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| Earth on Jan 16, 2013

Long term global warming trend continues

2012 was the ninth warmest year in the 132-year record. The ten warmest years have all occurred since 1998. The last cooler-than-average year was 1976.

Our planet’s warming trend continues.

Scientists report that 2012 was the ninth warmest year since 1880, continuing a long-term trend of rising global temperatures. The ten warmest years in the 132-year record have all occurred since 1998. The last year that was cooler than average was 1976.

This map, from NASA Earth Observatory, depicts temperature anomalies, or changes, by region in 2012. Reds and blues show how much warmer or cooler each area was in 2012 compared to an averaged base period from 1951–1980.

The line plot above shows yearly temperature anomalies from 1880 to 2011 as recorded by four different agencies around the world (NASA GISS, the National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center, the Japanese Meteorological Agency, and the Met Office Hadley Centre in the United Kingdom) that tally temperature data from stations across the globe and make independent judgments about whether the year was warm or cool compared to other years.

Although there are minor variations from year to year, all four records show peaks and valleys in sync with each other. All show rapid warming in the past few decades, and all show the last decade as the warmest.

Scientists emphasize that weather patterns cause fluctuations in average temperatures from year to year, but the continued increase in greenhouse gas levels in the atmosphere assures that there will be a long-term rise in global temperatures. Each individual year will not necessarily be warmer than the previous year, but scientists expect each decade to be warmer than the previous decade.

Scientists explain that carbon dioxide in Earth’s atmosphere traps heat and largely controls Earth’s climate. It occurs naturally but is also released by the burning of fossil fuels – such as gas and coal – for energy. The level of carbon dioxide in Earth’s atmosphere has been rising consistently for decades, largely driven by increasing human-made emissions. The carbon dioxide level in the atmosphere was about 285 parts per million in 1880, the first year of the GISS temperature record. By 1960, the atmospheric carbon dioxide concentration, measured at NOAA’s Mauna Loa Observatory, was about 315 parts per million. Today, that measurement exceeds 390 parts per million.

The continental U.S. endured its warmest year on record by far, according to NOAA, the official keeper of U.S. weather records. NOAA also announced that global temperatures were 10th warmest on record by their analysis methods.

It’s official: 2012 was warmest year on record for United States

Bottom line: 2012 was the ninth warmest year in the 132-year record. The ten warmest years have all occurred since 1998. The last cooler-than-average year was 1976. Scientists expect the warming trend to continue in coming decades.

Read more from NASA Earth Observatory