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The Paris Climate Plan Is on Life Support: Can Negative Emissions Deliver on Global Climate Ambitions?

By Tim Pfefferle

What a difference a year can make. 2015 marked a point of great enthusiasm about a turnaround in global climate policy. States signed on to the Paris climate agreement. As with any complex internationally negotiated deal, reactions were mixed. But most at least thought the Paris deal indicated one thing: that countries were politically committed to act on climate change. The outcome of the US election seems to threaten this fragile consensus.

Speaking to the New York Times, Dana Fisher, director of the Programme for Society and the Environment at the University of Maryland, put it bluntly: “The Paris Agreement and any U.S. leadership in international climate progress is dead.” Already vulnerable, US withdrawal from the Paris consensus could put global ambitions out of reach. In turn, a stuttering implementation process brings back an issue often kept under wraps: negative emissions technologies.

 Why Paris Was Inadequate Already

Donald Trump has packed his transition team for the Environmental Protection Agency with noted climate change deniers like Myron Ebell. In Scott Pruitt, the agency will be led by someone whose claim to fame is launching multiple lawsuits against it in the past. The astonishing selection of current ExxonMobil CEO Rex Tillerson as Secretary of State signals the extent to which fossil fuel companies retain a tight grip over both domestic and foreign policy. Trump’s own track record suggests he probably just does not understand climate change, having to be reassured by Chinese officials it’s not in fact a hoax concocted by them. And Republican majorities in both houses of Congress will ensure that most of the tacit progress made by the Obama Administration will be undone.

While China has surpassed the United States as the world’s largest greenhouse gas emitter, the United States remains a significant contributor towards annual global emissions. Currently, it is responsible for about 16 percent of them, more than the 28 EU member states and Japan combined. Before the election, Lux Research estimated that two terms of a Trump presidency would lead to 16 percent higher emissions compared to eight years of Clinton. To put these numbers in perspective: Under the Paris Agreement, 21 per cent of expected emissions reductions through 2030 were to come from the United States. That is no longer realistic.

Active climate denialism on the part of the US gives license to everyone else to start relaxing their ambitions.

The Paris Agreement is deliberately designed as a mechanism based on the lowest common denominator. After the disaster that was the Kyoto Protocol, negotiators shifted to a different approach that would give everyone an incentive to sign up to the deal. Instead of prescribing specific emissions cuts for individual countries, the Paris deal awards them the freedom to put their own offers on the table.

But countries’ current plans are wildly insufficient to reach the goal of limiting global temperature increases to below 2°C. The imperative for the US was to do more, not less. With a US policy reversal looming, the latter will be the case.

To understand why an agreement that has just come into force is already doomed, let’s take a look at the assumptions underlying the Paris document. To prevent warming past 2°C, carbon concentrations must not exceed 450 parts per million. Currently, the world is on track to reach 450 within 22 years. Temperatures have already increased by almost 0.9°C above pre-industrial levels, and current emissions stocks in the atmosphere mean that another 0.5°C is practically unavoidable.

Climate Action Tracker explains that

[t]he emissions pledge pathway that includes INDCs has over 90% probability of exceeding 2°C, and only a ‘likely’ (>66%) chance of remaining below 3°C this century. The current policy pathways have a higher than 99.5% probability of exceeding 2°C.

States are at least two steps removed from making two degrees a reality. Every participating state has made a certain pledge – so-called intended nationally determined contributions (INDCs) – to reduce emissions by some amount. So these vary from country to country. The United States, for example, has committed to reduce its greenhouse gas emissions by 26 to 28 percent below 2005 levels by 2025. Taken together, current INDCs would more than likely result in warming above 3°C.

To get everyone on board, the agreement is structured in such a way that enforcement of these pledges is essentially voluntary. For the most part, they are just that: pledges. In order to stay on the 2°C path, countries would have to make serious upgrades to their pledges and then make good on their promises. In a pre-Trump world, the agreement was already questionable. Success depended on countries holding each other to account, progressively producing more and more ambitious emissions commitments.

The upshot is that any effort to retain the 2°C goal begins with an acknowledgement of the science. Political conviction is equally important. But it should not supersede basic scientific realities.

