If we’re to adapt to our changing climate and to increase our resilience to the impacts of climate change, we need to have at least a reasonable idea of what our future climate might look like. We need to know what future to prepare for.

However, when it comes to our climate, the future is inherently uncertain. We don’t know what we’re going to do when it comes to greenhouse gas emissions. We don’t know how the climate will respond. And we don’t know how the myriad complexities that make up our climate systems will interact with each other.

But we can’t just wait around to see what happens. We need a way of cutting through the uncertainty and of getting a feel for what the future might hold. This is where climate scenarios come in.

Determining plausible futures

In planning terms, a scenario is a broad-brush idea of a potential future. It’s descriptive in nature and brings together a range of relevant factors that play a role in determining what the future might look like.

Scenario planners usually posit a suite of scenarios, depending on how they think things will pan out. Such scenarios are not definitive. And they don’t usually come with probabilities attached. But they do, at least, help to get us thinking about what the future might look like and how we might respond in each of the scenarios highlighted.

To determine a suite of plausible scenarios, we need to understand the main factors that will influence what the future might look like. When it comes to climate change, the key determinant of current and future climate impacts is global temperatures. And these are driven by greenhouse gas emissions and the concentration of such gases in the atmosphere.

Consequently, the most commonly-used climate scenarios tend to focus on these factors. After all, there’s a clear scientific consensus that greenhouse gas emissions are driving global temperature rises. We have a good understanding of the relationship between emissions, temperatures and a range of other climate-related factors. And researchers have developed powerful models that allow us to quantify the impact of a range of emissions trajectories on our global climate.

Emissions trajectories

We’ll look here at three popular sets of climate scenarios, which feature prominently in the way scientists and governments think about how our future might look. I’ll also highlight a fourth approach, which I really like because it looks at things in a slightly different way.

The first set of climate scenarios has been developed by the Scenario Model Intercomparison Project (ScenarioMIP), which is part of the World Climate Research Programme’s Coupled Model Intercomparison Project.

The ScenarioMIP approach proposes a series of likely future emissions trajectories, i.e. how we increase or decrease our greenhouse gas emissions over time. Researchers engaged in the project then run supercomputer-driven climate models that simulate the physics, chemistry and biology of the Earth’s atmosphere, land and oceans. This allows them model impact of these emissions trajectories on global mean surface temperatures.

The ScenarioMIP project focuses its analysis on seven potential emissions trajectories:

High (H): We roll back current climate policies and greenhouse gas emissions increase.

High-to-low (HL): Emissions rise at first, but are cut sharply in the second half of the century to reach net-zero by 2100.

Medium (M): Emissions remain consistent with current climate and carbon-reduction policies.

Medium-to-low (ML): Emissions are reduced slowly, eventually reaching net-zero emissions by the end of the century.

Low (L): Emissions are held at a level that is consistent with keeping warming below 2 degrees Celsius.

Very low (VL): Emissions are cut to a level that limits warming to close to 1.5 degrees Celsius by the end of the century, with limited overshoot beforehand.

Low-to-negative (LN): Emissions fall slightly slower than in the VL scenario, with temperatures just rising above 1.5C. Emissions then drop rapidly to negative to bring warming back down.

You’ll note that that the descriptions of the latter three of these scenarios (which I’ve paraphrased here for the sake of clarity) define the emissions trajectories in terms of their impact on global temperatures.

This seems like a bit of a cop-out, really, as these trajectories have evidently been created by working backwards from the desired result. But I can understand that the researchers are keen to include scenarios that reflect the 1.5 and 2 degree warming targets that form a key part of many countries’ climate policies.

The modelling of these scenarios yields the following results. The chart on the left shows the emissions trajectory in each scenario and the chart on the right shows the likely increase in global mean surface temperature above the pre-industrial average.

Source: Van Vuuren, D. P. et al. (2026) The Scenario Model Intercomparison Project for CMIP7 (ScenarioMIP-CMIP7), Geosci. Model Dev., 19, 2627–2656.

