In 2021, greenhouse gases rose more than ever before. According to the latest measurements, researchers are faced with a mystery: is climate change to blame?
New York/Geneva – Although more speed is being demanded for climate protection, the concentration of the climate change drivers methane and carbon dioxide in the atmosphere is increasing – apparently more strongly than ever before in the past year. “The reason for this extraordinary increase is not clear, but appears to be due to both biological and man-made processes,” the World Weather Organization (WMO) reported on Wednesday.
Never since systematic measurements began almost 40 years ago has the concentration of the powerful greenhouse gas methane in the atmosphere increased as much as in 2021. The World Weather Organization (WMO) in Geneva is puzzled by the increase: the concentration of methane in the atmosphere will have increased by 2021 reached a peak at the same time, as did that of carbon dioxide and nitrous oxide – each since measurements of these greenhouse gases began.
Climate change: This is the contribution made by the gases methane (CH4) and carbon dioxide (CO₂)
Methane (CH4) contributes the most to climate change after carbon dioxide (CO₂). It is created where organic material is broken down in the absence of air. It is 25 times more harmful to the climate than CO₂. However, it lasts much shorter in the atmosphere. In the case of methane it is a good ten years, in the case of CO₂ a considerable proportion is still in the atmosphere even after centuries.
CO₂ contributes around two thirds to the greenhouse effect, methane a good 16 percent and nitrous oxide around 6.5 percent. All greenhouse gases combined have led to an average global warming of 1.1 degrees since the late 19th century. In Germany it was 1.6 degrees.
This is how the increase looks in detail:
- Methane: According to WMO estimates, the global average concentration of methane rose by 18 to 1908 ppb (parts per billion) in 2021.
- Carbon dioxide: The concentration increased by 2.5 to 415.7 ppm (parts per million – parts CO₂ per million parts) in 2021.
Methane: The increase could be due to climate change
In 2020, the increase in methane, at 15 ppb, was also significantly larger than the long-term average. 1908 ppb is 262 percent of pre-industrial levels.
A large part probably comes from wetlands and paddy fields, writes the WMO in its annual greenhouse gas bulletin. It is still unclear whether this is a consequence of climate change, for example because wetlands are becoming wetter and warmer. The warmer, the faster organic matter breaks down, and aquatic breakdown without oxygen leads to higher methane emissions. But the WMO also writes: “The dramatic increase could also be due to natural annual variability.”
Carbon Dioxide: Increase attributed to burning of coal, oil, gas and destruction of forests
In the case of carbon dioxide, the increase in concentration from 2020 to 2021 was higher than the average for the ten previous years. The increase in 2021 corresponds to 149 percent of the level before the start of industrialization around 1750. CO₂ is produced, for example, by the burning of coal, oil and gas, cement production and other industrial processes as well as forest destruction.
Climate forecasts are difficult: Depending on the measuring stations and calculation methods, the WMO values deviate slightly from information from the US climate authority NOAA, for example. The WMO forms an average from the measurements of several stations.