The Role of Aerosols in our Climate: Insights from the nextGEMS Project

Aerosols, defined as tiny particles suspended in the atmosphere, play a pivotal role in the Earth’s climate system. Despite their minuscule size, often smaller than a human hair, these particles exert a significant influence on the planet’s climate. They originate from natural sources, including sea spray, dust storms, and wildfires, as well as human activities, such as industrial emissions and transportation.

How do aerosols impact our climate?

Aerosols affect the climate through both direct and indirect mechanisms. They can absorb or scatter solar radiation, and act as nuclei for cloud droplet formation. These dynamics result in:

– Cooling the Earth’s surface by reflecting solar radiation.

– Warming the atmosphere by absorbing heat.

– Influencing cloud formation, brightness, and lifetime.

While aerosols generally contribute to cooling the Earth, quantifying this effect is a complex scientific challenge due to uncertainties, particularly related to indirect effects.

Challenges in Aerosol Modeling

Accurately incorporating aerosol interactions within climate simulations has been a persistent difficulty. There are coarse-scale climate simulations with interactive aerosol models, but these models are very expensive. Moreover, they are not feasible to be used in km-scale climate simulations. Therefore, nowadays aerosols in km-scale climate simulations are not interactive but prescribed based on historical data. This approach fails to account for real-time atmospheric processes, such as the deposition of aerosols by winds and precipitation. In other words, this appeal overlooks critical dynamics.

Interactive aerosols in High-Resolution Climate Models

New high-resolution climate models, like those developed in the nextGEMS project, are addressing the limitations mentioned above. These models resolve essential processes in the Earth’s system down to a few kilometers, enabling detailed simulations of phenomena such as thunderstorms and tropical cyclones.

nextGEMS aims to integrate aerosols interactively within these advanced climate models. The process begins with a complex aerosol module, which operates at coarse resolutions. Scientists then simplify the micro-physical aerosol processes, before coupling the simplified version with the new climate model.

This research has produced a streamlined and efficient model, making the aerosol simulations more accurate and usable. The model’s design facilitates understanding and adaptation for other researchers, enabling detailed simulations of long-term processes on a global scale. It now includes intricate processes, such as the transport of aerosols by winds, cloud formation, precipitation, and the scattering or absorption of solar radiation.

Practical Implications and Future Research

The nextGEMS model provides a groundbreaking tool for examining specific events or broader phenomena related to aerosol movement through the Earth system. It improves our understanding of aerosol-cloud-radiation interactions and helps quantify aerosols‘ cooling effects more precisely. This advancement is crucial for better predicting both short-term weather events and long-term climate trends.

Practical applications of this model include investigating how future wildfires across regions like the Congo and the Amazon could affect local cloud formation and precipitation, or assessing the potential damage tropical cyclones may cause to coastal areas of Japan and Florida. Additionally, simulation with interactive aerosols could help us to better understand the radiative forcing and therefore better estimate by how much aerosols actually cool the Earth.

Future research will focus on tracking phenomena over time with high-resolution data and conducting regional studies in areas with unique characteristics or significant events. Furthermore, it will allow the performing of long-term simulations to explore different emissions scenarios. Collaboration with other projects and scientists will continuously refine the model, fostering interdisciplinary research within and beyond the nextGEMS initiative.

Understanding aerosols and their interactions with our climate, we magnify our ability to predict and mitigate the impacts of Climate Change, contributing to a sustainable future for our planet.

Source: Weiss, P., Herbert, R., and Stier, P. (2024). ICON-HAM-lite: simulating the Earth system with interactive aerosols at kilometer scales. EGUsphere [preprint]. DOI: 10.5194/egusphere-2024-3325.

Visualisations created by: Latest Thinking GmbH