Is 1.5C still realistic? The crumbling consensus over key climate target

Sultan al-Jaber, chief executive of Abu Dhabi’s state oil company, has put one message front and centre since being named president of the UN COP28 climate summit: the world must not give up on the 1.5C target for curtailing rising temperatures.

Ahead of the 28th gathering of world leaders to discuss climate change, which will take place in Dubai this year, Jaber has embarked on a global tour during which he has repeatedly emphasised the importance of meeting the targets embedded in the 2015 Paris climate accord. That agreement, signed by 195 parties, strove to limit the rise in global average temperatures since pre-industrial times to well under 2C and ideally to 1.5C.

The figure has become the blueprint for global action on climate change, underpinning government and business plans to slash greenhouse gas emissions and becoming a rally cry for climate activists. Paris signatories have pledged to reach net zero greenhouse gas emissions, many of them by 2050. But that entails emissions falling 43 per cent by 2030 using 2019 as a baseline: a huge feat for a world reliant on fossil fuels.

Jaber has said that the goal of limiting temperature rises to 1.5C “is just non-negotiable”. But more than seven years after that momentous evening in Paris and with just seven years until 2030, the viability of the 1.5C target is under intense scrutiny.

Some climate scientists think 1.5C is no longer feasible while others believe we can get back on track, but only with far more drastic action. There are those in the business community, particularly in fossil fuel production, who want to scrap it because retaining it would mean limits on the expansion of their industry.

There is already widespread debate, much of it in private, about what would happen if the world fails to meet the 1.5C goal, whether it is time to reassess, and who the winners and losers would be if the target were scrapped or watered down.

Later this month, the IPCC will issue a report that will focus heavily on the 1.5C target. It comes after carbon dioxide emissions hit a record high in 2022, partly because of the energy crisis caused by Russia’s invasion of Ukraine. Scientists estimate that the world has already warmed by at least 1.1C compared with pre-industrial levels.

For Sheldon Whitehouse, a Democratic senator who has spent years making weekly speeches on climate change in the Senate, the outlook is bleak. “At this point it is virtually certain we will blow through [the 1.5C] target,” he says, while warning that it is “much more dangerous to go beyond it”.

Business figures — including some of Jaber’s peers in the hydrocarbon industry — are starting to argue in private that it would be better to put more emphasis on planning for a world with warmer temperatures than to focus on what is now likely to be an unachievable goal.

Bill Gates, whose investment firm Breakthrough Energy invests in climate change innovations, has repeatedly said the 1.5C target is no longer achievable. He argues that as well as trying to limit warming, we will need to prepare for a hotter world. 

For some, Jaber’s own support for retaining the 1.5C goal sits awkwardly with his role as chief executive of the Abu Dhabi National Oil Company, where in 2021, he pledged to rapidly increase the oil output capacity of the United Arab Emirates by 2030 while also arguing emissions can be reduced. That puts him at odds with the world’s scientific community, which has warned that existing and planned fossil fuel projects are already putting the world on course to miss the 1.5C target.

But many scientists and campaigners worry that admitting defeat in the battle to limit warming to 1.5C is a way of justifying slower action from countries and companies.

“The solution is not to change the target. The science hasn’t changed, the evidence hasn’t changed,” says Mark Howden, vice-chair of the Intergovernmental Panel on Climate Change, the influential UN group that pulls together scientists and specialists around the world. “What we have to do is accelerate the emissions reductions.”

The rise of 1.5

The 1.5C goal was in large part the work of the Alliance of Small Island States, an organisation made up of 39 members including the Maldives, Belize and the Cook Islands concerned about the huge dangers climate change posed to them. They feared their homes and livelihoods could be destroyed by unabated global warming. Some, such as the Solomon Islands, had already lost islands to rising sea levels.

At the make-or-break Paris climate talks, most western countries and large emitters of carbon were focused on a 2C target. But AOSIS issued a proposal for a 1.5C goal ahead of the meeting. “The ‘1.5 to stay alive’ moto has long been the AOSIS rally cry,” says Fatumanava-o-Upolu III Pa’olelei Luteru, current chair of AOSIS, who is from Samoa. “It represents that level beyond which many small islands will be overwhelmed by climate change…. for us, 1.5 is our red line.”

The 1.5C and 2C targets “were informed by science but also political need”, says Howden, who is also director of the Institute for Climate, Energy and Disaster Solutions at the Australian National University. “If it was just down to the science we might have slightly different numbers, if it was down to the politics we might have had different numbers.”

The inclusion of 1.5C in the final agreement was a big victory for the small islands. Since then, it has morphed into the de facto standard for the climate movement, thanks in part to a 2018 IPCC report that revealed the stark increase in damage to the world if it warmed by 2C rather than the lower number.

While half a degree might not sound like much, Howden says “there is a surprising amount of increased damage by going to 2C rather than limiting to 1.5C”.

Chart showing the different that half a degree of warming can make to crop yields, coral reefs and species loss

More warming could, according to scientists, lead to the disappearance of summer ice in the Arctic that reflects the sun’s warmth back into the atmosphere and helps regulate ocean and air temperature. It could expose billions more people to more extreme weather, cause increased flooding, result in the loss of ecosystems and reduce agricultural production.

Temperatures rising above the optimal 1.5C could also result in profound health effects, says Juliette White, vice-president of sustainability at pharmaceutical group AstraZeneca. At the lower number, the IPCC has estimated that 14 per cent of the population will be exposed to severe heat at least once every five years. At 2C, this figure jumps to 37 per cent.

Tim Lenton, who holds the chair in climate change at the University of Exeter, says about 10mn people globally were exposed to an annual average temperature of 29C or more in the 1970s. But as the world warms, hundreds of millions more could quickly find themselves experiencing such averages, according to a working paper from Lenton and others.

