The Honest Broker

Build your own climate scenario

This site allows you to build your own climate scenario and compare it to the newly-released CMIP7 scenarios that will underlie climate research and policy for many years. Your choices for — variables can produce — different scenarios*. The tool is based on methods I first described in my book The Climate Fix (2010) and have expanded on in recent years at The Honest Broker at Substack. Explore the tool and then tell me how to improve it (or if you find any errors). Honest brokering is a group activity.

Start from a scenario

Then move the sliders to build your own.

Or visit each of the Learn More pages from the buttons below to understand each scenario element and produce a more informed input to your bespoke scenario.

A note on uncertainties: This dashboard provides central estimates of projected warming from a curve fitted to FaIR v2.2 runs of the seven CMIP7 marker scenarios. The approximation of the CMIP7 scenarios uses cumulative CO₂ and 2100 methane, so two trajectories with the same cumulative total give the same warming, another simplification. These results are illustrative only. Full ESM runs will have considerable uncertainties and a range of values around their central estimate, based on factors such as model design, data uncertainties, parameterizations, assumptions, and more. Caveat lector!

Methodology (PDF) — every number, source and calculation behind this site.

Whatever you type here names your line on the chart, in the table and on everything you download.

The Honest Broker
Data: ScenarioMIP CMIP7 marker scenarios; Energy Institute, World Bank and Global Carbon Budget Analysis by Roger Pielke Jr., The Honest Broker
Cumulative CO₂, 2025 to 2100
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Warming in 2100 above 1850–1900
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Added warming from now
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Your 2100 world looks like
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The Honest Broker
Data: Energy Institute, World Bank and Global Carbon Budget for the observed rates; ScenarioMIP for the CMIP7 HIGH column Analysis by Roger Pielke Jr., The Honest Broker

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