For example, the ‘High’ emissions trajectory is projected to result in a temperature rise of about 3-4 degrees by 2100 and 4-5 degrees by 2150. And all of the emissions trajectories project a temperature rise of more than 1.5 degrees (albeit in some cases only temporarily), which is regarded as ‘safe’ level of global warming.

Something important to note is that these – and other – climate scenarios don’t tell us what we should be doing. They simply provide us with information on the likely impact of different emissions trajectories on future global mean surface temperatures. What we and our governments choose to do with this information is up to us.

Concentration pathways

The second set of climate scenarios has been created through the use of Representative Concentration Pathways (RCP), which have been developed collaboratively by a multidisciplinary team of scientific researchers and social scientists.

The RCPs differ from the emissions trajectory scenarios outlined above in that they focus on the concentration of greenhouse gases in the atmosphere and its impact on what’s known as radiative forcing, which is a measure of the change in the balance of energy flowing into our planet’s atmosphere.

In broad terms, an increase in greenhouse gas concentrations leads to an increase in radiative forcing, which in turn leads to higher global temperatures.

There are four RCP scenarios, which (in case you’re interested) are named after the expected changes in radiative forcing values (in watts per square metre) in each scenario from the year 1750 to the year 2100.

The four scenarios, the descriptions of which I’ve paraphrased slightly for clarity, are as follows:

RCP2.6: Radiative forcing peaks at ~3 W/m² (~490 ppm CO₂ equivalent) before 2100 and then declines to 2.6 W/m2 by 2100.

RCP4.5: Radiative forcing rises and then stabilises at 4.5 W/m² (~650 ppm CO₂ equivalent) after 2100. This is the most probable baseline scenario (i.e. what happens if we don’t implement any climate policies), taking into account the fact that we’ll (presumably) run out of fossil fuels at some point.

RCP6.0: Radiative forcing rises and then stabilises at 6 W/m² (~850 ppm CO₂ equivalent) after 2100.

RCP8.5: Radiative forcing rises to 8.5 W/m² (~1370 ppm CO₂ equivalent) by 2100. This is generally taken as the basis for worst-case climate change scenarios. There is, however, suggestion that this scenario is no longer plausible, given global pressure to reduce emissions.

This is how the different scenarios look in terms of greenhouse gas concentrations. Each of the three charts below looks at a different greenhouse gas: carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O). The overall impact is, of course, cumulative.

Source: van Vuuren, D.P. et al. (2011) The representative concentration pathways: an overview, Climatic Change 109, 5.

Climate modellers suggest that the likely impact of each of these scenarios on global mean surface temperatures (by around 2100) would be as follows. The figures in brackets represent the range of plausible temperatures generated by the underlying models.

Here are the potential ranges of temperature increases for each of the scenarios shown visually:

There are obviously clear links between the two sets of scenarios discussed so far, as they’re ultimately both driven by greenhouse gas emissions. And it’s clear that, as you would expect, the two sets of scenarios paint a fairly consistent picture of potential global mean surface temperatures at the end of this century.

Socioeconomic pathways

The third main set of climate scenarios comes at things from a different direction. The Shared Socioeconomic Pathways are a suite of scenarios that were set out in the Sixth Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC).

Rather than focusing on the impacts of our actions on greenhouse gas emissions and concentrations, the Shared Socioeconomic Pathway (SSP) scenarios focus on our actions themselves. In doing so, they’re essentially taking a step back from the drivers of the scenarios discussed previously, to think about how we got there in the first place.

There are five SSPs. I’ve summarised the definitions, because the ones used by the IPCC are quite lengthy.

SSP1 Sustainability / Taking the green road: The world shifts gradually, but pervasively, toward a more sustainable path, emphasizing more inclusive development that respects perceived environmental boundaries.

SSP2 Middle of the road: The world follows a path in which social, economic, and technological trends do not shift markedly from historical patterns.

