Recently, according to the South China Morning Post, a well-known international media in Hong Kong, a study published in the Proceedings of the National Academy of Sciences found that China's rapid reduction in aerosol emissions has led to a rise in ocean temperatures in the Northeast Pacific Ocean and the west coast of North America, a phenomenon known as "sudden warming".
The phrase "rapid reduction of aerosol emissions" may sound too formal, but in the final analysis, it is actually "eliminating smog".
The study notes that China has made significant progress in reducing aerosol emissions from fossil fuel combustion over the past decade, which has improved China's air quality but also reduced the cooling effect of aerosols on the Earth's surface.
The study, led by Chinese scientists, uses climate models to analyze how local temperature changes due to reduced aerosols in China affect warming in other parts of the globe, observers note.
China's air is getting cleaner, but it's causing North America's oceans to warm
In recent years, China has made remarkable progress in reducing air pollution, and air quality has improved significantly.
However, a new study has found that this environmental action may have contributed to the sudden warming of North America's oceans. The researchers noted that China's reduced aerosol emissions have led to rising sea surface temperatures and an increase in extreme weather phenomena in the Northeast Pacific and the west coast of North America.
Aerosols are tiny particles suspended in the air that can be emitted by burning fossil fuels. Over the past decade, China has significantly reduced aerosol emissions by reducing the use of fossil fuels, which not only improves air quality in the country, but also reduces the reflection of solar radiation on the Earth's surface and reduces the cooling effect of aerosols.
A study led by Chinese scientists used climate model simulations to find that local temperature changes caused by China's reduction in aerosol emissions had a significant impact on the rest of the world. The research team includes scientists from the United States and Germany, who have published papers in the Proceedings of the National Academy of Sciences. The study pointed out that from 2010 to 2020, the sea surface temperature in the Northeast Pacific Ocean reached a record high, and several sustained extreme ocean warming events occurred one after another.
Professor Zheng Xiaotong of Ocean University of China said sea surface temperatures from Alaska to the coast of California have risen abruptly over the past decade, and these warming events are what researchers call "warm patches" and are accompanied by extreme weather phenomena such as the 2013-2016 California drought, which cost agriculture billions of dollars.
While year-to-year climate change may have played a role in ocean warming events that cause extreme weather, researchers say it doesn't fully explain the appearance of these warm patches. Professor Cheng pointed out that global warming is an ongoing phenomenon and will not lead to such specific warming. He added that there had been no change for a while, and then there had been a sudden warming over the past decade, so they hypothesized that the phenomenon could be related to other anthropogenic factors.
Using climate models, the research team found that China's rapid reduction in aerosol emissions would trigger atmospheric circulation anomalies outside its source region, leading to significant mean surface warming in the Northeast Pacific.
Aerosols counteract the warming effects of greenhouse gases. Beijing's clean air policies have significantly reduced pollutants emitted by burning fossil fuels from power plants and factories over the past decade, including black carbon (or soot) and sulfates, which have been linked to health problems such as lung disease.
Aerosols can reflect solar radiation back into space, preventing some of the energy from reaching the Earth's surface, creating a cooling effect. Aerosols can also increase the ability of clouds to reflect solar radiation. However, some aerosols can also absorb sunlight, causing the surface to cool temporarily, but ultimately contributing to warming.
A scientist's point of view
Professor Zheng said that the local warming effects of aerosol reduction in China have been studied before, but their impact on other regions has been neglected. The team compared a model reflecting the reduction of aerosols in China with a model that simulated the flatness of aerosol emissions and found that the downward trend in aerosol emissions coincided with an increase in average warming in the Northeast Pacific.
In simulations in which aerosols were the only variable and greenhouse gases were fixed at pre-industrial levels, the team found that sea surface temperatures in the Northeast Pacific continued to cool until around 2007 and then warmed rapidly as emissions decreased.
This phenomenon occurs because localized warming along the coast of Asia strengthens the Aleutian Depression – an area of atmospheric depression off the coast of Alaska – and shifts it southward. Atmospheric circulation anomalies weakened surface winds, which inhibited evaporative cooling in the Northeast Pacific, leading to a rise in sea surface temperatures.
