What is a "heatshed"?
What a heatshed is, where the term came from, and what this newsletter will be
Our cities were built for a climate that no longer exists.
That’s the sentence I’ve been repeating in media interviews, in public and academic talks, and in discussions with policymakers. It’s also why I’m starting this newsletter.
Extreme heat is the deadliest weather hazard in the United States. It kills more people than hurricanes, floods, and tornadoes. Yet the world is less prepared for extreme heat than for other hazards, even though heat risk is rapidly increasing due to both climate change and how we plan and build our cities.
One reason we’re unprepared for extreme heat is that it’s a largely invisible hazard. Its impacts are less visually dramatic than hazards like wildfires or floods. These hazards also have hazard zones we can plan for: floods have floodplains and wildfires have wildland urban interface areas.
Another reason is that regional planning decisions that increase the urban heat island span jurisdictional boundaries. Similarly, when heatwaves occur, their impacts often span city, region, state, and even national borders, often exceeding our capacity to respond.
Until recently, there were also no dedicated heat plans, policies, or officials responsible for addressing it. The nascent efforts to address heat risk have historically been siloed off in professions like urban planning, public health, and emergency management. Compare this to other hazards, for which there are entire dedicated professions and government structures for protecting communities.
The causes of extreme heat exceed political boundaries, and the solutions to address it must span sectors and levels of government.
That is what a “heatshed” names. It’s the physical and policy scale at which heat actually operates, and therefore the scale at which it has to be planned for and governed.
heat·shed | /ˈhētˌshed/ | noun
1. The spatial and policy area across which extreme heat must be understood and governed as a shared condition — crossing city, regional, and national boundaries, as a watershed does for water. A heatshed does not stop at jurisdictional boundaries, and neither do the solutions required to address it.
2. A critical turning point at which extreme heat must be rapidly addressed to protect health and livelihoods worldwide. We are living through a heatshed moment.
— After watershed, which holds both senses: the land where all water drains and the critical moment things change forever.
Where the term “heatshed” came from
I first used “heatshed moment” in my TEDx talk, referring to a critical turning point where heat has to be addressed as urgently as any other climate risk. I then made the case for the “heatshed moment” in a commentary with Sara Meerow in the Journal of Urban Affairs, which also builds on our earlier work defining heat resilience and heat governance.
Ironically, I think the spatial and policy area comparison of a heatshed to a watershed is the more useful part of the term. We already accept that no city manages its water in isolation. We have interstate compacts, regional authorities, and decades of case law around the basic fact that water crosses jurisdictional lines. Nobody argues that a river or floodplain should respect a city boundary.
Heat behaves the same way, but we plan for and govern it as though it doesn’t.
What this newsletter is
It's summer in the Northern Hemisphere, and climate change is reliably breaking temperature records again. Most of the coverage on extreme heat still repeats the same beats I see year after year, with more headlines on how many temperature records were broken and how many people died. That’s necessary, but it’s not enough. The harder questions are the ones after that. How will we better prepare for the next inevitable record-breaking heatwave? How do we plan our cities better to reduce the urban heat that is within our local control? What lessons can we learn from the places that have already started addressing heat?
That’s what I work on, and that’s what this newsletter will be about: how we plan for and govern extreme heat. Sometimes from my research, sometimes from observations of policymaking, sometimes from the field.
What to expect
I’m an academic, and let’s be honest, I’m used to having my writing thoroughly peer reviewed and published at the speed of peer review (hint: not fast). This is my attempt to experiment with the opposite — to think in public and at the speed at which extreme heat is actually happening.
Some posts will be a full-fledged argument. More often, they will be my response to a timely extreme heat topic, a snippet from something longer I’m working on, or a question I don’t have an answer to yet.
I’ll aim to post monthly, for now.
It’s free, and it will stay free.
If that sounds useful, subscribe below. And if you know someone who wants to address the challenge of extreme heat, send it their way.
— Ladd
Good post, Ladd. I really like your definition of heatshed, and will use that terminology in my posts as well. I'm excited to read more of your articles soon.