COP26 climate summit: A scientists’ guide to a momentous meeting

Despite 30 years of climate diplomacy, urgent and aggressive action is needed to halt global warming. Nature explains what success looks like, and what’s on the line.

People take part in the 'Global march for climate justice' ahead of Glasgow's COP26 meeting, in Milan, Italy.

Credit: Guglielmo Mangiapane/Reuters

Credit: Guglielmo Mangiapane/Reuters

Some 20,000 people from 196 countries — including world leaders, scientists and activists — will soon converge in Glasgow, UK, for the most anticipated United Nations climate summit in years. Climate researchers have been warning about the dire and increasing impacts of global warming for more than three decades, and for some, the meeting, set to begin on 31 October, represents one final opportunity for the governments of the world to craft a collective plan to meet their most ambitious goals for curbing climate change.

During the two-week event, the 26th UN Climate Change Conference of the Parties (COP26), government officials and business leaders will present their latest commitments to cut greenhouse-gas emissions, while scientists discuss efforts to track emissions, understand impacts and advance potential climate solutions. Negotiators will also continue discussions of financial aid for low-income countries, which have contributed the least to the climate crisis but must now prepare for its consequences and develop their economies without relying on fossil fuels.

Arguments still rage over how to define and track climate finance, but even wealthy countries acknowledge that they have yet to meet a commitment, made 12 years ago, to provide US$100 billion annually to developing nations by 2020. Scientific assessments have also confirmed that pledges made by governments at the 2015 COP held in Paris haven’t been met, and promises made since then still fall short of the official goal to limit global warming to 1.5–2 °C above pre-industrial levels.

“Glasgow is the moment,” says Johan Rockström, a climate scientist who heads the Potsdam Institute for Climate Impact Research in Germany. Rockström stresses that countries have a legal obligation under the Paris agreement to submit climate plans that are in line with the latest scientific assessments. “It’s a big ask,” he says, “but it’s actually what every country knows is expected in Glasgow.”

Here, Nature explains what’s on the line at COP26, while taking stock of scientists’ hopes and fears for the meeting.

There have been 25 COPs before. Why do researchers say this one is so important?

Aerial views of the site of the COP26 international climate change conference to be held in Glasgow during November 2021.

COP26 will be held at the Scottish Event Campus in the heart of Glasgow. Credit: Alamy

COP26 will be held at the Scottish Event Campus in the heart of Glasgow. Credit: Alamy

In 1992, more than 100 nations signed a treaty — called the UN Framework Convention on Climate Change — to cut back global emissions and preserve Earth’s climate. Developed and developing countries (as they are described by the treaty) agreed that they had different responsibilities in fighting climate change, but that all nations needed to work together and, by consensus, address the problem. However, it wasn’t until the 2015 Paris meeting, the 21st conference of parties to the treaty, that all countries formally agreed to take action to limit warming to 1.5–2 °C (see ‘A brief history of climate action’).

Six years later, COP26 represents the first major test of the Paris agreement, which committed countries to holding global warming to well below 2 °C above pre-industrial levels and — at the insistence of small island states and developing nations existentially threatened by rising seas and other climate impacts — “pursuing efforts” to prevent more than 1.5 °C of warming. But scientific assessments showed from the outset that national commitments to curb greenhouse-gas emissions would fall short of that ambitious goal.

As part of the Paris accord, 196 governments agreed to periodically assess their progress, both nationally and collectively, and update their pledges. That was originally supposed to happen for the first time in 2020, but after a delay due to the COVID-19 pandemic, nations are poised to make their first updates in Glasgow. More than 100 countries have submitted new climate pledges so far.

“It’s very clear that Paris is driving action, but it’s just not fast enough,” says Claire Stockwell, a climate-policy analyst with Climate Analytics, a non-profit organization based in Berlin, Germany, that tracks climate commitments and advises developing countries in COP negotiations. Carbon dioxide concentrations in the atmosphere continue to rise at a pace that scientists predict will have dangerous consequences for the planet.

A Brief History of Climate Action

Despite more than 30 years of warnings from scientists, and global efforts, carbon emissions are still increasing.

1958: Charles ‘David’ Keeling takes the first reading of atmospheric carbon dioxide concentrations, registering 313 parts per million.

