Greenhouse gas levels record high, raising climate tipping point concerns:Report

New Delhi: Heat trapping greenhouse gas (GHG) concentrations reached a new record last year and continued to increase in 2023, the World Meteorological Organisation (WMO) said on Wednesday.

Global averaged concentrations of carbon dioxide (CO2), the most important greenhouse gas, in 2022 were a full 50% above the pre-industrial era for the first time, WMO’s greenhouse gas bulletin released on Wednesday said.

It added that the rate of growth in CO2 concentrations was slightly lower than in 2021 and the average for the decade. But that was most likely due to natural, short-term variations in the carbon cycle but new emissions as a result of industrial activities continued to rise.

The (NOAA) Annual Greenhouse Gas Index shows that from 1990 to 2022, the warming effect on our climate called radiative forcing by long-lived greenhouse gases increased by 49%, with CO2 accounting for about 78% of this increase, WMO said.

The global mean CO2 concentration in 2022 was 417.9 ppm compared to 415.7 ppm in 2021.

The abundance of GHG concentrations needs to be tracked carefully in the light of consequences it can trigger. WMO has said more information is needed on tipping points for example. The climate system may be close to so-called “tipping points”, where a certain level of change leads to self-accelerating and potentially irreversible cascade of changes, the statement said. Examples include rapid die-back of the Amazon rainforest, slowing of the northern ocean circulation or the destabilisation of large ice sheets among others. Information is also needed on natural variability in the concentration of GHGs.

The three major greenhouse gases--CO2, Methane and Nitrous Oxide have substantial variability driven by natural processes combined with anthropogenic factors (For example, El Niño). This variability can either amplify or subdue changes over certain periods.

Although the scientific community has broad consensus on the implications of climate change, there are still some uncertainties about the carbon cycle and the fluxes in the ocean, the land biosphere and the permafrost areas.

“These uncertainties, however, must not deter action. Instead, they highlight the need for flexible, adaptive strategies and the importance of risk management in the path to net-zero and the realisation of the Paris Agreement’s goals. Provision of accurate, timely, and actionable data on greenhouse gas fluxes becomes more critical,” the bulletin said.

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The 2.2 parts per million (ppm) increase in the annual average CO2 concentrations from 2021 to 2022 was slightly smaller than 2020 to 2021 and for the past decade (2.46 ppm yr).

The most likely reason is increased absorption of atmospheric CO2 by terrestrial ecosystems and the ocean after several years with a La Nina event. The development of an El Nino event in 2023 may therefore have consequences for greenhouse gas concentrations, the bulletin said.

Methane is also a powerful greenhouse gas which remains in the atmosphere for about a decade. Methane accounts for about 16% of the warming effect of long-lived greenhouse gases while nitrous oxide accounts for about 7% of the radiative forcing.

“The first impact of greenhouse gas concentrations going up in the atmosphere is the increase in the greenhouse effect and consequently average temperature. With the increase in average temperature, water vapour goes up. With every degree rise in warming there is a 7% increase in water vapour availability. This has led to a rise in extreme rainfall events during our monsoon season. It can also lead to a rise in extreme weather events over certain parts of the world,” said M Mohapatra, director general, IMD.

“The increase in greenhouse gases is the most important reason for global warming and associated extreme weather events. We are moving in a wrong but disastrous path. Another concern is increase in methane and nitrous oxide also along with carbon dioxide. All our emission targets are off track. It looks like no one is worried about emissions,” added M Rajeevan, climate scientist and former secretary, ministry of earth sciences.

“Such high concentrations of GHG means varied impacts on the atmosphere. It means that we have started melting of glaciers. For example, the Swiss glaciers lost more than 10% of their mass during the past two summers. And we know from history that when we had similar level of CO2 concentrations the sea level was 10 to 20 metres higher than today. So gradually the mountain glaciers will disappear by the end of this century and we will have Greenland and Antarctic glaciers left and they are going to melt for upto thousands of years contributing to half to 1 metre sea level every century. So far, we are heading to 2.5 to 3 degree C warming now and we need to meet the Paris Agreement goals. The 1.5 degree C goal will be breached fairly soon,” said Petteri Taalas, the secretary-general of the World Meteorological Organization during a press briefing on the GHG bulletin on Wednesday.

On X, NOAA posted, saying, “Earth just had its warmest October on record—the fifth month in a row of record-warm temperatures. There is a greater than 99% chance that 2023 will rank as the world’s warmest year on record.”

“Such extreme concentration of GHGs is leading to extreme events, impacts on cryosphere. We can expect wider change in atmosphere including increase in heat waves, flooding events. This negative trend is expected to continue at least till 2060’s,” he added.