SSP3 Regional rivalry / A rocky road: A resurgent nationalism, concerns about competitiveness and security, and regional conflicts push countries to increasingly focus on domestic or, at most, regional issues.

SSP4 Inequality / A road divided: Highly unequal investments in human capital, combined with increasing disparities in economic opportunity and political power, lead to increasing inequalities and stratification both across and within countries.

SSP5 Fossil-fuelled development / Taking the highway: This world places increasing faith in competitive markets, innovation and participatory societies to produce rapid technological progress and development of human capital as the path to sustainable development.

The likely impact of each of these scenarios on atmospheric CO₂ concentrations is as follows:

And here’s the impact on global mean surface temperatures:

Targets, policies and action

Each of the three sets of scenarios considered so far explores the impact of different courses of action on greenhouse gas emissions (or concentrations) and global temperatures. But what they don’t do is relate any of this to what we’re actually doing to reduce greenhouse gas emissions and to mitigate the impact of climate change.

Consequently, I’m a big fan of the Climate Action Tracker (CAT), which is an independent science-led project that monitors the actions that governments around the world are taking to reduce greenhouse gas emissions and to comply with the various agreements they’ve signed up to.

The CAT produces its own emissions pathway scenarios, which focus on:

• what countries have said they’ll do;

• what they are doing;

• what they could do if they tried (the ‘optimistic scenario’); and

• what they’d need to do to keep temperature rises below 1.5 degrees.

The likely impact of these different scenarios on greenhouse gas emissions and global temperature rises is as follows:

Source: Climate Action Tracker, https://climateactiontracker.org/global/emissions-pathways/

The CAT scenarios move beyond just the science of greenhouse gas emissions, to embrace the political aspects of what we’re actually doing about climate change. This makes them perhaps a little more challenging for scientists and politicians alike to embrace. But, in my view, they present us with valuable information in a clear and insightful way.

Limits and challenges

The scenarios that we’ve looked at here are, without doubt, informative and insightful. They give us a clear idea of the likely range of temperature increases over the course of this century, indicating that we can probably expect global mean surface temperatures to rise by between one and five degrees Celsius, depending on what and how much we do to rein in greenhouse gas emissions.

Each of these scenarios is based on complex, science-based and extensively peer-reviewed quantitative models. They draw on a fairly decent understanding of the impact of greenhouse gas emissions and other factors on global temperatures. But they are, nevertheless, models. They are simplified versions of reality.

While the models used by climate scientists are improving all the time, we don’t know everything. The potential impact of various climate ‘tipping points’ remains, in many cases, uncertain. Nations that had previously espoused commitments to reduce greenhouse gas emissions are, in some cases, rolling these back. And there is always the risk of ‘unknown unknowns’ – things we didn’t know we didn’t know.

The focus in the climate models on global mean surface temperatures also disguises the fact that temperature increases will not be uniform across the planet. A mean rise of two degrees might not sound that much (although it would, in fact, be fairly catastrophic), but it could easily result in increases in certain parts of the world of several times that.

The climate models also, in most cases, look only to the end of this century. However, climate change is not going to stop just because the calendar has reached a round number. Any warming trend is likely to continue, if we do not do enough to address the underlying causes. And so a two or three degree increase in temperature by 2100 would not be the end of the story. Not an issue for most of us, of course, but something of considerable concern to our descendants.

We must not forget, either, that climate change is not just about rising temperatures. Because such temperature rises will bring with them a whole host of other climate impacts, from physical changes to our weather patterns to political, industrial, economic and social challenges, from changing patterns of crop growth to climate-driven migration.

From data to action

These and other climate models remain, nevertheless, important. But our aim is not, ultimately, simply to get increasingly better models. To create an ever more precise picture of how bad things will get. That’s like rearranging the deckchairs on the Titanic.

We need to actually use what the models are telling us to take action. To mitigate against, to adapt to and to improve our resilience against the impacts of climate change.

