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Prof. Daniel Rosenfeld’s Lecture: Challenges in Understanding Global Warming Caused by Aerosols

Author:南赫学院 Time:2024-03-14 Views:

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On January 6, 2024, Professor Daniel Rosenfeld was invited to Nanjing-Helsinki Institute to deliver a lecture on “Challenges in understanding global warming caused by aerosols”. The lecture was hosted by Prof. Zhu Yannian, School of Atmospheric Sciences, Nanjing University.

Prof. Daniel Rosenfeld is an internationally renowned atmospheric scientist, a member of the European Academy of Sciences and Arts, a member of AGU, AMS and other international academic organizations. Prof. Rosenfeld is mainly engaged in atmospheric remote sensing, aerosol-cloud-precipitation interactions, weather modification. And he has published more than 200 high-level SCI papers, including more than 10 papers in Nature, Science and PNAS, which have been cited more than 30,000 times.

I. “Ship Tracks”

At the beginning of the lecture, Prof. Rosenfeld explained the importance of aerosols in understanding global warming. While greenhouse gases contribute to global warming in clear and easily quantifiable ways, aerosols offset some of the warming. As a result, aerosols add significantly to the uncertainty of global warming projections. There are two main sources of aerosols, natural ones including sea salt and volcanic eruptions, and anthropogenic activities such as industrial emissions and traffic exhaust. Changes in aerosols may have long-term and seasonal impacts on climate, so understanding and studying the indirect effects of aerosols is important for predicting climate change and taking countermeasures. How to quantify the indirect climate effects of aerosols on warming due to greenhouse gases remains a heated issue in the field of aerosol-cloud interaction research.

Prof. Rosenfeld started the topic by introducing “ship tracks”, which refer to the visible cloud lines or cloud trails left by ships traveling across the ocean. In other words, they are convective trails caused by ship exhaust emissions. “Ship tracks” can affect local and regional climate by influencing cloud properties and sunlight reflection, which are among the factors that contribute to the complex interactions between aerosols, clouds and climate.

Now, this process has important implications for cloud properties and climate:

Inhibition of precipitation processes: Clouds on “ship tracks” tend to exhibit the effect of precipitation suppression, leading to relatively little rain or snowfall.

Increased cloud albedo: More and smaller cloud droplets scatter and reflect more sunlight, increasing the cloud’s albedo, which may have an effect on the Earth’s energy balance.

Prolonged cloud life cycle: Clouds on “ship tracks” may have a longer life cycle due to smaller cloud droplets being suspended in the atmosphere for a longer period of time.

II. Effect of Aerosols of Different Particle Sizes on Aerosol-Cloud-Radiative Properties

“Prof. Rosenfeld then introduced his latest research results based on the “ship track”: the effect of aerosols of different particle sizes on the radiative properties of clouds. This composite effect refers to the overall cooling effect when fine aerosol and coarse sea salt aerosol interact together. When both of the aerosols work together, they ensure that the albedo of the cloud is large enough and prevent the loss of cloud water due to evaporation. Under this circumstance, the best cooling effect can be achieved. Thus, the overall cooling effect brought by optimal fine particle aerosols and coarse sea salt aerosols is more significant than the cooling effect produced by a single aerosol type.

III. After Lecture

Student Shirui Zhang said, “Prof. Rosenfeld’s lecture was very interesting and gave me a deeper understanding of aerosols’ influence on clouds and precipitation, which in turn affects the climate. The lecture gave me some new insights into climate models and prediction.”

Student Xinyu Yang said, “This lecture allowed me to further understand the impact of aerosols on global warming, to look at climate issues from a new perspective of aerosol-cloud interactions, and to deeply appreciate the complexity and innovativeness of scientific research.”

By delving into the impacts and challenges of aerosols, Prof. Rosenfeld’s lecture encouraged students to further understand the complex mechanisms of global climate change and to provide more targeted strategies to address climate change. In the future, Nanjing-Helsinki Institute will continue to cultivate a group of top talents with excellent academic knowledge, innovative spirit and international vision.

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