In my posts on climate change, I have tried to present evidence that natural variation explains most, if not all, climate changes we have experienced. That, of course, has produced many comments and arguments from proponents of anthropogenic global warming: those who contend that our carbon dioxide emissions, mostly from burning fossil fuels, are the principle cause of recent warming and that the warming is dangerous. I disagree with that contention.

Dr. S. Fred Singer, writing in American Thinker, has an essay titled “Climate Deniers Are Giving Us Skeptics a Bad Name.” In that article, Dr. Singer takes both “warmistas” as he calls AGW proponents, and “deniers” to task. Below, I reproduce the portion of the essay where Dr. Singer takes on the IPCC and warmistas. You can read the entire essay and comments here.

For those who don’t know: Dr. S. Fred Singer is professor emeritus at the University of Virginia and director of the Science & Environmental Policy Project, specializing in climate science and energy policy. “An expert in remote sensing and satellites, he served as the founding director of the US Weather Satellite Service and, more recently, as vice chair of the US National Advisory Committee on Oceans & Atmosphere.” He is also a member of the Heartland Institute.

Dr. Singer writes:

The warmistas, generally speaking, populate the U.N.’s IPCC (Intergovernmental Panel on Climate Change) and subscribe to its conclusion that most of the temperature increase of the last century is due to carbon-dioxide emissions produced by the use of fossil fuels. At any rate, this is the conclusion of the most recent IPCC report, the fourth in a series, published in 2007. Since I am an Expert Reviewer of IPCC, I’ve had an opportunity to review part of the 5th Assessment Report, due in 2013. Without revealing deep secrets, I can say that the AR5 uses essentially the same argument and evidence as AR4 — so let me discuss this “evidence” in some detail.

 IPCC-AR4 uses only the global surface temperature (GST) record. It exhibits a rapid rise in 1910-1940, a slight decline in 1940-1975, a sharp “jump” around 1976-77 — and then a steady increase up to 2000 (except for the temperature “spike” of the 1998 Super-El Niño). No increase is seen after about 2001.

 Most everyone seems to agree that this earlier increase (1910-1940) is caused by natural forces whose nature the IPCC does not specify. Clearly, the decline of 1940-1975 does not fit the picture of an increasing level of carbon dioxide, nor do the “jump” and “spike.” So the IPCC uses the increase between 1978 and 2000 as evidence for human (anthropogenic) global warming (AGW).

 Their argument is somewhat strained, and their evidence is questionable. They claim that their models simulating the temperature history of the 20th century show no warming between 1970 and 2000 — when they omit the warming effect of the steady, slow CO2 increase. But once they add the CO2 increase into the models, they claim good agreement with the reported global surface temperature record. Ergo evidence for AGW.

 There are three things wrong with the IPCC argument. It depends very much on detailed and somewhat arbitrary choices of model inputs — e.g., the properties and effects of atmospheric aerosols, and their temporal and geographic distribution. It also makes arbitrary assumptions about clouds and water vapor, which produce the most important greenhouse forcings. One might therefore say that the IPCC’s evidence is nothing more than an exercise in curve-fitting. According to physicist Freeman Dyson, the famous mathematician John von Neumann stated: “Give me four adjustable parameters and I can fit an elephant. Give me one more, and I can make his trunk wiggle.”

 The second question: can the IPCC fit other climate records of importance besides the reported global surface record? For example, can they fit northern and southern hemisphere temperatures using the same assumptions in their models about aerosols, clouds, and water vapor? Can they fit the atmospheric temperature record as obtained from satellites, and also from radiosondes carried in weather balloons? The IPCC report does not show such results, and one therefore suspects that their curve-fitting exercise may not work, except with the global surface record.

 The third problem may be the most important and likely also the most contested one. But first let me parse the IPCC conclusion, which depends crucially on the reported global surface warming between 1978 and 2000. As stated in their Summary for Policymakers (IPCC-AR4, vol 1, page 10): “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”

 But what if there is little to no warming between 1978 and 2000? What if the data from thousands of poorly distributed weather stations do not represent a true global warming? The atmospheric temperature record between 1978 and 2000 (both from satellites and, independently, from radiosondes) doesn’t show a warming. Neither does the ocean. And even the so-called proxy record — from tree rings, ice cores, ocean sediments, corals, stalagmites, etc. — shows mostly no warming during the same period.

Dr. Singer points out that the IPCC relies heavily on modeling and assumptions while actually presenting little physical evidence to support its position. The same has been my experience with commenters on this blog. The issue is important because of all the money being spent to try to prevent catastrophic global warming that seems to exist only in models. The tragedy is that money would be better spent on real problems. Also, “dioxycarbophobia,” the fear of carbon dioxide, is driving government agencies, especially the EPA, into policies that do grave harm to our economy, jobs, and even national security – all based on an unsupported concept that is more political than scientific.

It is the job of scientists to be skeptical, and I remain so.

UPDATE:

Commenters below invoke the authority of reports by NASA, NOAA, EPA, USFWS, USFS, USDA and other agencies. Dr. Craig Loehle has read many of these reports and finds them “usually vague on details of what bad things are expected to happen…” Loehle says “The true story is far from alarming.” For instance, here is his take on the specter of ocean acidification:

“One government draft report indicated that ocean pH has decreased (become more acid) by 0.1 units, and that this represents a 30% increase in acidity since 1750. Because pH is a log scale, estimating percent increases in acidity is problematic and a change of 0.1 units could not represent a 30% change in acidity as stated. A serious issue not addressed by the report is that a global time series of pH data for the oceans does not exist. Thus, the provenance of the 0.1 unit change in value is dubious, and the confidence intervals on such an estimate would no doubt be large. Furthermore, daily, seasonal, and between year pH fluctuations at any given location are on the order of ±0.3 pH units or more (Middelboe and Hansen 2007; Pelejero et al. 2005).”

Read more here.

See also:

Journalist Donna LaFramboise’s exposé on the IPCC: The Delinquent Teenager Who Was Mistaken for the World’s Top Climate Expert, an IPCC Exposé.

The Assumed Authority