How humans are changing the climate | Letter

“Civilized humanity has never seen a climate as severe as global warming.”

“The Earth has the ability to look after its own climate, but only if we are prepared to wait a few hundred thousand years.” — University of Chicago climatologist David Archer, author of “The Long Thaw.”

It’s a long-term perspective on human-caused global warming and a short-term view that we talk about daily — an accessible read with a historical and scientific focus.

It looks back a century and forward a century, explaining the greenhouse effect. Archer also gives a forecast for the next century for temperatures, sea level rises, floods and storms. Then he turns to paleoclimatology and the reconstruction of past climates covering 400 millennia. How does what we are doing to the climate today compare to this history?

“Mankind is becoming a force in climate comparable to the orbital variations that drive glacial cycles.

“The global warming climate event is not unprecedented in Earth history. Climate changes through the glacial cycles were probably as severe as global warming has the potential to be. The Earth and the biosphere will survive.

“Viewed in the same time perspective, however, human civilization is totally unprecedented in Earth History. Civilized humanity has never seen a climate as severe as global warming.

“The climate of the Earth takes a few centuries to warm. If it warms by 3 degrees C by 2100, there could be another 2 Degrees C of warming in the pipeline.”

The IPPC Report suggests 2100 may see a 3 degrees C increase in temperature and about half a meter of sea level rise. But the paleoclimate comparisons suggest that such a temperature rise would match a 50 meter sea level — the difference is huge. How fast can the earth’s ice melt?

“Ultimately the future of Earth’s climate comes down to decisions about coal.”

C F. Baumgartner

Mercer Island