Still, the fact that the agreement is pretty much voluntary in nature was a politically expedient design feature. The goal was to devise an institutional pathway to limit warming to a manageable level. That pathway has just suffered a potentially fatal blow.

Active climate denialism on the part of the US gives license to everyone else to start relaxing their ambitions. Domestically, political pressure groups in other countries can point to the United States and demand less stringent climate regulations. Internationally, everyone from Saudi Arabia to Australia will be able to weaken their ambitions.

The fundamental problem is that there was already essentially no wiggle room. What was needed over the next four years was really a sea change in how countries approach the issue. We needed more Costa Ricas, Denmarks, and Moroccos. What we got instead is Rex Tillerson.

Johannes Ackva and Dominic Roser highlight how steep the challenge is already. For a 66 percent chance of staying below 2°C, Europe would have to completely decarbonise by 2030 – four times over. The emissions gap amounts to four Europes. When you think about how long it has taken a supposed climate leader like Germany to get to a power supply that is 33 percent renewable, you start to realise that the global chasm between goal and ambition is quite wide.

In March, Oxford University researchers put out a study. They come to the conclusion that if we take the 2°C goal halfway seriously, we have to stop building fossil fuel infrastructure by next year. That’s 2017. Earlier research suggests that, given current reserves, 35 percent of oil, 52 percent of natural gas, and fully 88 percent of coal has to be left in the ground. Such numbers are nowhere near reflective of current policy pathways. And the US electorate – or more precisely the American electoral system – has literally just thrown oil into that fire.

Earlier this year, a group of scientists published a paper in the journal Nature Climate Change. The authors raise a worrying point. Their paper makes the case that there is a misguided preoccupation with near-term impacts. But current emissions are locking us in to climate dynamics that will reverberate well beyond 2100, and commit the planet to “long-term, irreversible climate change”. Current policies may thus have an outsized effect on disastrous climate impacts well beyond this century alone.

To make matters worse, there is still significant uncertainty about the precise relationship between emissions stocks and temperature increases among scientists. A recent study led by Tobias Friedrich of the University of Hawaii at Mānoa finds that warmer climates are more sensitive to changes in CO² levels than colder ones. A warming climate means that additional emissions will have an exacerbated effect. The result: average global temperatures are projected to rise an almost unfathomable 5.9°C above pre-industrial levels.


Conventional warming projections (red) versus new research by Friedrich et al. (blue)

Can Negative Emissions Make Up the Difference?

It sounds paradoxical to say that we have to move past an agreement that has just come into force. After all, a lot of people fought a lot of difficult battles to get to this point. But the numbers tell a different story.

Kevin Anderson has been particularly vocal about the questionable assumptions underlying the 2°C goal. The deputy director of the Tyndall Centre for Climate Change Research explains that of the 400 IPCC model scenarios that keep warming below the Paris Agreement target, 344 involve the deployment of negative emissions technologies (NETs). In fact, the agreement itself specifically calls for “removals by sinks of greenhouse gases in the second half of this century”.


A sketch of what a negative emissions scenario would look like (via

NETs are measures to take carbon out of the air after the fact. There is a variety of ways to go about doing that. Carbon Brief, for example, lists ten different NETs. These range from reforestation to tinkering with the composition of ocean water and agricultural soils. A number of these technologies are really quite speculative and many years away from development.

The most promising NET is called bioenergy with carbon capture and storage (BECCS). This involves burning biomass and subsequently storing the resulting emissions. Effectively, this takes carbon out of the air. While BECCS may sound like a pipe dream, we already assume that it can be deployed successfully. 101 of the 116 IPCC scenarios that achieve a “likely” chance of staying below 2°C rely on BECCS. In two thirds of them, BECCS would account for at least 20 percent of the world’s primary energy by the end of the century. Through the backdoor, NETs have become a central part of global climate plans. In fact, it’s the dirty secret of the Paris deal.

So far there have been few other success stories when it comes to NETs. Scientists who have looked at the current state of negative emissions technologies conclude that “there is no NET … currently available that could be implemented to meet the <2°C target without significant impact on either land, energy, water, nutrient, albedo or cost”. Therefore, the researchers say, reducing greenhouse gases as much as possible should be the main focus.

