2020 closes hottest decade on record as world targets climate milestone
As 2020 ends, it leaves in its wake the warmest decade on record and one of the three hottest years ever measured, according to the UN weather agency.
Despite a cooling La Niña event, 2020 has been a year of exceptional heat that is now mature and impacting weather patterns in many parts of the world, the World Meteorological Organisation (WMO) said.
According to most models, La Niña is expected to peak in intensity this month and continue through the early part of the year.
“Record warm years have usually coincided with a strong El Niño event, as was the case in 2016”, said WMO chief Petteri Taalas.
However, he noted, “we are now experiencing a La Niña, which has a cooling effect on global temperatures, but has not been sufficient to put a brake on last year’s heat.”
“Despite the current La Niña conditions, last year has already shown near record heat comparable to the previous record of 2016,” said the top WMO official.
WMO has also documented the last six years as being the warmest. This month, the UN agency will issue consolidated temperature figures for 2020, based on five global temperature datasets.
This will be incorporated into a final report on the State of the Climate in 2020, which will be issued in March and will include information on selected climate impacts.
To date, all five datasets for the first 10 months of 2020 has placed last year as the second warmest for the year to date, following 2016 and ahead of 2019.
Based on monthly reports from the European Unions’s Copernicus Climate Change Service, the United States National Oceanic and Atmospheric Administration and NASA’s Goddard Institute for Space Studies and the Japan Meteorological Agency, November has been classified as either the warmest or second warmest on record.
The difference between the warmest three years is small and exact rankings for each data set could change once data for the entire year are available, according to WMO.
Ranking temperatures for individual years is less important than long-term trends, the UN weather agency explained. Since the 1980s each decade has been warmer than the previous one. And because of record levels of heat-trapping greenhouse gases in the atmosphere, the trend is expected to persist.
In particular, carbon dioxide is driving the planet to future warming because it remains in the atmosphere for many decades.
According to WMO’s Global annual Decadal Climate Update, there is a one-in-five chance that the average global temperature will temporarily exceed 1.5 °C by 2024.
Meanwhile, the relentless rise of carbon dioxide levels in the atmosphere – a phenomenon that has continued despite a travel lull during the pandemic – will fuel temperature rise for decades to come.
“The average global temperature in 2020 is set to be about 1.2 °C above the pre-industrial (1850-1900) level. There is at least a one in five chance of it temporarily exceeding 1.5 °C by 2024”, WMO Secretary-General said.
The 1.5 degree threshold represents a milestone the world is trying not to reach: the 2015 Paris agreement on climate change, backed by almost every country on earth, calls for keeping the global temperature to 1.5°C above pre-industrial era levels.
To slow temperature rises, the world needs radical action. Countries must decrease production of fossil fuels by six per cent per year between 2020 and 2030 if the world is to avert “catastrophic” global temperature rise, according to the UN-backed Production Gap report released recently.
Climate records have fallen like dominos in the past decade, so notching up merely the third hottest year on record may seem to suggest some respite. But that would be a false conclusion, because 2020’s heat rose in a year when the world was experiencing a La Niña weather pattern, which normally means lower temperatures.
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