Global warming

Global warming is a natural cyclical phenomenon. The earth's average air temperature has increased 600 times over the last 900,000 years and then decreased again each time. These cycles of approximately 1,500 years can be seen in proxy records such as the Vostok Ice Core. [1]

Since the beginning of written historical records in Ancient Rome, there has been a warm period, followed by the cool period of the Dark Ages, followed by the Medieval Climate Optimum (when Greenland was colonized), a Little Ice Age (when European settlers abandoned Greenland), and since around 1850 a Modern Warm Period. All of this is natural, according to S. Fred Singer.

Variations in carbon dioxide levels correlate closely with the ups and downs of global air temperature, lagging behind by about 800 years. Although correlation is not causation, some scientists think that the variations in carbon dioxide are driven by the variations in air temperature.