Christopher Callahan
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ccallahan45.bsky.social
Christopher Callahan
@ccallahan45.bsky.social
2.6K followers 290 following 210 posts
climate scientist, bicycle cavalry in the war on cars. iuclimateandsociety.com
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ccallahan45.bsky.social
RIP to the late Friday afternoon AGU sessions attended by 2 people 😥
screenshot with AGU saying the conference ends at 1pm friday
November 5, 2025 at 11:21 PM
ccallahan45.bsky.social
Dartmouth says no to the compact:
October 18, 2025 at 2:56 PM
ccallahan45.bsky.social
@joerirogelj.bsky.social might be the other person who has this on hand. This fig from 2016 is one way of visualizing something along these lines. From: www.nature.com/articles/nat...
September 30, 2025 at 8:46 PM
ccallahan45.bsky.social
September 23, 2025 at 5:38 PM
ccallahan45.bsky.social
September 18, 2025 at 10:16 PM
ccallahan45.bsky.social
NEW: Climate change to increase emergency department visits in California. New paper in Science Advances, led by @gouldcf.bsky.social, shows that ED visits respond linearly to temperature, increasing dramatically with warming, despite nonlinear mortality response.
www.science.org/doi/10.1126/...
increasing ED visits in california over the rest of the century because of global warming
July 30, 2025 at 6:15 PM
ccallahan45.bsky.social
July 29, 2025 at 8:34 PM
ccallahan45.bsky.social
🤔
July 29, 2025 at 8:00 PM
ccallahan45.bsky.social
I will admit that seeing this plot (fig 4) was my first real “uh oh” moment about this
June 30, 2025 at 8:18 PM
ccallahan45.bsky.social
Europe has been sweltering under a heat dome for days - the same weather system that has driven deadly heat in Europe the past. Our research has shown that with every degree of global warming, the same type of heat dome will get deadlier and deadlier.
eartharxiv.org/repository/v...
heat dome over europe in august 2003 increasing mortality from heat domes with increasing global mean temperature
June 30, 2025 at 4:26 PM
ccallahan45.bsky.social
The 2003 France heat wave was catastrophic - and, our newest estimate is that climate change killed >6,000 of those 15,000 people. Even more than 20 years ago, extreme heat mortality was inextricably tied to dangerous anthropogenic interference with the climate.

eartharxiv.org/repository/v...
June 24, 2025 at 1:23 PM
ccallahan45.bsky.social
June 10, 2025 at 12:52 AM
ccallahan45.bsky.social
NEW: Climate mitigation has huge health benefits by limiting wildfire smoke. In our new preprint, we find every million tons of CO2 reduced saves $15 million in the US via avoided smoke-related mortality. These benefits alone compensate for 25% of the IRA's abatement cost.
www.nber.org/papers/w33829
Human-induced climate change has increased wildfire risks, associated air pollution, and health damages in North America. Despite its large potential for damage, climate-induced wildfire smoke is rarely incorporated in estimates of the societal costs of climate change. We develop an integrated framework to estimate PM₂.₅ from climate-induced wildfire smoke and the associated mortality damage in the U.S. Our framework combines econometric estimates of smoke-mortality relationships, machine learning estimates of climate-smoke relationships, and econometric estimates of negative feedbacks between current and future wildfire activity. We estimate that 3°C of future warming will lead to 46,200 annual deaths associated with smoke pollution in the US, doubling estimated mortality from smoke during 2011-2020. For an additional tonne of CO₂ emitted in 2025, we estimate a partial social cost of carbon of $15.1 (95%CI: $2.5-$49.3) due to climate-induced wildfire smoke mortality in the U.S, which doubles current estimates of the U.S. domestic social cost of carbon. We estimate that smoke-related mortality benefits due to projected emissions reductions from the 2022 Inflation Reduction Act are alone equal to 25% of estimated abatement costs associated with the Act.
May 26, 2025 at 2:54 PM
ccallahan45.bsky.social
For people who said our fossil fuel producer attribution paper lets consumers off the hook: here is the drum I will keep banging
On the other hand, there are difficult political and normative questions about how to assign responsibility across the fossil fuel value chain. More than half of the emissions attributed to the top 10% of individuals arise from the consumption behavior of those individuals, and consumption decisions are constrained by political, technological, and economic structures. For example, many homeowners cannot choose the fuel that their utility uses to produce the electricity that flows through their wall sockets. Given that fossil fuel producers and electricity utilities had relatively early knowledge of global warming and engaged in campaigns of disinformation and delay to prevent emissions reductions, it may be more appropriate to assign responsibility to the producers of fossil fuels rather than the end users of those fuels. Other scientific efforts to attribute climate impacts to major fossil fuel producers may therefore be an important complement to the present work.
May 7, 2025 at 2:23 PM
ccallahan45.bsky.social
No, but this is something we discuss explicitly in the paper
April 23, 2025 at 4:38 PM
ccallahan45.bsky.social
q: why do we need noaa? a: we're about to find out
March 7, 2025 at 10:00 PM
ccallahan45.bsky.social
NEW: Mass heat mortality events are coming. In our new preprint, we project tens of thousands of deaths per week in Europe, if the weather patterns that produced heat waves historically happen again at future -- or even current -- global temperatures.

eartharxiv.org/repository/v...
thousands of excess deaths resulting from extreme heat conditions at increasing levels of global temperature
January 15, 2025 at 2:15 AM
ccallahan45.bsky.social
Guy on the right i.ytimg.com/vi/IlUGLaymh...
December 14, 2024 at 1:30 AM
ccallahan45.bsky.social
In April of last year, we published a paper in BAMS showing that warmer air temperatures increase home runs in MLB. Now, a companion analysis has been released showing the same relationship in Japanese baseball! Very cool stuff. journals.ametsoc.org/view/journal...
warmer games in nippon professional baseball (japan) have more home runs
December 6, 2024 at 10:45 PM
ccallahan45.bsky.social
On Friday afternoon at #AGU24, I'll be presenting this new (and, frankly, worrying) work of ours on extreme heat and mortality. Come see it! Poster GC53C-0380.
agu poster outlining our calculations of the mortality impacts of worst-case extreme heat impacts in europe
December 4, 2024 at 4:05 PM
ccallahan45.bsky.social
looking at every new paper breaking basic regression tools
that sign can’t stop me because I can’t read
December 1, 2024 at 2:37 AM
ccallahan45.bsky.social
I love,,, the Bay Area
weather forecast of many days of rain in a row
November 20, 2024 at 4:39 PM
ccallahan45.bsky.social
Funniest part about all of this was when the grads dug up his old posts about <checks notes> heliskiing
November 12, 2024 at 6:42 AM
ccallahan45.bsky.social
Not exactly floods but this figure from Kerry Emanuel’s 2011 paper on hurricane damage is about structural damage to buildings from winds - below a threshold the building is fine but then damage rapidly rises above the threshold

journals.ametsoc.org/view/journal...
November 7, 2024 at 3:05 AM
ccallahan45.bsky.social
Last year, western North Carolina was identified a hotspot of property overvaluation due to a lack of consideration of flood risk. So much for "safe havens" from climate change.
www.nature.com/articles/s41...
Overvaluation of residential property values as a fraction of properties' current value, from Gourevitch et al., Nature Climate Change, 2023.
October 1, 2024 at 11:04 PM