The consumption of shallow groundwater with elevated concentrations of arsenic is causing widespread disease in many parts of South and Southeast Asia. In the Bengal Basin, a growing reliance on groundwater sourced below 150-m depth—where arsenic concentrations tend to be lower—has reduced exposure. Groundwater flow simulations have suggested that these deep waters are at risk of contamination due to replenishment with high-arsenic groundwater from above, even when deep water pumping is restricted to domestic use.

World demand for rare-earth elements and the metal yttrium—which are crucial for novel electronic equipment and green-energy technologies—is increasing rapidly. Several types of seafloor sediment harbour high concentrations of these elements.

Afforestation, the conversion of croplands or marginal lands into forests, results in the sequestration of carbon. As a result, afforestation is considered one of the key climate-change mitigation strategies available to governments by the United Nations. However, forests are also less reflective than croplands, and the absorption of incoming solar radiation is greater over afforested areas. Afforestation can therefore result in net climate warming, particularly at high latitudes.

Emissions of CO2 are the main contributor to anthropogenic climate change. Here we present updated information on their present and near-future estimates. We calculate that global CO2 emissions from fossil fuel burning decreased by 1.3% in 2009 owing to the global financial and economic crisis that started in 2008; this is half the decrease anticipated a year ago. If economic growth proceeds as expected, emissions are projected to increase by more than 3% in 2010, approaching the high emissions growth rates that were observed from 2000 to 2008.

Mapping variations in regional sea level changes of different parts of the Indian Ocean could help developing countries better adapt to the effects of climate change, according to a study.

Instrumental observations suggest that Lake Tanganyika, the largest rift lake in East Africa, has become warmer, increasingly stratified and less productive over the past 90 years. These trends have been attributed to anthropogenic climate change.

The world

Nearly one sixth of the global population is malnourished. The problem is particularly acute in tropical Africa, where constant or recurrent food shortages affect over 30% of the population

Reducing atmospheric carbon emissions from tropical deforestation is at present considered a cost-effective option for mitigating climate change. However, the forces associated with tropical forest loss are uncertain. Here we use satellite-based estimates of forest loss for 2000 to 2005 to assess economic, agricultural and demographic correlates across 41 countries in the humid tropics.

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