Scientists tracking a dramatic shrinkage in Arctic sea ice over the past few years have come to a worrisome conclusion: If the trend continues, it could speed up the melting of Arctic permafrost as well. The environmental consequences of such a development are uncertain, but they could spell trouble for plants, animals, and humans in those regions that depend on solid ground underfoot.

In a bid to control greenhouse gas emissions linked to climate change, the European Union has been operating the world's first system to limit and to trade carbon dioxide. Despite its hasty adoption and somewhat rocky beginning three years ago, the EU "cap-and-trade" system has operated well and has had little or no negative impact on the overall EU economy, according to an MIT analysis.

Living near green space makes little or no difference in how much people exercise during their leisure time, Dutch researchers said on Wednesday.

In fact, people who live closest to green areas in urban or rural areas walk and cycle less often and for shorter amounts of time than other residents, they reported in the journal BioMed Central Public Health.