The increase in aerosol emissions due to China's industrialization may have "significantly slowed" warming in the Northeast Pacific in the past. The reduction in aerosol emissions and the subsequent rise in sea surface temperatures may reflect "previously suppressed warming".
Despite the potential impact that reducing aerosol emissions in one place may have on other regions, Professor Cheng said it is still important to improve air quality because anthropogenic aerosol emissions have negative health impacts.
He added that relying on aerosol emissions to slow ocean warming is unrealistic because of its high environmental and social costs, and as air pollution decreases, any previously suppressed ocean warming "is bound to rebound".
According to the paper, the study highlights the increased risk of anthropogenic aerosol emission reductions that need to be taken into account when assessing the impacts of climate change. Professor Cheng hopes that their research will contribute to "accurate climate prediction and effective climate change adaptation".
The complex relationship between environmental protection and global climate
China's environmental policies over the past decade have yielded remarkable results, reducing air pollution and improving the quality of life for its citizens. However, this study reveals a complex reality: reducing aerosol emissions, while improving local air quality, can have unintended impacts on the global climate.
The reduction in aerosols allows more solar radiation to reach the Earth's surface, causing local temperatures to rise.
This localized warming affects regions far from the source, such as the Northeast Pacific Ocean and the west coast of North America, through atmospheric circulation. This finding illustrates that the global climate system is highly interconnected, and that environmental initiatives in one region can have far-reaching effects on the rest of the globe.
Climate model simulations show that between 2010 and 2020, sea surface temperatures in the Northeast Pacific reached record highs, leading to several extreme ocean warming events. These "warm patches" are closely linked to extreme weather phenomena, such as the drought in California, which has caused huge economic losses to agriculture.
This phenomenon not only affects the economy, but also causes damage to the ecosystem.
For example, warm waters have contributed to the outbreak of toxic algal blooms, affecting the habitat of marine life and even threatening human health and safety. These extreme weather events remind us that the effects of climate change are not just about rising temperatures, but also about changing weather patterns and destroying ecosystems.
The study highlights the importance of global cooperation to combat climate change. While China's environmental policies have been successful at home, their impact on the global climate needs to be coordinated with other countries. This requires countries to develop environmental policies that take into account not only their own interests, but also their global impacts.
Climate change is a global problem that requires a concerted global effort. Countries need to coordinate their efforts to address global climate change from reduced aerosols while reducing greenhouse gas emissions. This may include the development of new technologies to replace the cooling effects of aerosols while reducing their negative health and environmental impacts.
To address the complexities of climate change, we need to rely on technology and innovation. Researchers can address the effects of reduced aerosol emissions by developing new environmentally friendly technologies that reduce dependence on fossil fuels while finding alternatives. For example, increasing the use of renewable energy, improving energy efficiency, and developing carbon capture and storage technologies.
In addition, governments and businesses need to work together to promote sustainable development. Promote the development and application of green technologies through policy support and economic incentives. At the same time, public awareness and participation in environmental protection are also important factors in achieving climate goals. Education and awareness can help the public understand the complexities of climate change and encourage more people to get involved in environmental action.
A little summary
China's efforts to reduce aerosol emissions show the duality of environmental policies.
On the one hand, the improvement of air quality has significantly improved the quality of life of people and reduced health risks. On the other hand, this measure has had unexpected climate impacts on a global scale.
This reminds us that environmental protection requires a global perspective and cooperation, and that the efforts of a single country, while important, are not enough to address the challenge of global climate change.
In the future, we need to work together in scientific and technological innovation, policy coordination and public participation to promote global sustainable development. Only in this way can we truly achieve a harmonious coexistence between man and nature and create a better planet for future generations.
Through this research, we see the complexity and urgency of climate change, as well as the need for global cooperation and scientific and technological innovation.
It is hoped that this discovery will inspire more research and action to jointly address the challenge of climate change and move towards a more sustainable future.