Climate change: Covid shutdown linked to record rainfall in China

Image source, AFP

Scientists say that a rapid drop in emissions because of Covid played a key role in record rainfall in China in 2020.

The decline in greenhouse gases and aerosols caused atmospheric changes that intensified the downpours.

Hundreds of people died and millions were evacuated during the summer.

Long-term emissions cuts are unlikely to cause similar events.

Parts of eastern China experienced flooding in June and July of 2020. The reductions in emissions contributed to a third of the rain.

Image source, Getty Images

In June and July of this year, the Yangtze river saw the most rain since 1961, with a 79% increase in June and July compared to the previous 41 years.

A number of scientific studies have looked at what caused the flooding events, some pointing to the extreme conditions in the Indian Ocean.

A new theory has been put forward by an international team. They argue that the sudden reduction in emissions of greenhouse gases and aerosols was the cause of the intense downpours.

The increase in the number of aerosols in the atmosphere has led to a decrease in summer rain in eastern and central China over the past four decades.

These particles are associated with the burning of coal and can reduce the occurrence of large-scale storms.

Image source, Getty Images

The absence of these particles and lower greenhouse gas emissions in 2020 caused the opposite effect of a major increase in rain, according to a new study.

The chain of events that lead to the floods is complex.

The lead author explained that there was heating over land due to aerosol reductions but also cooling over the ocean due to a decrease in greenhouse gases.

Increased sea level pressure over the South China/Philippines sea and intensified winds brought moist air to eastern China which then saw intense precipitation.

Image source, Getty Images

Governments around the world are trying to reduce emissions of warming gases and aerosols by shifting their energy systems away from fossil fuels. Is there a danger that the shift could cause extreme events like the ones that happened in China in 2020?

Prof Yang said it was a good question.

Because emissions were reduced in early 2020 when the Covid-19 pandemic emerged, it caused an immediate and abrupt change in various components of the climate system.

The sudden change of the climate system would be very different from the gradual reduction of emissions.

The journal Nature Communications has published a new study.

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