(4/30/2009) Two Natural Components of the Recent Climate Change: (1) The Recovery from the Little Ice Age (A Possible Cause of Global Warming) and (2) The Multi-decadal Oscillation (The Recent Halting of the Warming)

• Main Author: Syun-ichi Akasofu
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Arctic Ocean; Climate change; Global warming; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.393.732; http://people.iarc.uaf.edu/~sakasofu/pdf/two_natural_components_recent_climate_change.pdf

Two natural components of the currently progressing climate change are identified. The first one is an almost linear global temperature increase of about 0.5°C/100 years, which seems to have started in 1800–1850, at least one hundred years before 1946 when manmade CO2 in the atmosphere began to increase rapidly. This 150~200-year-long linear warming trend is likely to be a natural change. One possible cause of this linear increase may be the earth’s continuing recovery from the Little Ice Age (1400~1800); the recovery began in 1800~1850. This trend (0.5°C/100 years) should be subtracted from the temperature data during the last 100 years when estimating the manmade contribution to the present global warming trend. As a result, there is a possibility that only a small fraction of the present warming trend is attributable to the greenhouse effect resulting from human activities. It is also shown that various cryosphere phenomena, including glaciers in many places in the world and sea ice in the Arctic Ocean that had developed during the Little Ice Age, began to recede after 1800 and are still receding; their recession is thus not a recent phenomenon. The second one is oscillatory (positive/negative) changes, which are superposed on the linear