Do any of the scenarios we’ve looked at here tell us what the future will look like? No, they don’t. But they do tell us how the future might look. At least, in terms of greenhouse gas emissions and global mean surface temperatures, which in turn drive many other climate impacts.

Being based on robust science and comprehensive modelling, they also provide us with a sound basis for getting to grips with where we’re at and for analysing how things might progress over the course of the rest of this century. They also, critically, provide us with insight into the likely range of climatic conditions for which we must prepare.

Dear Patron,

A very warm welcome to The Berenson Report. My name’s Simon Perks and I’m The Berenson Report’s founder and editor-in-chief.

I’d like to start this, my very first patrons-only monthly editorial newsletter, by thanking you for your support. In founding The Berenson Report, I’m setting off on a journey. And I’m delighted to have the pleasure of…

Read more

A very warm welcome to The Berenson Report. My name’s Simon Perks and I’m The Berenson Report’s founder and editor-in-chief.

The Berenson Report is your trusted source of insight, analysis and critical thinking on the impact of our changing climate on the way we live our lives, how we can adapt to the changes we’re experiencing and how we can enhance our resilience to the more significant changes that are yet to come.

Whether you’re a policymaker, a business leader, a researcher, an activist or simply someone who cares, The Berenson Report is for you. Read on to find out more about what I’m doing, why I’m doing it and how you can get involved.

The climate crisis

It’s a fact that the burning of fossil fuels and other human activities have increased substantially the amount of carbon dioxide and other greenhouse gases in the Earth’s atmosphere. It’s also a fact that this increase in atmospheric greenhouse gases has led to significant changes in the climate systems and process of the planet that we call home.

Before we started burning fossil fuels in industrial quantities, the concentration of carbon dioxide in the Earth’s atmosphere was about 280 parts per million (ppm). A ‘safe’ level of atmospheric carbon dioxide, which would allow us to maintain a reasonably stable climate, is regarded by climate scientists as about 350ppm.

We passed that threshold in 1990. We’re now at 430ppm. And despite repeated commitments from governments around the world to reduce carbon emissions, we’re collectively adding another couple of ppm every year. In fact, we’ve stopped talking about the 350ppm threshold now. Instead, we’re talk about 450ppm or 550ppm scenarios.

The impacts of this are severe. Global mean surface temperatures are hovering around 1.5 degrees Celsius above the pre-industrial average. And they’re set to rise further. Anywhere from 2 degrees to 5 degrees by the end of this century, depending on how much action you think we’ll take between now and then. And this is just by 2100. Rising temperatures won’t stop just because the calendar has hit a round number.

Changing climate, human impact

The increasing temperature is playing havoc with our climate systems. We’re seeing warmer air, warmer land masses and warmer oceans. Sea ice and glaciers are melting. Ocean levels are rising. The water in our oceans is becoming more acidic. Ocean currents are changing. Weather patterns, at both a global and a more local scale, are becoming more extreme. We’re seeing more – and more serious – heatwaves, wildfires, floods and more.

Our changing climate is also having a substantial impact on the way we live our lives. Water supplies to various parts of the world are at serious risk of drying up. Crops that once grew reliably in particular areas are struggling. Long-standing fisheries are failing. The habitable regions of pests and diseases are expanding. Heat stress, tempestuous weather and flooding are damaging our infrastructure. Millions face food insecurity. Millions more face conflict. Climate-driven migration is on the rise.

And this is just the start. As global temperatures increase and the effects become more severe, it’s possible that we’ll reach various natural ‘tipping points’ that make things even worse. We may also find that our ability to adapt to these climate changes in a gradual way becomes more difficult, if not impossible. Our energy networks, our supply chains, our financial systems and other essential elements of the infrastructure that we rely on for our day-to-day lives could – one day, and if we do nothing about it – quite simply cease to function.

