center." Caruba has no scientific credentials whatsoever, but in addition to signing the Oregon Petition he has editorialized on his own website against the science of global warming, calling it the "biggest hoax of the decade," a "genocidal" campaign by environmentalists who believe that "humanity must be destroyed to 'Save the Earth.' . . . There is no global warming, but there is a global political agenda, comparable to the failed Soviet Union experiment with Communism, being orchestrated by the United Nations, supported by its many Green NGOs, to impose international treaties of every description that would turn the institution into a global government, superceding the sovereignty of every nation in the world."

When questioned in 1998, OISM's Arthur Robinson admitted that only 2,100 signers of the Oregon Petition had identified themselves as physicists, geophysicists, climatologists, or meteorologists, "and of those the greatest number are physicists." This grouping of fields concealed the fact that only a few dozen, at most, of the signatories were drawn from the core disciplines of climate science - such as meteorology, oceanography, and glaciology - and almost none were climate specialists. The names of the signers are available on the OISM's website, but without listing any institutional affiliations or even city of residence, making it very difficult to determine their credentials or even whether they exist at all. When the Oregon Petition first circulated, in fact, environmental activists successfully added the names of several fictional characters and celebrities to the list, including John Grisham, Michael J. Fox, Drs. Frank Burns, B. J. Honeycutt, and Benjamin Pierce (from the TV show M*A*S*H), an individual by the name of "Dr. Red Wine," and Geraldine Halliwell, formerly known as pop singer Ginger Spice of the Spice Girls. Halliwell's field of scientific specialization was listed as "biology." Even in 2003, the list was loaded with misspellings, duplications, name and title fragments, and names of non-persons, such as company names.

OISM has refused to release info on the number of mailings it made. From comments in Nature:

"Virtually every scientist in every field got it," says Robert Park, a professor of physics at the University of Maryland at College Park and spokesman for the American Physical Society. "That's a big mailing." According to the National Science Foundation, there are more than half a million science or engineering PhDs in the United States, and ten million individuals with first degrees in science or engineering.

Arthur Robinson, president of the Oregon Institute of Science and Medicine, the small, privately funded institute that circulated the petition, declines to say how many copies were sent out. "We're not willing to have our opponents attack us with that number, and say that the rest of the recipients are against us," he says, adding that the response was "outstanding" for a direct mail shot. [3]

Is there a scientific basis for Robinson's claim that increased carbon dioxide levels will contribute to increased growth of some plants? Some research has gone into investigating this possibility, but the evidence does not point to the type of reassurance that the OISM is peddling. Fakhri Bazzaz, a plant physiologist at Harvard, has found that carbon dioxide-enriched air accelerates short-term plant growth, but his studies were carried out under controlled greenhouse conditions and are difficult to translate to a larger scale. Plant growth in natural systems may be constrained by a shortage of soil nutrients despite the greater availability of carbon dioxide. Moreover, Bazzaz's experiments involved carbon dioxide concentrations at levels 100% greater than those now existing in our atmosphere, whereas the greenhouse warming we are experiencing right now results from only a 20% increase in world carbon dioxide levels. Clearly, it is irresponsible to predict "benefits" from increased carbon dioxide in the atmosphere when such "benefits" may only appear after we suffer the consequences of a five-fold increase over current anthropogenic emissions of greenhouse gases. Finally, Bazzaz found that different plant species vary dramatically in their response to increased carbon dioxide. Plants such as sugar cane and corn were not improved, but weeds were stimulated. There is not much real benefit in warming the planet by several degrees just so we can maybe make it easier for weeds to grow.

Notwithstanding the shortcomings in Robinson's theory, the oil and coal industries have sponsored several organizations to promote the idea that increasing the amount of carbon dioxide in the atmosphere is "good for earth" because it will encourage greater plant growth. The Greening Earth Society, a front group of the Western Fuels Association, has produced a video, titled "The Greening of the Planet Earth Continues," publishes a newsletter called the World Climate Report, and works closely with a group called the Center for the Study of Carbon Dioxide and Global Change.

As of the Fall of 2007, OISM continued to mail petition cards along with a reprint of "Environmental Effects of Increased Atmospheric Carbon Dioxide," now cited as having been published in the Journal of American Physicians and Surgeons (2007) 12, 79-90, with Arthur B. Robinson, Noah E. Robinson, and Willie Soon listed as the authors. The journal is published by the Association of American Physicians and Surgeonswhose director is Jane Orient (see above), a professor at the Oregon Institute of Science and Medicine. Also included in the mailing is a copy of a Wall Street Journal Op-Ed article entitled "Global Warming is 300-Year-Old News" authored by Arthur and Noah Robinson and dated January 18, 2000.

re: #289:
“And what’s with quotes on “skeptic”?”

