More than ten years have passed since the 2015 Paris climate conference, and the progress in addressing climate change can, at best, be described as stagnant. While the number of electric vehicles on our roads has increased and renewable sources now generate more global electricity than coal, countries continue to emit over 41 gigatonnes of carbon dioxide annually. Simultaneously, fossil fuel corporations are planning expansions, and governments are scaling back environmental measures.
The Paris conference was marked by considerable optimism, with nations pledging to limit the global average temperature increase to 1.5°C above pre-industrial levels. A decade later, this objective appears to be effectively unattainable. The method for officially confirming when the world crosses the 1.5°C threshold means the actual occurrence might be known only around 2040, a full ten years after it happens.
The 1.5°C mark has become synonymous with the point of dangerous climate change, influencing all facets of climate policy. Warnings have been issued about the significantly increased risk of critical climate system elements tipping over once 1.5°C is breached, leading to further warming and catastrophic consequences. However, even these dire projections have not spurred the emission reductions that scientific consensus demands.
Understanding the Shortfall
The core issue lies in the perception of 1.5°C. For many, it was treated not as a hard limit to stay below but rather as an aspirational target. A limit implies a boundary not to be crossed, whereas a target is something to strive for.
At the time of the Paris conference, the Earth had warmed by just over 1°C, with the prevailing rate of warming around 0.18°C per decade. This pace created an impression of ample time for action. Various parties exploited this perception. Governments and fossil fuel companies, eager to delay climate action, contended that business as usual could continue for the immediate future, with the time for significant measures yet to arrive. Consequently, the annual burning of fossil fuels continues to release 37 gigatonnes of carbon dioxide into the atmosphere.
Searching for a New Benchmark
As the world drifts past the 1.5°C mark, a lively discussion is underway regarding a replacement benchmark. Some have proposed entirely different metrics for progress, such as the rate of renewable energy adoption. However, the most relevant metric remains the global temperature rise. This is the standard against which the climate system’s response is measured and allows for comparisons with past instances of rapid global warming. It is a metric that is broadly understood, even if its full implications are not universally grasped.
Considering the critical impact of every fraction of a degree, some propose setting a new limit at 1.6°C or 1.7°C. Yet, these will likely face the same fate. Firstly, they would probably be reinterpreted as targets by those seeking to circumvent stricter policies. Secondly, at the current warming rate of 0.27°C per decade, both of these thresholds would be surpassed by the mid-2030s. The realistic outlook suggests there is virtually no chance of implementing emissions reductions quickly enough to avoid exceeding either of these points.
Rethinking the Approach
Adopting a new limit that would inevitably become a target would likely exacerbate the situation, and basing policy on such a benchmark would set us up for recurring failure. Perhaps the focus should shift away from limits altogether, concentrating instead on impactful methods to publicly signify the annual global average temperature increase.
This would initially require a methodology that permits instantaneous stipulation of this figure, rather than the current decade-long delay. Fortunately, Richard Betts at the UK Met Office and his colleagues have already developed such a system.
Following this, a visual representation would be needed to convey this information clearly to everyone. An “Earth Thermometer,” updated annually, could serve this purpose. Drawing a parallel with the Bulletin of the Atomic Scientists, which announces the Doomsday Clock each January to signify existential threats to civilization, a similar annual event could highlight the escalating global temperature on the same date each year. This would be presented alongside the tipping points that are either on the verge of being crossed or have already been surpassed. Such an approach would provide an unambiguous measure of the alarming impact human activities are having on the planet’s temperature and would signal the inevitable locking-in of an increasingly perilous future without urgent action.
Bill McGuire is professor emeritus of geophysical and climate hazards at University College London. His next book, “The Fate of the World: A history and future of the climate crisis,” is published by HarperNorth in May.