Science & Tech
2012: A record year for Arctic ice melt and CO2 emissions
The American Meteorological Society (AMS) Tuesday published its climatic report card for 2012, “State of the Climate in 2012.” The comprehensive report, peer-reviewed along with scientists from the US National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center, paints a gloomy picture highlighting continuing Arctic ice melt, unprecedented CO2 emissions from fossil fuels and identifying 2012 as being one of the 10 warmest years on record.
Sourcing data compiled by almost 400 scientists across 52 countries, the report’s editors reckon 2012 was the eighth or ninth warmest year since 1850. The long-term average global temperatures rose to between 0.14 and 0.17°C above the average recorded for the period 1981-2010. The period since 1998 contains the 10 warmest years on record, says the report, during a time when the warm Pacific El Niño current has been at its most powerful. Both Argentina and the United States experienced their warmest years ever in 2012.
One of the major environmental stories of 2012 was the continuing disappearance of Arctic ice, both sea ice and on land, the latter in the shape of the Greenland ice sheet. The Arctic region broke a number of records with sea ice shrinking to its smallest summer minimum since satellite records began in 1979. In Greenland, the change was just as marked with an unprecedented 97 percent of the massive Greenland ice sheet showing some form of melt during summer 2012. Putting that in perspective, the continental ice melt in Greenland was four times the average summer ice melt extent for the years 1981-2010.
Launching “State of the Climate in 2012,” acting NOAA Administrator Kathryn D. Sullivan, Ph.D. said, “Many of the events that made 2012 such an interesting year are part of the long-term trends we see in a changing and varying climate — carbon levels are climbing, sea levels are rising, Arctic sea ice is melting, and our planet as a whole is becoming a warmer place.”
Ms. Sullivan continued, “This annual report is well-researched, well-respected and well-used; it is a superb example of the timely, actionable climate information that people need from NOAA to help prepare for extremes in our ever-changing environment."
The comprehensive report used dozens of climate indicators to gauge changes and identify trends in the Earth’s climate system. Indicators used included greenhouse gas concentrations, temperatures in the lower and upper atmosphere, cloud cover, sea surface temperature, sea-level rise, ocean salinity, sea ice extent and snow cover. Each of these indicators included thousands of measurements from multiple independent datasets assembled from various points around the globe.
Other highlights from the “State of the Climate in 2012,” were:
- Permafrost, permanently frozen land, where huge reservoirs of methane, a greenhouse gas 20 times more potent than carbon dioxide are “locked” in a frozen state, experienced a record temperature high in northernmost Alaska. There are fears that if significant permafrost thaw occurs in areas like Alaska and Siberia, the resultant release of methane into the atmosphere could see Earth experience a runaway greenhouse effect, with global temperatures rising sharply.
- Antarctic sea ice extent reached a record high of 7.51 million square miles on Sept. 26. This is 0.5 percent higher than the previous record high extent of 7.47 million square miles that occurred in 2006 and 7 percent higher than the record low maximum sea ice extent of 6.96 million square miles that occurred in 1986.
- The globally averaged sea surface temperatures for 2012 was among the 11 warmest on record, this despite the years 2000-12 having shown little upward trend in contrast to a 30-year period from 1970 to 1999 which saw a consistent rise in global sea surface temperatures. This contrast is thought to be linked to the influence of La Niña-like currents during the 21st century, which typically lead to lower global sea surface temperatures.
- The heat contained in Earth’s oceans remains at near record levels. Heat content in the upper 2300 feet of ocean depth was at near record highs during 2012. At deeper levels, a rise in ocean temperature was recorded at depths between 2,300 to 6,600 feet. The report noted an increase in water temperatures even in the ocean deeps beyond 6600 feet over the period 2011 to 2012. Such increases in ocean temperatures can only point to even more violent storms. The warmer the ocean temperature, the more water vapor is given up into the atmosphere “charging” hurricanes and similar weather phenomena as they form over the oceans. These “super-energized” storms must dissipate their energy somewhere and often do so with destructive force, Hurricane Sandy being a prime example from 2012.
- Sea levels also reached record highs in 2012, another factor contributing to the greater destructive effect of super-energized storms. Following a sharp decrease in global sea level in the first half of 2011 linked to the effects of La Niña, sea levels rose to reach record highs in 2012. Over the past 20 years, globally, sea level has increased at an average rate of 3.2 ± 0.4 mm per year.
- Ocean salinity increased in areas of high evaporation, including the central tropical North Pacific, but ocean water became less saline (fresher) in areas of high precipitation like the north central Indian Ocean. This suggests that precipitation is increasing in already rainy areas while evaporation intensifies in drier locations.
Greenhouse gases resume upward trend
The amount of greenhouse gases, concentrations of carbon dioxide, methane, and nitrous oxide in the atmosphere, all rose in 2012. That man-made emissions can be curtailed was evidenced prior to 2012, probably not as a result of emissions quotas, but more likely as a result of the global economic downturn since the banking collapse of 2008.
Global CO2 emissions from the burning of fossil fuels and cement production reached a record high in 2011 of 9.5 ± 0.5 petagrams (1,000,000,000,000,000 grams) of carbon , and a record of 9.7 ± 0.5 petagrams of carbon is estimated for 2012. The atmospheric concentration of CO2 increased by 2.1 parts per million (ppm) in 2012, reaching a global average of 392.6 ppm for the year.
Ominously, in spring 2012, atmospheric CO2 concentration exceeded 400 ppm at several Arctic observational sites, the first time this level had ever been recorded. This is a particularly significant level as many scientists regard it as being the beginning of the point of no return for global warming.
The full State of the Climate in 2012 report can be read here at the National Climatic Data Center section of the NOAA website.