Paralysed by uncertainty? Index mooted to solve climate dilemma

Setting pace of emissions cuts by observed warming could see off climate policy objections, say UK researchers

Proposed index would set pace of emissions cuts by observed warming (Pic: Flickr/kris krug)

Proposed index would set pace of emissions cuts by observed warming (Pic: Flickr/kris krug)

By Megan Darby

Faced with uncertainty over how fast greenhouse gas emissions will trigger unacceptable levels of global warming, policymakers have a choice.

They can adopt the precautionary principle, which means preparing for the worst, with high cost measures.

Or they can do little and wait for more evidence – an approach that looks cheap until climate-linked disaster strikes.

To resolve this dilemma, researchers at Oxford University are proposing a way to automatically adjust climate policies depending on how warming unfolds.

“Uncertainty in climate science is often used as an excuse not to do anything,” explained lead author Friederike Otto.

Alternatively, people propose “robust” measures that are very expensive, she told RTCC. “For politicians, who care a lot of course about the economic uncertainty – they are taken aback by these very precautionary strategies…

“So we were thinking: how can we find an index that shows that for the problem we have to solve, this uncertainty doesn’t matter?”

Instead of aiming to be “robust” or getting paralysed by conflicting evidence, policymakers should go for “anti-fragile” strategies, she said. In other words, make carbon cutting policies adaptable to changing evidence or circumstances.

Human-induced warming set against accumulated carbon dioxide emissions (

Human-induced warming set against accumulated carbon dioxide emissions (

At the moment, countries are drawing up national plans to tackle emissions based on a political as well as scientific considerations.

Experts do not expect these pledges to collectively be enough to limit warming to 2C above pre-industrial levels – the international goal.

Otto’s team is proposing a way to link the pace of emissions cuts to the observed level of warming that is attributable to human activity.

It sets a clear direction – as the temperature rise nears 2C, emissions globally will be phased to zero – but allows flexibility over the speed.

That way, if the planet turns out not to be too sensitive to greenhouse gas increases, carbon cutting can be slowed down.

It neutralises one of the main objections to climate policy raised by “lukewarmers” and amplified by fossil fuel interests.

If on the other hand warming happens rapidly, there is a ready mechanism for speeding up action.

Hey presto, “disputes over the climate response are no longer an impediment to policy adoption,” argues the paper in Nature Climate Change.

Report: Global warming halfway to UN’s 2C limit – New Scientist

While subject to small adjustments, the index should be stable enough to give a signal to investors, say the researchers.

They suggest three types of climate policy that could be tweaked according to this index: cap-and-trade, carbon tax or sequestration mandate for fossil fuel producers.

The first two are established tools for pricing carbon pollution – an approach that the World Bank and several oil majors endorse.

The last is more novel, requiring coal, oil and gas companies to pay for an increasing proportion of emissions from their product to be stored. That could mean investing in carbon capture and storage or large-scale tree planting.

Negotiators are working towards an international climate deal in Paris this December to limit warming to 2C.

It is expected to work on a “pledge and review” basis – countries are drawing up national plans that will be periodically ramped up.

The proposed index would help to evaluate progress, Otto said – although it would not settle the vexed question of how to share responsibility.

“It would not solve the problem that not all countries will contribute the same. It will just maybe make it more transparent.”

Read more on: Climate science | Research | UN climate talks