Global Warming

Warming Greenland ice sheet passes point of no return

Nearly 40 years of satellite data from Greenland shows that glaciers on the island have shrunk so much that even if global warming were to stop today, the ice sheet would continue shrinking.

The finding, published today, Aug. 13, in the journal Nature Communications Earth and Environment, means that Greenland’s glaciers have passed a tipping point of sorts, where the snowfall that replenishes the ice sheet each year cannot keep up with the ice that is flowing into the ocean from glaciers.

Climate change, not hunters, may have killed off woolly rhinos

Rather than getting wiped out by Ice Age hunters, woolly rhinos charged to extinction in Siberia around 14,000 years ago when the climate turned warm and wet, a study of ancient DNA suggests.

Numbers of breeding woolly rhinos stayed relatively constant for tens of thousands of years until at least about 18,500 years ago, more than 13,000 years after people first reached northeastern Siberia, scientists report online August 13 in Current Biology. Yet only a few thousand years later, woolly rhinos died out, probably because temperatures had risen enough to reshape arctic habitats. A shift to warm, rainy conditions, which occurred between roughly 14,600 and 12,800 years ago, likely played a large role in the rapid decline of this cold-adapted species.

Tropical Soil Leaks CO2

Tropical forest soil warmed in experiments to levels consistent with end-of-century temperature projections released 55 percent more CO2 than control plots, exposing a previously underestimated source of greenhouse gas emissions, researchers reported Wednesday.

Before humanity began loading the atmosphere with carbon pollution by burning fossil fuels, the input and outflow of CO2 into soil – one key element in Earth’s complex carbon cycle – remained roughly in balance.

Gases emitted by deadwood and decaying leaves, in other words, were cancelled out by microorganisms that feed on such matter. But climate change has begun to upset that balance, according to a new study, published in Nature.

In experiments, researchers placed heating rods in a one-hectare plot of undisturbed primary forest on Barro Colorado Island, Panama. They warmed the soil to a depth of just over one metre (three feet) by 4C over a period of two years. The findings shows an increase in in the release of CO2 of 55 per cent above the basal rates.

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