The hundreds of scientists from 100 countries meeting in this Japanese port city are putting finishing touches on a massive report emphasizing the gravity of the threat the changing climate poses for communities from the polar regions to the tropics.

"Although it focuses on a whole analytical and sometimes depressing view of the challenges we face, it also looks at the opportunities we face," said Christopher B. Field, the co-chair of the Intergovernmental Panel on Climate Change.

"This can not only help us to deal with climate change but ultimately build a better world."

Japan's awareness of the severity of climate change has been driven home by record temperatures of over 40 C (104 F), and in Yokohama, by unusually heavy snows this winter, said the environment minister, Nobuteru Ishihara.

Japan plans to release an adaptation plan of its own by the summer of 2015 that would focus on a more "eco-friendly lifestyle," he said. That includes improvements in energy efficiency ahead of the 2020 Tokyo Olympic games.

"We aim to take full environmental consideration so that the Tokyo Games will be the 'environmental Olympics,'" Ishihara said.

Japan is struggling to rein in its own emissions of greenhouse gases after it shut down its nuclear plants following the disaster in Fukushima after the March 2011 earthquake and tsunami. Increased burning of natural gas, coal and oil to compensate for lost generating capacity have undone much of the progress the country had made in cutting carbon emissions.

While each region faces its own mix of challenges, research conducted by thousands of scientists around the world underscores the need for urgent measures, J. Lengoasa, deputy head of the World Meteorological Organisation, said in a recorded message to Tuesday's meeting.

He said countries in Africa already spend USD7 billion to USD15 billion a year on climate adaptation.

"Time is running out. We must take action," he said. "It is our obligation and our duty to inform the world of the prospects and risks that lie ahead.