The global effort to keep climate change to safe levels – ideally within 1.5°C above pre-industrial temperatures – is moving far too slowly. And even if we stopped emitting CO² today, the long-term impacts of the gas already in the air would continue for decades. For these reasons, we will soon have to focus not only on halting but on reversing global warming.

We can do that in two ways. The first is by “drawdown” – strengthening natural processes on Earth that withdraw CO² from the atmosphere. The second is through vast experiments with the climate known as geo-engineering, some of which sound like science fiction, and could be extremely dangerous if ever tried.

Yet this approach does nothing to remove CO² from the atmosphere, or to reduce the rising acidity of the oceans. It’s like a Band-Aid over a festering sore. And, beyond its cooling effect, its impact on the climate system as a whole is unknown: no one to my knowledge has modelled the effects of using the jet fleet in this way.

No international treaty exists to regulate such experiments. In April 2022, the US start-up company, Make Sunsets, released weather balloons designed to reach the stratosphere, carrying a few grams of sulphur particles. There was no public scrutiny or scientific monitoring of the work. The company is already trying to sell “cooling credits” for future flights that could carry larger volumes of sulphur.

Drawdown’s potential to store carbon
Drawdown, by contrast, involves withdrawing CO² from the atmosphere and storing it in other planetary organs, such as rocks, oceans or plants. Drawdown is much longer term than geoengineering, and most initiatives are only in the research and development stage. The most advanced and practical, by far, is forest protection and reafforestation.

Today humans emit about 51  billion tonnes of CO² a year. Protecting and regenerating forests draws down 2 billion tonnes a year. Other approaches, such as direct air capture of CO², draw down much smaller volumes.

So forest protection and reafforestation is our best bet for getting us closer to limiting warming to 1.5°C. A recent paper in the Nature journal argues we could draw down as much as 226 gigatonnes by allowing existing forests in areas where few humans live to recover to maturity, and by regrowing forests in areas where they have been removed or fragmented.

Today humans emit about 51  billion tonnes of CO² a year. Protecting and regenerating forests draws down 2 billion tonnes a year. Other approaches, such as direct air capture of CO², draw down much smaller volumes.

So forest protection and reafforestation is our best bet for getting us closer to limiting warming to 1.5°C. A recent paper in the Nature journal argues we could draw down as much as 226 gigatonnes by allowing existing forests in areas where few humans live to recover to maturity, and by regrowing forests in areas where they have been removed or fragmented.

We should not ignore other drawdown pathways, however. Seaweed is a promising option for drawing down a billion tonnes or so of CO² by 2050. But we need a lot more scientific research to understand how to do that, and what its wider impacts might be. Today only one commercial kelp farm exists – Kelp Blue, off the coast of Namibia, where four hectares of kelp are not only storing carbon but are used to make biodegradable food packaging and crop stimulants.

What the Albanese government should do
For these reasons, the Albanese government should focus its drawdown efforts on forest protection and regrowth. This could be a theme of the UN climate conference Australia is bidding to co-host with Pacific nations in 2026. Our temperate forests contain more carbon per hectare than almost anywhere on Earth. Stopping old-growth logging would be a magnificent contribution to arresting climate change.

The government should also back research and development on seaweed and silicate rocks so that the country’s huge resources can be responsibly deployed in future. Finally, Australia must push urgently for a global treaty to restrain sulphur geoengineering.