RIO DE JANEIRO, March 9 (Xinhua) -- Brazil's drought in 2005, the worst-ever hitting the Amazon, was caused by global warming instead of the El Nino weather phenomenon as previously thought, the country's National Space Research Institute (INPE) announced Sunday.

    "The idea that a drought comes with every El Nino is simply not correct," said INPE researcher Carlos Nobre who studied the temperature of the Atlantic Ocean and Amazon rainfall. "El Nino does not affect the southwestern Amazon region."

    The warming of the Atlantic's waters is an effect of global warming, the U.S. National Center for Atmospheric Research (NCAR) found. The temperature of the ocean has risen 0.7 degrees in the past five decades.

    "The temperature of the North Tropical Atlantic in 2005 was among the highest in many years, and our meteorological analysis shows it triggered a low pressure system above these waters," said the INPE's Jose Marengo, who led the study.

    "This low pressure system changed the winds throughout the tropics, and the result was less rainfall in Amazon."

    In October 2005, the Solimoes, which becomes the Amazon after mixing its waters with the Rio Negro, went so dry that navigation in the region was halted.