Jupiter and CMIP6: Unlocking the Next Generation of Global Climate Models
The most recent update to ClimateScore Global™ cemented Jupiter as the first provider of climate data from the sixth Coupled Model Intercomparison Project (CMIP6).
These models, which will power next year’s sixth report from the Intergovernmental Panel on Climate Change, represent seven years of innovation in the climate community. They also shift climate scenarios from Representative Concentration Pathways (RCPs), which considered Earth’s response to varying levels of radiative forcing, to Shared Socioeconomic Pathways (SSPs), which tie the world’s actions to radiative forcing and then to climate change. These SSPs illustrate the interconnectedness of transition and physical risks, and they are a powerful framework for corporations seeking to understand the breadth of climate risks and opportunities that they face.
It’s an exciting time in the climate community. With next year’s sixth report from the Intergovernmental Panel on Climate Change inching closer, the global climate models that will support its conclusions, from the sixth Coupled Model Intercomparison Project (CMIP6), are just now releasing results. The CMIP6 data archives are much richer than those of CMIP5, with more models and ensembles contributing their perspective on Earth’s changing climate. And not only do these models represent more than seven years of innovation — a lifetime in such a dynamic field as climate science — but the models also incorporate Shared Socioeconomic Pathways, which provide additional context for how greenhouse gas emission scenarios are tied to socioeconomic conditions globally. These new climate scenarios will help users think more broadly and consistently about the climate crisis.
This October, Jupiter released version 2.0 of ClimateScore Global, which models physical climate risk everywhere in the world. With this release, Jupiter became the first climate data provider to put these new CMIP6 models and scenarios in the hands of users as the bedrock for our models of future flooding, extreme wind, heat, hail, drought, wildfire, and precipitation. So how will CMIP6 make a difference for users? What is to be gained? Here, we discuss the implications of the update and in particular the new Shared Socioeconomic Pathway. Next month, we’ll discuss how this information can be turned into the foundation for disclosures in the TCFD, PRA, and other frameworks.
Given the rapid advances in the field, it is important for climate data users to seek out the latest consensus science from the community. For example, the newest global climate models (GCMs) expect between 0.4°C and 0.9°C of additional warming by the end of the century, even when holding constant Earth’s radiative forcing (a measure of Earth’s ability to trap heat based on greenhouse gas concentrations, land use, and other factors). Even the RCP 2.6 scenario, which was designed under CMIP5 to keep warming well under 2°C by 2100, now results in a mean warming of 2.1°C across CMIP6 models. Users trying to estimate how their business could be affected by climate change — and in particular, those running stress tests — should pay special attention to these effects.
The newest GCMs also benefit from seven further years of data. CMIP6 models commence simulations in 2014, while CMIP5 start from 2007. These seven additional years of emissions, land use, sea level, and more have led to different models for radiative forcing trajectories. In particular, achieving an RCP 2.6 scenario will require stronger mitigation efforts in later years, given the weaker-than-expected efforts to limit emissions over the past 13 years. On the other hand, scenarios resulting in higher warming are more likely. The updated models provide much more realistic estimates for how climate change might play out, which helps users make more practical business decisions today and provide more realistic estimates to their shareholders and regulators.
The CMIP effort standardizes GCMs in ways that make their results easier to compare. It includes a few practical features (e.g., data is available from a central repository and variable names are consistent), and, critically, it specifies scenarios for how the remainder of this century and beyond could play out.
Under CMIP5, these scenarios were specified as Representative Concentration Pathways: how the “radiative forcing” would change over time. Scenarios such as RCP 8.5 are so named because they result in an additional 8.5 Watts per square meter of radiative forcing by the end of the century. Each GCM took the “pathway” of rising radiative forcing as an input to their simulations; the outputs were the resulting changes in temperature, precipitation, and other factors. This helped the GCMs speak the same language: researchers could view several opinions for how the same amount of forcing could lead to different air temperatures, ice melting, precipitation patterns, and more around the world.
A key feature of the CMIP6 models is the inclusion of new Shared Socioeconomic Pathways (SSPs). In CMIP6, we can see how certain socioeconomic conditions can be linked with radiative forcing, and how that forcing in turn causes the climate to change. In CMIP5, the radiative forcing trajectory was taken as a given, and the only variable was the degree to which the climate changed. This has given CMIP6 models much more flexibility to explore how humans might affect the climate: how much energy is generated from fossil fuels vs. renewable sources? How much do we preserve our rainforests? How well do we succeed at mitigating climate change or are our efforts focused on adapting to it? How do our institutions and populations respond, and how does this differ between developing and developed countries? These factors were distilled into five socioeconomic pathways.
With the SSPs determined, modelers then had to determine which SSPs could lead to future radiative forcing scenarios: the old RCPs. By combining economic, social, and simplified climate models, researchers evaluated what conditions could lead to emissions that are consistent with particular physical climate change scenarios. For example, SSP5 — in which the world continues to burn fossil fuels at a rapid rate — was found to be the only scenario that could result in RCP8.5 levels of radiative forcing and a warming of more than 4°C by 2100; all other scenarios lead to less forcing and less warming. Conversely, SSP1 — in which the world prioritizes sustainability — could result in as little as 1.9 or 2.6 Watts per square meter of forcing and less than 2°C of warming. To express these relationships, pairs of socioeconomic pathways and representative concentration pathways are written together: SSP5–8.5, for example.
Towards a Combined View of Physical and Transition Risk
The new SSP-RCP framework is incredibly powerful because it gives users a consistent language to tie the actions of the world to the consequences for the planet. This is critical for companies conducting scenario analysis. Under the old RCP framework, users conducting stress tests were guided to the most extreme scenario (RCP 8.5) simply because it stressed their balance sheet the most. But with SSP-RCP pairings, users can create more realistic situations: for example, they can use the SSP to determine how their firm is affected by conforming business practices to a < 2°C world and then couple that information with the physical risk of a world that will eventually be 2°C warmer. In other words, it helps users build scenarios that harmonize varying degrees of transition risk with the resulting physical risk. In the past, users discussed transition risk scenarios like “hothouse world” and “disorderly transition,” and the physical risk was linked purely to the amounts of radiative forcing. But now, users can see the collective impact on their balance sheet of both sources of risk: how sharper reductions in carbon usage (higher transition risk) lead to lower radiative forcing (lower physical risk) and vice versa.
The world faces complex choices as it seeks to blunt the impact of climate change while also allowing our economies to thrive. With CMIP6 and the new SSP-RCP framework, these trade-offs are laid out alongside each other for the first time. Jupiter is excited to incorporate these new models as a key component of our climate projections and put years of scientific research in the hands of our users so that they can understand these risks.