Earth’s Changing Climate

The Intergovernmental Panel on Climate Change (IPCC) issued an important special report yesterday on climate change.  In the accompanying press release, they state the following:

    • Limiting global warming to 1.5°C would require “rapid and far-reaching” transitions in land, energy, industry, buildings, transport, and cities.  Global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45 percent from 2010 levels by 2030, reaching ‘net zero’ around 2050. This  means that any remaining emissions would need to be balanced by removing CO2 from the air.
    • This report will be a key scientific input into the Katowice Climate Change Conference in Poland in December, when governments review the Paris Agreement to tackle climate change.
    • We are already seeing the consequences of 1°C of global warming through more extreme weather, rising sea levels and diminishing Arctic sea ice.
    • Warming of 1.5ºC or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems.

In the Summary for Policymakers, the IPCC states that “warming from anthropogenic emissions from the pre-industrial period to the present will persist for centuries to millennia and will continue to cause further long-term changes in the climate system, such as sea level rise, with associated impacts.”

This last point is very important.  Even if humanity disappeared from the face of the Earth tomorrow, it will take centuries to millennia for greenhouse gases in our atmosphere to return to pre-industrial levels.

Richard Wolfson, Professor of Physics at Middlebury College in Middlebury, Vermont, states in his excellent 2007 video course, “Earth’s Changing Climate” (The Great Courses, Course No. 1219),

The atmosphere, living things, soils, and surface ocean waters all represent short-term carbon reservoirs.  Cycling among these reservoirs occurs mostly on relatively short time scales.  In particular, a typical carbon dioxide molecule remains in the atmosphere only about five years.  But the rapid cycling of carbon through the atmosphere-biosphere-surface ocean system means that any carbon added to that system remains there much longer—for hundreds to thousands of years. Because the added carbon cycles through the atmosphere, the level of atmospheric carbon dioxide goes up and stays up for a long time.

We’ve known about this aspect of climate change for a long time.  It is based on solid science.  Any action we take now, either positive or negative, will affect Earth’s environment many generations into the future.

I know of no better introduction to climate science than Richard Wolfson’s video course.  Even though it was produced 11 years ago, it is still completely relevant.

Earth’s Changing Climate, The Great Courses, Course No. 1219

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