The United Nations said yesterday that agreeing to a climate change deal is crucial to fighting global hunger, which Brazil’s president described as “the most devastating weapon of mass destruction.”


Government leaders and officials met in Rome for a three-day U.N. summit on how to help developing countries feed themselves, but anti-poverty campaigners and even some participants were already writing off the event as a missed opportunity.


“There can be no food security without climate security,” U.N. Secretary-General Ban Ki-moon told the summit. “Next month in Copenhagen, we need a comprehensive agreement that will provide a firm foundation for a legally binding treaty on climate change,” he said.


Africa, Asia and Latin America could see a decline of between 20 and 40 percent in agricultural productivity if temperatures rise more than 2 degrees Celsius, the U.N. says.


Sub-Saharan Africa is expected to be the hardest hit from global warming as its agriculture is almost entirely rain-fed.