The climate is always changing. Everyone agrees on that. Ice core data tell us why. The bubbles in ice cores from Antarctica going back 800,000 years tell us that the concentrations of carbon dioxide and methane rise about 50 percent over 100,000-year cycles from cold ice ages to the 9 degrees F warmer interglacial periods. The ice ages are triggered by changes in the Earth’s orbit, but the magnitude of the changes cannot be explained without also accounting for the influence of carbon dioxide and methane on the Earth’s energy balance.
The carbon dioxide concentration in the atmosphere has jumped 40 percent in the last 150 years, mostly because of fossil fuel combustion. Methane has tripled. The ice cores tell us the surface temperature and sea level should rise in response. The last time carbon dioxide was at its present value, there was no ice on Greenland and the sea level was 80 feet higher. It’s only a matter of time before the ocean and land ice respond to the recent greenhouse gas increases. However, the Greenland ice can still be saved if we quickly switch from fossil fuel to carbon-free energy, so biology can slowly pull carbon from the atmosphere.
Steve Ghan, Richland
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