Scientists, including Lenton, have identified other tipping points that could be reached if average temperatures rise by more than 1.5C. These include the potential melting of the Greenland ice sheet, which could eventually lead to large rises in sea levels around the world, and changes to convection currents in the north Atlantic that could cause big temperature changes in Europe and disruption to the monsoon seasons in Africa.

‘Difficult but achievable’

But just as the impact of global warming has become more apparent, with the world experiencing destructive climate-related shocks such as the catastrophic flooding in Pakistan and severe wildfires in the US, Australia and Europe, doubts about the feasibility of the 1.5C target have also grown.

When the Paris Agreement was signed, scientists said the world could conceivably cut emissions sufficiently to avoid breaching 1.5C but that it would be difficult. But since 2016, emissions of carbon-based greenhouse gases have increased each year except 2020 as the world burns through its so-called carbon budget — the cumulative amount of carbon we can emit before the world risks breaching 1.5C.

That means “something has to happen drastically in the next two to three years” if the world is to limit temperature rises to 1.5C, according to Joyeeta Gupta, professor of environment and development in the global south at the Amsterdam Institute for Social Science Research. “Everyone has been delaying action,” she says. “Now we have to go down so fast [in terms of emissions] that it is very painful.”

But some scientists already believe the 1.5C target is dead. An anonymous survey of IPCC authors by Nature in 2021 found more than 75 per cent of those who responded thought heating would reach or exceed 2.5C by the end of the century. A 2021 report from the Australian Academy of Science stuck a similarly downbeat note: “Limiting climate change to 1.5C is now virtually impossible.”

Laurie Laybourn-Langton, lead author of a recent report on 1.5C from think-tanks the Institute for Public Policy Research and Chatham House, says some are declaring the death of the 1.5C target in a bid to “shock us out of our complacency”.

But he adds the narrative also benefits those who would rather the world continues to burn fossil fuels and shifts the focus to ameliorating the immediate symptoms of climate change, such as the impact of flooding, rather than tackling the root causes.

“Saying that [1.5C is dead] increases the chances for vested interests to step in…The winners [if the 1.5C goal is dropped] could be fossil fuels and people who don’t want the transformational change society needs to tackle the climate crisis.”

In some quarters of the oil and gas industry, there is already talk of emerging technology that could potentially allow the world to warm beyond 1.5C but then claw the increase back — even though the IPCC has warned that some impacts of exceeding 1.5C will probably be long lasting or irreversible.

At the energy industry’s CERAWeek conference this month, Occidental Petroleum chief executive Vicki Hollub said that direct air capture — an emerging technology to directly remove carbon dioxide from the air — could allow the oil and gas industry to continue operating for decades to come.

Myles Allen, one of the key authors of the 2018 IPCC report on 1.5C, says that while it is too late for the world to stop warming simply by cutting emissions from fossil fuels, carbon capture and storage into geological formations can still play a key role in achieving the target.

But Jaber told the oil executives assembled in Houston that even as new technology emerges, they needed to raise their game. “We know we are way off track,” he said. “We need a major course correction.”

Reasons for optimism

Despite rising carbon emissions, Laybourn-Langton says there are signs change is afoot. Russia’s war on Ukraine has accelerated a transformation in Europe’s energy system, with a speedy roll out of renewable energy and energy-saving measures helping to offset the restart of some coal-fired power stations in response to reduced gas supplies from Russia.

In the U.S, Joe Biden’s US$369bn Inflation Reduction Act is also propelling huge investments in green technologies. “People are recognising that we need to move off hydrocarbons, that they are ultimately bad for energy security and national security,” says David Blood, who co-founded Generation Investment Management with former U.S vice-president Al Gore.

“Those conversations are converging to make this [shift to decarbonise rapidly] more of a reality.”

Research by Exeter’s Lenton and others identified three so-called positive tipping points that could trigger a cascade of decarbonisation in sectors representing 70 per cent of the world’s greenhouse gas emissions. These are mandating the sale of electric vehicles, directing public-sector entities to buy plant-based proteins instead of some meat, and replacing the more polluting components of agricultural fertiliser with ammonia from renewable sources.

“I am optimistic [we can reach the 1.5C target] because I still have a glimmer of hope from the positive tipping points,” says Lenton. “It could be a small thing that makes a big difference.”

Detlef van Vuuren, a senior researcher at PBL Netherlands Environmental Assessment Agency, points out that rapid advances in electric vehicle technology mean the transport system is “on the brink of progress”.

Nick Stansbury, head of climate solutions at Legal and General Investment Management, argues the best policy to ensure the world meets that 1.5C target is an effective price on carbon. “You can make the carbon intensive thing more expensive by taxing it, or you subsidise everything else,” he says.

In the meantime there is no shortage of public support for retaining the 1.5C target at the COP28 summit, not least from the people who helped instigate it seven years ago.

“If we are not able to stay within the 1.5, it is going to be devastating for many small island developing states,” says Luteru of the AOSIS. “We see 1.5 as our security blanket, our shield against the devastation [of climate change].”

Discussions about whether 1.5C can be achieved any longer are missing the point, says van Vuuren. “It doesn’t matter too much if 1.5C is realistic enough. The lowest we can get to is the most attractive,” he adds. “It should not become 2. What it should mean is if we can’t reach 1.5, we don’t pass 1.6.”

Stansbury says it is still “perfectly feasible” to put ourselves on track to achieve the 1.5C target but, like others, warns that time is running out. “Is there a point where that window closes? Yes, there is, and that point is not that far away.”

The IPCC’s Howden acknowledges that as things stand, achieving the 1.5C target is “a low-probability event” but pushes back against abandoning it. “We need to turn around the narrative of ‘we can’t do to this’ to ‘this is something we can’t afford not to do’.”