What if climate change will get much worse than we think?
There is a non-negligible chance that climate change will be catastrophic. We need to be prepared.
By Soemano Zeijlmans · Published 1/2025 · Updated 1/2025

The Course of Empire - Destruction, painting by Thomas Cole © expired, public domain
We need to be prepared in case climate change will be even worse than we expect. When we think about climate change, most discussions focus on the most likely scenarios - the steady rise in temperatures, more frequent storms, and gradual sea level rise that scientists can predict with relative confidence. But what about the climate disasters that probably won't happen, but would be catastrophic if they did? If your flight had a 3% chance of crashing, you would board it. If a bet leaves you with a 3% chance of losing your house, you wouldn’t take it. We cannot take similar risks with the impacts of climate change.
We know for sure that climate change is bad, but it might get much worse than we expect. Climate science will always have some uncertainty, and we can’t bet the future of our planet on ‘most likely’ estimates if there’s a non-zero chance of disaster. For example, climate scientists are baffled over heat records that were shattered in 2023 and 2024. If the Earth is in fact warming up much faster than we thought, we could overshoot global climate goals by several degrees. That would be disastrous.
When potential damages are massive enough, even a small chance of disaster can dominate the calculation of expected costs. Think of it this way – if there’s even a 1% chance of an outcome that would disrupt civilization, leave many people dead, and cause trillions in damage, that tiny probability multiplied by the enormous impact makes it more important than many more likely but less severe risks.
Economists and climate scientists call the potential for extreme, catastrophic outcomes “fat-tailed uncertainty”. If we draw how hot the world is likely to become if we double the amount of greenhouse gases in the atmosphere, we see that the global temperature will be a little bit more than 2 °C (3.5 °F) warmer than before the industrial revolution. However, there is a small but non-negligible chance that global warming will reach 5 °C or even 8 °C (9 °F to 14 °F).

There are three main sources of uncertainty for how bad climate change will be:
How much greenhouse gases will we emit? Luckily, future emissions are likely to be lower than we once expected. In 2020, Climate Action Tracker expected that the world would emit 54 GtCO₂e per year in 2050, but by the end of 2024 it “only” expects 49 Gt CO₂e – about 9% lower. Climate policies and actions are – slowly – starting to work. However, we should be aware that climate policies can be reversed. For example, the American president Trump has announced his intentions to drill for more oil and repeal climate policies.
How much global warming will these emissions lead to? It seems like the chance that the Earth system is much more sensitive to greenhouse gases than we thought has slightly decreased. In 2013, the IPCC estimated that there’s a 5% chance that doubled CO₂ emissions would lead to 6 °C warming or higher by the end of the century. In 2021, that was “only” 5 °C. That’s still very high, but not as high as we once thought.
How bad will the impacts of global warming be? Even if we can precisely predict how hot it will get, we don’t know how bad that will be. Climate change has both direct and indirect effects, and we don’t know for sure how bad these will be. It could lead people to flee their countries, spread infectious diseases, create political tensions, increase global conflicts, and cause food shortages.
What can we do about these extreme risks?
We don’t have to wait and hope climate change won’t be catastrophically bad. There are many things we can do to avoid this scenario or prepare ourselves in case climate change does turn out worse than expected.
First of all, we need to rapidly stop using fossil fuels and emitting zero greenhouse gases. As long as we’re burning fossil fuels and have a food system that clear-cuts forests and releases methane into the air, the Earth will keep getting warmer. Stabilizing emissions doesn’t stop global warming – we need to get emissions to zero. Think of it like a bathtub: if your bathtub is almost overflowing, simply reducing the flow isn’t a final solution. You need to turn off the faucet. This means taking bold action to transition to renewable energy and sustainable food systems as rapidly as possible.
Second, we need to be prepared for a much hotter world. That not only means adapting to current and projected impacts of climate change, but also preparing for climate disasters. For example, how can we feed the world if multiple world regions all see failed harvests in the same year? Some organisations, like ALLFED, are already researching ways to build resilience against global catastrophes and preparing adequate responses.
Finally, we need to know what happens if we pull the ‘emergency brake’ on global warming by intervening in the climate system. Through climate engineering (or geoengineering), humanity can reflect more heat to outer space or store more carbon in oceans or rocks. Climate engineering is controversial, as it could be seen as an excuse to slow climate action or could have negative unintended consequences. However, at some point, climate engineering could become a necessity, and even a single country might decide to interfere in the climate. We already need to understand what the positive and negative consequences of climate engineering will be, and ensure that decisions to intervene are taken equitably.
What can I do to make a difference?
Besides working to rapidly bring down global greenhouse gas emissions, there are several ways you can use your skills to prepare for extreme climate risks. In this section, we mainly highlight opportunities for researchers and for your career.
Rapidly reducing greenhouse gas emissions
The most straightforward way to lower the probability of extreme climate change is to bring down global emissions to zero as quickly as possible. We highlight ways you can contribute to climate change mitigation in other places on our website.
