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What are the different climate scenarios?
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As the impacts of climate change become increasingly evident, understanding the possible futures that lie ahead is crucial. Climate scenarios provide a framework for exploring these futures by modeling how different actions - or inaction - could shape the world’s climate. They are essential for governments, businesses, and communities to plan and prepare for the environmental changes that are coming our way.
In this article, we’ll explore what climate scenarios are, why they matter, and how they help us navigate the uncertain future of our planet. We’ll also break down key frameworks like the Representative Concentration Pathways (RCPs) and Shared Socioeconomic Pathways (SSPs), which serve as the foundation for most global climate projections.
👉 What are climate scenarios? How do they inform our understanding of future climate risks and opportunities?
What are climate scenarios?
Climate scenarios are not predictions, but rather scientifically grounded possibilities of what the future climate could look like depending on a range of factors. These include human activities such as energy use, deforestation, and greenhouse gas emissions. By adjusting these variables in sophisticated climate models, scientists can simulate various futures and assess the potential outcomes of our actions - or inaction.
The purpose of climate scenarios is to help governments, industries, and communities plan for a range of potential future climates. These scenarios allow decision-makers to identify risks and opportunities, guiding efforts in climate adaptation and mitigation. The goal is to understand the range of possible futures, from best-case scenarios where emissions are drastically reduced, to worst-case scenarios where global temperatures rise unchecked.
At the core of climate scenarios are powerful tools called General Circulation Models (GCMs), which simulate how the Earth's atmosphere, oceans, and land systems interact. These models use physical equations to predict how changes in factors like CO2 levels or population growth will affect temperature, sea levels, and weather patterns. The scenarios generated from these models help us envision what the planet could look like in 20, 50, or even 100 years.
The evolution of climate scenarios
Climate scenarios have evolved significantly, incorporating new scientific knowledge and technological advancements. Early climate models, such as the Special Report on Emissions Scenarios (SRES), focused primarily on future greenhouse gas emissions without accounting for potential climate policies. These early models were essential in laying the groundwork for understanding how different emissions levels might shape the future climate.
However, as climate science advanced, more detailed and sophisticated frameworks emerged. The most recent climate models now include not only emissions but also socioeconomic factors such as population growth, urbanisation, and technological development. These advancements led to the development of Representative Concentration Pathways (RCPs) and Shared Socioeconomic Pathways (SSPs) - the current gold standard for projecting future climate outcomes.
These newer models provide a more comprehensive view of the future by factoring in the complex interactions between human society and the environment. For example, the SSPs consider how global progress in education, healthcare, and sustainable development might impact climate action. By integrating these broader societal factors, climate scenarios now offer more realistic insights into the challenges and opportunities ahead.
This evolution in climate scenarios has been instrumental in shaping international climate policies and helping stakeholders make informed decisions to mitigate the most dangerous impacts of climate change.
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Key types of climate scenarios
Representative Concentration Pathways (RPCs)
The Representative Concentration Pathways (RCPs) are a set of climate scenarios developed by the scientific community to explore different possible futures based on varying levels of greenhouse gas emissions. These pathways are named after the level of radiative forcing (the warming effect) they project for the year 2100, measured in watts per square meter (W/m²).
- RCP2.6: This is the most optimistic scenario, aiming to limit global warming to below 2°C. It assumes that aggressive measures are taken to reduce emissions rapidly, with CO2 emissions peaking in the 2020s and declining sharply afterward.
- RCP4.5: In this intermediate scenario, emissions peak around 2040 and then decline, leading to moderate global warming of around 2.5°C by the end of the century.
- RCP6.0: Another intermediate pathway, RCP6.0 projects a scenario where emissions peak later, around 2080, and result in global warming of about 3°C by 2100.
- RCP8.5: Often referred to as the "business-as-usual" or worst-case scenario, RCP8.5 assumes that emissions continue to rise throughout the 21st century. This pathway could result in over 4°C of global warming by 2100, with severe and widespread impacts on ecosystems, sea levels, and weather patterns.
These RCP scenarios are widely used in climate research and policy to assess the range of potential outcomes and guide efforts to prevent the most extreme consequences of climate change.
