These climate changes are irreversible in the short term, and humans will have to learn to cope with their consequences.

McCarthy says one of the most important messages that comes from the report is that "we must begin now to anticipate what some of these effects will be and prepare adaptation strategies to minimize the loss of life, livelihood and property that will otherwise be a certain consequence of this."

He stresses that humans have already changed the climate significantly and prospects for reducing or reversing human impact on the climate are slim.

During the last two weeks, McCarthy has become a scientific celebrity for his work in bridging the gap between science and policy.

At Harvard, he also serves as Pforzheimer House Master and Director of the Museum of Comparative Zoology.

The kind of work he did in Geneva is not new territory for him.

In the 1980s, for example, McCarthy founded the journal Global Biogeochemical Cycles and served as the head of the International Geophere Biosphere Program, one of the first organizations that sought to coordinate the study of global climate change. His most current work is along similar lines.