Martin Weitzman, an inventive economist who argued that governments would see climate change as a more urgent matter to address if they took more seriously the small but real risks of the most catastrophic of outcomes, died on Aug. 27 in Newton, Mass. He was 77.

On Wednesday, the Massachusetts medical examiner ’s office, which had been awaiting the results of laboratory tests, ruled the death a suicide by hanging. Colleagues said Professor Weitzman had grown increasingly despondent after being passed over for the Nobel Prize in economics last year and had left a note questioning whether he any longer had the mental acuity to contribute to his field.

Most economists have relied on a cost-benefit analysis when considering how ambitiously governments might try to reduce heat-trapping carbon emissions, either by imposing caps on how much can be emitted or by taxing the polluters .

But Professor Weitzman demonstrated that such prevailing cost-benefit analyses understated the small but nevertheless credible risks that worst-case environmental damage posed to the world and its economy, from its agricultural production to its delivery of goods and services. Were governments to take these catastrophic scenarios into account more seriously, he said, they would be more vigorous in their efforts to slow or even reverse global warming.