IPCC Fourth Assessment Dampens Global Warming Alarmism

Published June 1, 2007

On February 2, the United Nations’ Intergovernmental Panel on Climate Change released an 18-page Summary for Policymakers of its yet-to-be-published (at press time) Fourth Assessment Report on global warming.

The summary was authored by a committee of 33 scientists, many of whom have differing views and expertise on the subject. The parent document, which will weigh in at nearly 1,000 pages, is scheduled to be released in May.

I was an official reviewer of the overall report. Because various versions of the document have leaked onto the Internet in recent months, I’ll take the liberty of using it as a reference guide for the forthcoming summary.

Nothing New

Want my candid opinion about the summary? Ho-hum.

Despite breathless news reports, there’s very little in it that’s new to anyone involved in global warming science. There have been dozens of stories about how scientists now believe there is a definite human influence on mean global surface temperature, and that, in recent decades, much of the warming can be attributed to the effect of increasing amounts of carbon dioxide and methane in the atmosphere.

Scientifically, this is tantamount to concluding that Las Vegas is awash in poker chips.

For longer than any active climate scientist has been alive, it has been known that increasing atmospheric carbon dioxide should result in a preferential warming of winter (versus summer) temperatures, a warming of the coldest nights of the winter more than the hottest days of summer, and a general cooling of the global stratosphere.

All three have been observed for well over a decade. So much for the big “news” in the IPCC summary.

Reduced Sea-Level Predictions

Nor should this surprise: The biggest story in the summary was largely missed by the environmental media. The IPCC now projects, in its mid-range scenario for carbon dioxide emissions, that the maximum-scenario rise in global sea level in this century will be around 17 inches.

That’s a reduction of 30 percent from what was in the Third Scientific Assessment, published just six years ago.

That’s huge news, or at least it should be.

But instead of listening to what the IPCC is saying, people are opting for the science fiction of Al Gore’s An Inconvenient Truth, whose central disaster scenario is that Greenland sheds the majority of its ice this century, raising sea level as much as 20 feet. Much of Florida disappears, and the Mall in Washington goes under water.

Greenland Melting Unlikely

Even the much lower IPCC sea-level predictions may be overstating future sea-level rise. This is because IPCC’s sea-level projections “include a contribution due to increased ice flow from Greenland and Antarctica, but these flow rates could increase or decrease in the future.”

That’s excellent hedging by the IPCC, because the authors of the summary surely knew that a paper was about to appear in the journal Science showing that an increase in the loss of ice from Greenland’s big glaciers in 2004 had stopped and reversed by 2006.

And was the loss of ice ever as gargantuan as Gore’s imagery? Hardly. Satellite data, also published in Science last October, show Greenland was losing a total of only 25 cubic miles of ice per year.

That’s teeny. There are 630,000 cubic miles of ice up there. Dividing 25 into 630,000 and multiplying by 100 gives the rate of loss: 0.4 percent of Greenland’s ice per century.

Implausible Scenario Assumed

It is unfortunate that the summary didn’t take on Gore’s Greenland science fiction head-on. It would have been as simple as highlighting the temperature history of southern Greenland–the region of greatest ice loss–in the UN’s own climate history.

Temperatures in the most recent decade aren’t at all warm compared with the 50 years between 1915 and 1965. If Greenland didn’t raise sea level appreciably then (and it didn’t), why will it suddenly do so now?

Instead, climate models in the upcoming report take an awfully long time to shed the majority of Greenland’s ice: After 1,130 years, 60 percent disappears if we maintain the concentration of atmospheric carbon dioxide at four times above the level it was around 1900.

Right now, we’re only about 1.3 times that value, and there’s a reasonable debate about whether we will ever get to twice that figure, because in the time frame required, technology is likely to change dramatically, in ways we can’t imagine today.

Things Will Change

For an interesting thought experiment, consider how technology has changed in a century. Between 1800 and 1900 technology progressed from horse power and hand-carried letters to iron-horse power and the telegraph.

Then consider the changes from 1900 to today. With this in mind, does anyone seriously believe we will be a fossil fuel-powered society, industrially respiring massive amounts of carbon dioxide, in the year 2500?

IPCC estimates of maximum sea-level rise also may be too high as a result of methane projections. All of IPCC’s scenarios for the future include an increase in atmospheric methane, a potent global warming gas, at least through 2050, and most increase it even beyond then.

However, methane increases in the atmosphere began to slow some 20 years ago, and in recent years the concentration has actually declined.

Snowmelt Overstated

While it’s hard to disagree with the IPCC’s broad conclusions about human-induced warming and sea-level rise, there are several instances where the summary misses some obvious and important findings.

For example, it asserts, “mountain glaciers and snow cover have declined on average in both hemispheres.” While that is generally (but not specifically) true for glaciers, data from the Global Snow Laboratory at Rutgers University show total Northern Hemisphere snow cover has been unchanged for the past 20 years.

Recent Developments Ignored

A very important part of the IPCC summary talks about how the top 10,000 feet of “the ocean has been absorbing more than 80 percent of the heat added to the climate system.”

Last summer, however, after the IPCC drop date, J.M. Lyman of the National Oceanic and Atmospheric Administration demonstrated a remarkable change between 2003 and 2005 that “represents a substantial loss of heat over a two-year period, amounting to about one-fifth of the long-term upper-ocean heat gain between 1955 and 2003.”

In two years, somehow the vast expanse of the upper ocean suddenly lost the equivalent of a decade’s worth of warming!

Furthermore, most of the ocean’s warming is centered in a band in the middle of the Southern Hemisphere. As the esteemed Roger Pielke Sr. of the University of Colorado recently wrote, “The actual global ocean warming reported in the IPCC [summary] over the last several decades occurred in just a relatively limited portion of the oceans.”

This is certainly not indicated in the climate models that serve as much of the basis for the upcoming Fourth Assessment.

So let’s give the IPCC somewhere around two cheers. That’s probably about the best that can be expected when 18 pages, written by a committee of 33 contentious scientists, are supposed to summarize about 1,000 succeeding pages, which themselves were not afforded the most recent science.

Patrick Michaels ([email protected]) is senior fellow in environmental studies at the Cato Institute, and a research professor of environmental sciences at the University of Virginia. An earlier version of this article appeared in the March 11 San Diego Union-Tribune, and it is reprinted with permission.