1. SCIENCE: Study appears to refute climate change skeptics' research (ClimateWire, 10/14/2008)

Jessica Leber, ClimateWire reporter

Challenging the latest assertions of longtime global warming contrarians, a 17-member team has published new results finding no mismatch between the tropical warming trends predicted by climate models and actual observations.

The study, published online in the International Journal of Climatology on Friday, concludes that it has resolved a decade-old problem largely by using more recent data and accounting for the effect of natural climate variations on satellite and weather balloon measurements. The team's result was that no fundamental disagreement exists.

This is one more nail in the coffin of those who remain skeptical of human-induced climate change, said climatologist Gavin Schmidt, one co-author on the paper. Not that another nail is needed, he added -- there are already more than enough.

"Rather than worrying about how many angels are dancing on the head of the pin, we ought to worry about designing better measurement systems," agreed the study's lead author, Lawrence Livermore National Laboratory climatologist Benjamin Santer.

Solving the tropical mystery

Climate models have long forecast that the Earth's lower atmosphere should warm more quickly than the surface. This prediction, in the past, has not matched observational records. But more recent studies led the U.S. Climate Change Science Program to conclude that there was no major discrepancy on a global scale.

One problem area remained: the tropics. Last year, a team of known climate change skeptics, including professional contrarian S. Fred Singer, a scientist who now heads the Science & Environmental Policy Project, published a peer-reviewed paper in the International Journal of Climatology. It found a "significant" disagreement between climate model predictions and tropical observations. The study concluded that climate change projections for the future are seriously flawed.

At the Lawrence Livermore National Laboratory, Santer was dubious. "We had a look at the paper and decided pretty quickly that the statistical test these folks had applied was completely inappropriate," said Santer.

Any series of temperature measurements, he explained, are imprinted with human-influenced slow warming, but there's also natural noise -- especially in the tropics, where there are many yearly complications due to El Niño, for example. Said Schmidt: "They basically ignored the uncertainty in the data."

In addition to correcting the statistical test, the new study addresses a gap in scientific understanding. This paper is certainly important if it determines whether there is a discrepancy or not, said Isaac Held, a scientist with the National Oceanic and Atmospheric Administration's Geophysical Dynamics Fluid Laboratory who was not involved with either study.

While Santer held out hope that global warming skeptics might cease and desist on at least this particular issue, that outcome is unlikely. Both Singer and co-author John Christy, a scientist at the University of Alabama, Huntsville, said the new study grossly misinterprets their results and the data. Singer, in an e-mail message, maintained that the disagreement between tropical observations and climate warming gives him reason to doubt that the human contribution to climate change is significant.

Better measurements needed

The whole issue highlights a crucial need to collect better climate data, said Schmidt. Most climate data, from satellite measurements to weather balloon drops, are gathered to keep track of the weather. While meteorologists want to use the best equipment and procedures available to them at the moment, a climatologist needs consistent data over the long term.

"We don't have an agency whose job it is to make sure that we collect climate-quality records," he said.

Better monitoring will help determine the success or failure of future actions to mitigate climate change or reduce greenhouse gases, said Santer. It will also help improve models so that future ambiguities, like those addressed in his study, will be easier to resolve.

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