In the previous millenium, the rate and duration of warming during the 20th century was much greater than during any of the previous 9 centuries. Similarly, the 1990s were the warmest decade of that century and 1998 the warmest year of the previous 1,000 years.
In 2001, Greenfacts, the Intergovernmental Panel on Climate Change, published the following information:
The average surface temperature of the Earth has increased over the 20th century by about 0.6C. This increase occurred mainly from 1910 to 1945 and 1976 to 2000. The increase is larger at night and over land area.
Temperatures have risen during the past four decades in the lowest 8 kilometers of the atmosphere.
Snow cover and ice extent have decreased.
The sea level has risen by 10 to 20 cm ( 4 to 8” ) during the 20th century. Ocean temperature has increased since the late 1950’s.