• Greenhouse gas levels surged to a new record in 2023, according to a report from the World Meteorological Organisation (WMO), which shows once again that urgent action and not words is needed from the world’s major polluters to protect us all from climate change.

• Carbon dioxide (CO2) — one of the three main greenhouse gases, along with methane and nitrous oxide — is accumulating in the atmosphere faster than any time experienced during human existence, rising by more than 10 per cent in just two decades. 

• Key greenhouse gas-producing events include forest fires and the El Nino weather phenomenon which fuelled drier conditions and a “surge” in gas concentrations in the latter part of 2023. Its analysis shows that just under half of CO2 emissions remain in the atmosphere, just over one quarter are absorbed by the ocean and just under 30 per cent are retained on land.

• During El Nino years, greenhouse gas levels tend to rise because drier vegetation and forest fires reduce the efficiency of land carbon sinks.

WMO Greenhouse Gas Bulletin

The WMO Greenhouse Gas Bulletin is one of WMO’s flagship publications released to inform the UN Climate Change conference, COP, and is now in its 20th issue. The Greenhouse Gas Bulletin has been published annually since 2004. This publication presents the latest analysis of observations from the WMO Global Atmosphere Watch (GAW) Programme on concentrations of long-lived greenhouse gases in the atmosphere for 2023.

What are greenhouse gases?

• The Earth has a natural greenhouse effect due to trace amounts of water vapour (H2O), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in the atmosphere. These gases let the solar radiation reach the Earth’s surface, but they absorb infrared radiation emitted by the Earth and thereby lead to the heating of the surface of the planet. 

• In simpler terms, gases that trap heat in the atmosphere are called greenhouse gases.

• The main greenhouse gases whose concentrations are rising are carbon dioxide, methane, nitrous oxide, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs) and ozone in the lower atmosphere.

• The current level of greenhouse gas concentrations puts us on the pathway of an increase in temperatures well above the Paris Agreement targets by the end of this century. This will be accompanied by more extreme weather, including intense heat and rainfall, ice melt, sea-level rise and ocean heat and acidification. 

Carbon dioxide

• Carbon dioxide is the single most important greenhouse gas in the atmosphere, accounting for approximately 64 per cent of the warming effect on the climate, mainly because of fossil fuel combustion and cement production.

• Just under half of CO2 emissions remain in the atmosphere. Just over one quarter are absorbed by the ocean and just under 30 per cent by land ecosystems like forests — although there is considerable year-to-year variability in this. As long as emissions continue, CO2 will continue accumulating in the atmosphere leading to global temperature 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.

• The 2023 increase of CO2 in the atmosphere was higher than that of 2022, although lower than that of the three years before that. The annual increase of 2.3 parts per million (ppm) marked the 12th consecutive year with an increase greater than 2 ppm, while the increase within the year 2023 was one of the largest (2.8 ppm).

• In 2004, the concentration of carbon dioxide in the atmosphere was 377.1 ppm, while in 2023, this reached 420 ppm.

• Given the extremely long life of CO2 in the atmosphere, the temperature level already observed will persist for several decades even if emissions are rapidly reduced to net zero.

• 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.

Methane

• Methane is a powerful greenhouse gas which remains in the atmosphere for about a decade.

• Methane accounts for about 16 per cent of the warming effect of long-lived greenhouse gases. Approximately 40 per cent of methane is emitted into the atmosphere by natural sources (for example, wetlands and termites), and about 60 per cent comes from anthropogenic sources (for example, ruminants, rice agriculture, fossil fuel exploitation, landfills and biomass burning).

• The growth in atmospheric methane in 2023 was smaller than 2022, but was record high for the five-year period. Detailed analysis indicates an emission increase from sources such as wetlands and agriculture, which could at least partly be due to on-going climate feedback that further increases greenhouse gas emissions from the natural systems.

Nitrous Oxide

• Nitrous Oxide is both a powerful greenhouse gas and ozone depleting chemical. It accounts for about 6 per cent of the radiative forcing by long-lived greenhouse gases.

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

• For nitrous oxide, the increase from 2022 to 2023 was lower than that observed from 2021 to 2022, which was the highest increase observed in our modern time record.

World Meteorological Organisation (WMO)

• The World Meteorological Organisation (WMO) is a specialised agency of the United Nations. 

• It is the UN system’s authoritative voice on the state and behaviour of the Earth’s atmosphere, its interaction with the oceans, the climate it produces and the resulting distribution of water resources.

• The WMO has 193 Members, including 187 Member States and 6 territories, maintaining their own meteorological services.

• It originated from the International Meteorological Organisation (IMO), which was founded in 1873.

• Established in 1950, WMO became the specialised agency of the UN in 1951 for meteorology (weather and climate), operational hydrology and related geophysical sciences. 

• WMO facilitates the free and unrestricted exchange of data and information, products and services in real or near-real time on matters relating to safety and security of society, economic welfare and the protection of the environment. It contributes to policy formulation in these areas at national and international levels.

• WMO coordinates the activities of National Meteorological and Hydrological Services in 193 States and territories so that basic weather, climate and water services are made available to anyone who needs them.

• The Secretariat, headquartered in Geneva, is headed by the Secretary-General.

Additional Read:

India is world’s second largest emitter of nitrous oxide

India emerged as the world’s second largest source of nitrous oxide (N2O), according to a report published in Earth System Science Data. The top 10 emitters are China, India, the United States, Brazil, Russia, Pakistan, Australia, Indonesia, Turkey, and Canada.

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