The problem is some fuzziness in the use of English:

1) SKEPTIC: To me, the terms “skeptic” and “skeptical thinking” have usually meant someone takes nothing on blind faith, examines alternate viewpoints carefully, weighs evidence, and changes their mind when new data arrives. I think those are good things. Of course, if you look it up in various dictionaries, you find various meanings.

I’ve known lots of good scientists, and they generally work this way, and are mostly perfectly happy with real skeptics. I’m always happy to have a few well-informed skeptics poking at mainline theories, since sometimes advances come from studying inconsistencies. Occasionally, really wacko-sounding ideas work out.

2)CERTAINTY: However, some people have been 100% sure (often in temporal order) that:
- there is no warming, temperatures jiggle naturally anyway, and scientists don’t understand any of this
- well, satellites disagree with with ground stations
- well, maybe there is warming, but it’s not caused by humans
- well, if some of the warming is caused by humans, we don’t know how much
- well, if there is warming, it’s caused by {changes in Sun, cosmic rays, etc},and besides the Mars polar cap is melting, so it’s nothing to do with humans.
- well, we can propose mechanisms that might cancel the warming.
- well, even if there is AGW, we can’t do anything about it, so we shouldn’t try, people should just migrate away from the coasts.
- well, we aren’t 100% certain, so we should study it more.
- well, under no circumstances should we damage our economy by conserving energy [i.e., we should never be so silly as to act like California, which is relatively energy efficient, and whose economy must therefore be just awful. (The Wall Street Journal editorial page regularly mocks CA for such activities, even as the news sections applaud CA business. :-)]

The problem is, such a view is “skeptical” of AGW, but many people have trouble according it the positives of the classical skeptic in 1), and hence write “skeptic” or sometimes *denialist*. In my experience, good climate scientists are happy to answer questions from real skeptics [RC is a fine example], but rightfully get weary of denialists.

3) SKEPTICAL THINKING For instance, a *real* skeptical thinker might want to do the following: do as I did in 2002-2003, averaging an hour a day across several years. It would take much less time now, because there’s a lot more data, and some of the annoying inconsistencies have evaporated, and some of the lingering questions now have plausible hypotheses to help explain them, and there are good websites like RC. Here’s what I did then (and for background, my undergrad work was math+physics, followed by MS/PhD in computer science, and I’m a AAAS member, so I’m fairly comfortable looking at primary research articles when needed. I’m certainly not part of any climate-science establishment, although I used to help design supercomputers used by such people.)

a) Read books by mainstream scientists, such as the IPCC books, several of Stephen Schneider’s, John Houghton’s “Global Warming”, Mackay et al “Global Change in the Holocene”, Krauskopf & Bird, “Introduction to Geochemistry”, etc. If someone were starting now, Ruddiman’s Plows, Plagues, and Petroleum” is my favorite, especially if one doesn’t have a technical background.

Read Science (or Nature) every week.
Join the AGU for a while to see what else the professionals are doing.

b) Get a few alarmist books, like Berger’s “Beating the Heat” (which irked me by lamenting the future disappearance of penguins from the Arctic.)

c) On the other side, read Lomborg’s “Skeptical Environmentalist”; Fred Singer’s “Hot talk Cold Science”, Essex & McKitrick’s “Taken by Storm”, etc.

d) Follow ongoing discussions, websites, Look at NOAA, USHCN, etc to understand measurements. I also watched John Daly’s website, and CO2science, and GreeningEarthSociety, etc, etc. I followed the McIntyre & McKitrick papers, and later (2006) studied the Wegman Report.

e) Keep a list of outstanding objections to AGW. When appropriate, backtrack references to primary research papers. Watch how the list changes with time,and how it relates to ongoing research.

f) When possible, interact with real climate scientists. I had the fun of being the “skeptical discussant” for a (very good) Stephen Schneider seminar at Stanford: I brought in my current stack of booksd, asked a few tough questions, and asked what else I should look at. He explicitly had no problem with someone questioning AGW, if they were doing it rationally, rather than reflexively. His talk carefully discussed degrees of uncertainty, and if he was upset at anyone, it was at those were 100% sure that AGW didn’t exist, not at those who approached AGW as classical skeptics.

g) MOST IMPORTANT, and the reason one can’t do this overnight: to understand the science and (necessarily) politics of a theory like AGW, you need to track it for several years, especially to calibrate the players. If you study history of science:

- a new hypothesis appears, which of course must at least be consistent with existing data, and preferably makes further predictions that can be tested, and preferably, is as simple as possible, but no more.