1988: NASA climate scientist Jim Hansen tells the US Congress: “The greenhouse effect has been detected and is changing our climate now.”

1990: The United Nations Intergovernmental Panel on Climate Change issues its first report on global warming, with a foreword calling it “potentially the greatest global environmental challenge facing mankind”.

1992: At the Earth Summit in Rio de Janeiro, Brazil, 154 nations agree to the UN Framework Convention on Climate Change (UNFCCC), which enters into force two years later.

1995: The first conference of the parties, COP1, is held in Berlin.

1997: Parties to the UNFCCC adopt the Kyoto Protocol, which sets the first binding emission-reduction targets for wealthy nations.

2009: At COP15, global leaders adopt the Copenhagen Accord, setting a goal of limiting warming to 2 °C above pre-industrial temperatures and calling for emissions pledges from all countries for the first time.

2015: Countries sign the Paris Agreement, which sets the first legally binding requirements for all 196 participating governments to limit warming to 1.5–2 °C.

2017: Then-president Donald Trump says he will pull the United States out of the Paris accord, calling it “less about the climate and more about other countries gaining a financial advantage over the United States”.

2021: Under President Joe Biden, the United States rejoins the Paris Agreement as nations prepare to update their pledges for the first time at COP26.

Source: US National Oceanic and Atmospheric Administration

What would a successful outcome look like for COP26?

UN Secretary-General Antonio Guterres (L) attends a virtual briefing in prep for COP26, at the UN headquarters in New York.

UN Secretary-General António Guterres has called on world leaders to take decisive action to fight climate change. Credit: Alamy

UN Secretary-General António Guterres has called on world leaders to take decisive action to fight climate change. Credit: Alamy

The simplest answer is a well-defined set of policy commitments from various governments to curb emissions by shutting down power plants that run on coal (the dirtiest fuel ), phasing out vehicles running on carbon-emitting internal combustion engines, and ramping up the use of clean-energy technologies. A combination of these actions and many others targeting sectors such as agriculture and industry, researchers say, could achieve the 1.5 °C goal from the Paris agreement.

Most of the major emitters have already stepped forward with fresh commitments to cut emissions over the next decade, and some countries have even pledged to reach net-zero emissions by around the middle of the century (see ‘Laggards and leaders’). But commitments are just the first step: after Glasgow, leaders will need to implement those policies at home to bend the emissions curve.

Laggards and leaders

The Climate Action Tracker (CAT), a group of scientists and policy experts, assesses the potential impact of countries’ climate commitments. Most nations are currently falling short of what is required to meet the goals of the Paris Agreement.

Critically insufficient: Of the nearly 40 countries tracked by the CAT, 6 have climate policies and commitments that have been rated as critically insufficient, indicating that they reflect “minimal to no action” on climate. These nations include Russia and Saudi Arabia, which continue to rely on and export oil and natural gas.

Highly insufficient: The CAT ranks 15 countries — including Canada, Brazil and India — as having highly insufficient climate policies that are inconsistent with the Paris 1.5 °C goal and, in many cases, will lead to rising emissions. For instance, although India has set ambitious targets for the development of renewable energies, including solar power, the country continues to invest in — and subsidize — coal-fired electricity generation.

Insufficient: Eight countries, including the United States and Japan, plus the European Union rank as having insufficient policies, indicating that “substantial improvements” are needed to be compatible with the Paris 1.5 °C goal. Although the United States’ Glasgow pledge to cut emissions by 50% from 2005 levels by 2030 would mark a step forward, Democratic President Joe Biden is struggling to implement his climate policies in the face of opposition from Republicans and some members of his own party.

Almost sufficient: The policies of seven countries ranked as “almost sufficient”, or compatible with the Paris Agreement’s 2 °C goal. They include Kenya, Costa Rica and the United Kingdom, which received the highest rating of any wealthy country. But the United Kingdom has yet to provide a clear road map for achieving its commitment to curb emissions by 68% by 2030, compared with 1990 levels.

Compatible with 1.5 °C: The CAT has ranked only one country, Gambia, as compatible with the 1.5 °C goal. Although policies are not yet in place to achieve the country’s commitments, it is ramping up renewable energy production and, with international support, could curb emissions by an estimated 55% by 2025, compared with projections in a business-as-usual scenario.

