Back in 2001, Kenneth Mellersten and Michael Obersteiner came up with a novel idea that forever changed the calculation of carbon emissions and changed the world’s path to net zero.
At the time, oil and gas companies were working to capture carbon from fossil fuels, a process that would reduce emissions from energy production to nearly zero. By burning plants instead, the two researchers thought, the industry could generate negative emissions, or energy trapped in wood and other biofuels, minus the energy obtained by burning them.
This concept helped pave the way for the world to adopt negative emissions as the centerpiece of climate planning. The concept is a key element of official emissions reduction plans submitted to the United Nations by major economies such as the UK, Brazil and Australia.
Ahead of COP30 in Belém, Brazil, this week, analysis by Climate Action Tracker, a partnership of climate researchers, reveals that most countries that have submitted emissions plans with net-zero targets rely on carbon removal to reach their targets.
But Mellersten and Obersteiner are far from thrilled. The problem, they say, is that carbon capture was intended to offset past emissions. Rather, this strategy has created overconfidence that fossil fuels can be replaced even when reductions are difficult.
For example, many countries simply plan to exceed their targets or do not bother to spell out how they will achieve their targets. Since the world agreed to transition away from fossil fuels at the COP two years ago, around 60 countries have updated their climate change plans, but none of them include targets to reduce oil and gas production. Meanwhile, around 20% of promised emissions reductions are not reflected in countries’ climate change plans, according to the Climate Action Tracker group. It is assumed that many of them will be captured, he added.
Obersteiner, now director of the Institute for Environmental Change at the University of Oxford, said: “We emphasized that the possibility of future negative emissions should never be used as an excuse to delay emissions reductions.” “If we try to solve the climate problem, we might go to heaven. At the same time, because we caused overshoot, we should go to hell.”
What is overshoot?
“Overshoot” is the idea that it is okay for the world to exceed climate temperature targets because carbon can be removed from the atmosphere later. It was incorporated into climate projections used by the Intergovernmental Panel on Climate Change and then used by governments to set their own climate goals, said Laurie Laybourne, executive director of the Strategic Climate Risk Initiative, a think tank that advises governments and businesses on climate risks. (He interviewed Mellersten and Obersteiner on the podcast Overshoot: Navigating a World Beyond 1.5 degrees, published last month.)
The two researchers were among a group of scientists in the early 2000s who were looking for alternative plans in case other emissions-reduction approaches, such as renewable energy, failed in time. And even if the world were on track to limit warming, they reasoned, a world with temperatures even 1 or 1.5 degrees Celsius warmer than pre-industrial norms would have problems with extreme weather. At early climate conferences, Mellersten and Obersteiner proposed their idea as a way to reduce CO2 concentrations and reduce these effects.
Modeling at the time suggested it would be difficult to reduce emissions enough to stop temperatures from rising, making solutions such as carbon removal attractive to scientists and policymakers tackling climate change. In 2007, IPCC scientists brought this up at a conference and incorporated it into scenarios for how to reduce global warming.
“People were using these modeling results without knowing the assumptions or caveats,” says Rayborn. “It gave them political cover to do noble things. So 2 degrees Celsius is possible, 1.5 degrees Celsius is possible.”
Emissions have continued to increase for 20 years since then. Some of these need to be reversed if the world has any hope of meeting climate goals, Laybourn says. The IPCC said in its latest report that all scenarios that limit warming to 1.5 degrees Celsius or even 2 degrees Celsius include carbon dioxide removal.
dangerous approach
However, relying on carbon removal is risky for several reasons.
Nature-based carbon removal, which involves planting trees and restoring other carbon sinks such as peat bogs, is limited by land availability. Meanwhile, capturing carbon directly from the air or by burning biofuels for energy is in its infancy and requires significant financial support to scale up.
It is also unclear how much bioenergy will help reduce emissions, as wood products can be used instead for other purposes that do not emit carbon, and the process of cutting down and planting trees can generate large amounts of emissions. Direct atmospheric capture uses large amounts of energy and has limited land availability to store the captured carbon.
Another problem is that relying on carbon removal rather than immediate emissions reductions increases the risk of sudden effects of climate change, such as the collapse of the Atlantic Meridional Overturning Circulation, the ocean current that warms Europe.
“We’re rolling the dice every day, and eventually we could reach a tipping point,” Rayborn said. “When temperatures rise above 1.5 degrees, we enter this intolerable danger zone and we need to get out of it as quickly and as best we can.”
How do Mellersten and Obersteiner feel about what happened to an idea they had high hopes for as a solution to climate change? They say they’ve done their best to make it clear that these technologies are add-ons, not replacements, for reducing emissions.
Nevertheless, they still feel disillusioned by the experience. “I’m not surprised,” Mellersten says. “This is deeply discouraging and confirms the great difficulty humans have in acting decisively against abstract existential threats that primarily affect future generations.”
Rudgard writes for Bloomberg.
