Jhe past year has seen an endless drumbeat of climate-related disasters. And yet, the climate story of the past decade has been one of slow but steady progress. Global CO2 emissions have stabilized 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 for hope is that clean energy has become cheaper much faster than expected. The cost of solar power and batteries has increased tenfold over the past 10 years and the cost of wind power by two-thirds. Solar is the cheapest form of new electricity to build in much of the world today, and electric vehicles now account for 13% of new vehicle sales worldwide.
But that doesn’t mean we can rest on our laurels. Far from there. We are still far from where we need to be to achieve our climate goals. In the latest report from the Intergovernmental Panel on Climate Change (IPCC), to which I contributed, we found that if we want to limit warming to 1.5°C, we can only emit 420 billion tons of additional CO2, or about 10 years of current emissions. This means that even with the progress we have made, the increase in global temperatures is very likely to exceed 1.5°C in the early 2030s.
So where are we? The short answer is: “It’s complicated.
To begin with, it is important to point out that climate change is happening gradually rather than in big leaps. There is no evidence that 1.5C represents a boundary between manageable and catastrophic impacts. But the further we push the climate beyond what it was for the past few million years, the greater and more unpredictable the risks become. Major climate changes in Earth’s past and potential future tipping points such as the release of CO2 from melting permafrost should give us pause: we cannot easily predict what might happen. Every tenth of a degree counts if we want to minimize the harm we inflict on ourselves and pass on to future generations.
But also, it is not because we exceed 1.5°C that there is no turning back. We know that if we manage to reduce emissions to zero, the world will effectively stop warming. And climate models show that if we remove more CO2 from the atmosphere than we emit, it will actually cool the world. Removing CO2 from the atmosphere and oceans was highlighted in the recent IPCC report as an “essential element” to achieving our climate goals. Virtually every climate model suggests we need to eliminate 6 billion tons of CO2 per year by 2050 next to rapid reductions in emissions to bring temperatures down to 1.5°C by the end of the century.
A form of carbon dioxide removal that people are already familiar with comes in the form of trees and soil. Earth’s living systems already sequester around a quarter of the CO2 we emit today (with another quarter absorbed by the oceans). There is real potential to enhance this “natural carbon sink” by protecting forests, planting more of them, and changing the way we manage farmland and pasture to get more carbon out of the ground. This is a relatively low cost today, but it is also likely to prove temporary. Trees can be felled, burned or die from beetle infestations, while the ground can dry up due to drought or heat – and these risks will increase due to climate change. There are also limits to the land available for use. Overall, the models suggest that trees and soil could only provide half of the carbon dioxide removal we need.
There are other, more reliable ways to extract carbon from the atmosphere over the long term. Such approaches are still in their infancy, but are rapidly being developed by hundreds of companies around the world. They include direct air capture, which draws CO2 directly from the atmosphere; take agricultural waste or wood and store the carbon deep underground; spreading minerals like basalt that absorb CO2 from the atmosphere on agricultural fields; remove CO2 directly from seawater; make ocean water less acidic so it absorbs more CO2; and sink kelp or other plants into the deep ocean where the carbon they absorbed will remain for millennia.
These approaches are less likely to be reversed and are less constrained by available land. But they tend to be a lot more expensive, at least for now. It follows that we should strive to make them cheaper, as we have done with renewables. That’s the goal of Frontier, a $925 million advanced market engagement that Stripe, where I lead climate research, 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 develop these technologies early on, we will buy them. This approach was tested a decade ago to accelerate the development of pneumococcal vaccines in low-income countries and has saved an estimated 700,000 lives.
We have a saying in the world of climate science – that CO2 is forever. It will take almost half a million years before a ton of CO2 emitted today by burning fossil fuels is completely removed naturally from the atmosphere. This means that when we try to neutralize or cancel fossil fuel emissions – for example, with carbon offsets – these interventions must work over a similar timeframe: one tonne of emissions from cutting down trees can be neutralized by putting more carbon in trees or soils, but CO2 from fossil fuels must be balanced by more permanent carbon removal. That’s why the respected Science Based Targets initiative only allows actions that permanently remove carbon from the atmosphere to neutralize a company’s remaining fossil fuel emissions within their net-zero standard – and only alongside deep emission reductions.
We should not overestimate the role of carbon removal. The vast majority of the time, it is cheaper to reduce emissions than to remove CO2 from the atmosphere afterwards. Models that limit warming to 1.5C show that we need to reduce global CO2 emissions by around 90%, while only using carbon removal for around 10%. But 10% of the solution to a problem as serious as climate change is still something we cannot afford to ignore.
In 2021, the world spent a total of $755 billion to reduce 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 decades to come. By investing today, we can ensure we are well positioned to make net zero a reality, prevent the world from continuing to warm, and give ourselves the tools to ultimately reverse global warming in the future.
Ending Fossil Fuels: Why Net Zero Isn’t Enough by Holly Jean Buck (Back, £9.99)
Under white skies: 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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