This is the first story or post I personally have read on the IPCC’s Coupled Intercomparison Project (CMIP) round 7. I’m sure people who do climate science for a living are all over it. But I am not exactly a layperson – I’m an engineer who should aware of and probably incorporating climate science into my daily work. And not to brag but I am an engineer who has done Ph.D.-level research on how to use climate science and climate modeling outputs in daily engineering work. So if this is only on the periphery of my awareness, it is nowhere in the awareness of the typical intelligent and educated engineer out there designing the infrastructure that is going to be in place for the next decades to century in our cities.

As climate folk will know, the community is currently embarking on a new round of climate model simulations to support analyses and projections for the next IPCC report (due in 2028/9). This new effort has been dubbed CMIP7, because it is the sixth iteration of the CMIP effort (IYKYK), that started in the late 1990s. For each of these iterations, a new set of projections has been formulated for the modeling groups to use and the ones for this round were just published (van Vuuren et al., 2026).

For those who don’t know, the scenarios mentioned here are the inputs to the global circulation models that actually give us projections of what the global climate might look like under various…er…scenarios. Here is the abstract of the reference mentioned above:

The Scenario Model Intercomparison Project for CMIP7 (ScenarioMIP-CMIP7)

Scenarios represent a critical tool in climate change analysis, enabling the exploration of future evolution of the climate system, climate impacts, and the human system (including mitigation and adaptation actions). This paper describes the scenario framework for ScenarioMIP as part of CMIP7. The design process, initiated in June 2023, has involved various rounds of interaction with the research community and user groups at large. The proposal covers a set of scenarios exploring high levels of climate change (to explore high-end climate risks), medium levels of climate change (anchored to current policy action), and low levels of climate change (aligned with current international agreements). These scenarios follow very different trajectories in terms of emissions, with some likely to experience peaks and subsequent declines in greenhouse gas concentrations. An important innovation is that most scenarios are intended to be run, if possible, in emission-driven mode, providing a better representation of the earth system uncertainty space. The proposal also includes plans for long-term extensions (up to 2500 AD) to study slow climate change-related processes, and (ir)reversibility. This proposal forms the basis for further implementation of the framework in terms of the derivation of climate forcing pathways for use by earth system models and additional variants for adaptation and mitigation studies.