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When the Deepwater Horizon oil rig suffered a catastrophic explosion and blowout on April 21, 2010, leading to the worst oil spill in the history of the petroleum industry, the well’s operators thought they would be able to block the leak within a few weeks. On May 9 they succeeded in lowering a 125-ton containment dome over the broken wellhead. If that measure had worked, it would have funneled the leaking oil into a pipe that carried it to a tanker ship above, thus preventing the ongoing leakage that made the spill so devastating. Why didn’t the containment work as expected?

The culprit was an icy mixture of frozen water and methane, called a methane clathrate. Because of the low temperatures and high pressure near the seafloor, the slushy mix built up inside the containment dome and blocked the outlet pipe, preventing it from redirecting the flow. If it hadn’t been for that methane clathrate, the containment might have worked, and four months of unabated leakage and widespread ecological devastation might have been prevented.

How hot our planet will become for a given amount of greenhouse gases is a key number in climate change. As the calculation of how much warming is locked in by a given amount of emissions, it is crucial for global policies to curb global warming.

It is also one of the most hotly debated numbers in climate science. Observations in the past decade seem to suggest a value that is lower than predicted by models. But a University of Washington study shows that two leading methods for calculating how hot the planet will get are not as far apart as they have appeared.

The massive Kaskawulsh Glacier in northern Canada has retreated about a mile up its valley over the past century.

Last spring, its retreat triggered a geologic event at relatively breakneck speed. The toe of ice that was sending meltwater toward the Slims River and then north to the Bering Sea retreated so far that the water changed course, joining the Kaskawulsh River and flowing south toward the Gulf of Alaska.

Traffic-related air pollution may increase cardiovascular disease risk by lowering levels of high-density lipoprotein (HDL), commonly known as “good” cholesterol, according to new research in the American Heart Association’s journal Arteriosclerosis, Thrombosis, and Vascular Biology.

Since 2007, scientists have been searching to find the cause of a sudden and unexpected global rise in atmospheric methane, a potent greenhouse gas, following almost a decade in which concentrations had stayed relatively constant.

Recent studies have explored a range of possible causes. Suggestions have included a rise in oil and natural gas extraction, increased emissions from tropical wetlands or increases in emissions from growing East Asian economies.