December 2, 2008

Will the U.N. Chill Out on Climate Change?

10,000 people from 86 countries have descended upon Poznan, Poland for yet-another United Nations meeting on climate change. This time, it’s the annual confab of the nations that signed the original U.N. climate treaty in Rio in 1992. That instrument gave rise to the infamous 1996 Kyoto Protocol on global warming, easily the greatest failure in the history of environmental diplomacy.

Kyoto was supposed to reduce global emissions of carbon dioxide below 1990 levels during the period 2008-2012. But since it was signed, the atmospheric concentration of this putative pollutant continued to rise, pretty much at the same rate it did before Kyoto. (Even if the world had lived up to the letter of the Kyoto law, it would have exerted an influence on global temperature that would have been too small to measure.)

The purpose of the Poznan meeting is to work out some type of framework that goes “Beyond Kyoto.” After completely failing in its first attempt to internationally limit carbon dioxide emissions, the U.N. will propose reductions far greater than those called for by Kyoto. Kyoto failed because it was too expensive, so anything “beyond” will cost much more.

The fact is that the world cannot afford any expensive climate policies now. Economic conditions are so bad that carbon dioxide emissions—the byproduct of our commerce—are likely going down because of the financial cold spell, not the climatic one. Indeed, a permanent economic ice-age would likely result from any mandated large cuts in emissions. If you’re liking your 401(k) today, you’ll love “Beyond Kyoto.”

Before proposing an even harsher treaty the U.N. ought to pay attention to its own climate science. It regularly publishes temperature histories from its Intergovernmental Panel on Climate Change (IPCC), which was formed in the late 1980s with the express charge of finding a scientific basis for a global climate treaty.

Since Kyoto, a very funny thing has happened to global temperatures: IPCC data clearly show that warming has stopped—even though its computer models said such a thing could not happen.

According to the IPCC, the world reached its high-temperature mark in 1998, thanks to a big “El Niño,” which is a temporary warming of the tropical Pacific Ocean that occurs once or twice a decade. El Niño years are usually followed by one or two relatively cold years, as occurred in 1999 and 2000. The cooling is, not surprisingly, called La Niña. No one knows what really causes these cycles but they have been going on sporadically for millennia.

Wait a minute. Starting an argument about global warming in 1998 is a bit unfair. After all, that’s starting off with a very hot temperature, followed by two relatively cool years.

Fine. Take those years out of the record and there’s still no statistically significant warming since 1997. When a scientist tells you that some trend is not “significant,” he or she is saying that it cannot mathematically be distinguished from no trend whatsoever.

More important, as shown in our Figure 1, there’s not going to be any significant trend for some time.

Assume, magically, that temperatures begin to warm in 2009 at the rate they were warming before the mid-90s, and that they continue to warm at that rate.

We show two alternatives. One includes the El Niño/La Niña cycle of 1998-2000. Assuming that the old rate of warming reappears in 2009 and continues, the warming since 1998 does not become statistically significant until 2021.

Our other alternative simply removes the El Niño/La Niña cycle and starts in 1997. Under that assumption, warming doesn’t become significant until 2020.

Whatever the assumption, even if the earth resumes warming at the pre-1998 rate, we will have nearly a quarter-century without a significant warming trend.


Figure 1. Top: Observed temperature, 1998-2008 (blue circles), plus a constant rate of warming beginning in 2009 at the rate established from 1977 through 1997 (0.17°C/decade) (red circles). Warming since 1998 does not become statistically significant until 2021.

Bottom: Same as above, but the observed temperatures beginning in 1997 through 2008 (filled blue circles), and ignoring the El Niño/La Niña swing in 1998-2000 (open blue circles). The constant rate of warming is assumed to begin in 2009 (filled red circles). In this case, warming does not become significant until 2020.

Perhaps the delegates at Poznan ought to look at the IPCC’s latest (2007) compendium on climate. It used 21 different climate models to forecast the future, and subjected each to different “storylines” (in the U.N.’s parlance) for global emissions of carbon dioxide. They are there for the world to see, on page 763 of the volume on climate science (reproduced as our Figure 2). Not one of them predicts a quarter-century without warming—even under a scenario in which emissions increase faster than they already are.


Figure 2. Temperature projections from 2000 to 2100 from the suite of climate models used by the IPCC for three different “storylines”—SRES A2 (top); SRES A1B (middle); SRES B1 (bottom) (source: IPCC AR4, page 763).

The bottom line is that the U.N.’s own climate models have failed, barely a year after they were made public. They have demonstrated a remarkable inability to even “predict” the present! Can 10,000 people in Poznan somehow ignore this?

They shouldn’t. Instead they should be thankful. The lack of recent and future warming almost certainly means that the ultimate warming of this century is going to be quite modest. Instead, they should keep in mind that expensive policies to fight a modest climate change will only worsen the unprecedented cold snap affecting the global economy.




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