They only come out at night: "The Dark Side of Climate Change"

Photo by Tyrone Turner/National Geographic - infrared showing heat loss from NYC buildings

Looks like they’ve discovered what great heat sinks asphalt and concrete make:

From the National Resources Defense Council via press release posted at (h/t to Mark)


New Focus on Sweltering Highs in Night-Time Temperatures to Outline Risks to Human Health, Environment; Record Night-Time Highs Seen in More than Three Dozen States: AL, AZ, AR, CT, DE, FL, GA, IL, IN, IA, KS, KY, LA, ME, MD, MA, MI, MN, MS, MO, NH, NJ, NM, NY, NC, ND, OH, OK, PA, RI, SC, SD, TN, TX, VA, WV, and WI.

WASHINGTON, D.C./NATURAL RESOURCES DEFENSE COUNCIL – September 15, 2010 ( renewable energy/green newswire) – While it is common knowledge that the summer of 2010 posted record-high temperatures across the United States, almost no attention has been paid so far to the equally disturbing trend of pervasive record high night-time temperatures where evening cooling did not occur this summer, according to a new analysis to be released at 11 a.m. EDT Thursday (September 16, 2010) by Natural Resources Defense Council (NRDC).

More than three dozen states (and a correspondingly significant share of the nation’s population) contain weather stations that recorded record high night-time temperatures, the “dark side of climate change” under which temperatures do not cool off overnight. The NRDC analysis breaks out the number of U.S. counties and their respective population that experienced these record night-time temperatures.

The 37 states with record high night-time temperatures highlighted in the report are: Alabama, Arizona, Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Virginia, West Virginia, and Wisconsin.

News event speakers will be:

  • Dan Lashof, director, Climate Center, Natural Resources Defense Council; and
  • Kim Knowlton, senior scientist, Health Program, Natural Resources Defense Council.

The NRDC analysis outlines the danger of heat deaths and other impacts that are linked to the growing problem of summer temperatures that do not drop overnight.

TO PARTICIPATE: You can join this live, phone-based news conference (with full, two-way Q&A) at 11 a.m. EDT on September 16, 2010 by dialing 1 (800) 860-2442. Ask for the “worst summer ever?” news event.

CAN’T PARTICIPATE?: A streaming audio replay of the news event will be available on the Web at as of 3 p.m. EDT on September 16, 2010.

CONTACT:  Ailis Aaron Wolf, (703) 276-3265 or


The Natural Resources Defense Council is a national nonprofit organization with more than 1.3 million members and online activists. Since 1970, our lawyers, scientists, and other environmental specialists have worked to protect the world’s natural resources, public health, and the environment.

NRDC has offices in New York City, Washington, D.C., Los Angeles, San Francisco, Chicago, Livingston, MT, and Beijing. Visit NRDC on the Web at


Here’s an infrared photo of before and after at a USHCN climate station in Fayetteville, NC

Here is what you see in visible light:

Here is what the infrared camera sees:

Note that the concrete surface is around 22-24°C, while the grassy areas are between 12-19°C. This was shortly after a rain, about 2 hours before sunset. The rain did nearly nothing to cool down the concrete.


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“Its darker than we thought!”

Phil's Dad

I ran the initials NRDC through my text to speech programme. It pronounced it as “nerds”. I think I will stick with that.


Pretty easy to see this. Compare summertime Manhattan to Eastern Long Island or the North Bronx. It even holds true in the winter time, it would be raining in Manhattan, and I’d take a 30 min subway ride to the Bronx and it’d be snowing there. There is a serious amount of heat stored in the city concrete, and everyone who tries to escape New York in the summertime knows this.


I like this study, it shows how much heat is held in by our infrastructure, which is why nightime record highs are probably being set more often since the infrastructure holds the heat in. Because of this effect, it’s likely that the ‘warming’ going on is not CO2 related, or if it is related to CO2, there is much stronger case for it being the concrete/asphalt that has caused a lot of the manmade warming


Think this might have something to do with it? . And let’s not forget the heat from power lines, and all forms of mechanical transportation as well as that from millions of air conditioners, etc. that is hidden in the glare of the city lights. I’d say the entire USA is one giant UHI.

You folks may be hot in USA, but……You might be interested to know that in most of central, east and SE Australia we have been getting lowest winter and spring temps in many areas for at least 10 to 20 years or more. Wettest for 10 or 20 years or more or much longer. The Murray River main river has been flooding. Water restrictions are being mainly lifted. Dams are filling or full. flooding has occurred in many areas. September so far is well below max temps in most areas, rainfall is already past the Sept mean in many areas. The Centre of Australian desert areas resemble the green pastures of England and nare full of wildflowers. Salt Lake Eyre is good for boating, and at present tasmani is suffering heavy snow and 130km/hr winds!
Scan all these for details of Australias return to the 60’s, 70’s and 80’s weather this winter and spring!