Shared Socioeconomic Pathways (SSPs)
The Shared Socioeconomic Pathways (SSPs) add an additional layer to climate scenario modeling by incorporating human development factors, such as economic growth, technological innovation, and societal shifts. These pathways consider how global socioeconomic trends will influence greenhouse gas emissions and climate change mitigation.
- SSP1 (Sustainability): This scenario envisions a world where society shifts towards sustainability, with a focus on well-being, equity, and environmental conservation. Emissions are drastically reduced, aligning closely with the goals of RCP2.6.
- SSP2 (Middle of the Road): In this scenario, development follows historical trends, with moderate progress towards sustainability and uneven global development. This pathway aligns with RCP4.5.
- SSP3 (Regional Rivalry): This scenario envisions a fragmented world where countries focus on national interests and security. Economic growth is uneven, and global cooperation on climate action is limited, leading to high emissions (aligned with RCP7.0).
- SSP4 (Inequality): This scenario highlights stark inequalities between and within countries. While a global elite drives technological innovation, a significant portion of the world faces slow economic growth and limited access to resources. Emissions can vary widely but tend to align with RCP6.0.
- SSP5 (Fossil-fueled Development): In this pathway, society pursues rapid economic growth driven by fossil fuels, resulting in high emissions and aligning with the worst-case RCP8.5.
Together, the RCPs and SSPs provide a comprehensive framework for exploring different futures, helping policymakers and scientists understand the broad range of possibilities based on human actions and policy choices.
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How do climate scenarios inform policy and decision-making?
Climate scenarios play an important role in shaping global and national policies, particularly when it comes to addressing the challenges of climate change. These scenarios provide decision-makers with critical insights into the potential consequences of different actions, helping them to weigh the risks and benefits of various policy pathways.
One of the most significant ways climate scenarios influence policy is by guiding the development of Nationally Determined Contributions (NDCs) under the Paris Agreement. Countries use climate models to understand how their greenhouse gas emissions contribute to global warming and then set targets for reducing those emissions based on different scenarios. By assessing the potential impacts of following pathways like RCP2.6 or RCP8.5, nations can design policies that align with global efforts to limit temperature increases to 1.5°C or 2°C.
In addition, scenarios like the SSPs help policymakers understand how societal and economic changes might interact with climate action. For example, a country with rapid population growth and urbanisation might focus on reducing emissions from transportation and energy, while nations with aging populations might prioritise healthcare and energy efficiency.
On a more local level, cities and businesses also rely on climate scenarios to plan for the future. Urban planners use projections from these models to prepare for sea-level rise, extreme weather events, and shifts in resource availability. Similarly, businesses in sectors such as agriculture, insurance, and energy use climate scenarios to assess risks, ensure resilience, and make long-term investment decisions.
Ultimately, climate scenarios are not just about anticipating the future - they are about empowering decision-makers to take informed, proactive steps to shape a more sustainable and resilient world. By understanding the different pathways, policymakers can design strategies that mitigate the worst impacts of climate change while capitalising on opportunities for innovation and growth.
Limitations and uncertainties in climate scenarios
While climate scenarios are invaluable tools for planning and policy-making, they are not without limitations. One of the key challenges lies in the uncertainties inherent in predicting complex systems like the Earth’s climate. These uncertainties stem from a variety of factors, including the complexity of the climate system itself, the unpredictability of human behavior, and the limitations of current models.
- Scientific uncertainty: Scientific uncertainty arises from the fact that models can only approximate the behavior of Earth's climate system. Factors like cloud formation, ocean currents, and the feedback loops between different elements of the climate system are difficult to model accurately, especially at smaller scales. Although models have become more sophisticated over time, certain variables - such as regional rainfall patterns or the intensity of future storms - remain challenging to predict.
- Scenario uncertainty: Scenario uncertainty is another significant factor. This relates to the fact that we don’t know which path society will ultimately take. Will global cooperation succeed in reducing emissions rapidly, or will economic growth continue to be driven by fossil fuels? Climate scenarios explore a range of possibilities, each dependent on different socioeconomic and policy choices.
