Have you heard the one about the frog in the boiling water?
Put a frog in a pot of boiling water and it will leap out.
But put it in cool water and slowly heat it up, and it’ll boil to death.
That’s not literally accurate - the frog would definitely try to escape in either case.
But metaphorically?
This scenario is playing out in all of our cities - just over years and decades, not
minutes.
You may be thinking - “but Cheddar, isn’t the whole world getting hotter?”
And yeah, you’re right.
But, of all the Earth’s surface, cities are getting the hottest.
And for the vast majority of us who live in cities, this spells danger, because extreme
heat is the deadliest of all weather hazards.
Even our one respite from the heat - cool nights - is disappearing in urban areas.
And unlike the frog, we can’t leap out.
Barring rapid expansion of these guys’ new hobby, we’re stuck here.
There’s nowhere to go.
Images like these are really shocking.
But in terms of overall deadliness, extreme heat beats them all.
affects people inside their homes.
You know, you don't see the images of property destruction like you would after a storm after
a heat wave.
The exact mechanisms of heat deaths are complex, but they boil down to two types.
The first is heat stroke, which is directly attributable to heat - in short, the body
can no longer cool itself down, which can trigger central nervous system dysfunction
or even multiple organ failure.
There’s also a phenomenon called ‘wet bulb’ deaths, which is where a combination
of heat and humidity makes it so that sweat can no longer evaporate.
"We need to keep our temperature in this narrow range, right?
We're not- we're not reptiles.
So the way we do it is through sweating...But...if there's too much moisture in the air, I can't
effectively sweat."
The second type of heat fatalities are called ‘excess deaths.’
"So excess deaths are people who die due to pre-existing
conditions that are exacerbated by heat or during a heat events."
"Often those won't be listed as heat related deaths.
But- but the extreme heat loaded the dice and turned up the risk."
Ironically, it’s the increasing heat after the sun goes down that could be the most dangerous.
At night, dense materials release the heat they absorbed during the day, which is causing
a dramatic increase in nighttime temperatures and stifling our chance to cool down.
"As the nighttime lows that don't get below 86 degrees, which
is kind of the average skin temperature to humans, the body can't have a chance to cool
back down."
So why does this happen in cities?
Three words: urban heat islands.
"The concept of urban heat island is very simple."
"Things that are more dense take longer to heat and then longer
to release the heat back into the environment.
So bricks, concrete, steel, are all very dense materials."
"Whereas in a forest or a meadow where there's a lot of surface
and a lot of moisture on those surfaces, a lot of the sun's energy, instead of directly
warming things up, will be evaporating some of that water, which is a process that doesn't
create as much heat."
To put it very simply, the sun’s energy has roughly three options when it reaches
Earth: 1) become an ingredient for plant photosynthesis; 2) evaporate nearby water.
Neither of those cause much of a temperature rise, and can even cool down an area by providing
shade or putting water in the air.
The trouble comes with option 3: heat up whatever other materials are around.
And in cities - especially dense ones like New York - there are a lot of ‘other materials.’
Just look at these maps.
See the near-perfect overlap of vegetation and cooler temperatures?
This also highlights the disparities between neighborhoods - note how the coolest neighborhoods
with the most vegetation are also the wealthiest.
So, even though greenhouse gases heat the whole world roughly equally, cities - and
especially poorer neighborhoods - are often hotter than suburban or rural areas by up
to 15-20 degrees.
"It might be the same amount of warming in the city as the
surrounding areas, but because the cities are starting from a higher baseline, there's
more risk."
This is already evident in New York, which was recently reclassified from a humid continental
climate to humid subtropical.
"The number of days above 90 degrees Fahrenheit will triple towards
the end of the century.
And so, you know, New York City is going to start feeling more like Birmingham, Alabama."
Speaking of Alabama, their state flower, the camellia, is now successfully growing in New
York.
We’ve known about UHIs - for a long time - as far back as the
early 1800s, when amateur meteorologist Luke Howard began comparing temperatures in London
to the countryside.
But we put the matter...on the backburner...for nearly two centuries.
A 2020 report noted “very few studies” of UHI before 1990, then a gradual uptick
until it reached 300/year in 2015.
"It hasn't been until about the 1990s, when climate change was really
being brought into the conversation, that we started looking at the urban heat island."
But now, the situation seems to be coming to...a boiling point.
Since it’s unlikely that everyone will move elsewhere, cities need ways to turn down the
heat.
Fortunately, there are many solutions.
First: trees.
"Having more trees that can provide shade and they can evapo-transpire
moisture into the atmosphere, which also reduces the- the heating."
Unfortunately, the US is losing trees at an alarming rate - about 36 million per year.
This is why the first part of New York’s plan was planting 1 million trees between
2007 and 2017 as part of a heat mitigation strategy.
The second solution takes place well above the trees: on rooftops!
"So cool roofs are essentially a white or reflective surface
on a roof.
And so, generally, when you have a lighter surface, it doesn't absorb as much energy."
"When you cluster these cool roofs in close geographic proximity,
you can actually start seeing a reduction in neighborhood temperatures and ambient temperatures.
We've already coated 10 million square feet of rooftops across the city and our goal is
to continue to- to coat one million square feet each year."
In addition to reflective paint, building owners can reduce heat by installing rooftop
gardens or solar panels.
There are a few other mitigation strategies, like opening cooling centers, prioritizing
lighter construction materials, and deploying tens of thousands of air conditioners to vulnerable
people - which is what New York did to protect low-income residents during last summer’s
stay-at-home orders.
Ultimately, though, there’s only one way out of this.
You know what’s coming - it’s a climate change video, we have to talk about it.
Reducing greenhouse gas emissions.
"So I do have confidence that we could quickly bend the curve towards
reducing fossils emissions.
But I have to be honest and say that I'm not, like, totally optimistic.
But unfortunately, when we look at the other side of the coin, the side of how quickly
climate change is happening, how quickly we're seeing extreme long lasting heat waves.
There I think it's very hard to be optimistic cause it looks to me like things are happening
a lot faster than our climate models predicted."