Global warming, accelerating?

  • Global mean temperatures with HadCRUT4. Credit: Met-Office.

    Graph of temperature trends in relation to El Niño and La Niña events. (Credit: NASA/GSFC/Earth Observatory; fig. upd. 2016-01-25).

  • Global warming, accelerating?
    30.01.2016 16:16

    A combination of a strong El Niño and the ongoing rise in greenhouse gases in the atmosphere has meant 2015 was the warmest year since the records began. What does this mean?

    The three state-of-the-art organizations which monitor temperatures world-wide evaluated the global mean temperature and published their findings in January.  They measure and calculate the global mean temperature in different ways but they agree that 2015 was the warmest on record.

    There was a debate about a “hiatus” or “pause” in the global warming that with the result of 2015 has come to an end. For the first time since the industrial revolution the average global temperature was about 1 °C warmer, according to the Met Office. Not only was 2015 the warmest year on record, but also remembered for many exceptional weather events across the globe with many typhoons, storms and extreme weather. However, the hurricane season in the Atlantic was quite calm, mainly due to the effects of El Niño.

    According to the Met Office and the University of Anglia's Climatic Research Unit who made the HadCRUT4 database to estimate that he global mean temperatures were  0.75 ±0.1 °C above the long-term (1961-1990) average, a record since at least 1850.  Updates to the HadCRUT4 dataset are compiled from many thousands of temperature measurements taken across the globe, on land and at sea, each day.

    The Goddard Institute for Space Studies, a laboratory of NASA  claim that “averaged temperatures in 2015 shattered the previous mark set in 2014 by 0.23 degrees Fahrenheit (0.13 Celsius). “ It produces the GISTEMP database with 6300 weather stations, ship and bouy-based observations of sea surface temperatures and measurements from Antarctic stations.

    NOAA scientists agreed with the finding that 2015 was the warmest year on record based on separate, independent analyses of the data. Because weather station locations and measurements change over time, there is some uncertainty in the individual values in the GISTEMP index. Taking this into account, NASA analysis estimates 2015 was the warmest year with 94 percent certainty.

    Later, the World Meteorological Organization combined this datasets with a reanalysis  by the ECMWF to declare 2015 as the “hottest on record”, pointed out that fifteen of the 16 warmest year on record have all been this century.

    The warming slowdown for the last 15 years has come to an end with a change in an ocean cycle known as the Pacific Decadal Oscillation swapping into a warm phase too. Some scientists say that we may be at the start of an acceleration of global warming even when El Niño phases out this year. The continued increase of greenhouse will keep a warming trend in the long term as well as natural variability. At this stage, 2016 looks like being another very warm year globally speaking.