James Hansen

From Freepedia

James E. Hansen is a climate scientist and director of the NASA Goddard Institute for Space Science. His primary interests are radiative transfer and climate modeling.

He was born in Iowa in 1941. Hansen studied at the University of Iowa under James Van Allen.

He believes that:

global warming is 0.5–0.75°C in the past century, and at least ~0.3 in the last 25 years
climate sensitivity to CO₂ doubling is 3°±1°C

He has taken an active part in the debate around global warming, and has argued that:

some "greenhouse skeptics" subvert the scientific process, ceasing to act as objective scientists, rather presenting only one side, as if they were lawyers hired to defend a particular viewpoint.

In 2004 he wrote a paper called Defusing the global warming time bomb [1], containing:

At present, our most accurate knowledge about climate sensitivity is based on data from the earth’s history, and this evidence reveals that small forces, maintained long enough, can cause large climate change.

Human-made forces, especially greenhouse gases, soot and other small particles, now exceed natural forces, and the world has begun to warm at a rate predicted by climate models.

The stability of the great ice sheets on Greenland and Antarctica and the need to preserve global coastlines set a low limit on the global warming that will constitute “dangerous anthropogenic interference” with climate.

Halting global warming requires urgent, unprecedented international cooperation, but the needed actions are feasible and have additional benefits for human health, agriculture and the environment.

He has charged that Patrick Michaels misrepresented his work to Congress in 1998, and lists a number of areas where he disagrees with Richard Lindzen [2].

In 1998 Hansen argued that uncertainties in climate forcings have supplanted global climate sensitivity as the predominant issue [3]; the paper is discussed here.