- as new data arrives, the hypothesis might be rapidly disconfirmed, or it might need to be adjusted (Ruddiman gives a good example in PPP: Chapter 11).

- there is *always* ambiguous or contradictory or missing data.

For a hypothesis to become a well-accepted theory:
+ new data tends to confirm it
+ ambiguities tend to get narrowed
+ contradictions tend to get resolved

BUT, you have to watch it for a while to see that happening.

Over time, better theories tend to be better approximations of reality, but even great theories (like Relativity or Quantum Mechanics) don’t explain *everything* - legions of physicists have labored mightily for decades to create a theory that subsumes both of them, but in the meantime, GPS satellites work and so do transistors, even in the absence of an all-encompassing theory.

Scientists, being human, sometimes defend their data and hypotheses like a lioness defends her cubs, but most are careful to calibrate the quality of data and areas of uncertainty, with numerous caveats, and most change their minds as data accumulates. This puts them at great debating disadvantage with people who have always been 100% sure that AGW doesn’t exist, especially in a sound-byte era.

4) AGW After watching all this for a few years, my opinion got increasingly firm:

- In the early 1990s, there had been plenty of room for uncertainty about AGW (not about the basic physics, of course), but there were more loose ends, temperature jiggles for which the explanations were more uncertain. It seemed to me that there were alarmist views that were premature, but:

- Over time, data piled up overpoweringly, contradictions (like satellites vs ground stations) got resolved… etc. I’m used to science: there are always measurement errors, and one would always like more data, and yes, clouds and aerosols are not perfectly understood, but That’s Life.

- This left very little room for doubt of the basic AGW theory, if one actually studied the science, and especially if one had even modest technical background. I was pretty clear that mainline scientists were not being alarmists, but had pretty good reasons for saying what they were saying.

- Occasionally, I was uncomfortable with the ways summarization happened, and data presented graphically. Specifically MBH98+MBH99 (well-caveated) -> IPCC TAR main report -> IPCC TAR TS -> IPCC SPM
(whose specific hockey-stick chart with gray error zone had to be unconsciously misleading for the intended audience, which I’d guess is unlikely to think much about error bars and uncertainty.) I was sensitive to this because of long-running similar issues in my own discipline (computer science, especially performance characterization, which often tries to be overly precise to make things simple.)

I always thought that was an unfortunate evolution, which started with studies heroically trying to extract signal from difficult historical data, with appropriate caveats, but emerged looking like everyone was really sure of one line, even though that certainty was clearly not true when one back-tracked through the eventual layers of proper caveats. It’s too bad IPCC didn’t think of a better way to present that data, but I sympathize with people who do understand uncertainty arguing with people who are always 100% sure.

I thought that it really didn’t matter whether the current temperature was slightly above or slightly below the peak of the MWP. What mattered to me was that the temperature was going up fast, that the lag time effects meant it would keep going up for many decades, no matter what, and that there were at least 10X more people on the planet now. Having grown up on a small farm, I heard about “carrying capacity” before I was 10.

5) “SKEPTICS” It also became clear was that there existed a relatively small number of vocal people and organizations, who were not acting like classic skeptics, but had the clear point of view described in 2), apparently arising mostly from other-than-scientific concerns:
- specific political or ideological beliefs
- economics
“It’s hard to convince someone if their livelihood depends on not believing.”

Certain tactics became apparent, a lot like those used to obfuscate research on smoking-cancer link (unsurprising: some of the same people/organizations, but funded by ExxonMobil rather than RJ Reynolds Tobacco).

-Arguments were made via whitepapers, web pages, OpEd pieces, not peer-reviewed research.

-Old, long-debunked claims were cited over and over.

-New data was ignored.

-Completely irrelevant claims were thrown up (Mars!)

-Sham polls were produced. [I might be interested in a real poll by AGU or AAAS of their members who are practicing climate scientists. “Polls” like OSMI’s: no way.]

-Claims of major scientific controversy, based almost always on the opinions (but not usually peer-reviewed) of a minuscule handful of scientists, of whom only a few were actually climate scientists. Scientists are always always arguing about details, but I sure couldn’t find major controversy, just normal observational science in progress.

-Claims that some paper contradicted AGW, but when I’d go read the primary research journal, it wasn’t true.

-There was constant cherry-picking of data [like saying the Wegman Report was a refutation of AGW (it wasn’t), like picking a few weather stations showing downward trends, like saying there was no sea-level rise by citing Stockholm’s sea-level records. A random layperson might be forgiven Stockholm, but not a professional oceanic meteorologist, who couldn’t possibly be unaware of Post Glacial Rebound (PGR).]

