The World Bank is urging stepped-up efforts to meet world carbon reduction goals after looking at what it says would be the catastrophic consequences if average world temperatures rise more than 4 degrees Celsius (7.2 degrees Fahrenheit) by the end of the century.
World climate goals aim to hold the mean temperature increase to under 2 degrees Celsius, by curbing emissions of greenhouse gases that trap heat -- a phenomenon already felt to have boosted average temperatures nearly 1 degree from levels present before the start of the Industrial Age, Mr. Kim said in a briefing last week.
That goal is unlikely to be met, he said, with an increase of 3 or 3.5 degrees Celsius now considered probable.
The report noted that a drop in average temperature of around 4.5 degrees Celsius (8.1 degrees Fahrenheit) triggered the last Ice Age, and it predicted that a temperature increase of that magnitude would similarly reshape the planet.
In looking at the effects of a 4-degree increase, Mr. Kim said the bank was hoping to spark countries to act more aggressively to achieve climate goals and to prompt poorer nations to begin planning ways to offset the long list of potential impacts.
Those could include sea levels as much as 3 feet higher than now expected -- a potentially devastating problem for large coastal cities in Asia and Africa. Warming on such a scale could also limit access to fresh water for irrigation and cause heat, drought and disease problems that could make it more difficult to meet world food demands and improve health.
"The kind of sea-level rise we are talking about is going to make the process of urban planning and services to the poor absolutely fundamental," said Rachel Kyte, the World Bank's vice president for sustainable development. "The race to heat-resistant and drought-resistant strains [of staple food crops] becomes fundamental."
Ms. Kyte said the bank has begun more intense and frequent talks with poorer nations over how to prepare for climate change -- usually at the instigation of officials who have seen the effects of more intense weather and climate patterns and now feel that they need to plan for the worst.