Economists On Climate Change: Do We care?

"In that sense it doesn't make sense to spend money right now," Mendelsohn said, adding that beyond 2050 and a 2 degrees Celsius rise the damage and need for action grows.

He added that he does not cost species extinctions and health effects, and only crudely measures the cost of island inundations.

Richard Tol, Senior Research Officer at Ireland's Economic and Social Research Institute, has a similar stance.

"(My damage estimate) does hide some things that some people will get very upset about," Tol said. "From an economic perspective small island states are so tiny and people are moving out of there anyway."

As an example Tol estimates the welfare loss of the Maldives submerging at three times the inhabitants' annual salaries, in addition to the 100 percent loss of the country's GDP.

Citizens are happy to value the preservation of the global ecosystem at a cost of 50 euros per person per year, Tol says, but added he does not factor in the risk of rapid sea level rise.

UNDERESTIMATES

A third camp treats with suspicion both cost and damage estimates, fearing they could be huge underestimates.

"I worry that existing damage estimates have little to do with what we'll actually see," said John Reilly, senior research scientist at MIT. "They do not really value the widespread ecological changes that are likely to occur."

A particular concern is the cost of runaway climate change, where temperature rises spin out of control, and which could trigger knock-on disasters like conflicts, or sudden sea level rise which could wipe out part or whole countries like the Netherlands, Egypt and Bangladesh.