-In general, the arguments seemed directed to keep the public confused, as opposed to contributing to science. That is, it would be plausible for someone to propose a testable, alternate hypothesis that explained the existing data, but this wasn’t that, this was “anything but AGW”. The closest I could find that looked like a serious hypothesis was Lindzen’s IRIS hypothesis, which remains up in the air, at best, and in any case, is more of a claim of a mechanism that could automatically ameliorate AGW.

It is quite easy for people who haven’t studied this in detail to pick up denialist ideas, because they are usually packaged as simple sound-bytes that are easy to remember. There may be masses of real science that refutes them, but the latter do not lend themselves to quick simplicity. I’m actually surprised that climate scientists are as patient as many are, giventhat they’ve had to deal with this for years.

Anyway, over time (and it takes a while, because a snapshot at any onetime doesn’t capture the dynamic behavior), it became clear that the underlying position:

(”under no circumstances conserve fossil fuels or regulate CO2″)

was the constant, and that there were a continuing (but ever-changing) series of ideas thrown up against AGW, not with the idea of improving scientific models to better approximate reality, but in support of particular political/economic views, using tactics to keep the public as confused as long as possible. (And it’s OK with me to promote one’s views … but I’d rather it be done by being upfront, not by obfuscating science.) Such tactics can work fairly well, as they did for RJ Reynolds (it took a long time to restrict smoking, didn’t it?) It is totally unsurprising that trying to mitigate AGW (especially by conservations) is simply not in the short-term interests of some companies, just as restricting smoking is not in RJR’s.

6) CONCLUSION So, I started from a classical skeptic viewpoint, studied the problem in fair depth (for a non-climate scientist), and got convinced that the AGW science was quite solid, notwithstanding some occasional problems in graphics/statistics presentation akin to ones I’ve seen in my own discipline).

I also got convinced that there was a small, but vocal group who were *not* skeptics, but “skeptics” or denialists. I don’t think that real climate scientists have a problem with classical skeptics, just with 100%-sure denialists calling themselves skeptics.

4. Is there legitimate scientific debate about the accuracy of the hockey stick graph?

Yes, but mainly about the details, not the essential point. Temperature fluctuations that predate written records are preserved in natural archives (e.g., tree rings, ice cores, boreholes) with various time periods (e.g., seasonal, annual, decadal). The scientific discussion has focused on the best statistical method for combining these various records to accurately capture temperature fluctuations for the Northern Hemisphere. As is typical of the scientific process, independent teams of researchers have worked to reproduce the results of the "hockey stick" by using their own approaches and even by using slightly different data. These studies sometimes produce slightly higher temperature fluctuations in the past compared with the initial study. But despite their differences, they still yield the same essential conclusion: the past 10- to 20-year period was likely the warmest of the past millennium.

5. How much does our understanding of global warming depend on the hockey stick graph?

The short answer is "very little." The hockey stick graph constitutes only one among literally thousands of pieces of evidence that have contributed to the present scientific consensus on the human influence on global warming. In 2001, the Intergovernmental Panel on Climate Change (IPCC) concluded in its authoritative third assessment report that "there is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities." As one climate expert observed: The IPCC report Climate Change 2001: The Scientific Basis is 881 pages in length. It weighs 5.5 pounds and contains over 200 figures and 80 tables. It would be absurd to think that the weight of its conclusions rests on any one figure or table; rather it paints a convincing picture in the totality of its science, as noted succinctly in its title."¹

We are now observing real changes due to higher temperatures. Here are some examples:

• The Mt. Kilimanjaro glacier, which has survived the past 11,000 years, is currently at risk of disappearing by 2020 if present rates of melting continue;

   

• Enormous tracts of Siberian peatlands, with vast stores of carbon, are beginning to thaw and release carbon dioxide and methane into the atmosphere;

   

• The Larsen B ice shelf in Antarctica has lost volume as large chunks (some as large as the state of Rhode Island) have recently broken free and melted;

• The annual surface area of Arctic sea ice has declined eight percent over the past several decades;
• Large-scale increases in ocean temperatures have been detected over the past 45 years; and
• Plants and animals are changing their habitation ranges, sometimes dramatically, such as robins and mosquitoes in the Arctic that were previously unknown there.

Antarctic ice core records vividly illustrate that atmospheric carbon dioxide (CO2) levels today are higher than levels recorded over the past 650,000 years (see figure below).  Atmospheric CO2 levels have risen 30 percent in the last 150 years, with half of that rise occurring only in the last three decades. It is a well-established scientific fact that CO2 (and other gases emitted from industrial and agricultural sources) traps heat in the atmosphere, so it is no surprise that we are now witnessing a dramatic increase in temperature.

