The scenarios aren't predictions, so they're not "right" or "wrong". They are possible futures depending on our actions. The good news is that emissions are now tracking below older "business-as-usual" pathways because of climate policy in spite of Trump: thebulletin.org/premium/2025...

Future carbon emissions scenarios will be determined by politics. The warming *associated with* those scenarios will be determined by physics. If you fail to acknowledge the fundamental difference between these two things, you're either as dim-witted or dishonest (or both) as Donald Trump.

Climate change: From the deep past to the distant future The science about where we are going is more settled than the public conversation suggests. The uncertainty that actually matters is which version of the future we choose. New essay, with three figures: justdean.substack.com/p/climate-ch...

While the usuals are overhyping the not new result that RCP8.5 is implausible this century, many things are on the table beyond 2100 and allowing for carbon cycle feedbacks. Fossil fuels use and reserves are uncertain. The climate story is still tied to human decisions.

My latest Substack introduces the 10,000 Year Anthropocene Loop — a visual synthesis of what the deep past and deep future tell us about the journey ahead. From the 1850 hinge point through the 2100 U-turn and back to geological equilibrium. The road back is long and uncertain.

With the new NMME model update, even the more conservative relative Oceanic Nino Index metric now has us roughly tied with 1998 and 2026 El Nino events: dashboard.theclimatebrink.com#enso

The arc of the scenario universe is long, but it bends inevitably toward more realistic emissions. A new paper outlining the emissions scenarios we will be using in the upcoming IPCC AR7 report notes that "the CMIP6 high emission levels (quantified by SSP5-8.5) have become implausible".

"Clark et al. (2016) showed that decisions made in the next few decades will lock in sea level rise, ice sheet loss, and temperature change that persist for thousands of years — well beyond any planning horizon human civilization has ever contemplated."

I am pleased and honored that my post, Human-caused climate change is unmistakably distinct from Earth’s natural climate variability, was reposted by Skeptical Science today, April 14th. skepticalscience.com

This is the paleoclimate CO₂–temperature relationship zoomed out to show the full range of Cenozoic climate states — from deep ice ages near 175 ppm and 8°C, all the way to the Eocene hothouse at over 1200 ppm and 33°C.

Once more but with feeling this time! justdean.substack.com/p/human-caus...

I have now annotated my canonical GMST vs CO2 diagram to try and make the message clear at a glance. Modern climate change has driven Earth into a CO2-temperature space with no analog in 66 million years of Earth history. justdean.substack.com/p/unpreceden...

Really interesting figure putting present and future climate change in context with paleoclimate data Read the details on his substack here: open.substack.com/pub/justdean...

My experience with the DOE Climate Working Group report is that their analysis is based on cherry picking, misrepresentation, omitting contrary data, and every other scientific felony you can name. This video by Prof. David Romps shows exactly how the "bad science" sausage is made.

I have combined the previous essays into one essay, Today's Combination of CO2 and Temperature are Unprecedented in 66 Million Years. The case does not rest on models, projections, or consensus. It is written in the paleoclimate record itself. justdean.substack.com/p/todays-com...

I have revisited my previous post on Substack. I have a new post that really explores all the nuances of the equilibrium diagram. "How One Diagram Reveals the Climate Change Story" justdean.substack.com/p/how-one-di...

We are conducting an unprecedented experiment. By rapidly increasing CO₂, we’re pushing Earth’s climate away from the equilibrium it maintained for thousands and millions of years. I tried to explain the evidence clearly and visually: justdean.substack.com/p/anthropoge...