“…While it is common knowledge that the summer of 2010 posted record-high temperatures across the United States,…”
“Across the United States” makes it sound like the entire U.S., but here in Washington State we have had a very cool summer. In the lower southestern valleys of the state we are 1 month behind in the production of tomatoes because of the cool summer. In the Walla Walla Valley we have had only a couple of days of reaching triple digit highs when we usually will at least have a week or two of consecutive triple digit highs during the summer.


Yep, it’s worse than we thought.


CO2 is more powerful at night.

Theo Goodwin

Gee, I have been intimately familiar with this phenomenon since moving to St. Louis in 1971. The old city environment was one gigantic heat sink. When a modest skyscraper was added to the environment, the heat trapping effect was noticeably increased. The worst part of the phenomenon was that the environment did not cool at night. This effect does not exist in the newer suburbs, 1960’s and later. The newer suburbs usually have some green material between any two concrete structures. This heat sink effect creates UHI. The UHI causes higher temperatures for longer periods at night. If the thermometers are in these areas then there is your global warming, so-called. By the way, the city in which I reside now recorded record highs this summer. I made the trip to the airport and discovered that the thermometer sits right on a runway.

Theo Goodwin

Pardon me for being a broken record, but this startling new information would have been known long ago if meteorologists and climate scientists did not have the absolutely weird habit of recording a contrived temperature for each day and place. What they do is take the average of a daytime and a nighttime reading. Is that weird or what. Folks, we are scientists. Stick with the facts. Record an actual measured temperature for day and another actual measured temperature for night. Do not average them. Do not report an average. The average is worthless to science.

I’m sure glad these folks want to educate me. The only way we can get tomatoes to ripen on the vine here in Calgary, is to create a micro climate that keeps the night time temperature as high as possible. I use the south side of my house and place the plants against the concrete foundation. It is still hit and miss however. Last year lots, this year a few. Now is that a heat island inside a heat island? I wounder if my wife will let me paint the thing black?

Ian Mc Vindicated

I’ll never forget a trip I made to Los Angeles about 15 years ago as a tourist. We were driving around downtown L.A. ( where the tall buildings are ) and it was boiling, around 94 F. We had a brand new Mustang convertible as a rent-a-car. It was so hot we decided to head for Venice Beach, another tourist hot spot. Well…… we left downtown, the temperature dropped , so much so that we ended up pulling over and putting the roof up, and when we got to the beach, it was about 68 F. We went to the beach like idiots and found a hollow in the sand and laid on the towels and wondered why no one else was there too…….( too cold ) . However it did highlight to me the effects of (1) how the ocean as it cooled the beach and (2) the immense effect of an urban heat island. It was quite a reversal of extremes.


Gee, what remarkable conclusion. Working on air conditioning across the US for 25 years, it didn’t take much to notice the temperature drop moving from th city to the suburbs to rural areas on the same day.


I guess their flop of a movie on “ocean acidification” which was cross-promoted across the country along with NOAA, was not effective enough….so they resort to this.
Also, anyone notice where their offices are?
NRDC has offices in New York City, Washington, D.C., Los Angeles, San Francisco, Chicago, Livingston, MT, and Beijing.
Norfolk, VA, USA


So if we simply ban night, along with CO2, everything will be OK!

Leon Brozyna

After years of belittling UHI, it’s now embraced to highlight record high low temps.
Now I’m sure that some rural locales experienced record high low temps. In itself that proves nothing. It happens. But citing UHI night time temps as a metric of anything proves nothing, other than letting the local residents know that it’s hot and uncomfortable.
Now how about a story about record low high temps? Where can we hear about those? Oh, that’s right, nobody covers those stories like WUWT.


Rocks on mountains/deserts/anywhere hold heat…. its NOT artificial (ie Mann made, haha), ONLY its “Natural” UHI, is probably mostly natural ROCK or “cement” if you like, so nothing special here guys/gals move on.. Imagine the whole “Andes”, Himalayas etc… heat effect in summer idem same thing chao/


I see NJ on the list.
I didn’t notice any such thing, and I usually take a little stroll around the grounds at night.
I was not tempted to sleep outside ( which is what I usually think of when it is hot at night )
Hate to personalize and anecdotalize this but my observations of 2010 were,
that there was an extended cold period, that was cold for a long time, but not out of range at all and not approaching memorable lows.
And in the summer, there was an extended hot period, that lasted ( With no rain)
for a long time but did not break or reach any records. I did NOT notice any extreme night-heat. ( and I am looking for it)
Just weather. Nothing to see here.

Baa Humbug

I’d like to see a comparison between urban and rural t data.
Also, what about cloud cover over these areas?

