This article is part of TPM Cafe, TPM’s home for opinion and news analysis. It was originally published at The Conversation.
When the Paris agreement on climate change was gavelled into being in December 2015, it briefly looked like that rarest of things: a political victory for climate activists and delegates from the poorest regions of the world that, due to colonization by today’s wealthy nations, have contributed little to the climate crisis — but stand to suffer its worst ravages.
The world had finally agreed an upper limit for global warming. And in a move that stunned most experts, it had embraced the stretch target of 1.5°C, the boundary that small island states, acutely threatened by sea-level rise, had tirelessly pushed for years.
Or so, at least, it seemed. For soon, the ambitious Paris agreement limit turned out to be not much of a limit at all. When the Intergovernmental Panel on Climate Change (or IPCC, the world’s foremost body of climate experts) lent its authority to the 1.5°C temperature target with its 2018 special report, something odd transpired.
Nearly all modeled pathways for limiting global heating to 1.5°C above pre-industrial levels involved temporarily transgressing this target. Each still arrived back at 1.5°C eventually (the deadline being the random end point of 2100), but not before first shooting past it.
Scientists responsible for modeling the response of Earth’s climate to greenhouse gas emissions — primarily caused by burning fossil fuels — called these “overshoot” scenarios. They became the dominant path along which mitigating climate change was imagined to proceed, almost as soon as talk of temperature limits emerged.
De facto, what they said was this: staying below a temperature limit is the same as first crossing it and then, a few decades hence, using methods of removing carbon from the atmosphere to dial temperatures back down again.
From some corners of the scientific literature came the assertion that this was nothing more than fantasy. A new study published in Nature has now confirmed this critique. It found that humanity’s ability to restore Earth’s temperature below 1.5°C of warming, after overshooting it, cannot be guaranteed. Many impacts of climate change are essentially irreversible. Those that are might take decades to undo, well beyond the relevant horizon for climate politics. For policy makers of the future, it matters little that temperatures might eventually fall back again; the impacts they will need to plan for are those of the overshoot period itself.
The rise of overshoot ideology
Even if global average surface temperatures are ultimately reversed, climate conditions at regional levels might not necessarily follow the global trend and might end up different from before. Delayed changes in ocean currents, for instance, could mean that the North Atlantic or Southern Ocean continue warming while the rest of the planet does not.
Any losses and damages that accumulate during the overshoot period itself would of course be permanent. For a farmer in Sudan whose livestock perishes in a heatwave that would have been avoided at 1.5°C, it will be scant consolation to know that temperatures are scheduled to return to that level when her children have grown up.
Then there is the dubious feasibility of planetary-scale carbon removal. Planting enough trees or energy crops to make a dent in global temperatures would require whole continents of land. Direct air capture of gigatons of carbon would consume prodigious amounts of renewable energy and so compete with decarbonization. Whose land are we going to use for this? Who will shoulder the burdens for all this excess energy use?
Time to bury the time machine
Just as the climate movement scored an important political victory, compelling the world to rally behind an ambitious temperature limit, an influential group of scientists, amplified by the world’s most authoritative scientific body on the subject, effectively helped water it down. When all is said and written about the post-Paris era, this surely should stand as one of its greatest tragedies.
By conjuring up the fantasy of overshoot-and-return, scientists invented a mechanism for delaying climate action and unwittingly lent credibility to those (and they are many) who have no real interest in reigning in emissions here and now; who will seize on any excuse to keep the oil and gas and coal flowing just a little longer.
The findings of this new paper make it perfectly clear: There is no time machine waiting in the wings. Once 1.5°C lies behind us, we must consider that threshold permanently broken.
There then remains only one road to ambitious mitigation of climate change, and no amount of carbon dioxide removal can absolve us of its inconvenient political implications.
Avoiding climate breakdown demands that we bury the fantasy of overshoot-and-return and with it another illusion as well: that the Paris targets can be met without uprooting the status-quo. One limit after the other will be broken unless we manage to strand fossil fuel assets and curtail opportunities for continuing to profit from oil and gas and coal.
We will not mitigate climate change without confronting and defeating fossil fuel interests. We should expect climate scientists to be candid about this.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
