Wildlife Commentary: "North America's Bears"

Three bears currently find space in the Nearctic Faunal Region (North America). Their general descriptions appear on the page shown here from my wildlife textbook.

Because modern humans currently emit more greenhouse gases than they sequester and because they currently destroy more carbon sinks (forests, grasslands, fertile soils, etc.) than they conserve or restore, it is more than likely that by 2100 (or before) there will be only two species of bears living free in the Nearctic region.

Climate change (global warming) that reduces the extent of Arctic sea ice (or reduces it altogether) also reduces/eliminates the principal habitat of polar bears and their chief food source-- seals.  No sea ice, no ice seals, no ice bears.

See the "Climate Feedback Loop 2" (ice-albedo feedback) post (January 4, 2013), and look for future posts on endangered Arctic wildlife species.

"North American Bears" from Fred Montague's wildlife textbook, Wa-Maka-Skan. 

"North American Bears" from Fred Montague's wildlife textbook, Wa-Maka-Skan. 


Environmental Science Classroom: Climate Feedback Loops 3 & 4

Here is another unintended effect of our greenhouse gas emissions.  (See the January 4, 2013 post for feedback loop 2.)

Both of the global warming feedback loops shown below involve the potential release of hundreds of millions of tons of methane, currently frozen in tundra soils and shallow ocean sediments.

On a molecule-for-molecule basis, methane is 30 to 70 times more effective than carbon dioxide at trapping heat in the atmosphere.

In an exhibit of chemical irony, after about 12 years in the atmosphere, the methane molecules degrade (oxidize) into carbon dioxide and water vapor-- both important greenhouse gases.

Climate feedback loops 2, 3, & 4 are all positive feedbacks (or runaway feedbacks) and tend to amplify (rather than counteract) the effects of human greenhouse emissions.

Climate Feedback Loops 3 & 4 (methane). © 2013 Fred Montague

Climate Feedback Loops 3 & 4 (methane). © 2013 Fred Montague

Environmental Science Classroom: 116-year U. S. Annual Temperature Trend

The graph shown below was downloaded from the U. S. National Oceanic and Atmospheric Administration's National Climatic Data Center website. It includes a summary of temperature records for weather stations in the lower 48 states over the span of time that reliable records have been kept (1895 - present).

The dense black horizontal line (A) represents the 116-year average temperature for the lower 48 states. The gray line (B) represents the temperature trend over the same period. It reveals an overall warming of 1.392 degrees F.

Be cautious about the "average temperature line." It serves merely for reference as the 116-year average.  As the average changes with each year's additional data, this line will go up or down, depending on the new average.  If I were printing the average line, I would have it be a dotted line.  The "trend line," on the other hand, is a smoothed plot of the 116--year net change.

To project this trend forward to 2050 (just 37 years from now) would be to predict a mid-century U. S. average warming of 1.86 degrees F (from 1895 until 2050). If we consider the positive feedback loops that we are discussing (see January 4, 2012 post), there is good reason that the warming will be greater.

If you visit the NCDC website, you can generate 116-year temperature (and precipitation) plots for any state, region, or individual weather station (usually cities, towns, and government facilities).  This could be the basis of a school (or university) term paper or science project. The availability of these data enable everyone to study climate change and monitor global warming.

Graph showing annual average temperature over time in the contiguous U.S., 1895-2011. Generated at  NCDC website , accessed January 2nd, 2013.

Graph showing annual average temperature over time in the contiguous U.S., 1895-2011. Generated at NCDC website, accessed January 2nd, 2013.