Multispeed mitigation strategies to limit mid-century overshoot and return to 1.5°C
This study proposes a "multispeed mitigation" strategy combining immediate actions against super pollutants and deforestation with long-term energy transition efforts to limit peak warming to 1.9°C by 2060 and return global temperatures to 1.5°C by 2130, demonstrating that while fast mitigation levers are critical for minimizing overshoot, both fast and slow strategies are essential for achieving long-term climate goals.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
The world is warming, and the goal set by nations to keep that warming below 1.5 degrees Celsius above pre-industrial levels has become increasingly difficult to reach. Scientists have long understood that greenhouse gases trap heat, but they also know that these gases behave differently. Some, like carbon dioxide, linger in the atmosphere for centuries, locking in warming for a long time. Others, such as methane and black carbon, are much shorter-lived but are far more potent at trapping heat in the short term. For years, the global conversation has focused almost entirely on the long-term problem: shifting away from fossil fuels to clean energy. While this transition is essential for the future, it takes decades to fully transform global power systems and infrastructure. Meanwhile, the planet continues to heat up, and the risk of crossing dangerous climate tipping points grows with every fraction of a degree. The critical question for policymakers is no longer just how to stop warming eventually, but how to slow the rate of warming right now to buy time for the long-term transition, and how to bring temperatures back down if they temporarily rise too high.
A team of researchers at the University of Maryland has tackled this challenge by proposing a strategy they call "multispeed mitigation." Using advanced computer models that simulate the global economy and the Earth's climate system, they tested a new approach that treats different climate solutions based on how quickly they can be implemented and how fast they cool the planet. Instead of waiting for the slow, decades-long shift to renewable energy to do all the heavy lifting, the researchers combined it with immediate actions that target short-lived pollutants and deforestation. Their simulations show that this combined approach is the only way to limit the peak warming to a manageable level and return the planet to the 1.5-degree target later this century. Without these quick actions, the planet would heat up much faster and stay hotter for much longer, even if the energy transition proceeds as planned.
The researchers built a series of scenarios to see what happens when different tools are used alone or together. They started with a baseline where current trends continue without new policies, which leads to a world that is nearly 4 degrees warmer by the end of the century. They then tested what would happen if the world focused only on the slow transition to clean energy. In this scenario, the energy system changes rapidly, but the planet still overshoots the 1.5-degree target significantly, peaking at more than 2 degrees and staying there for decades. This happens because the shift away from fossil fuels also reduces the release of sulfur dioxide, a pollutant that currently has a temporary cooling effect by reflecting sunlight. As this cooling shield disappears, the warming from carbon dioxide becomes more visible, delaying the temperature drop.
To fix this, the team introduced "fast" mitigation strategies. These include rapidly cutting emissions of super pollutants like methane from agriculture and waste, and stopping deforestation in the tropics. When they added these fast actions to their models, the results changed dramatically. The combination of fast and slow strategies, which they call the "multispeed" pathway, limits the peak warming to just under 1.9 degrees around the year 2060. This is a crucial difference. By acting quickly on the short-lived pollutants and protecting forests, the planet avoids the worst of the mid-century heat. The models show that these fast actions are responsible for about two-thirds of the temperature reduction needed to keep the peak low by the middle of the century. They act like a brake, slowing the heating while the long-term engine of the energy transition gears up.
The study also looked at what happens after the peak. The researchers found that while the fast strategies are vital for the near term, the slow strategies—specifically the shift to clean energy and the removal of carbon dioxide from the air—become the dominant force for the long term. By the year 2100, the energy transition accounts for more than 60 percent of the total cooling effect. However, the fast strategies do not disappear; they continue to provide significant cooling benefits well into the future, outperforming some high-tech carbon removal methods. The most successful scenario, the multispeed pathway, allows global temperatures to peak and then begin a steady decline, returning to the 1.5-degree target by the year 2130. This is a stark contrast to the scenario relying only on slow mitigation, which leaves the world significantly hotter for the rest of the century.
One of the most important findings is that delaying these actions makes a huge difference. The researchers simulated what would happen if the world waited ten years to start the fast mitigation strategies. That delay would result in a much higher peak temperature that would be harder to reverse. Similarly, waiting to start the slow energy transition would make it impossible to bring temperatures back down to 1.5 degrees later on. The study suggests that the two types of strategies are not interchangeable; they are complementary. The fast actions buy the time needed for the slow actions to take effect, and the slow actions ensure that the temperature stays down once the fast actions have done their initial work.
The paper also highlights a gap in current global efforts. While trillions of dollars are flowing into the energy transition, less than 5 percent of climate finance is going toward these fast mitigation strategies. The researchers argue that this imbalance is a mistake. To keep the 1.5-degree goal within reach, even if it is temporarily exceeded, the world needs to mobilize investment and policy action for methane reduction and forest protection with the same urgency as the shift to renewable energy. The study does not claim that the problem is solved or that the 1.5-degree target is easy to achieve. Instead, it offers a clear, simulated roadmap showing that a coordinated, two-speed approach is the only viable way to minimize the damage of overshooting the target and to guide the planet back to safety. The path forward requires immediate, aggressive action on the short-term pollutants and forests, paired with a relentless, long-term commitment to decarbonizing the global economy.
Drowning in papers in your field?
Get daily digests of the most novel papers matching your research keywords — with technical summaries, in your language.