How does twentieth century climate change compare to past, known climate change?



  1. 0 Votes

    We know that in the past, the climate has been changed by natural causes such as changes in the Earth’s orbit, changes in the sun’s intensity, and volcanic eruptions (interestingly enough, aerosol and CO2 emissions from volcanic eruptions cause the same problems as man-made pollution). The National Academy of Sciences actually has done some studies to try to reconstruct historical temperature trends and compare them to present climate phenomena. Some key findings according to the EPA website:

    “There is a high level of confidence that the global average temperature during the last few decades was warmer than any comparable period during the last 400 years.

    “Present evidence suggests that temperatures at many, but not all, individual locations were higher during the past 25 years than any period of comparable length since A.D. 900. However, uncertainties associated with this statement increase substantially backward in time.

    “Very little confidence can be assigned to estimates of hemisphere average or global average temperature prior to A.D. 900 due to limited data coverage and challenges in analyzing older data.”

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