For Fred Singer, a climatologist at the University of Virginia and another co-author, the current warming "trend is simply part of a natural cycle of climate warming and cooling that has been seen in ice cores, deep sea sediments and stalagmites ... and published in hundreds of papers in peer reviewed journals."
How these cyclical climate take place is still unknown, but they "are most likely caused by variations in the solar wind and associated magnetic fields that affect the flux of cosmic rays incident on cloudiness, and thereby control the amount of sunlight reaching the earth's surface and thus the climate."
Singer said at a recent National Press Club meeting in Washington that there is still no definite proof that humans can produce climate change.
The available data is ambiguous, Singer said: global temperatures, for example, rose between 1900 and 1940, well before humans began to burn the enormous quantities of hydrocarbons they do today. Then they dropped between 1940 and 1975, when the use of oil and coal increased, he said.
Singer believes that other factors -- like variations of solar winds and terrestrial magnetic field that impact cloud formations and the amount of sunlight reaching the Earth's surface, and thus determining the temperature -- are much more influential than human-generated greenhouse gas emissions.
