Mandatory reductions in sulfur emissions from international shipping routes in 2020 are partly responsible for the record temperatures set in the summer of 2023.
The summer of 2023 will see a surprising rise in global temperatures, even in the context of the current warming trend caused by greenhouse gases. It has puzzled many scholars. Their simulations did not show this kind of increase.
“Climate scientists have been saying this is basically impossible, and it’s crazy to see a jump like this all of a sudden,” Daniele Vigeni, an associate professor in Cornell University’s Department of Earth and Atmospheric Sciences, said in a statement. “People were saying: Climate change is suddenly accelerating.” “We’ve never seen anything like this before.” His new research published in Earth system dynamicsgets to the heart of the matter.
The researchers found that mandatory reductions in sulfur emissions from international shipping routes in 2020 are partly responsible for the record temperatures. Reducing the amount of aerosol particles in the atmosphere reduces cloud cover. Consequently, the ability of clouds to reflect solar radiation back into space is diminished. The study results suggest that future policy decisions on abrupt reductions in tropospheric aerosols should take into account their impact on surface temperatures.
Previous research suggested that such a change would lead to a smaller increase in global temperature due to reduced cloud formation, but Visioni and co-author Ilaria Quaglia, a postdoctoral researcher in the Sibley School of Mechanical and Aerospace Engineering (Cornell Engineering), used Earth system model simulations To demonstrate the importance of the sudden decline in sulphate emissions from shipping.
These changes in the shipping industry have been discussed for years, and the International Maritime Organization (IMO) made a decision in 2014 to start enforcing stricter sulfate emissions by 2020, Vigne said. Low-sulfur fuels are much more expensive, so it took time. long. While the industry has to adapt, he said.
The regulations obligated ships to use fuel with a sulfur content not exceeding 0.5%, down from the previous limit of 3.5%. This reduction resulted in a more than 80% reduction in total sulfur oxide emissions from shipping.
While there has been talk of such compensation within the shipping industry, there have been few attempts to draw widespread attention to the potential impact, he said.
“There was no attempt to say we should have all our eyes on the shipping lane,” Vigne said. “In hindsight, it would have been nice to have studied this four years ago before the problem presented itself.”
Nearly a tenth of a degree Celsius
Cornell University researchers analyzed monthly global temperature anomalies over the period 2020-23, removing the assumed linear contribution of greenhouse gases and seasonality, to determine the impact of the shipping industry on temperature anomalies. They found that removing sulfur dioxide from ship fuel would likely increase the planet’s temperature by 0.08 degrees Celsius.
“The unprecedented heat turned into a normal warm year once we took that into account,” Vigne said.
Quantifying the extent to which these polluting aerosols reflect heat back into space to cause a significant increase in Earth’s temperature is not a suggestion that pollution reduction efforts should be reduced, according to Vigeni.
“The improvement in air quality is immediate and everyone will always try to achieve that. One lesson we can learn from this is that we make trade-off decisions all the time,” he said. “We are working to reduce air pollution more than would have been expected 10 years ago, so There needs to be a more open discussion. “This means that the urgent need to reduce emissions has become greater.”
The shipping industry, like many others, has turned to alternative fuels to meet IMO decarbonisation targets, with methanol, hydrogen, ammonia, wind-assisted propulsion systems and other technologies gaining ground.
“We have to be more aggressive when it comes to reducing emissions,” Vigne said. “We have a gap to overcome, but we have to work to prevent global warming by other means. “Cloud brightening and geoengineering climate interventions are not things that will reduce emissions, but they are things we may need to avoid further global warming.”
(tags for translation)LA PRENSA
