Wind-blown embers fly from an ancient oak tree that burned in the Silver Fire near Banning, California last summer. The fire broke out shortly after 2 p.m. near a back-country road south of Banning, about 90 miles (145 km) outside Los Angeles in Riverside County, and within hours had blackened more than 5,000 acres, California Department of Forestry and Fire Protection spokesman Daniel Berlandt said. Photo: Reuters/David McNew
A Brazilian crosses the muddy bottom of the Rio Negro, a major tributary to the Amazon river, in the city of Manaus. A drought pushed river levels in Brazil's Amazon region to record lows, leaving isolated communities dependent on emergency aid and thousands of boats stranded on parched riverbeds. Photo: Reuters/Euzivaldo Queiroz
Splinters of ice peel off from one of the sides of the Perito Moreno glacier in a process of a unexpected rupture during the southern hemisphere's winter months, near the city of El Calafate in the Patagonian province of Santa Cruz, southern Argentina, in this file photo. Photo: Reuters/Andres Forza
Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. The country has invested 51 billion yuan ($7.4 billion) towards the construction of 2,712 projects for the treatment of eight rivers and lakes including Huaihe River, Haihe River, Liaohe River, Chaohu Lake, Dianchi Lake, Songhua River, the Three Gorges region of the Yangtze River and its upstream area, according to Xinhua News Agency. Photo: Reuters/Jianan Yu
An aid worker using an iPad films the rotting carcass of a cow in Wajir near the Kenya-Somalia border, July 23, 2011. Since drought gripped the Horn of Africa, and especially since famine was declared in parts of Somalia, the international aid industry has swept in and out of refugee camps and remote hamlets in branded planes and snaking lines of white 4x4s. This humanitarian, diplomatic and media circus is necessary every time people go hungry in Africa, analysts say, because governments - both African and foreign - rarely respond early enough to looming catastrophes. Combine that with an often simplistic explanation of the causes of famine, and a growing band of aid critics say parts of Africa are doomed to a never-ending cycle of ignored early warnings, media appeals and emergency U.N. feeding - rather than a transition to lasting self-sufficiency. Photo: Barry Malone
A home is seen protected from encroaching floodwaters by a levee near Yazoo City, Mississippi. Floodwater released from a key Mississippi River spillway surged through the Louisiana bayou on Tuesday, and levees protecting the state's two biggest cities held as river flows neared their peak. Weeks of heavy rains and runoff from an unusually snowy winter caused the Mississippi River to rise, flooding thousands of homes and 3 million acres (1.2 million hectares) of farmland in Mississippi, Tennessee and Arkansas and evoking comparisons to historic floods in 1927 and 1937. Photo: Reuters/Eric Thayer
A male polar bear carries the head of a polar bear cub it killed and cannibalized in an area about 300 km (186 miles) north of the Canadian town of Churchill. Climate change has turned some polar bears into cannibals as global warming melts their Arctic ice hunting grounds, reducing the polar bear population, according to a U.S.-led global scientific study on the impacts of climate change. Photo: Reuters/Iain D. Williams
A boy floats on a river, covered by duckweed, to cool off during a hot summer day in Jiaxing, Zhejiang.
An aerial view shows a cleared forest area under development as a palm oil plantation by palm oil companies in the Ketapang district of Indonesia's West Kalimantan province. The photograph was taken as part of a media trip organised by conservationist group Greenpeace, which has campaigned against palm oil expansion in forested areas in Indonesia. Documents written between 2008 and January 2010 and sent between lobbyists, scientists and high-ranking European civil servants, released after Reuters invoked transparency laws, exposed a huge rift in Brussels over biofuels policy and also undermined Europe's ambition of using alternative fuels to wean the continent off oil by showing how vested interests have influenced the science behind a cornerstone of the continent's clean energy policy. Photo: Reuters/Crack Palinggi
A man cools off at the flooded Danube river banks in downtown Belgrade, June 16, 2010, when the Danube rose to dangerous levels. Photo: Reuters/Ivan Milutinovic
A farmer walks on a dried-up pond on the outskirts of Baokang, central China's Hubei province. Photo: Reuters
Graffiti art is seen on a wall next to the Regent's Canal, in Camden in London December 22, 2009. British media have attributed the new work to acclaimed British street artist Banksy. Photo: Reuters/Luke MacGregor
A cow stands in her pen at the National Institute of Agricultural Technology in Castelar, on the outskirts of Buenos Aires. Argentine scientists are taking a novel approach to studying global warming, strapping plastic tanks to the backs of cows to collect their burps. Researchers say the slow digestive system of cows makes them a producer of methane, a potent greenhouse gas that gets less public attention than carbon dioxide. Photo: Marcos Brindicci.