Source: Climate Action Tracker

But COP26 isn’t just about national carbon commitments and negotiations between countries. Business and industry associations will be stepping forward with new commitments, as well: this month, the cement industry, for instance, pledged to go carbon neutral by 2050. Philanthropists will also be highlighting their own plans, including a project dedicating several billion dollars to land conservation and Indigenous land rights. Scientists have linked Indigenous land rights with biodiversity conservation and reduced deforestation — and thus carbon emissions — in the Amazon rainforest and across the tropics.

For David Kaimowitz, an economist who heads the forest and farm facility at the Food and Agriculture Organization of the UN in Rome, the emphasis on Indigenous peoples at COP26 represents a refreshing shift in thinking. “I don’t think we’ve seen anything like this at any previous COP, and that’s being reflected by a much greater willingness to put money into the topic,” Kaimowitz says.

Perhaps the biggest question is whether lingering tensions over commitments, climate finance and a lack of representation owing to travel challenges associated with the COVID-19 pandemic will overshadow any positive developments at COP26. People need to walk away from the summit with a sense of progress, says David Victor, a political scientist at the University of California, San Diego. The idea that this diplomatic process is “credible and alive and well”, Victor says, “is really, really important”.

Have past COPs actually achieved anything?

A freshly burned landscape is seen as the French Fire continues to spread on August 25, 2021 near Wofford Heights, California.

Scientists have determined that climate change is causing wildfires to increase in frequency in certain parts of the world. Credit: David McNew/Getty

Scientists have determined that climate change is causing wildfires to increase in frequency in certain parts of the world. Credit: David McNew/Getty

Many, including Swedish youth activist Greta Thunberg, are sceptical that they have. She encapsulated how she feels about past climate pledges at a pre-COP26 meeting of finance ministers in Milan, Italy, in September, with this six-word summary: “Thirty years of blah, blah, blah.” Even seasoned environmental activists and academics have raised questions about whether the UN climate convention, with its tradition of making decisions by consensus among nations rather than majority vote, is capable of meeting the challenge. Nonetheless, the shift away from fossil fuels and towards clean-energy technologies has accelerated over the past decade, and many experts say climate diplomacy has had a role.

“Clearly, we have failed in delivery,” Rockström says, “but we have also made some remarkable progress.” The problem, he says, is one of scale: eliminating fossil fuels represents a wholesale transformation of the modern global economic system. “It’s not an environmental issue, it’s a massive societal challenge.”

As it stands, the Climate Action Tracker (CAT), a consortium of science and academic organizations, estimates that policies put in place since the Paris agreement could shave 0.7 °C off the predicted increase in average global temperatures this century, resulting in an estimated warming of 2.9 °C above pre-industrial levels by 2100. Fresh government commitments announced ahead of COP26 would strip off another 0.5 °C, the CAT estimates (see ‘The climate multiverse’). And if all 131 countries that have announced or discussed net-zero pledges were to follow through, the projected global temperature increase would be limited to around 2 °C above pre-industrial temperatures. That is still short of the Paris 1.5 °C goal, but a marked improvement compared with the future scientists were predicting a decade ago.

The climate multiverse

Climate policies put in place since the Paris Agreement was signed have reduced the projected temperature in 2100 by 0.7 °C, to 2.9 °C. New pledges made ahead of COP26 would improve the situation if fully implemented, but still don’t meet the goal of 1.5–2 °C of warming that the globe is aiming for.

Source: Climate Action Tracker

Will the COVID-19 pandemic affect the meeting’s outcome?

People wearing face masks to prevent the spread of covid-19 walk along Orchard Road, the famous shopping district, Singapore.

Credit: Maverick Asio/SOPA Images/LightRocket/Getty

Credit: Maverick Asio/SOPA Images/LightRocket/Getty

The pandemic has impacted the meeting in multiple ways already. The summit’s one-year delay gave countries more time to develop climate commitments, and gave the UN Intergovernmental Panel on Climate Change more time to prepare its latest report on the state of the art in climate science.