Andy Skuce notes in the Bulletin of Atomic Scientists that “human beings would have to develop a huge carbon capture and sequestration industry that is about triple the size of the entire current fossil fuel industry”. That translates to building 250 such plants every year for the next 70 years. Currently, there are 14 of these plants – worldwide.

These technologies are regarded as an insurance mechanism; they cannot replace serious mitigation efforts.

Beyond technical challenges, there are also policy problems. NETs entail a moral hazard. Just like buying insurance for your house or car may make you more reckless, the same conundrum applies to atmospheric safeguards such as NETs. If we think that carbon can be removed from the air after the fact, the incentive to reduce emissions consequently goes down. Simply relying on NETs might just lock us in to our current carbon addiction.

Skuce is similarly sceptical. However, he also says that some amount of emissions is essentially unavoidable. This includes things like agriculture, cement manufacture, and the steel industry. What to do with these in the absence of negative emissions? There is also an inherent problem in the way we talk about 2°C as though it were actually a safe level of warming. It most likely is not. Ideally, we would want to go way below 2°C, which again necessitates some amount of negative emissions.

Skuce therefore thinks about NETs as a kind of “emergency planetary liposuction” if countries can’t get their act together. It would be better, he says, to change the diet (meaning mitigating emissions). However, with every year in which the global community does not take drastic action to mitigate emissions, the need to take carbon out of the air in the second half of the century rises in step.

The upshot is that any effort to retain the 2°C goal begins with an acknowledgement of the science. Political conviction is equally important. But it should not supersede basic scientific realities. We should therefore spend much more public money on developing more innovative technologies, including possible insurance measures such as NETs. The Paris deal itself is already banking on them, so we may as well.

While technological fixes can never be a comprehensive answer, it looks more and more as if they will have to become part of a green strategy. The earlier that debate takes place, the higher the chances these technologies will not be co-opted by other forces.

In 2016, the United States is spending $6.4 billion on clean energy research, including nuclear. By contrast, the federal budget devotes more than $70 billion to research and development in the defence sector alone. At the European level, the EU allocates less than €6 billion to non-nuclear energy research in the period between 2014 and 2020. Given that energy is the defining technological challenge of our lifetimes, these numbers are shockingly low.

More thought too needs to go into what kinds of concepts can deliver negative emissions. Myles Allen, a physicist at Oxford University who was one of the first people to do research on global carbon budgets, champions a carbon take-back scheme. This would require companies that sell products to consumers to take back a progressively rising percentage of emissions. As an analogy, think of the sorts of packaging take-back schemes popular in Europe.

To make NETs a viable option, it would have to be clear that these technologies are regarded as an insurance mechanism. They cannot replace serious mitigation efforts, and funding would have to be additional, not substitutive. In that sense the risks are real. But there’s also little point in blowing through every emissions scenario without giving yourself the chance to have something like NETs in the back pocket. In order to reduce risk, more redundancy has to be built into the system. This means thinking creatively about ways in which technological options such as NETs can mitigate more risk than they create.

The way forward is therefore a balanced mix between mitigation, adaptation, and the development of negative emissions technologies. Bringing down emissions to zero will require some measure of carbon removal. And the persistently glacial progress on mitigation commitments is making the Paris deal seem more and more like a charade. So more options should be on the table. Otherwise, we should just ditch the 2°C goal (which is an entirely different argument in itself).

For good reason, COP22 did not provide the platform to think about such big ideas. It was always intended as a space to put meat on the bones of the Paris framework. People in attendance were as shell-shocked as anyone about the news from the US. Perhaps born out of denial, some hope that the US can somehow be persuaded not to switch course. But making the Paris Agreement great again is not enough, unfortunately. It misses the forest for the trees.

The task for green parties in Europe is therefore to debate how much of the bitter NET pill to swallow. While technological fixes can never be a comprehensive answer, it looks more and more as if they will have to become part of a green strategy. The earlier that debate takes place, the higher the chances these technologies will not be co-opted by other forces. It’s better to be pro-active now than to wait until NETs become inevitable. No one wants to have a liposuction. But when you do need one, it’s nice to have the tools available.