The last seven years have been the hottest on record globally "by a wide margin," according to the European Union's climate monitoring service, which also raised the alarm about sharp increases in methane concentrations in the atmosphere.

In recent years, countries around the world have been bombarded by a relentless barrage of weather disasters linked to global warming, including record-breaking wildfires in Australia and Siberia, a once-in-a-thousand-years heatwave in North America, and extreme rainfall that caused massive flooding in Asia, Africa, the United States, and Europe.

The Copernicus Climate Change Service (C3S) confirmed in its most recent annual assessment that 2021 would join the unbroken warm streak that began in 2015.

Reports recorded that last year was the fifth warmest on record around the world, slightly warmer than 2015 and 2018. Accurate measurements can be traced back to the mid-nineteenth century.

Between 1850 and 1900, the annual average temperature was 1.1 to 1.2 degrees Celsius higher than pre-industrial levels, according to C3S, despite the natural cooling effect of the La Nina weather phenomenon.

Overall, the monitoring service discovered that the last seven years "have been by far the warmest years on record."

"2021 was yet another year of extreme temperatures with the hottest summer in Europe, heatwaves in the Mediterranean, not to mention the unprecedented high temperatures in North America," said C3S Director Carlo Buontempo.

"These events are a stark reminder of the need to change our ways, take decisive and effective steps toward a sustainable society and work towards reducing net carbon emissions." 

Methane surge 

The C3S also measured atmospheric concentrations of the planet-warming gases carbon dioxide and methane and discovered that both had increased with no sign of slowing.

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Methane, in particular, has risen "significantly", reaching an annual high of around 1,876 parts per billion (ppb).

Growth rates for 2020 and 2021 were 14.6 and 16.3% per year, respectively. This is more than double the previous 17-year average annual growth rate.

However, a variety of human and natural causes made it difficult to pinpoint why there had been such a significant increase in recent years, according to C3S.

After CO2, methane (CH4) is the gas most responsible for global warming. While it has a shorter lifetime in the atmosphere, it is many times more powerful than CO2. 

Wetlands are natural sources, while human-induced sources include leaks from natural gas and oil production, coal mining and landfills, rice paddies, livestock, and manure handling.

Observational evidence, according to Vincent-Henri Peuch, Director of the Copernicus Atmosphere Monitoring Service, which tracks greenhouse gas increases, is critical in the effort to avoid "climate catastrophe". 

Can we reduce methane?

Reducing the amount of methane in the atmosphere would quickly result in a slowing of rising temperatures and contribute to closing the so-called emissions gap between the Paris Agreement target of a 1.5°C cap on warming and the 2.7°C we are heading for even if all nations keep their carbon-cutting promises.

This has piqued the interest of policymakers eager to find the quickest ways to reduce emissions.

At last year's COP26 climate summit, nearly a hundred countries pledged to reduce methane emissions by at least 30% over the next decade.

The oil and gas industry has the greatest potential for rapid reductions, owing to the detection and repair of gas leaks during production and transportation.

While global warming may appear gradual, its impact on extreme events is "dramatic", according to Rowan Sutton of the National Centre for Atmospheric Science at Reading University in the United Kingdom.

"We should see the record-breaking 2021 events, such as the heatwave in Canada and floods in Germany, like a punch in the face to make politicians and public alike wake up to the urgency of the climate emergency," he told the Science Media Centre.  

"Moreover, the continued increases in greenhouse gas concentrations in the atmosphere screams out that the underlying causes have yet to be addressed."