‘Overshoot myth’ risks catastrophic global warming

The idea that we can “overshoot” global warming targets then fix the problem with technology is a dangerous myth, scientists have warned.

In the 2015 Paris Agreement, world leaders committed to try to limit warming to 1.5°C (compared to pre-industrial levels) and keep it “well below” 2°C.

Writing today in The Conversation, three scientists say continued fossil fuel production and record greenhouse gas emissions give these pledges a “surreal quality”.

The authors – Dr James Dyke, Professor Sir Robert Watson and Dr Wolfgang Knorr – say dangerous climate change is already here and net zero plans to get humanity back to safety increasingly rely on “science fiction” solutions.

A 2021 article by the same authors – “Concept of net zero is a dangerous trap” – won a journalism award from Covering Climate Now.

Three years on, they conclude the situation is worsening with increasing reliance on future machines to remove carbon dioxide from the air, or geoengineer the climate.

“Like the proverbial frog in the heating pan of water, we refuse to respond to the climate and ecological crisis with any sense of urgency,” said Dr Dyke, from the Global Systems Institute at the University of Exeter.

“The solution is clear: we must rapidly reduce greenhouse gas emissions from industry, transport, energy (70% of total) and food systems (30% of total), while improving energy efficiency.

“However, many current pledges and policies suggest we can avoid dangerous climate change without doing this.

“Instead, they say we can overshoot past any amount of warming then deploy planetary-scale carbon dioxide removal and even reduce the amount of sunlight reaching the Earth’s surface to drag temperatures back down by the end of the century.

“This destroys any attempt to limit warming to 1.5°C, locks us into energy- and material-intensive solutions that mostly exist only on paper, and says the quiet bit out loud: we simply don’t care about the suffering and deaths that will result while a recovery is worked on.”

The article says carbon-removal technology is presented as a “time machine” that means emissions can continue.

Professor Watson, Emeritus Professor in Environmental Sciences at the University of East Anglia and previous chair of the IPCC and IPBES, said: “In 2021, we argued that net zero was a dangerous trap.

“Three years on and we can see the jaws of this trap beginning to close, with climate policy being increasingly framed in terms of overshoot.

“The resulting impacts on food and water security, poverty, human health, and the destruction of biodiversity and ecosystems will produce intolerable suffering.

“The situation demands honesty, and a change of course.”

The authors highlight threats from Earth system tipping points which, once triggered, may not simply be reversed even if the overshoot of climate targets is temporary. They also argue that natural carbon sinks cannot be relied upon to remove vast amounts of carbon dioxide from the atmosphere in a warming world.

The authors make four suggestions:

• Leave fossil fuels in the ground. Stop financing for new oil and gas.
• Focus on near-term reductions in fossil fuels. The situation demands immediate action, not promises of balancing carbon budgets decades into the future.
• Base policy on credible science and engineering. All climate policies must be based on what can be done in the real world now, or in the very near future. Speculative carbon-removal approaches must be removed from net zero plans.
• Get real. Net zero and overshoot are being used to argue that nothing fundamental needs to change in our energy intensive societies. Difficult truths need to be told. This includes highlighting the vast inequalities of wealth, carbon emissions, and vulnerability to climate change.

“The reality is that warming will soon pass 1.5°C, and that the Paris Agreement has failed,” said Dr Knorr, of Lund University.

“We must radically rethink how our economies and societies function, and whose interests they serve.

“Promises of net zero and recovery from overshoot are keeping us from taking action.

“They assure us nothing too drastic needs to happen just yet. Meanwhile, the planet boils.

“Owning up to the failures of climate change policy doesn’t mean giving up. It means accepting the consequences of past failure and not making the same mistakes.

“Rather than hoping future generations can undo the damage, we must act now to protect the planet.”

The Conversation article is entitled: “The overshoot myth: you can’t keep burning fossil fuels and expect scientists of the future to get us back to 1.5°C.”