More than mitigation

Our attention has, until now, focused primarily on mitigation. On reducing our emissions of carbon dioxide and other greenhouse gases, so as to limit global temperature rises to a manageable level. This is, of course, an important thing to do. Every barrel of oil that we don’t burn and every kilogram of carbon dioxide that we avoid putting into the atmosphere will make things easier for us – and for the other species that call Earth home – in the long run. It will, quite literally, save lives.

But it’s no longer enough. We’ve already done irreparable harm to our climate. The changes that we’re seeing around us are ‘baked in’. And we can’t (in all likelihood) undo them. Furthermore, the damage that we’ve already done is going to have further impacts that we’re probably not going to be able to avoid. Even if we were to stop burning all fossil fuels tomorrow, things would still get worse.

And so, in addition to thinking about ways to mitigate the impacts of climate change, we need also to think about how we can adapt to the changes that we’re facing and to make ourselves – together with our communities and societies – more resilient to those that are to come. Because our climate is changing. And we’re going to need to change, too.

This is where The Berenson Report comes in.

Introducing The Berenson Report

The Berenson Report explores the impact of our changing climate on the way we live our lives. On our families and communities, our jobs, our political and economic systems, our industrial and financial markets, our energy and travel infrastructure, our military readiness and national defence, our homes, our sport and leisure activities and much, much more.

It also, perhaps more importantly, considers what we need to do to adapt to the changes that we’re already experiencing. And on how we can enhance our resilience to the much more significant changes that are yet to come.

The Berenson Report is based in the United Kingdom, with a European focus and a global outlook.

Whether you’re a policymaker, a business leader, an academic researcher, a social entrepreneur, an investment manager, an advisor, a climate activist, a student or just someone who’d like to learn more, my aim is to bring you insight, analysis and critical thinking that will help you to make informed decisions about the future. Independent, objective and evidence-based. And presented in a thoughtful and (hopefully) engaging way.

Because we need better ideas

Why am I doing this? Quite simply, because I have as many questions as you do. And I’m determined to find answers.

The Nobel Prize-winning economist Milton Friedman wrote that:

“Only a crisis - actual or perceived - produces real change. When that crisis occurs, the actions that are taken depend on the ideas that are lying around. That, I believe, is our basic function: to develop alternatives to existing policies, to keep them alive and available until the politically impossible becomes the politically inevitable.”

We’re in crisis. And it’s only going to get worse. But we’ve been so focused on combating the crisis itself – or, in some cases, on pretending that it’s not happening – that we’ve not really thought about how to respond to its impacts. And when we do, we’ll reach for whatever ideas might be lying around.

My aim with The Berenson Report is to help to ensure that those ideas are good ones.

A bit about me, the founder and editor-in-chief

I should probably take this opportunity to introduce myself. As I wrote earlier, my name’s Simon Perks and I’m The Berenson Report’s founder and editor-in-chief.

I have a background in political philosophy, public finance and the physical sciences. Academically, I have degrees in politics and physics. I’m two different sorts of chartered accountant. And I’m a graduate of the Oxford Climate Emergency Programme at the University of Oxford’s Saïd Business School.

Professionally, I’ve worked for twenty five years as an advisor to governments and other public sector organisations. Alongside this, I ply my trade as a science writer, exploring the scientific impact of developments in politics, economics and society. And, likewise, helping people to understand the practical implications of scientific developments and discoveries.

I live in Somerset, in the south west of the United Kingdom, with my wife and our Labrador dogs. When it comes to our own lives, we try to practice what we preach. In addition to our professional activities, my wife and I run what I call a ‘sort-of’ homestead, where we grow much of our own food, generate much of our own energy and try to live in an eco-friendly, climate-conscious way.

I’m keen to weave together these various strands of my life in a way that helps me and others to respond to the growing impacts of climate change. And The Berenson Report seems like the ideal way to do it.

What The Berenson Report does

At the heart of The Berenson Report is my free fortnightly email newsletter. In each issue, we’ll explore a particular theme relating to the impact of climate change, how we can adapt to it and how we can improve our climate resilience.