Compared with other factors that influence climate (including solar variation, volcanic eruptions, and pollutant emissions such as sulfur dioxide), human activities-primarily burning fossil fuels and deforestation-have been a major contributor to climate change over the last 50 years.

Atmospheric carbon dioxide record data sources: Keeling and Whorf (2004),
Petit et al. (1999), IPCC (2001), Ahn et al. (2004).
Art credits: astronaut, pyramid: (c) photos.com; car, mammoth: (c) clipart.com.

6. What evidence demonstrates that the recent increase in global temperature is unprecedented?

The National Climate Data Center (NCDC) has maintained global average monthly and annual records of combined land and ocean surface temperatures since 1880, the earliest year for which reliable instrumental records were available worldwide. Based on NCDC data, nine of the top 10 warmest years globally have occurred since 1995. Adding to the evidence of direct temperature measurements, multiple studies by independent teams of researchers indicate that, across the Northern Hemisphere, the 1990s were likely the warmest decade of the past millennium-and possibly the past 2,000 years.

7. How do past climate trends help us understand future temperature?

Reconstructions of past climates help us build accurate projections of how future climates will be affected by global warming. Much as the Air Force builds computer programs to simulate aircraft flight under different conditions, climate scientists build computer programs to help simulate global climate under different conditions. These computer programs, called General Circulation Models (GCMs), use various assumptions about physical, chemical, and biological processes that occur within Earth's atmosphere and oceans and on its land surfaces. To ensure accuracy, each model is checked to see if it generates results that correctly reproduce the past and current climate. Once accuracy is established, the computer program can then be used to explore the likely future climate if, for example, we double the atmospheric concentration of carbon dioxide.

Exactly.  Much of this thread I am filtering through my own experience on this site on the subject of climate change.  There are 3 distinct ways this topic could be viewed. 

1. The first, science, is my pov as it is objective and subject to verification.

2. Political - In the US, as Mike points out, this subject is politically controversial.  The talking heads routinely parrot misinformed interest group propaganda and the populace routinely repeats these assertions as if they have merit.  The blogosphere has hugely magnified the influence of those who spread misinformation.

3. Conspiracy theories - Both sides, I suppose, view their opponents as either part of or sadly misinformed by the conspirators.

My point is that this one topic can lead to heated arguments (not debate as that word implies some sort of boundaries within which fact and rules of order are important).  If I had my preferences I would prefer scientific discussions, because they are fact based and subject to further scientific evidence.  In the case of climate change, the science is clear, although incomplete.  There is, indeed, general consensus in the scientific community on at least the broad outlines of the science, but there are those who claim the scientific community is, itself, a conspiracy.  Who is going to be the arbiter to decide who is making fallacious, uninformed, dishonest, political or otherwise biased comments on the subject, and then consign them to the appropriate thread or section of the site?  I'm not sure any of us could adequately perform that function because we are all subject to bias.

Instead, as in science, I guess I prefer to let everyone make his or her contribution and let the truth sort itself out.  The only restriction I would approve is one of common decency, and I think the moderators have done a fine job of sanctioning those who cross the lines.

Thank you for proving my point. Dogmatic, and clearly both conjectural and controversial.

The IPCC is absolutely NOT an unbiased source. Any panel created to do anything on tax-payer funds must find that their necessary, or by default that entity becomes vestigial, and loses its funding. Climate is not the only area where nebulous findings equal sustained fiscal support; the Salmon of the Columbia River have been slowly dying off so that biologists can run tests on how to sustain their population.

After 21 years, they are alive only because the hatcheries haven't stopped spawning them. Humans have essentially eliminated the habitat and stock of wild fish. Climate is, and will be the exact same. Nebulous results with ominous implications. Solutions? Never! It'd mean WORK rather than RHETORIC.

Any claims counter to what you accept on the good faith of others is lambasted as "blogosphere pseudoscience".
Quite clearly, several of us, trained as scientists have found the IPCC report lacking and wanting in the area of evidence to support their claim.

Those of us who have done the "minimal bit of research", and have some background in the subject have found it inconclusive, and as such conjectural. Reviewing some of the threads, I noted two atmospheric physicists who came to the same conclusion as I. Don't take it as an attack, it simply is what it is.

Your assertions are not fact checked either - simply cross referenced with people who believe what you believe.
I truly hope you see the wisdom in divorcing yourself from such doxology and taking a less biased view of the issue.

It truly is not "proven", and again, as a atmospheric scientist, I do not see any evidence that leads me to believe it is irrefutably a human phenomonon, nor a runaway train to oblivion.