Global warming appears to have stalled. Climatologists are puzzled as to why average global temperatures have stopped rising over the last 10 years. Some attribute the trend to a lack of sunspots, while others explain it through ocean currents.

At least the weather in Copenhagen is likely to be cooperating. The Danish Meteorological Institute predicts that temperatures in December, when the city will host the United Nations Climate Change Conference, will be one degree above the long-term average.

Otherwise, however, not much is happening with global warming at the moment. The Earth's average temperatures have stopping climbing since the beginning of the millennium, and it even looks as though global warming could come to a standstill this year.

Ironically, climate change appears to have stalled in the run-up to the upcoming world summit in the Danish capital, where thousands of politicians, bureaucrats, scientists, business leaders and environmental activists plan to negotiate a reduction in greenhouse gas emissions. Billions of euros are at stake in the negotiations.

ScienceDaily (Nov. 18, 2009) -- Professor Guillermo Bazan and a team of postgraduate researchers at UC Santa Barbara's Center for Polymers and Organic Solids (CPOS)  have announced a major advance in the synthesis of organic polymers for plastic solar cells.

Bazan's team reduced reaction time by 99%, from 48 hours to 30 minutes, and increased average molecular weight of the polymers by a factor of more than 3.

The reduced reaction time effectively cuts production time for the organic polymers by nearly 50%, since reaction time and purification time are approximately equal in the production process, in both laboratory and commercial environments.

The higher molecular weight of the polymers, reflecting the creation of longer chains of the polymers, has a major benefit in increasing current density in plastic solar cells by as much as a factor of more than four. Over polymer batches with varying average molecular weights, produced using varying combinations of the elements of the new methodology, the increase in current density was found to be approximately proportional to the increase in average molecular weight.

Researchers have long debated what triggered the extinctions that struck North American megafauna between 14,000 and 11,000 years ago (SN: 12/4/99, p. 360), and one of the prime candidates has been habitat change caused by a warming climate. The appetites and activities of humans streaming into the continent across a land bridge from Asia provide another possible culprit.

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Sediments that accumulated in lakes in Indiana and New York provide evidence for the claims of Williams and his colleagues. In that material, the researchers looked at long-term trends in the amounts of tree pollen, charcoal bits and spores of fungi in the genus Sporormiella. Digestive processes in large herbivores are an integral part of the fungi's life cycle, and spores have been isolated from the dung of ancient mammoths, Williams says.

Recent studies suggest that when the number of Sporormiella spores in a sample of lake sediment is less than 2 percent of the number of grains of tree pollen, it's a sign that the surrounding area is home to few if any herbivores producing the large quantities of dung required for the fungi to thrive, says Jacquelyn Gill, also a paleoecologist at the University of Wisconsin-Madison and a coauthor of the new report.

Analyses of sediments pulled from Appleman Lake in northeastern Indiana reveal that the numbers of Sporormiella spores began to decline about 14,800 years ago. But it wasn't until 13,700 years ago, more than a millennium later, that the spore-to-pollen ratio dropped below 2 percent, signaling a disappearance of the mammoths from the local area.

Also around 13,700 years ago is precisely when pollen grains from broad-leaved and presumably tasty trees such as ash and ironwood began to show up in lake-bottom sediments in substantial numbers. That's no coincidence, the researchers argue: These presumably tasty trees could only flourish when the megafauna that ate them were no longer present in large numbers.

Over the years, the toxicity of PCBs has slowly emerged. Some have been designated not only as probable carcinogens, but also as agents that diminish immunity and pollutants that lower birth weight and IQ. Now, researchers with the Anniston, Ala., Environmental Health Research Consortium report that these toxic pollutants also appear to impair vascular health.

A Monsanto plant in Anniston manufactured PCBs from 1929 to 1971. To probe for any lurking human impacts of widespread contamination in communities around the plant, the federal government funded a group of universities and community groups to study blood and other health indicators. For the new investigation, they focused on about 750 randomly selected men and women in the community nearest to the former PCB-production facility.

David Carpenter of the University of Albany, in Rensselaer, N.Y., and his colleagues discovered a dose-dependent climb in risk of both systolic and diastolic hypertension with rising blood concentrations of PCBs. "We're excited by this relationship," Carpenter says. "It's very novel."

His team reported the finding at the recent Dioxin 2009 conference in Beijing (the August meeting's formal name is the 29th International Symposium on Halogenated Persistent Organic Pollutants).