Henry chance

If we have higher dew points, the temps drop less at night time.


The NDRC has done good work in the past decade in trying to make the US government face up to its role in allowing overfishing on the Georges Banks. A series of lawsuits has forced the government (viz the National Marine Fisheries Service) to set targets for rebuilding the fish stocks – larger stocks will mean more fish for future fisheries. Unfortunately, a court challenge has allowed the NMFS to weasel out of targets for rebuilding the cod and a few other important species.
At least they are focussed on something other CO2 as a cause of warming here. Lovely pics both from the study and from Anthony.

Layne Blanchard

In the IR photo, note the heat of the pipe atop which sets the instrument….. looks toasty.


Thanks for posting the link to the NRDC. I have always distrusted them, but never had a reason to visit their websiste before. I visited the site for a laugh, but got a scare instead!
The NRDC is a highly organized, well funded (and dangerous) eco-totalitarian organization using good old fashioned economic blackmail and coercion in government offices and corporate board rooms around the world. I guess that I shouldn’t be surprised that they’re using another recent news event to create a new straw man scare tactic out of “the growing problem of summer temperatures that do not drop overnight” in an attempt push their agenda.
Do some people actually use those form letters?


How many record nights do you have to have to make that list? One? We did NOT have a hot summer here in ND. Nothing like we’ve had other years. Just how stupid do they hope people are?


I don’t doubt the UHI component to this.
I am curious, tho, to what degree C02 and feedbacks add to this particular problem. By that, I mean, do we get more heat-trapping at night because of C02 and associated positive feedbacks, even if UHI is the primary storer of that heat during the day?
Climate Change is a great big complex problem with lots of moving parts.

tom s

HEAT ISLAND? Noooo. Who woulda thunk it? I’m perplexed. What about the tree ring data? (/sarcasm)


Seems like this is just a reflection of the persistent weather pattern we’ve had since spring; cooler than average in the west and warmer than average in the east. But of course the announcement didn’t say anything about the cool western summer.

tom s

Henry chance says:
September 15, 2010 at 6:47 pm
If we have higher dew points, the temps drop less at night time.
And if we have asphalt/concrete jungles we retain mucho heato! Have some dewpoint data you’d like to share?

Jeff L

Of course, if you re starting out warm in the morning, chances are you are going to be warmer during the day as well , thus the record highs. So, the logical solution to this truly human induced warming is that we destroy all the cities, re-vegetate these areas & go live in caves, right?? That would solve the problem. I am sure the NRDC would love that.

tom s

I work in the 1st tier suburbs here in MSP and drive back to my house in town every night at around 10pm (fyi I’m a 20yr+ meteorologist working in the field). Most nights the temperature diff from my office with it’s grassy’er surroundings is on average about 3F+ cooler than when I drive past the airport/mall of america and the vast expanse of concrete there. I’m just south of the river valley and once I climb up to the valley to this nearly solid area of concrete/asphalt the temp rises several degrees.
At sundown after a sunny day, if you can stand with one bare foot on your lawn and one on your sidewalk that has been in the sun all day you’ll feel the tremendous temp diff.

Wayne Delbeke

Good Gosh Y’all. I wish I could find some of my old reports from the late 70’s that dealt with this issue and heat sinks. How can this be a “new” finding? We have known about heat sinks for years. That is why we insulated the runway at Rankin Inlet, NWT, put in a metre of gravel to keep the heat out of permafrost. For some installations we used “heat pipes” to carry the heat away. I am amazed that this should be considered new information when it has been in the literature for years. It is why even when it is 30 below outside I can keep a 2000 square foot house heated with just two fires a day because of the mass of the masonary fireplace – two very hot, smokeless fires.
Haven’t we got years of night time temperatures showing this? Is this a surprise? Or perhaps my engineering memory is fogged by the present. As a meteorologist though, I imagine Anthony noticed this a long time ago.


It’s been remarkably cold along the coast of California. Here in Carlsbad, we hardly had a summer at all. We keep telling each other that it will get hot soon… but it hasn’t yet. The ocean is much cooler than usual. The tourists are much cooler too, and rather grumpy about it.


Oh, and the UHI apparently wasn’t obvious to the people who do studies? Where would you rather sit on a hot evening… on the sidewalk that was in the sun all day, or a nice cool lawn? Up against a west facing building, or where it has been shaded since before noon?
Someone should hit them with a clue bat. Metaphorically, of course.


