The World Meteorological Organization(WMO) is warning that a new record level of greenhouse gases in the atmosphere in 2020 is jeopardizing the prospect of achieving the Paris Agreement temperature targets.

According to the WMO Greenhouse Gas Bulletin, 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 – and the trend is continuing in 2021.

, 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.

The numbers are based on monitoring by WMO’s Global Atmosphere Watch network.

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, with the other half 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.

Current rate of increase will see a temperature increase by the end of century far in excess of Paris Agreement targets of 1.5 to 2 degrees 

“The Greenhouse Gas Bulletin contains a stark, scientific message for climate change negotiators at COP26. At the current rate of increase in greenhouse gas concentrations, we will see a temperature increase by the end of this century far in excess of the Paris Agreement targets of 1.5 to 2 degrees Celsius above pre-industrial levels,” said WMO Secretary-General Prof. Petteri Taalas. “We are way off track.”

“The amount of CO2 in the atmosphere breached the milestone of 400 parts per million in 2015. And just five years later, it exceeded 413 ppm. This is more than just a chemical formula and figures on a graph. It has major negative repercussions for our daily lives and well-being, for the state of our planet and for the future of our children and grandchildren,” said Prof. Taalas.

“Carbon dioxide remains in the atmosphere for centuries and in the ocean for even longer. The last time the Earth experienced a comparable concentration of CO2 was 3-5 million years ago, when the temperature was 2-3°C warmer and sea level was 10-20 meters higher than now. But there weren’t 7.8 billion people then.”

“Many countries are now setting carbon neutral targets and it is hoped that COP26 will see a dramatic increase in commitments. We need to transform our commitment into action that will have an impact of the gases that drive climate change. We need to revisit our industrial, energy and transport systems and whole way of life. The needed changes are economically affordable and technically possible. There is no time to lose,” Prof. Taalas continued.

Carbon dioxide is the single most important greenhouse gas in the atmosphere

According to the WMO, carbon dioxide is the single most important greenhouse gas in the atmosphere, accounting for approximately 66% of the warming effect on the climate, mainly because of fossil fuel combustion and cement production.

The globally averaged concentrations for CO2 reached a new high of 413.2 ppm in 2020. The increase in CO2 from 2019 to 2020 was slightly smaller than 2018 to 2019 but larger than the average annual growth rate over the last decade. This is despite the approximately 5.6% drop in fossil fuel CO2 emissions in 2020 due to the COVID-19 restrictions.

Data from the monitoring stations clearly show that levels of CO2 continued to increase in 2021.

Methane accounts for about 16% of the warming effect of long-lived greenhouse gases, according to the US National Oceanic and Atmospheric Administration (NOAA). Approximately 40% of methane is emitted into the atmosphere by natural sources (for example, wetlands and termites), and about 60% comes from anthropogenic sources (for example, ruminants, rice agriculture, fossil fuel exploitation, landfills and biomass burning).

The increase from 2019 to 2020 was higher than 2018 to 2019 and also higher than the average annual growth rate over the last decade.

Reducing atmospheric methane in the short term could support the achievement of the Paris Agreement and help in reaching many Sustainable Development Goals due to multiple co-benefits of methane mitigation. But this does not reduce the need for strong, rapid and sustained reductions in CO2.

Nitrous Oxide is both a powerful greenhouse gas and ozone depleting chemical. It accounts for about 7% of the radiative forcing by long-lived greenhouse gases.

N2O is emitted into the atmosphere from both natural sources (approximately 60%) and anthropogenic sources (approximately 40%), including oceans, soils, biomass burning, fertilizer use, and various industrial processes.

Global human-induced N2O emissions, which are dominated by nitrogen additions to croplands, increased by 30% over the past four decades. Agriculture, owing to the use of nitrogen fertilizers and manure, contributes 70% of all anthropogenic N2O emissions. This increase was mainly responsible for the growth in the atmospheric burden of N2O.

A separate and complementary Emissions Gap Report by UN Environment will be released on tomorrow.

The Emissions Gap report assesses the latest scientific studies on current and estimated future greenhouse gas emissions; they compare these with the emission levels permissible for the world to progress on a least-cost pathway to achieve the goals of the Paris Agreement. This difference between “where we are likely to be and where we need to be” is known as the emissions gap.

Click here to download the WMO Greenhouse Gas Bulletin