IPCC Fifth Assessment Report, Part 1: The Physical Science Basis, By Henry Auer

Oct 7th, 2013 | By | Category: Climate Change

The Intergovernmental Panel on Climate Change issued Part 1 of its Fifth Assessment Report, “The Physical Science Basis”, on Sept. 30, 2013. The Report first summarizes past changes in the climate system. It states that the recent warming of the earth’s climate is “unequivocal.” Since the 1950s changes in many climate parameters including concentrations of greenhouse gases; temperature; loss of snow cover, glaciers and ice sheets; and rising sea levels are “unprecedented” considering the last decades to thousands of years. There are many recognized contributions to these effects but by far greatest single factor is the increase in the atmospheric concentration of the greenhouse gas carbon dioxide.

A variety of climate models of lesser or greater complexity successfully reproduce the earth’s recent climate history on global and regional scales and over longer periods of time, showing that the models adequately account for the major processes involved in evolving climate change.

These same models are then employed together with four scenarios of decreasing stringency concerning greenhouse gas emissions. Imposing rigorous emission constraints will limit further warming to a low, but still more elevated, level than the present by 2100; whereas continuing “business as usual”, an essentially unconstrained scenario, will lead to drastic increases in temperature by 2100 and induce severe changes in climate and the consequences thereof.

Furthermore, since carbon dioxide remains in the atmosphere for centuries or thousands of years, humanity’s actions today and in the near future will lead to irreversible and persistently higher global average temperatures for long time periods, affecting the lives and wellbeing of mankind’s progeny for generations. For this reason this writer believes it is now time for the member states of the United Nations to coalesce around a meaningful agreement to reduce GHG emissions toward zero in order to stabilize the climate at the lowest level possible of its new, higher greenhouse-mediated temperature.

For more on this story, visit: Global Warming Blog by Henry Auer: IPCC Fifth Assessment Report, Part 1: The Physical Science Basis.

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