Energy by Goldemberg Jose

Author:Goldemberg, Jose
Language: eng
Format: epub
Publisher: Oxford University Press, USA
Published: 2012-02-18T16:00:00+00:00

What are the facts concerning climate change?

The 11 years between 1995 and 2006 broke records in average temperature, as measured since 1850. Between 1906 and 2005, the Earth’s average temperature increased 0.74°C. The increase in temperature per decade over the last 50 years nearly doubled that observed in the last 100 years. In the last century, the increase in average temperature in the Arctic doubled that of the planet’s average.

Glaciers and mountain snow, as well as polar icecaps, decreased. In the Arctic, the spring defrost has increased by 15% since 1900. The dynamic defrosting effects contribute even more to the rise in ocean levels. The oceans absorb more than 80% of the heat incident on Earth and their average temperatures have increased to depths of up to 3,000 m, leading to a volumetric expansion and to an increase in sea level. The sea level rose 17 cm in the 20th century, at a rate of 1.8 mm a year in the period from 1961 to 2003 and 3.1 mm a year in the period from 1993 to 2003.

Rainfalls increased in the western regions of the Americas, Northern Europe, and North and Central Asia. Droughts increased in the Mediterranean, South Africa, and Sahel (between the Sahara Desert and the more fertile lands in the South) and parts of Southern Asia. There is evidence of increased cyclone activity, mainly in the North Atlantic. The increase in strong precipitation events is consistent with global warming and with the higher atmospheric concentration of water vapor. Intense and longer droughts have been more frequent since the 1970s, particularly in the tropics and subtropics. Also, associated with droughts are the alterations in ocean temperatures and wind standards and an increase in mountain defrosting.

Some of the increase in the number of extreme events is probably due to significant improvements in information access and to population growth. Extreme events are relatively rare and occur only 5% or less of the time. They are identified on the basis of the event’s occurrence over time. On the basis of this definition the number of earthquakes per year has been approximately constant since 1960, but the number of cyclones has increased some 50% and the number of floods has increased 100% since 1995.

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