Is the cleaner air global warming, we are more than expected?

Climate scientist James Hansen, who is known to alert the US Congress for global warming in the 1980s, has again defined his warning that we are reducing the climate effect of declining air pollution.

“Humanity made a bad deal, a foster deal, when we used aerosol to offset for about half of greenhouse gas warming,” Hansen said. Briefing Hosted by the United Nations Sustainable Development Solution Network.

But other researchers say that this conclusion is based on unstable foundation, and we still do not know how much lack of air pollution is contributing to global warming. Hansen’s findings “we are hovering around the top end of what we consider laudable,” says Michael Diamond At Florida State University, which did not join with research.

In 2023 and 2024, a record spikes in global average temperatures have argued whether the speed of global warming is getting faster than expected. The rising levels of greenhouse gases and a warming Pacific Ocean increased the most increase in temperature, but other unknown contributors pushed the average temperature, which could be explained alone by the factors.

Hansen and his colleagues Before Air is associated with a quick rate of warming with a decrease in pollution. They now offer a new analysis that argued that the decline in air pollution may explain the spike in temperature over the last two years. In air pollution, both aerosols indicate sunlight away from the earth and interact with the clouds – which are also implicated as a factor in summer.

They especially focus on the impact of a 2020 regulation that reduces the amount of harmful sulfur used in shipping fuel. A sudden decline in air pollution on the oceans has provided an unexpected experiment to researchers that allow them to determine the climate effects of aerosol with greater accuracy.

Henson and his colleagues saw the busy shipping corridors in the Pacific Ocean to estimate the effect, measuring changes in the planet’s solar radiation in those areas because air pollution declined. From this, they guess that the total change in shipping aerosol increased the Earth’s energy imbalance to 0.5 watt per square meter. This is equal to the warming effect of a decade of global carbon dioxide emissions at today’s levels.

This additional warming would be sufficient for the unexplained part of the heat seen in the last two years, they found. But the implications are widespread: this will also mean that the cooling effect of air pollution is masking the entire range of warming effects of greenhouse gases – in other words, the warming experienced till date does not represent the full effect of our emissions. .

Hansen and his colleagues have warned that this means that climate is more sensitive than the rising levels of greenhouse gases. As a result, they argue, the world is getting closer to climate tipping points more rapidly, such as the recession of the major Atlantic ocean currents and the collapse of the west Antarctic snow. To combat this, they say that we should consider more seriously how to cool the planet with intervention such as solar geoenizing.

However, at the core of the new analysis, the 0.5 watt per square meter number is much higher than other estimates of the warming effect of changes in shipping emissions, says Tianley Yuan At the Maryland Baltimore County University. But he says that it is not completely impossible.

Gavin shmit NASA states that the number is “very much more likely” because it assumes that all changes in the absorbed sunlight are due to changes in shipping aerosol, rather than other changes such as low air pollution or natural variability than China.

Changes in aerosol may also not be necessary to explain the 2023 spike, says Shiva Priyam Raghuraman In Urbana-Shampain of the University of Illinois-he first found that it can be explained Pacific Ocean temperature changes alone. He says that more work is required to cover various estimates of aerosol’s warming effects.