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06-20-2024

Aerosols have an underestimated effect on clouds and climate

Aerosols, the tiny particles floating in the air from sources like dust, smoke, and pollution, play a role in climate change. They act as “seeds” for cloud formation, with more aerosols leading to thicker, more reflective clouds that can cool the Earth. But a new study has discovered a crucial factor that has been overlooked: the connection between clouds and the Earth’s surface.

Cloud-surface coupling

The researchers, led by the Earth System Science Interdisciplinary Center (ESSIC), investigated how clouds interact with the Earth’s surface, a phenomenon known as cloud-surface coupling. 

This coupling influences the vertical exchange of heat and moisture between the surface and the atmosphere. 

When coupling is strong, warm air from the surface rises, creating updrafts that transport aerosols into the cloud layer. This leads to a more homogeneous distribution of aerosols within the clouds, resulting in more consistent cloud droplet sizes and a stronger cooling effect on climate due to increased reflection of sunlight. 

Conversely, when coupling is weak, this vertical transport is diminished, leading to an uneven distribution of aerosols within the clouds and a greater variability in cloud droplet size. 

The variability in cloud properties introduces significant uncertainty into our understanding of how aerosols influence climate.

“Aerosol-cloud interaction has remained the largest source of uncertainty in understanding Earth’s climate and projecting its future changes, especially those incurred by anthropogenic emissions such as sulfate, nitrate, and black carbon,” said Zhanqing Li, Distinguished University Professor at UMD and lead author of the study.

By understanding how cloud-surface coupling influences interactions between aerosols and clouds, scientists can better predict how aerosols will affect our climate. This is crucial because it helps explain why climate models and real-world observations often don’t match up.

A global perspective

The team’s findings have far-reaching implications. “If we can determine cloud-surface coupling across the globe, we could significantly improve our quantification of aerosol climate effects,” explained Tianning Su, a co-author of the study.

This translates to improved climate modeling and forecasting capabilities, allowing for more precise predictions about future climate change scenarios. 

Furthermore, this enhanced understanding of aerosol-cloud interactions can help researchers better quantify the impact of human activities – such as the burning of fossil fuels – on the climate system. 

This knowledge is essential for developing effective mitigation and adaptation strategies to address the challenges posed by climate change.

Aerosols, clouds and climate science

The research not only reveals the intricate nature of climate science but also serves as a stark reminder that seemingly minor elements within the Earth’s climate system can wield substantial influence. 

The interplay between clouds and the Earth’s surface, once considered a secondary factor, is now recognized as a key player in the broader climate change narrative.

This study underscores the imperative for continued and comprehensive research into the multifaceted mechanisms that govern our planet’s climate. Each new discovery, like the significant role of cloud-surface coupling, adds another piece to the complex puzzle of climate change.

By diligently investigating and ultimately understanding these intricate processes, scientists can develop more precise and effective strategies to mitigate the escalating effects of climate change. 

This knowledge empowers policymakers and communities alike to make informed decisions and take proactive measures to safeguard the planet for current and future generations.

Reducing uncertainty

The researchers are now focused on applying their findings on a global scale, hoping to integrate this new understanding into broader climate projections. 

“The goal is to integrate this new understanding into broader climate projections to reduce uncertainty and make more accurate predictions about climate change,” said Su.

The study of cloud-surface coupling and its impact on aerosol-cloud interaction is a major step forward in our understanding of climate change. It’s a reminder that the Earth’s climate system is a complex web of interconnected processes, and that even the smallest details can have a significant impact

By continuing to explore these connections, we can gain valuable insights into how our planet is changing and what we can do to protect it.

The study is published in the journal Science Advances.

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