The Big Idea: Stopping Climate Change Isn’t Enough – We Need To Reverse It | Science and nature books

TThe past year has seen an endless stream of climate-induced disasters. And yet the climate story of the past decade has been one of slow but steady progress. Global CO2 emissions have leveled off and countries accounting for 88% of global emissions have adopted or announced plans to reach net zero in the second half of the 21st century.

Another reason to be hopeful is that clean energy became cheaper much faster than expected. The costs of both solar energy and batteries have increased tenfold in the last 10 years and that of wind energy by two-thirds. Solar power is today the cheapest form of new electricity to build in much of the world, and electric vehicles now account for 13% of global new vehicle sales.

But this does not mean that we can rest on our laurels. Far from it. We are still far from where we need to be to achieve our climate goals. In the most recent Intergovernmental Panel on Climate Change (IPCC) report, to which I contributed, we found that if we wanted to limit warming to 1.5°C, we could only emit 420 billion more tons of CO2 – equivalent to about 10 years of current emissions. This means that even with the progress we have made, global temperature rise is very likely to exceed 1.5°C by the early 2030s.

So where does that leave us? The short answer is, “It’s complicated.”

To begin with, it is important to emphasize that climate change is happening incrementally rather than by leaps and bounds. There is no evidence that 1.5°C forms a boundary between manageable and catastrophic consequences. But the further we push the climate beyond where it has been for the past few million years, the greater and more unpredictable the risks become. Major climate shifts in Earth’s past and potential future tipping points, such as CO2 emissions from thawing permafrost, should make us think: We can’t easily predict what might happen. Every tenth of a degree matters if we want to minimize the damage we do ourselves and want to leave to future generations.

Still, just because we’re passing 1.5C doesn’t mean there’s no turning back. We know that if we can reduce emissions to zero, global warming will effectively stop. And climate models show that if we remove more CO2 from the atmosphere than we emit, the world will cool down again. Removing CO2 from the atmosphere and oceans was highlighted in the recent IPCC report as an “essential element” to meet our climate goals. Virtually all climate models suggest that we need to remove 6 billion tons of CO2 per year by 2050 alongside rapid emission reductions to reduce temperatures to 1.5°C by the end of the century.

One form of carbon dioxide removal that people are already familiar with is the form of trees and soil. Earth’s living systems already capture about a quarter of the CO2 we emit today (and another quarter is absorbed by the oceans). There is real potential to improve this “natural carbon sink” by protecting forests, planting more and changing the way we manage farmland and pasture to get more carbon into the soil. This is relatively cheap these days, but it will probably also prove to be temporary. Trees can be cut down, burn or die from beetle infestations, while soils can dry up from drought or heat – and these risks will increase with climate change. There are also limits to the available land. All in all, models suggest that trees and soil can provide only half of the CO2 removal we need.

There are other, more reliable long-term ways to remove carbon from the atmosphere. Such approaches are still in their infancy, but are being rapidly developed by hundreds of companies around the world. They include direct air capture, which sucks CO2 straight from the atmosphere; taking agricultural waste or wood and storing carbon from it deep underground; spreading minerals such as basalt that absorb CO2 from the atmosphere on agricultural lands; remove CO2 directly from ocean water; making ocean water less acidic so that it absorbs more CO2; and sinking kelp or other plants into the deep ocean where the carbon they absorbed will remain for millennia to come.

These approaches are less likely to be reversed and less constrained by available land. But they are usually much more expensive, at least at the moment. It follows that we need to focus on making it cheaper, as we did with renewables. This is the goal of Frontier, a $925 million forward-thinking market commitment that Stripe, where I lead climate research, has launched alongside Alphabet, Shopify, Meta, and McKinsey. The idea is simple: by guaranteeing money up front, we send a signal to entrepreneurs and researchers that if they build and scale those early technologies, we will buy them. Tried a decade ago to accelerate the development of pneumococcal vaccines in low-income countries, this approach has saved an estimated 700,000 lives.

We have a saying in the world of climate science: CO2 is forever. It will take almost half a million years for a ton of CO2 emitted today from the burning of fossil fuels to be completely naturally removed from the atmosphere. This means that when we try to neutralize or reverse fossil fuel emissions – with carbon offsets, for example – those interventions should work over a similar time frame: a ton of emissions from cutting trees could be neutralized by putting more carbon in trees or soils but CO2 from fossil fuels must be compensated by more permanent carbon removal. This is why the respected Science Based Targets initiative only allows measures that permanently remove carbon from the atmosphere to neutralize a company’s remaining fossil fuel emissions in their net zero standard – and only in addition to deep emission reductions.

We should not exaggerate the role of carbon removal. Most of the time, it is cheaper to reduce emissions than to remove CO2 from the atmosphere afterwards. Models limiting warming to 1.5C show that we need to reduce global CO2 emissions by about 90%, while only using carbon removal for about 10%. But 10% of the solution to a problem as big as climate change is still something we cannot ignore.

By 2021, the world will have spent a total of $755 billion on reducing emissions. We should probably aim to spend about 1% of that money on carbon removal technologies. But we can’t just sit back and assume that ways to remove billions of tons of CO2 per year will magically appear in the coming decades. By investing today, we can ensure that we are well positioned to achieve net zero, prevent the world from warming further and give ourselves the means to ultimately reverse global warming in the future.

Read further

Ending Fossil Fuels: Why Net Zero Isn’t Enough by Holly Jean Buck (Verso, £9.99)

Under a White Sky: Can We Save the Natural World in Time? by Elizabeth Kolbert (Vintage, £9.99)

How to avoid climate catastrophe: the solutions we have and the breakthroughs we need by Bill Gates (Allen Lane, £20)

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