Researching the extreme risks of climate change
We need a better understanding of how bad climate change will be, and what are promising approaches to reduce these risks. This is especially relevant if you are employed in academia, or willing to switch your career to academic research. You might be a particularly good fit for this type of research if you have a background in earth sciences. If you have a background in the social sciences or economics, you can research the effects of climate change on civilisation.
80,000 Hours, a career advice charity, recommends several important research fields:
Runaway greenhouse gas effects, where increased warming leads to even further increased warming. Studying permafrost, methane clathrate, and cloud feedback loops seem especially important.
How sensitive is the global climate system to (more) greenhouse gas emissions? In other words: how likely is it that it will get much hotter than we expect?
Improving our understanding of extreme warming (more than 5 °C), such as whether it could form a threat of civilisational collapse.
How can we reduce the risks of extreme climate change?
Building resilience to climate disasters
We need advocates, lobbyists, and public intellectuals to inform governments and civil society about the importance of preparing for extreme climate change. This includes advocating for solid climate adaptation plans and ways to feed people when there are large-scale crop failures. Organisations that do this type of work are scarce, so it might be promising to start an organisation yourself, or you can try to work for a national government or the European Union.
People with many academic backgrounds can contribute to research to climate disaster resilience. ALLFED has listed important research questions specific to food resilience, and has a database with research projects with a need for more researchers. You can contribute to these questions in academia or think-tanks.
Researching climate engineering and managing its risks
If you have a background in the natural sciences or economics, you can contribute by doing research into the positive and negative effects of climate engineering and its feasibility. It is important to know whether climate engineering will work, and whether there will be major negative consequences. For example, scientists are concerned that ocean iron fertilisation – which is a type of climate engineering – could lead to harmful algae blooms. Solar radiation management – another form of climate engineering – could lead to droughts if not implemented properly. We need a better understanding of these risks in case we are left with no other choice than to use climate engineering, or if a single country decides to start climate engineering at scale.
With climate engineering being increasingly considered, the world needs an effective and equitable way to make decisions about climate engineering. Global climate engineering governance needs to ensure that climate engineering does not become an excuse to slow down emissions reductions. At the same time, we need global coordination for when and how to use climate engineering. Involving low and middle income countries in this discussion is vital, as they are hit hardest by climate change.
Organisations working on extreme risks and climate engineering
Non-profit organisations in preparing for climate disasters
ALLFED seeks to identify resilient food solutions and help governments and companies implement these solutions in case of a global catastrophe.
Non-profit organisations in climate engineering
SilverLining advocates for research into climate engineering.
The Alliance for Just Deliberation on Solar Geoengineering focuses on involving civil society and policymakers in discussions on solar radiation management (SRM) policy. It emphasizes the perspectives of climate-vulnerable countries, which are often underrepresented in global deliberations.
The International Centre for Future Generations (ICFG) is dedicated to ensuring that emerging technologies are governed transparently and equitably, benefiting both current and future generations. ICFG's Climate Intervention team focuses on fostering inclusive and accountable governance frameworks for technologies capable of altering global ecosystems and climate systems.
The Carbon Removal Standards Initiative (CRSI) provides technical assistance to non-profits and policymakers on quantifying removed carbon dioxide emissions across industries and jurisdictions.
4 Corners Carbon Coalition (4CCC) is a platform for local communities to drive carbon dioxide removal projects.
Carbon Plan analyzes the efficacy and design of carbon offsets, carbon removal, and climate risks.
Research institutes
Centre for the Study of Existential Risk at Cambridge University
Climate Knowledge Initiative at Columbia Business School
More resources
Books
Climate Shock by Gernot Wagner and Martin Weitzman (2015) describes low-probability high-negative impact climate futures and how we should act.
Geoengineering: the Gamble by Gernot Wagner (2021) provides a balanced take on the possible benefits and all-too-real risks of climate engineering.
Podcasts
Martin Weitzman discusses the non-trivial risk of a climate catastrophe in the EconTalk podcast.
Kelly Wanser on whether to deliberately intervene in the climate – an episode of the 80,000 Hours podcast about climate interventions that are already happening, the most promising ideas, and if/when they should be deployed.
David Denkenberger on using paper mills and seaweed to feed everyone in a catastrophe, ft Sahil Shah – also on the 80,000 Hours podcast.
Articles and shorter reading
Good news on climate change, a post on the EA forum by Johannes Ackva and an anonymous contributor, outlines how catastrophic climate risk has become less likely.
How engineers can work on civilisational resilience – a career advice article by High Impact Engineers
Giving Green’s reports on carbon dioxide removal and solar radiation management as philanthropic climate change strategies.
CDR Primer – fundamental of carbon dioxide removal.
Academic and technical
Weitzman (2011). Fat-Tailed Uncertainty in the Economics of Catastrophic Climate Change.