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Cloud engineering can temporarily cool our planet

A recent study from the University of Birmingham brings exciting news: cloud engineering might cool our planet more than we thought.

The researchers highlight the significant role of increased cloud cover in cooling the Earth, suggesting that marine cloud brightening (MCB) could be a powerful tool against global warming.

Cloud engineering: A potential “painkiller”

Think of cloud engineering as a potential way to temporarily lower the Earth’s temperature. It won’t directly address the root cause of global warming – the excess greenhouse gases in our atmosphere.

However, it could offer some short-term cooling, providing valuable time to implement the essential long-term solution of reducing greenhouse gas emissions.

The concept involves injecting tiny particles (aerosols) into the atmosphere. The particles would act as additional “seeds” for water droplets within clouds, leading to denser and brighter clouds. This increased brightness would reflect more sunlight back into space, resulting in a cooling effect on the planet.

How does cloud engineering work?

Clouds are a collection of tiny water droplets or ice crystals suspended in the atmosphere. But how exactly do these droplets form? It all boils down to microscopic particles called cloud condensation nuclei (CCN).

These CCN act as like tiny platforms or seeds that water vapor can cling to and condense upon. The more CCN present, the easier it is for water vapor to condense and form those visible water droplets or ice crystals that make up clouds.

This is where cloud engineering comes in. The idea is to introduce more CCN into the atmosphere, specifically over the vast areas of ocean where many marine clouds reside. By introducing these additional CCN (often in the form of tiny sea salt particles or aerosols), the theory goes that more water vapor will condense around them, forming a greater number of cloud droplets.

Denser, brighter clouds

The additional droplets would create denser clouds. Imagine a fluffy white cloud compared to a thick, gray storm cloud. The denser cloud has more water droplets packed together, giving it a more substantial appearance. In cloud engineering, the goal is to create more clouds with this denser characteristic.

Now, here’s the key part: why would denser clouds help cool the planet? Clouds have a particular property – they reflect sunlight. Think about how much brighter a cloudy day feels compared to a sunny one.

The denser a cloud is, with more water droplets packed together, the more sunlight it reflects. This reflected sunlight gets sent back out towards space, preventing it from reaching Earth’s surface and heating it up.

In essence, cloud engineering aims to create more reflective clouds, like giant mirrors in the sky, to deflect sunlight and produce a cooling effect.

The Kilauea volcano study

Volcanoes naturally release large amounts of aerosols into the atmosphere. Scientists seized a unique opportunity to study the real-world effects of these aerosols on clouds by focusing on Hawaii’s Kilauea volcano.

Initially, the researchers collected historical satellite and weather data from periods when the volcano was both active and inactive. They then used advanced machine learning techniques to build a model. This model could simulate how clouds would have behaved naturally if the volcano hadn’t been erupting.

By comparing actual observations during volcanic eruptions to their model’s predictions (what would have likely happened without the volcano), they could pinpoint the direct impact the volcanic aerosols had on cloud formation.

Findings supporting cloud engineering

The study revealed these significant results. When the volcano was actively erupting, cloud cover in the region increased by an impressive 50%. This suggests the volcanic aerosols were acting as additional “seeds” (CCN) for water vapor, leading to the formation of more clouds in the area.

The increased cloud cover produced a substantial cooling effect within the region, measured at up to -10 watts per square meter (W/m²).

To put this in context, the scientists estimate that doubling the amount of CO2 in the atmosphere would lead to a global average warming of approximately +3.7 watts per square meter. This comparison highlights the potential of cloud engineering strategies to counteract some degree of warming.

Potential benefits and risks

The results of the Kilauea volcano study hint that cloud engineering might be a more powerful tool for temporary cooling than previous models suggested. This is a significant finding, but it’s important to emphasize that the approach is far from a simple solution to climate change.

Currently, our understanding of the potential full-scale global impacts and risks associated with cloud engineering remains limited.

For example, intentionally altering cloud brightness could unintentionally disrupt rainfall patterns, potentially leading to droughts or floods in certain regions. We urgently need extensive research to fully grasp these potential consequences.

It’s crucial to stress that cloud engineering does not address the underlying problem of global warming: the excessive amounts of greenhouse gases in our atmosphere.

This technology, even if successful, would only offer a temporary reduction in temperature. The essential task remains drastically reducing greenhouse gas emissions to achieve long-term climate stability.

Study significance

The Kilauea study has fueled global interest in cloud engineering. Research programs across the UK and the US are investigating the possibilities and risks of the technology. The goal is to provide policymakers with solid scientific evidence to make informed decisions about this potential tool.

Could spraying particles into the atmosphere help combat global warming? The short answer is that it might have some potential. However, it’s far too early to say whether it’s a safe and effective solution, as much more research is needed.

The key message is that reducing greenhouse gas emissions remains our most urgent and essential task in tackling the climate crisis.

The study is published in the journal Nature Geoscience.


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