However you view the evidence, whatever set of measurements you examine, the picture that emerges is consistent: the Earth is heating up.
The US National Oceanic and Atmospheric Administration (NOAA) reports: “In 2013, the vast majority of worldwide climate indicators − greenhouse gases, sea levels, global temperatures, etc − continued to reflect trends of a warmer planet.”
This, NOAA says, is the picture painted by the indicators assessed in a report, State of the Climate in 2013, published online by the American Meteorological Society.
Scientists from NOAA’s National Climatic Data Center were the lead editors of the report, compiled by 425 scientists from 57 countries. It provides a detailed update on data collected by monitoring stations and instruments on air, land, sea and ice.
“These findings reinforce what scientists for decades have observed: that our planet is becoming a warmer place,” said the NOAA‘s administrator, Dr Kathryn Sullivan.
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In 2013, the vast majority of worldwide climate indicators − greenhouse gases, sea levels, global temperatures, etc − continued to reflect trends of a warmer planet
Changes tracked
The report tracks patterns, changes, and trends of the global climate system, including: greenhouse gases; temperatures throughout the atmosphere, ocean, and land; cloud cover; sea level; ocean salinity; sea ice extent; and snow cover.
It says greenhouse gases continued to climb, with concentrations of major gases − including carbon dioxide (CO2), methane and nitrous oxide − once again reaching historically high levels. Atmospheric CO2 concentrations rose by 2.8 parts per million (ppm) in 2013 and reached a global average of 395.3 ppm for the year.
Many scientists argue that once CO2 concentrations reach 450 ppm it will be difficult to prevent global average temperatures from rising more than 2°C above their level for most of human history. The present rate of increase suggests that, without drastic emission cuts, that threshold will be reached before mid-century.
Four major independent datasets show that 2013 was among the warmest years on record, ranking between second and sixth, depending upon the dataset used. Sea surface temperatures increased to place 2013 among the 10 warmest on record.
Sea level also continued to rise, in step with a trend of 3.2 ± 0.4 mm per year over the past two decades.
The Arctic went on warming , marking its seventh warmest year since records began in the early 20th century. Record high temperatures were measured at a depth of 20 metres at permafrost stations in Alaska.
The Arctic sea ice extent was the sixth lowest since satellite observations began in 1979. All seven lowest sea ice extents on record have occurred in the past seven years.
Contradictory trends
The Antarctic, too, was consistent, even if only in the apparently contradictory trends it showed. The extent of the sea ice reached a record high for the second year in a row, of 7.56 million square miles on October 1 − 0.7 per cent higher than the previous record high of 7.51 million sq miles in 2012 and 8.6 per cent higher than the record low maximum of 6.96 million sq miles in 1986. But the South Pole station experienced its highest temperature since records began in 1957.
The number of tropical cyclones during 2013 was slightly above average, but the North Atlantic Basin had its quietest season since 1994. However, in the Western North Pacific Basin, Super Typhoon Haiyan had the highest wind speed ever known for a tropical cyclone, with one-minute sustained winds estimated at 196 miles per hour.
State of the Climate in 2013 is the 24th edition in a peer-reviewed series published annually as a special supplement to the Bulletin of the American Meteorological Society.
