The year 2019 was the second warmest on record and the average temperatures for the past 5 years and the past 10 years have been the highest on record, according to the World Meteorological Organization (WMO). Each decade since 1980 has been warmer than the previous one and this trend is expected to continue given record levels of heat-trapping greenhouse gases in the atmosphere. Effects include unexpected weather patterns including severe droughts and outbreaks of waterborne disease.
WMO’s report consolidated five leading international datasets and revealed that, on average, the annual global temperature in 2019 was 1.1°C warmer than the average for 1850-1900. The latter dates are considered to represent pre-industrial conditions.
Of note, 2016 was measured to be the warmest year, due to the combination of a very strong El Niño and climate change, more generally.
“The average global temperature has risen by about 1.1°C since the pre-industrial era and ocean heat content is at a record level,” said WMO Secretary-General Petteri Taalas. “On the current path of carbon dioxide emissions, we are heading towards a temperature increase of 3 to 5 degrees Celsius by the end of century.”
The high temperatures in 2019 have been reflected in record sea levels, increasing ocean heat, retreating ice, and very importantly, extreme weather events across the globe. More than 90 percent of the excess heat is stored within the world’s oceans, and therefore ocean heat content can quantify the rate of global warming. The past five years have been measured to be the top five warmest years in the ocean and the past ten years are also the top ten years on record.
Taalas further comments: “The year 2020 has started out where 2019 left off – with high-impact weather and climate-related events. Australia had its hottest, driest year on record in 2019, setting the scene for the massive bushfires so devastating to people and property, wildlife, ecosystems and the environment. Unfortunately, we expect to see much extreme weather throughout 2020 and the coming decades, fuelled by record levels of heat-trapping greenhouse gases in the atmosphere,” said Mr Taalas.
WMO draws on monthly climatological data developed by the United States National Oceanic and Atmospheric Administration (NOAA), NASA’s Goddard Institute for Space Studies, the United Kingdom’s Met Office, Europe’s Copernicus Climate Change Service, and the Japan Meteorological Agency. Methodology includes combining millions of meteorological and marine observations, including from satellites, with models to produce a complete assessment of the atmosphere.
According to the WMO, this combination of observations with models makes it possible to estimate temperatures at any time and in any place across the globe, even in data-sparse areas such as the polar regions.
The spread between the five data sets was 0.15°C with both the lowest (1.05°C) and the highest (1.20°C) being more than 1°C warmer than the pre-industrial baseline.