- Natural variability: The natural variability of the climate system adds another layer of unpredictability. For example, phenomena like El Niño and La Niña can cause significant year-to-year fluctuations in weather patterns, making it harder to distinguish long-term climate trends from short-term natural variability.
- Downscaling: Lastly, while downscaling techniques allow global models to project local impacts, these localised projections often come with reduced accuracy. This can be problematic for regional planners who need precise information about how climate change will affect specific areas. For example, while global models might indicate rising temperatures, it’s harder to predict exactly how that will influence rainfall or sea-level rise in a specific coastal city.
Despite these uncertainties, climate scenarios remain essential tools. By presenting a range of possible outcomes, they help policymakers and communities prepare for various futures, enabling more resilient and adaptable planning. Understanding these limitations underscores the importance of flexibility in decision-making and the need for continued advancements in climate science.
The role of the IPCC in shaping climate scenarios
The Intergovernmental Panel on Climate Change (IPCC) plays a crucial role in the development of climate scenarios. As the leading global authority on climate science, the IPCC synthesises research from thousands of scientists and creates comprehensive reports that inform policymakers and the public about the current state of the climate and the potential futures we face.
The IPCC’s climate scenarios are particularly influential because they represent the consensus of the scientific community. Through its Assessment Reports, the IPCC uses scenarios like the RCPs and SSPs to communicate the potential consequences of different emission pathways and socioeconomic trends. These scenarios are the foundation for global climate negotiations, including the Paris Agreement, and serve as a key reference point for national governments, businesses, and international organisations in crafting climate policies.
In the IPCC’s Sixth Assessment Report (AR6), for example, the panel emphasised five key Shared Socioeconomic Pathways (SSPs) that explore a range of futures from highly sustainable development (SSP1) to fossil-fuel-driven growth (SSP5). Each scenario is paired with a corresponding level of emissions (such as RCP2.6 or RCP8.5), showing how different human choices will lead to varying levels of warming by the end of the century.
| SSP | Description | Climate Impact | Socioeconomic Characteristics |
|---|---|---|---|
| SSP1-1.9 | Sustainability: Taking the Green Road | Lowest emissions, aiming to limit warming to below 1.5°C by 2100. | Strong global cooperation, focus on sustainability, reduced inequality, high investments in education, health, and green technologies. |
| SSP1-2.6 | Sustainability (Alternative): Similar to SSP1-1.9 but slightly higher emissions | Limits warming to around 1.8°C by 2100. | Focus on sustainability, gradual reduction in emissions, strong international cooperation. |
| SSP2-4.5 | Middle of the Road: Continuation of historical trends | Emissions peak mid-century, warming reaches about 2.7°C by 2100. | Moderate progress towards sustainability, uneven economic growth, and mixed efforts in reducing emissions. |
| SSP3-7.0 | Regional Rivalry: A Rocky Road | High emissions, leading to a rise of around 3.6°C by 2100. | Fragmented world with weak international cooperation, focus on national security and resource competition, high population growth. |
| SSP5-8.5 | Fossil-fueled Development: Taking the Highway | Highest emissions, potentially leading to 4.4°C of warming by 2100. | Rapid economic growth driven by fossil fuel use, high energy consumption, and little regard for environmental sustainability. |
One of the IPCC’s strengths is its ability to integrate different dimensions of climate change - physical science, impacts, adaptation, and mitigation - into a coherent framework. By combining these perspectives, the IPCC ensures that its scenarios are not only scientifically robust but also relevant to a wide range of stakeholders, from policymakers to businesses to civil society.
The credibility of the IPCC’s scenarios comes from the extensive peer-review process and the fact that they draw on the latest climate research. As a result, these scenarios are regarded as the most authoritative guides for understanding potential climate futures and for planning long-term strategies to combat climate change.
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Examples of climate scenarios in action
Climate scenarios are not just theoretical models - they are actively being used around the world to guide policy, inform planning, and drive action. From global initiatives to local efforts, these scenarios shape how governments, businesses, and communities prepare for a changing climate.
