The world is hotter than it has been for four centuries. (File photo)

    BEIJING, June 23 (Xinhuanet) -- The Earth is the hottest it has been in at least four centuries and perhaps in thousands of years, according to a new report released in U.S. 

    The report also claimed that human activities are responsible for it.

    The National Academy of Sciences, US, reaching the conclusion in a broad review of scientific work requested by Congress, reported Wednesday that the "recent warmth is unprecedented for at least the last 400 years and potentially the last several millennia."

    The 155-page report said average global surface temperatures in the Northern Hemisphere rose about 1 degree Fahrenheit during the 20th century.

    This is shown in boreholes, retreating glaciers and other evidence found in nature, said Gerald North, a geosciences professor who chaired the academy's panel.

    The 12-member panel of top climate scientists said that "human activities are responsible for much of the recent warming."

    Scientists widely believe that emissions of carbon dioxide from power plants and cars that get trapped in the atmosphere are helping drive global warming.

    The report was done for the chairman of the U.S. House of Representatives Science Committee, Sherwood Boehlert, who hopes it registers with people questioning whether global warming is a major threat.

    "There is nothing in this report that should raise any doubts about the broad scientific consensus on global climate change," Boehlert said.

    The National Academy of Sciences is a private organisation chartered by Congress to advise the government of scientific matters. Enditem

   (Agencies)