World

UN report: costs of climate change to poor much bigger than previously estimated

  • Fausta Ortiz, 38, Pastoruri's glacier guardian, stands guard while carrying her daughter Lisoyun, 2, in Huaraz, Peru, Thursday, Dec. 4, 2014. According to Alejo Cochachin, coordinator of the glaciology unit, the Pastoruri glacier retreated 576 meters between 1980 and 2014. Peru's glaciers have lost more one-fifth of their mass in just three decades, and the 70 percent Peru’s 30 million people who inhabit the country’s Pacific coastal desert, depend on glacial runoff for hydropower and to irrigate crops, meaning their electricity and long-term food security could also be in peril. Higher alpine temperatures are killing off plant and animal species in cloud forests and scientists predict Pacific fisheries will suffer. (AP Photo/Rodrigo Abd)

    Fausta Ortiz, 38, Pastoruri's glacier guardian, stands guard while carrying her daughter Lisoyun, 2, in Huaraz, Peru, Thursday, Dec. 4, 2014. According to Alejo Cochachin, coordinator of the glaciology unit, the Pastoruri glacier retreated 576 meters between 1980 and 2014. Peru's glaciers have lost more one-fifth of their mass in just three decades, and the 70 percent Peru’s 30 million people who inhabit the country’s Pacific coastal desert, depend on glacial runoff for hydropower and to irrigate crops, meaning their electricity and long-term food security could also be in peril. Higher alpine temperatures are killing off plant and animal species in cloud forests and scientists predict Pacific fisheries will suffer. (AP Photo/Rodrigo Abd)  (The Associated Press)

  • The Vallunaraju mountain stands high in the Andes, early morning in Huaraz, Peru, Wednesday, Dec. 3, 2014. Peru's glaciers have lost more one-fifth of their mass in just three decades, and the 70 percent Peru’s 30 million people who inhabit the country’s Pacific coastal desert, depend on glacial runoff for hydropower and to irrigate crops, meaning their electricity and long-term food security could also be in peril. Higher alpine temperatures are killing off plant and animal species in cloud forests and scientists predict Pacific fisheries will suffer. (AP Photo/Rodrigo Abd)

    The Vallunaraju mountain stands high in the Andes, early morning in Huaraz, Peru, Wednesday, Dec. 3, 2014. Peru's glaciers have lost more one-fifth of their mass in just three decades, and the 70 percent Peru’s 30 million people who inhabit the country’s Pacific coastal desert, depend on glacial runoff for hydropower and to irrigate crops, meaning their electricity and long-term food security could also be in peril. Higher alpine temperatures are killing off plant and animal species in cloud forests and scientists predict Pacific fisheries will suffer. (AP Photo/Rodrigo Abd)  (The Associated Press)

  • Women herd their sheep to their village in Huaraz, Peru, Wednesday, Dec. 3, 2014. Peru's glaciers have lost more one-fifth of their mass in just three decades, and the 70 percent Peru’s 30 million people who inhabit the country’s Pacific coastal desert, depend on glacial runoff for hydropower and to irrigate crops, meaning their electricity and long-term food security could also be in peril. Higher alpine temperatures are killing off plant and animal species in cloud forests and scientists predict Pacific fisheries will suffer. (AP Photo/Rodrigo Abd)

    Women herd their sheep to their village in Huaraz, Peru, Wednesday, Dec. 3, 2014. Peru's glaciers have lost more one-fifth of their mass in just three decades, and the 70 percent Peru’s 30 million people who inhabit the country’s Pacific coastal desert, depend on glacial runoff for hydropower and to irrigate crops, meaning their electricity and long-term food security could also be in peril. Higher alpine temperatures are killing off plant and animal species in cloud forests and scientists predict Pacific fisheries will suffer. (AP Photo/Rodrigo Abd)  (The Associated Press)

The U.N.'s environment agency says the cost to poor countries of adjusting to ever-hotter temperatures will be twice or even three times higher than previously thought — and that assumes a best-case scenario in which greenhouse gas emissions are dramatically reduced.

The dispute over who pays the bills for the impacts of global warming has long been the thorniest issue at the U.N. negotiations, now in their 20th round in Lima, Peru.

Rich countries have pledged to help the developing world convert to clean energy and adapt to shifts in global weather.

Earlier reports indicated it would cost poor countries $70 billion to $100 billion to adapt by 2050.

The new U.N. report says the costs likely will be "two to three times higher," possibly as high as $500 billion.