Global warming is set to exceed 1.5 degrees Celsius soon, meaning the world will most likely fail to meet the 2015 Paris Agreement goal of striving to cap the average temperature increase at 1.5 degrees C. Even if Earth warms more than that, though, this key aim isn’t a lost cause. Scientists say we could bring the global temperature back down again if we redouble our efforts. The concept of overshoot—to miss our mark but then return below it—offers both a warning and a path forward.
The warning is stark: even if we reduce warming to 1.5 degrees C sometime before century’s end, some losses will be irreversible. Ecosystems will be transformed, species will vanish and vulnerable communities will bear lasting scars. Nevertheless, ensuring that the overshoot of 1.5 degrees C is only temporary would curtail the damage and offer some chance of recovery.
Studies indicate that if we limit peak warming to well below two degrees C, there will still be some hope of bringing the temperature down in the future by removing far more carbon from the atmosphere than we emit, an approach called net-negative emissions. Simply achieving net-zero emissions—a major goal of many industrial countries—is no longer sufficient to limit warming to 1.5 degrees C.
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Admitting that we will exceed this threshold doesn’t justify delaying action; it demands acceleration. Every tenth of a degree of warming beyond 1.5 degrees C will cause more damage to Earth and people and make it more difficult for us to return to that level while adapting to a changing climate. It’s a challenging prospect, but at this point it may be our least bad option for limiting long-term climate harm.
LIMITING BY HOW MUCH WE EXCEED 1.5°C REMAINS CRITICAL
Exceeding 1.5°C of global warming will result in greater impacts on humans and ecosystems.
EVEN THOUGH WE WILL EXCEED 1.5°C, WE COULD BRING TEMPERATURE BACK DOWN AGAIN IF THE OVERSHOOT IS NOT TOO HIGH
Overshoot is a trajectory in which global temperature first exceeds a given threshold and later returns below it. The less overshoot we experience, the better.
OVERSHOOT CAN BE CHARACTERIZED BY HOW MUCH AND FOR HOW LONG 1.5°C IS EXCEEDED
By how much and for how long depends on the trajectory of net-negative CO₂ emissions, as well as emissions from other greenhouse gases.
A WORLD THAT RETURNS TO GLOBAL WARMING OF 1.5°C WILL BE A SIGNIFICANTLY ALTERED AND MORE DAMAGED WORLD
Some climate-related damage to humans and ecosystems will be irreversible, and some could be partially reversed with significant delay.
BRINGING GLOBAL WARMING BACK DOWN IN AN OVERSHOOT PATHWAY WOULD BE A COMPLEX PROCESS
The shape of that pathway will be informed by overarching conversations that reveal key tensions and forces at play—including answers to the questions below.
Angela Morelli and Tom Gabriel Johansen/InfoDesignLab; Source: “Overshoot: A Conceptual Review of Exceeding and Returning to Global Warming of 1.5 °C,” by Andy Reisinger, Jan S. Fuglestvedt, Anna Pirani et al., in Annual Review of Environment and Resources, Vol. 50; April 14, 2025 (reference)
