As a climate scientist and editor of a major atmospheric research journal, I must respond to the unsubstantiated global warming doubts raised by Gene Goltz (Letters, July 22).
Measurements from ice cores in Antarctica and Greenland going back 800,000 years show temperature rising and falling 8 degrees with the ice ages, in remarkable correlation with 100 parts per million changes in CO2 and 200 parts per billion changes in methane. Although the ice age cycles are triggered by periodic changes in the Earth's orbit, the ice ages can only be explained if the impact of changes in CO2 and methane on the Earth's energy balance are also considered.
CO2 concentration has risen 120 parts per million since 1850. If the Earth's climate is as sensitive to CO2 now as it was during the ice ages, common sense suggests warming of several degrees is in the pipeline.
The Earth hasn't warmed several degrees yet because it takes time to warm the ocean and because solar energy matters too. Cooling by sulfate aerosol from coal combustion is compensating some of the warming by CO2, but that cooling will fade as sulfate emissions are reduced. This is all understood and accepted by the vast majority of climate scientists.
STEVE GHAN, Richland