Monday, January 2, 2012

Global Warming: It's Real and Unprecedented

The fact that the earth is warming has been known for some time.  Analysis from HadCRU, NOAA, and NASA GISS have all shown similar trends.  Toward the end of 2011 another study was added to the mix.  This was known as the Berkeley Earth Surface Temperature Study.  Their analysis was another confirmation of the other analyses.  Keep in mind there have been at least a half dozen independent studies of NASA's analysis all of which confirmed the analysis.

Here is a comparison of the analyses:

The chart shows the annual land-surface average temperature using a 12 month moving average of surface temperatures over land. Anomalies are relative to the Jan 1950 - December 1979 mean. The grey band indicates 95% statistical and spatial uncertainty interval.  Image Credit: Berkeley Earth ( ).
The Berkeley study was headed by Dr. Richard Muller, a Professor of Physics at the University of California at Berkeley.  Data for over 39,000 reporting stations were used which was more than five times the 7,280 stations used in the Global Historical Climatology Network Monthly data set (GHCN-M) used in many climate studies to date.

The team headed by Muller concluded after extensive analysis that global warming was real.  Granted the study only looked at the global land temperature and did not analyze the oceans which will be looked at in a follow-up study.  It also made no attempt at attribution.  However, its significance is to confirm what we know by a former skeptic.

It is interesting that the analysis by HadCRU, which was at the center of the "Climategate", is a little cooler than the other analyses.  The deniers picked to wrong set to criticize.  The claim was that the data had been altered, a claim that has never been substantiated.  Its handling of arctic data is the reason why it is slightly cooler as it misses some of the regions experiencing the greatest warming.

About the same time came word of the continued increase in greenhouse gases.  The release from NOAA states:
NOAA’s updated Annual Greenhouse Gas Index (AGGI), which measures the direct climate influence of many greenhouse gases such as carbon dioxide and methane, shows a continued steady upward trend that began with the Industrial Revolution of the 1880s.

Started in 2004, the AGGI reached 1.29 in 2010. That means the combined heating effect of long-lived greenhouse gases added to the atmosphere by human activities has increased by 29 percent since 1990, the “index” year used as a baseline for comparison. This is slightly higher than the 2009 AGGI, which was 1.27, when the combined heating effect of those additional greenhouse gases was 27 percent higher than in 1990.

“The increasing amounts of long-lived greenhouse gases in our atmosphere indicate that climate change is an issue society will be dealing with for a long time,” said Jim Butler, director of the Global Monitoring Division of NOAA’s Earth System Research Laboratory in Boulder, Colo. “Climate warming has the potential to affect most aspects of society, including water supplies, agriculture, ecosystems and economies. NOAA will continue to monitor these gases into the future to further understand the impacts on our planet.” 

Global average abundances of the major, well-mixed, long-lived greenhouse gases - carbon dioxide, methane, nitrous oxide, CFC-12 and CFC-11 - from the NOAA global air sampling network are plotted since the beginning of 1979. These gases account for about 96% of the direct radiative forcing by long-lived greenhouse gases since 1750. The remaining 4% is contributed by an assortment of 15 minor halogenated gases (see text). Methane data before 1983 are annual averages from Etheridge et al. (1998), adjusted to the NOAA calibration scale [Dlugokencky et al., 2005].  Image Credit: NOAA.
The fact that methane is increasing once again is a disturbing trend.  It has a greater ability to increase warming over a shorter timescale.  The is some concern that it is related to the thawing of the tundra in the polar regions.  If true, this would represent a new phase in global warming.

Recently Svante Björck, a climate researcher at Lund University in Sweden, has now shown that global warming, i.e. simultaneous warming events in the northern and southern hemispheres, have not occurred in the past 20 000 years, which is as far back as it is possible to analyse with sufficient precision to compare with modern developments.

This is just one of a number of studies showing the current warming is unprecedented.  Joe Romm of Climate Progress listed some of these studies published in the past two years.  I list them here:

Here are other recent studies demonstrating that recent global warming is unprecedented in magnitude and speed and cause:

  1. Science (2011): Temperatures of North Atlantic “are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming.”
  2. GRL (2010):  “We conclude that the 20th century warming of the incoming intermediate North Atlantic water has had no equivalent during the last thousand years.“
  3. JGR (2010):  “The last decades of the past millennium are characterized again by warm temperatures that seem to be unprecedented in the context of the last 1600 years.”
  4. Unprecedented warming in Lake Tanganyika and its impact on humanity (2010)
  5. Human-caused Arctic warming overtakes 2,000 years of natural cooling, “seminal” study finds (2009)
Thus, we know that global warming is real, that greenhouse gases continue to increase, and that the warming is unprecedented in at least 20,000 years.  To deny the enhanced greenhouse effect is to deny the physics of infrared radiation.

We also know from ecologists that climate change is affecting the biology of the land and oceans.  More on that later.

Bottom Line: Isn't it time to start developing a strategy to combat global warming before it becomes unmanageable?