But travel restrictions and an unequal distribution of COVID-19 vaccines around the globe have also created a raft of challenges for attendees. Although the United Kingdom has pledged to provide vaccines to all negotiators and to pay for hotels for delegates who need to quarantine, some scientists and environmentalists from non-governmental organizations that serve as both watchdogs and advisers to developing countries are expected to have trouble attending.

Low-income nations have always been at a political disadvantage in the COP process, and the challenges in accessing vaccines and attending the meeting will only exacerbate those inequities, says Romain Weikmans, a political scientist at the Finnish Institute of International Affairs in Helsinki. “With the pandemic, it will be even more difficult for developing countries to get their voices heard,” he says.

Beyond Glasgow: what comes next?

The first rain in nearly five months arrives during a violent fast-moving tropical thunder near Santa Ynez, California.

Credit: George Rose/Getty

Credit: George Rose/Getty

For many, the core challenge after Glasgow will be to ensure that governments actually follow through on their promises at home. This is particularly true for vague pledges by some nations to achieve carbon neutrality by mid-century. What scientists want to see is definitive action taken to move away from fossil fuels.

Political promises aren’t enough, Stockwell says. “We’re not going to stop the climate crisis unless we have implementation of policies that actually reduce emissions.”

In many ways, the economic transformation that scientists are calling for has already begun (see ‘Fuelling the world’). The price of energy from renewable sources such as wind and solar has plummeted over the past decade, and in many places these sources are now cheaper than fossil fuels. In a report published on 13 October, the International Energy Agency projected that under current policies, coal consumption will peak and begin to decline as early as 2025; a peak in oil consumption will follow around a decade later. But the global economy still runs on fossil fuels, and scientists say the path forward will be anything but easy.

Fuelling the world

Thanks to both government incentives and falling prices, renewables such as wind and solar are expanding quickly. But backing out of existing fossil fuels will be difficult.

Renewable energy consumption has increased more than tenfold over the past two decades, and shows no sign of slowing as prices continue to decline for wind and solar power, as well as battery technologies that are enabling a new generation of electric vehicles.

Hydroelectricity remains fairly level, although a new generation of dams is in the works across the tropics and beyond.

Nuclear energy provides one of the largest sources of carbon-free power, but old plants are being retired faster than new ones can be built. Nuclear power peaked in 2006 and has declined by more than 11% since then.

Natural gas is the cleanest of the fossil fuels, and abundant supplies have helped to suppress demand for coal — the dirtiest of fossil fuels — particularly in the United States. But it too must be phased out if the world is to achieve carbon neutrality.

Oil is at the heart of the transportation industry, whether on the roads, at sea or in the air. The shift toward electric vehicles has caused many energy experts to project that oil consumption will peak over the coming decade, but without further action, the International Energy Agency predicts only a slight decrease by 2050.

Coal provides the world with more than five times as much energy as all of the renewable energy sources combined. Its popularity is declining rapidly across the globe, however, and many hope that COP26 will officially herald its end.

Source: BP Statistical Review of World Energy, 2021

What will this massive energy transformation look like? Scientists and academics have spent years studying everything from carbon taxes to the environmental impacts of wind and solar energy, and the social challenges that will arise around the world as countries rich and poor seek to forgo fossil fuels in favour of clean energy.

Politicians in the United States and other countries that depend on fossil-fuel production often focus on jobs that will be lost owing to this transition, but research suggests that the shift towards clean energy will generate more jobs than it destroys. One study1 published this year found that the changes required for the world to limit warming to well below 2 °C would generate an extra 5 million jobs in the energy sector by 2050 — an increase of roughly 24% compared with the job gain that would occur if current climate policies stayed in place.

Fossil-energy jobs will disappear and energy prices could increase in many places, however, so there will be clear losers unless governments step in with policies to retrain workers and protect poor people from rising energy costs, says Johannes Emmerling, an economist at the European Institute on Economics and the Environment in Milan and a co-author of the study. The fate of many politicians might well depend on whether and how quickly they can address these challenges as public demands for action increase.

“It’s certainly doable,” Emmerling says, “and I would say it’s also inevitable.”


  1. Pai, S., Emmerling, J., Drouet, L., Zerriffi, H. & Jewell, J. One Earth 4, 1026–1036 (2021).

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