They point to the so - called ice ages, when the earth was supposedly much cooler than it is now; and in support of natural warming, they cite evidence that cold regions, such as Greenland, at one time supported vegetation that prefers warm areas.
તેઓ એનું કારણ આપતા જણાવે છે કે પૃથ્વી પર ઠંડી - ગરમીનું ચક્ર ચાલ્યા કરે છે.