The U.S. government needs to cover $40 billion of that spending, which will "strengthen the capacity of vulnerable people" to cope with climate-related risks, according to the report commissioned by the U.N. Development Program.
The nearly 400-page Human Development Report comes just a week before the world's nations convene in Indonesia to negotiate a new climate treaty. It adds a dire economic perspective to previous U.N. scientific findings that carbon and other heat-trapping "greenhouse gas" emissions must stabilize by 2015 and then decline.
Without the money, the panel found, a warmer world "could stall and then reverse human development" in the countries where 2.6 billion people live on $2 a day or less.
Scientists have reported that temperatures rose an average 1.3 degrees Fahrenheit over the past 100 years, bringing the prospect of a century of extreme weather, rising seas, widening drought and disease and harm to fisheries, forests and farmland.
According to development officials, the unfortunate consequences include women and young girls walking further to collect water in the Horn of Africa, people erecting bamboo flood shelters on stilts in the delta of the Ganges River, and others planting mangroves to protect themselves against storm surges in the delta of the Mekong River.
"These impacts ... go unnoticed in financial markets and in the measurement of world gross domestic product (GDP)," the panel's report said. "But increased exposure to drought, to more intense storms, to floods and environmental stress is holding back the efforts of the world's poor to build a better life for themselves and their children."
Olav Kjorven, head of the U.N. Development Program's bureau for development policy, called the financial aid a sort of "climate-proofing" for the poor that is only natural "when we know that the frequency of droughts and floods is going up."
Because of global warming, he said, 600 million people more in sub-Saharan Africa will go hungry from collapsing agriculture, an extra 400 million people will be exposed to malaria and other diseases and an added 200 million will be flooded out of their homes.
The development panel says the greatest financial responsibility lies with the U.S. and other rich nations most responsible for the accumulating carbon dioxide and other heat-trapping gases in the atmosphere, mainly from man's burning of coal, oil and other fossil fuels.
"The countries of the world that are the principal culprits, if you wish, for creating this problem in the first place need to act strongly to safeguard the future of those that have done nothing to cause this problem but are the most vulnerable," Kjorven said.
Developed countries, meanwhile, are failing to meet their targets under the current climate treaty, the 1997 Kyoto Protocol, for cutting greenhouse gases by 2012, the report said. France, Germany, Japan and Britain have reduced their emissions somewhat, it said, but the European Union is falling short of its goal of a 20 percent cut by 2020.
"To say that the industrialized countries aren't meeting their Kyoto targets - that remains to be seen," said Annie Petsonk, a lawyer for the advocacy group Environmental Defense. "The targets only take effect for the years 2008 to 2012. The countries are getting ready for them."
Petsonk said developing nations' carbon-trading markets has the potential to generate large flows of private capital that could help provide much of the development money the U.N. recommends to help the poor adapt to global warming.