One high-profile example is the Paris Agreement, where countries commit to limiting global temperature rise to well below 2°C, with efforts to cap it at 1.5°C. The agreement itself is based on climate scenarios developed by the IPCC, particularly those that explore pathways to reduce emissions in line with the goals of limiting warming to 1.5°C (SSP1-1.9) or 2°C (SSP1-2.6). Countries use these scenarios to inform their Nationally Determined Contributions (NDCs), setting out plans for emission reductions, renewable energy transitions, and climate adaptation strategies.
On a national level, countries like France and Germany have incorporated climate scenarios into their long-term climate strategies. For example, France’s commitment to achieving carbon neutrality by 2050 is closely aligned with the SSP1 scenarios that focus on sustainability and low emissions. By using SSPs, policymakers can understand the societal changes necessary to meet these goals, from energy transitions to shifts in urban planning and transportation.
In the business sector, insurance companies increasingly rely on climate scenarios to model risks associated with extreme weather events and rising sea levels. For example, insurers use RCP8.5 (a high-emission, worst-case scenario) to estimate the potential costs of future climate impacts, such as more frequent hurricanes or flooding in coastal areas. This helps businesses adjust premiums and investment strategies accordingly, ensuring they are prepared for various climate outcomes.
Cities are also using climate scenarios to guide their resilience planning. For example, New York City has integrated climate scenarios into its strategy for addressing sea-level rise. Using projections from both RCP4.5 and RCP8.5, the city plans infrastructure upgrades and flood defenses that will protect vulnerable areas from storm surges and flooding over the next century.
These examples showcase how climate scenarios are used to anticipate risks, allocate resources, and set goals for emissions reduction. Whether at the global, national, or local level, scenarios provide the foundation for proactive climate planning that helps societies navigate the uncertain future posed by climate change.
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The future of climate scenarios
Climate scenarios play a crucial role in understanding and preparing for the possible futures we face as the climate continues to change. By mapping out a range of potential outcomes based on different greenhouse gas emissions trajectories, these scenarios allow policymakers, businesses, and communities to anticipate risks, evaluate the impact of various actions, and make informed decisions.
From the most optimistic pathways that align with the Paris Agreement goals to worst-case scenarios that highlight the severe consequences of inaction, climate scenarios underscore the importance of immediate, sustained efforts to mitigate climate change. However, it’s essential to recognise that these scenarios are not predictions, but rather tools for exploring plausible futures. Flexibility, adaptability, and a willingness to adjust strategies in response to emerging data are vital components of using scenarios effectively.
The IPCC’s continued refinement of scenarios, particularly through the integration of Shared Socioeconomic Pathways (SSPs), has provided stakeholders with a more comprehensive understanding of how societal choices will influence the climate. Ultimately, these scenarios remind us that the future is not fixed. The choices we make today will shape the climate outcomes of tomorrow, and by using these tools wisely, we can work towards a more sustainable and resilient world.
How Greenly can help your business
As the world navigates the potential outcomes of various climate scenarios, businesses must be ready to adapt and reduce their environmental impact. Greenly is here to support your sustainability journey, offering a range of carbon management services tailored to your specific needs.
Carbon Management
At Greenly, we offer a suite of services to manage and reduce your company’s carbon footprint:
Measure Your Carbon Emissions: Get real-time data on your Scope 1, 2, and 3 emissions. Our advanced platform offers detailed tracking and reporting, giving you the insights you need to take action.
Custom Reduction Plans: Our climate experts work with you to create a personalised strategy that targets your largest emission sources, helping you implement high-impact, practical solutions.
Monitor and Report Progress: Track your progress toward net-zero goals with our user-friendly platform, ensuring that your sustainability efforts stay on course and deliver measurable results.
Supply Chain Decarbonisation
Greenly’s tools help you address emissions throughout your supply chain by increasing transparency, engaging suppliers, and transitioning to low-carbon alternatives. We work with you to ensure your sustainability efforts extend across all areas of your business.
Seamless Integration
Greenly’s platform integrates seamlessly into your business operations, enabling tracking and reporting on your environmental impact. From monitoring progress on ESG goals to managing sustainability data, our platform streamlines the process so you can focus on growing a sustainable business.
👉 Start your sustainability journey with Greenly today and make a lasting impact in the fight against climate change.
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