Rising global temperatures portend uncertain futureJanuary 20th, 2011 by cdunagan
Global temperatures continue on a rising trend, according to scientists at NOAA’s National Climatic Data Center in Asheville, N.C. The implications of this trend are quite serious, and I’ll discuss some new studies after reviewing the temperature data for 2010.
The worldwide average surface temperature for the past year tied with 2005 as the warmest year on record, a record that goes back to 1880. And the year 2010 was the 34th consecutive year in which temperatures were above the 20th century average, according to a preliminary analysis by NCDC.
The decade of 2001–2010 was the warmest ever recorded for the
surface of the Earth during that 130-year time period. It was some
1.01 degree F. above the 20th century average. The previous record
for a full decade was also recent, 1991-2000, when the temperature
was .65 degrees F. above the average.
The years 2005 and 2010 were 1.12 degrees F. above the century average of 57.0 degrees F. when combining the land and ocean surface temperatures. The year 1998 is the third-warmest on record, measured at 1.08 degrees F. above the century average.
When looking at the Northern Hemisphere alone, 2010 was the warmest year on record for combined land and ocean surface temperatures. But in the Southern Hemisphere, temperatures were the sixth warmest on record.
For land surface alone, 2010 and 2005 tied for the second warmest on record, at 1.73 F. above the average. The warmest year on land was 2007, when the average temperature was 1.73 degrees F. above the century average.
Global ocean surface temperature for 2010 tied with 2005 as the third warmest on record, at .88 degrees F. above the century average.
Evidence shows an ongoing warming trend, and climatologists are fairly convinced that the temperature rise is related to an increase in greenhouse gases in the Earth’s atmosphere, including carbon dioxide (CO2), methane (CH4) and nitrous oxide (NO2).
From a summary by the Intergovernmental Panel on Climate Change:
“Atmospheric concentrations of CO2 (379 ppm) and CH4 (1774 ppb) in 2005 exceed by far the natural range over the last 650,000 years. Global increases in CO2 concentrations are due primarily to fossil fuel use, with land-use change providing another significant but smaller contribution.
“It is very likely that the observed increase in CH4 concentration is predominantly due to agriculture and fossil fuel use. CH4 growth rates have declined since the early 1990s, consistent with total emissions (sum of anthropogenic and natural sources) being nearly constant during this period. The increase in NO2 concentration is primarily due to agriculture.
“There is very high confidence that the net effect of human activities since 1750 has been one of warming. Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations. It is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent (except Antarctica).
“During the past 50 years, the sum of solar and volcanic forcings would likely have produced cooling. Observed patterns of warming and their changes are simulated only by models that include anthropogenic forcings. Difficulties remain in simulating and attributing observed temperature changes at smaller than continental scales.”
One of the factors that needs to be resolved with more precision is how fluctuations in solar energy reaching the Earth affect global temperatures. New satellite data have been examined, and new satellites will be going up soon to help resolve discrepancies in estimates of total solar irradiation.
In an announcement last week, the American Geophysical Union said the new solar data should help researchers better calculate the heat contribution from the sun going back 32 years.
Judith Lean of the Naval Research Laboratory in Washington, D.C., made this comment:
“We are eager to see how this lower irradiance value affects global climate models, which use various parameters to reproduce current climate: incoming solar radiation is a decisive factor. An improved and extended solar data record will make it easier for us to understand how fluctuations in the sun’s energy output over time affect temperatures, and how Earth’s climate responds to radiative forcing.”
Meanwhile, ongoing research continues to raise alarms about greenhouse gas emissions from human sources. A study by Jeffrey Kiehl of the National Center for Atmospheric Research suggests that if carbon dioxide emissions continue at their current rate through the end of this century, concentrations would reach levels that last existed 30 million to 100 million years ago, when global temperatures averaged about 29 degrees F. higher than in pre-industrial times.
Elevated levels of carbon dioxide would remain even if emissions were eliminated, and today’s rising temperature trend could be expected to continue for centuries. I’m not sure how much to rely on this one report, but makes you stop and think.
Here’s how Kiehl sees it:
“If we don’t start seriously working toward a reduction of carbon emissions, we are putting our planet on a trajectory that the human species has never experienced. We will have committed human civilization to living in a different world for multiple generations.”
Tags: American Geophysical Union, Climate change, Climatology, global warming, greenhouse gas emissions, Intergovernmental Panel on Climate Change, National Center for Atmospheric Research, Naval Research Laboratory, NOAA’s National Climatic Data Center