Is geoengineering the answer to the climate crisis?

What’s geoengineering?

Geoengineering is deliberately seeking to change the temperature of the planet. 

Humans have “accidentally” warmed the planet already, predominately as a side effect of burning fossil fuels and deforestation. Some scientists are saying we should deliberately seek to cool the planet through geoengineering techniques.

Why's geoengineering being promoted?

2024 was the first year the planet was 1.5 °C warmer than pre-industrial levels, although it may dip below this level in 2025.

The world’s governments have agreed through the Paris Agreement to keep the “global temperature rise this century well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius”.

But an analysis of current pledges by governments suggests that the planet is on course for a temperature increase of 2.6 - 3.1 °C over the course of this century. And many of the pledges aren’t even being met. For example, the UK isn’t yet on-track to meet its pledge to cut emissions by more than two-thirds by 2030. Some people are saying that, as well as cutting the emissions warming the planet, we’ll also need to take measures to cool it down.

What’s a safe level of warming?

The political agreement is to keep warming to below 2 °C, and to try and keep warming even lower to 1.5 °C. Already the planet is seeing more extreme weather. The melting of glaciers and ice sheets is leading to sea-level rises, and 80% of the world’s nature-rich coral reefs are severely damaged by warmer seas.

Scientists warn that the existing level of warming may mean we’ve already passed a point of no return for coral reefs. At 2 °C warming, there’s a real danger that we’ll pass the point of no return for the irreversible melting of the giant Greenland and West Antarctica ice sheets. If these ice sheets melt, sea levels will rise by more than 10 metres over hundreds of years, with 1 metre of this rise potentially occurring by the end of the century. A 1-metre sea rise would displace tens of millions of people, significantly harm food production and require hundreds of billions of dollars to be spent on coastal defences globally.

What geoengineering techniques exist, and are they safe?

There are 2 broad categories of geoengineering: carbon dioxide removal and solar radiation management.

Carbon dioxide removal

Carbon dioxide removal reduces the level of carbon dioxide in the atmosphere. Carbon dioxide levels have built up enormously over recent centuries as we’ve burned fossil fuels and chopped down forests. It's the main reason global temperatures are increasing. 

Carbon dioxide can be removed through large-scale tree planting and restoring peatlands, salt-marshes and mangroves. It can also be removed through chemically capturing carbon dioxide from the air and storing it underground. And better farming practices can increase the amounts of carbon stored in the soil, such as applying crushed rocks as a fertiliser. 

These are all broadly sensible and low risk if done properly, with some also delivering a bonus for nature. But done badly, these removal methods could lead to harms such as displacing communities or food production for afforestation, which means planting trees in an area where there were no trees.

There’s also another way to remove carbon dioxide that has the potential to be more damaging. Drax power station in Yorkshire imports huge quantities of wood chips from the USA, Canada and Eastern Europe to burn to make electricity. It’s planning to capture the carbon dioxide from the chimney and store it under the North Sea. The theory is that this technique, called Bioenergy with Carbon Capture and Storage (BECCS), will remove carbon dioxide from the atmosphere by, in effect, growing trees and storing them underground. The significant downside is that this large-scale tree felling is reported to cause massive harm to wildlife.

Solar radiation management

Solar radiation management means reflecting some of the sun’s energy back into space so that the planet is cooled. As with carbon dioxide removal, there are a range of techniques proposed. These include increasing sea ice or reducing the rate of melting, brightening clouds and injecting tiny particles such as aerosols high into the atmosphere.

All of these techniques aim to reflect solar energy back into space. The scientists promoting them don’t say they should be used instead of cutting carbon emissions, but rather that they're needed in addition.

But there are significant challenges with solar radiation management, including:

• Significantly altering weather systems. For example, this could lead to changes in monsoon patterns and regional droughts that could impact millions. There are also significant fairness issues that are poorly understood, such as some regions benefiting from altered weather systems while others suffer droughts.
• Delaying proven methods of climate action. There’s a real danger that politicians and those with vested interests such as fossil fuel companies will use the theoretical potential of solar radiation management to slow down action to reduce the carbon emissions that are driving climate change.
• Making decisions. There's no global agreement or framework on how to manage solar radiation management, but there are a lot of unanswered questions. For example, how much to deploy and where? Who foots the bill for unwanted side effects? What happens if a country unilaterally deploys these methods to favour its own climate at the expense of others? How will the voices of those most impacted by these techniques be considered?

Is the climate emergency so bad we need to deploy geoengineering?

We’re in a climate emergency and we’re already experiencing severe consequences, such as extreme weather costing lives and livelihoods as well as nature being pushed to the brink.

We should be carrying out activities that remove carbon from the atmosphere, especially those that have multiple other benefits. For example, peatland restoration reduces floods and increases wildlife while capturing carbon. But these activities need to be carried out carefully. For example, large-scale afforestation has to be done in a way that doesn’t harm nature or communities. 

Ultimately, carbon dioxide removal can only make a small difference, especially while we continue to burn fossil fuels. It’s like trying to empty a bath with a teaspoon while leaving the taps running. The most urgent action needed is to cut the use of fossil fuels and end deforestation.

Solar radiation management is untested and dangerous, so we shouldn’t deploy it. Scientists will want to research it more, and while in theory that isn’t harmful in itself, they must guard against sending a message to politicians that one day we could use it. In our opinion, it's more likely that it’ll never be safe to use. The last thing we need is to give politicians the idea that we can keep burning fossil fuels.

Isn’t geoengineering already happening?

As we know, nowadays conspiracy theories circulate at a rapid rate. One is that the trails left by planes are secret geoengineering, also known as chemtrails. But these trails are formed when water vapour and fine soot particulates from burning jet fuel freeze into ice crystals. In low air humidity, the crystals just disappear. In higher humidity, they persist and end up creating visible vapour trails over large areas of sky.

Instead of relying on risky fixes, we need political action and industry change to tackle the root causes of climate change, starting with slashing emissions now.