This’ll include ‘big picture’ themes like politics, economics and industrial strategy, as well as more personal ones like careers, community and psychological resilience.

By subscribing to the newsletter, you’ll get information, insight and analysis, direct to your email inbox. As well as ideas, opinions and critical thinking that will help you to get to grips with the topics we discuss, to assess their impact on the things that are important to you and to make informed decisions for the future.

Subscribe now

The newsletter, together with access to back issues, is – and will remain – absolutely free to anyone who wants to read or subscribe to it. Because the things we’ll be discussing are far too important to put behind a paywall.

But I do need to generate at least a small amount of income, so that I can cover the costs associated with running The Berenson Report and so that I can devote sufficient time to it to bring you the depth, breadth and quality of insight and analysis that we all need.

Consequently, I’m offering a reader-supported model, with paid-for options that unlock additional value for you and that help me to keep things running.

Added value for paid subscribers

My paid subscriber tier (with monthly and annual payment options) allows you to engage more deeply with the themes, topics and issues that we cover in The Berenson Report.

In addition to the fortnightly newsletter, paid subscribers receive:

• quarterly thematic deep-dive reports on critical issues relating to climate adaptation and resilience, such as energy, housing and migration;

• my annual ‘climate outlook’ report, bringing together the latest scientific evidence about climate change, its impacts and what we can do about them; and

• my summer reading list, with my recommendations for books, reports and other reading materials for you to take with you on your holidays.

You’ll also, of course, receive the satisfaction of knowing that you’re helping to support The Berenson Report and that you’re likewise helping to keep my fortnightly newsletter freely available to everyone who wishes to read it.

And even more value for patrons

I also offer a ‘patron’ level subscription, which allows you to get more involved in my mission here at The Berenson Report and to do more to support my work.

In addition to my fortnightly newsletter and the paid subscriber benefits, patron-level supporters also receive:

• my exclusive monthly editorial newsletter for patrons, where I share insight into the inner workings of The Berenson Report and make sure you’re the first to hear about my editorial plans and other exciting projects;

• exclusive quarterly ‘ask me anything’ patrons-only bulletins, where I’ll answer any specific questions you want to ask, whether they’re about The Berenson Report itself or about climate adaptation and mitigation more broadly; and

• a one-to-one, sixty-minute phone or video call with me once a year (or an in-person meet-up, if we find ourselves in the same place at the same time) to talk about all things pertaining to climate change mitigation, adaptation and resilience.

The Berenson Report is editorially independent and is funded entirely through subscriptions from supportive readers like you. And, for the moment, from my income from my ‘day job’. The Berenson Report receives no funding from any other sources and doesn’t accept advertisements, sponsorships, affiliate relationships or any other form of paid content.

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I also have a no-AI policy when it comes to writing my fortnightly newsletter and all of the other newsletters and publications associated with The Berenson Report. So every word you read in The Berenson Report has been written, edited, fact-checked, proof-read and agonised over by a human being. Usually me.

Be part of our community

I’m keen to build a community around The Berenson Report and I welcome feedback from readers. So please do feel free to engage in the comments section at the bottom of each post on the Substack website and app. And if you want to contact me directly, just hit reply to any of the emails you receive and your message will come straight to me.

And please do subscribe to The Berenson Report to receive updates direct to your inbox. It’s a great way to show your support for what I’m doing and to help me get the message out to a wider audience. My fortnightly newsletter is absolutely free and I give you my personal guarantee that it’ll stay that way.

And if you’d like to sign up for a paid or patron-level subscription, and unlock the extra value that comes with these, then that’s even better.

Climate change is the biggest challenge that we’ve ever faced. And while we need to continue to do everything we can to mitigate its impact, we need also to adapt to the changes that are already happening. And to make ourselves more resilient to those that are yet to come.

We have quite a task ahead of us.

So let’s get started.