2012 Was One Of The 10 Warmest Years On Record Globally
The end of weak La Niña, unprecedented Arctic warmth influenced 2012 climate conditions
Worldwide, 2012 was among the 10 warmest years on record according to the 2012 State of the Climate report released online recently by the American Meteorological Society (AMS). The peer-reviewed report, with scientists from NOAA’s National Climatic Data Center in Asheville, N.C., serving as lead editors, was compiled by 384 scientists from 52 countries (highlights, full report). It provides a detailed update on global climate indicators, notable weather events, and other data collected by environmental monitoring stations and instruments on land, sea, ice, and sky.
“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," said Acting NOAA Administrator Kathryn D. Sullivan, Ph.D. “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."
Conditions in the Arctic were a major story of 2012, with the region experiencing unprecedented change and breaking several records. Sea ice shrank to its smallest “summer minimum” extent since satellite records began 34 years ago. In addition, more than 97 percent of the Greenland ice sheet showed some form of melt during the summer, four times greater than the 1981–2010 average melt extent.
The report used dozens of climate indicators to track and identify changes and overall trends to the global climate system. These indicators include greenhouse gas concentrations, temperature of the lower and upper atmosphere, cloud cover, sea surface temperature, sea-level rise, ocean salinity, sea ice extent and snow cover. Each indicator includes thousands of measurements from multiple independent datasets.
- Sea level reaches record high: Following sharp decreases in global sea level in the first half of 2011 that were linked to the effects of La Niña, sea levels rebounded to reach record highs in 2012. Globally, sea level has been increasing at an average rate of 3.2 ± 0.4 mm per year over the past two decades.
- Ocean salinity trends continue: Continuing a trend that began in 2004, oceans were saltier than average in areas of high evaporation, including the central tropical North Pacific, and fresher than average in areas of high precipitation, including the north central Indian Ocean, suggesting that precipitation is increasing in already rainy areas and evaporation is intensifying in drier locations.
- Tropical cyclones near average: Global tropical cyclone activity during 2012 was near average, with a total of 84 storms, compared with the 1981–2010 average of 89. Similar to 2010 and 2011, the North Atlantic was the only hurricane basin that experienced above-normal activity.
- Greenhouse gases climb: Major greenhouse gas concentrations, including carbon dioxide, methane, and nitrous oxide, continued to rise during 2012. Following a slight decline in manmade emissions associated with the global economic downturn, global CO2 emissions from fossil fuel combustion 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 new record of 9.7 ± 0.5 petagrams of carbon is estimated for 2012. Atmospheric CO2 concentrations increased by 2.1 ppm in 2012, reaching a global average of 392.6 ppm for the year. In spring 2012, for the first time, the atmospheric CO2concentration exceeded 400 ppm at several Arctic observational sites.
Cool temperature trends continue in Earth’s lower stratosphere: The average lower stratospheric temperature, about six to ten miles above the Earth’s surface, for 2012 was record to near-record cold, depending on the dataset. Increasing greenhouse gases and decline of stratospheric ozone tend to cool the stratosphere while warming the planet near-surface layers.
The 2012 State of the Climate report is peer-reviewed and published annually as a special supplement to the Bulletin of the American Meteorological Society. This year marks the 23rd edition of the report, which is part of the suite of climate services NOAA provides to government, the business sector, academia, and the public to support informed decision-making. The full report can be viewed online.
NOAA’s mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources.
SOURCE: National Oceanic And Atmospheric Administration