The globe had another year where all-time records were either challenged or broken, as 2019 ranked among the world’s hottest. What’s more, greenhouse gases peaked to their highest levels on record, according to the 30th annual State of the Climate report.
This international annual review of the world’s climate, led by scientists from NOAA’s National Centers for Environmental Information and published by the Bulletin of the American Meteorological Society , is based on contributions from more than 520 scientists in over 60 countries. It offers insight on global climate indicators, extreme weather events and other valuable environmental data.
Notable findings from the international report include:
Last year continued Earth’s warming trend. The globally averaged annual surface temperature was 0.79°–1.00°F (0.44°–0.56°C) above the 1981–2010 average depending upon the dataset used. More specifically, NOAA and NASA both found 2019 to be the second-hottest year on record, behind 2016, while the United Kingdom’s Met Office ranked 2019 as the third-hottest year, behind 2016 and 2015 respectively. The six warmest years on record have all occurred in the past six years, since 2014.
Earth’s greenhouse gases were at their highest level on record. Continuing their rise, major greenhouse gas concentrations in the atmosphere—including carbon dioxide (CO2), methane and nitrous oxide—all reached another record in 2019. The global annual average atmospheric CO2 concentration was 409.8 parts per million (ppm). This was 2.5 ppm greater than 2018 amounts and was the highest in the modern 61-year measurement record as well as the highest ever measured in ice core records dating back as far as 800,000 years.
Sea-surface temperatures were near-record warm. The globally averaged 2019 sea surface temperature was the second highest on record, surpassed only by the record El Niño year of 2016.
- Sea levels were the highest on record, again. For the eighth consecutive year, global average sea level rose to a new record high and was about 3.4 inches (87.6 mm) higher than the 1993 average, the year that marks the beginning of the satellite altimeter record. Global sea level is rising at an average rate of 1.3 inches (3.2 cm) per decade. Melting of glaciers and ice sheets, along with warming oceans, account for the trend in rising global mean sea level.
- The Arctic and Antarctic saw near-record warmth. The annual mean surface air temperature for the Arctic land areas was the second highest in the 120-year record, trailing only 2016. In the Antarctic, 2019 was the second warmest year for the continent as a whole since the start of the reanalysis record in 1979, surpassing 2018 and behind only 1980.
- The Indian Ocean dipole affected weather from Africa to Australia. The Indian Ocean dipole—measured as the difference between sea-surface temperature departure from average in the eastern and western Indian Ocean—contributed to heavy rainfall over the Horn of Africa from October through December 2019, resulting in widespread flooding across East Africa. Meanwhile, record heat and dryness in Australia intensified drought conditions already in place, leading to severe impacts during late austral spring and summer, including catastrophic wildfires.
The State of the Climate report in a peer-reviewed series published annually as a special supplement to the Bulletin of the American Meteorological Society. The journal makes the full report openly available online, here.