Studie der Weltorganisation für Meteorologie, 25.10.2021 (engl. Originalfassung)
The abundance of heat-trapping greenhouse gases in the atmosphere once again reached a new record last year, with the annual rate of increase above the 2011-2020 average. That trend has continued in 2021, according to the World Meteorological Organization (WMO) Greenhouse Gas Bulletin.
Concentration of carbon dioxide (CO2), the most important greenhouse gas, reached 413.2 parts per million in 2020 and is 149% of the pre-industrial level. Methane (CH4) is 262% and nitrous oxide (N2O) is 123% of the levels in 1750 when human activities started disrupting Earth’s natural equilibrium. The economic slowdown from COVID-19 did not have any discernible impact on the atmospheric levels of greenhouse gases and their growth rates, although there was a temporary decline in new emissions.
As long as emissions continue, global temperature will continue to rise. Given the long life of CO2, the temperature level already observed will persist for several decades even if emissions are rapidly reduced to net zero. Alongside rising temperatures, this means more weather extremes including intense heat and rainfall, ice melt, sea-level rise and ocean acidification, accompanied by far-reaching socioeconomic impacts.
Roughly half of the CO2 emitted by human activities today remains in the atmosphere. The other half is taken up by oceans and land ecosystems. The Bulletin flagged concern that the ability of land ecosystems and oceans to act as “sinks” may become less effective in future, thus reducing their ability to absorb carbon dioxide and act as a buffer against larger temperature increase.
The Bulletin shows that from 1990 to 2020, radiative forcing – the warming effect on our climate - by long-lived greenhouse gases increased by 47%, with CO2 accounting for about 80% of this increase. The numbers are based on monitoring by WMO’s Global Atmosphere Watch network.
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