In central Florida it was unusually cool the beginng of summer. Then when it finally heated up (mid July) about 95% of the days had afternoon clouds and thunerstorms which cooled everything nicely As a comparison, I take my daughter swimming in the local lake almost every evening. Last year the lake was very warm all summer. This year the lake has been cool even now. That thunderstorm thermostat really works.


vigilantfish says:
September 15, 2010 at 6:54 pm
The NDRC has done good work in the past decade in trying to make the US government face up to its role in allowing overfishing on the Georges Banks.
Well if they had actually just focused on legitimate causes like that and not adopted the typical modern environmental flag waving, they might have gained more supporters, like me.
Unfortunately….they lost me on their national “ocean acidification” tour.
In a similar vein, I would support the ACLU in principle (civil liberties), but in practice they represent just one one-dimensional and extremely far left, political agenda.
So…they alienated me from the start. No chance of supporting that.
Point is, I applaud their efforts to halt overfishing.
But it is sad that all their other more vacuous agendas throw the good baby out with the dirty nasty bathwater.
Norfolk, VA, USA

Steve In Tulsa

Um, I live in Oklahoma and it has been the mildest August this year. We have had cool nights since early in August. Quite often September is quite warm but not this year. I am running the heat at night half the time. We never saw anywhere near 110 degrees all summer. And we close in on that pretty often too.

Jim Reedy

Wayne Delbeke says:
September 15, 2010 at 7:08 pm
Cynical me says…
Its a “NEW” discovery so that you can get money to do research on it…
no one is putting up money to research old (i.e. known) information.
, many previously known things will be “newly” discovered so that research funding
can continue to flow…
cheers J

Bill DiPuccio

A little known 2004 NOAA aerial survey reported that US manmade surfaces (Impervious Surface Area) are about equal in area to the state of Ohio. That’s a pretty big heat island!
The survey includes a national map. For more info see:


Sorry, but I gag whenever I see “NRDC”. They’re the doofi who talked Clinton into canceling the Integral Fast Reactor (IFR). If not for that, we wouldn’t be having this discussion.

Wayne Delbeke

Steve the shark
NRDC has offices in New York City, Washington, D.C., Los Angeles, San Francisco, Chicago, Livingston, MT, and Beijing.
Livingston, Montana!!!! Interesting. Militia central. Some very interesting people in that region. Maybe its just coincidence, but an office in place with a population of 7,000 people versus those other places with millions. No offense to Livingston. It is a nice place that I have been through often.

Daniel H

What we’re seeing is the reframing of climate change as a “public health issue”. This was discussed on WUWT a couple of months ago:

Framing climate change as a public health problem seems to make the issue more relevant, significant and understandable to members of the public even some who don’t generally believe climate change is happening, according to preliminary research by George Mason University’s Center for Climate Change Communication (4C).

Notice that in the The Dark Side of Climate Change press release, NRDC is not discussing melting ice caps, species extinction, or the usual alarmist global warming themes we’ve come to expect. Instead they state:

The NRDC analysis outlines the danger of heat deaths and other impacts that are linked to the growing problem of summer temperatures that do not drop overnight.

Suddenly they’re concerned about our health and welfare. It’s an unusual about-face for an environmental advocacy group that normally places human needs last in their hierarchy of values. I’ve been seeing an increase in these sort of “public health” stories ever since reading the aforementioned climate change strategy. For example, in California there was a recent news story that interviewed nurses protesting at an appearance by Carly Fiorina (who is currently running against Boxer for the CA senate seat) over her support for Proposition 23 which seeks to overturn California’s disastrous AB32 climate change statute. Here is what the article stated:

When asked why the nurses were there, Martha Kuhl, CNA treasurer, said, I want people to know Fiorina is too extreme for California. Kuhl and several others nurses said they were most worried about the public health consequences of repealing AB32. Loosening clean-air regulations would only increase the number of patients they have suffering from asthma and other respiratory ailments, several said. We have an asthma epidemic here in California, said Chuck Idelson, a CNA spokesman. Why is Fiorina aligned with Texas oil companies instead of kids with asthma?

This raises several important questions: Which group or groups is mobilizing these idiot nurses to protest at pro Prop 23 rallies and what are their motives? How does a harmless trace gas that we exhale and which is essential to all life on Earth contribute to an asthma epidemic in California? How will limiting CO2 emissions in CA prevent asthma in children? These questions are never actually discussed in the article, which you can read here:


It’s worse than the growing urbania problem we thought it was.
Where’s the data on the 50 state average, or any other hard numbers? has already outlined the siting issues and lack of proper coverage.
The US does not consist entirely of the concrete & asphalt jungle.
But most of the stations are located in it.

Philip Bradley

Minimum temperatures don’t measure night time temperatures, they measure early morning temperatures (which is when the daily minimum temperature generally occurs), and while warmer nights may be the cause of increased minimum temperatures, increased minimum temperatures could equally well be caused by increased early morning sunlight reaching the ground due to decreased near horizon haze and particulate pollution, which has certainly occurred in major urban centers over the last 30 years.
The take away points are,
The only way to determine if night time temperatures are increasing is to look at temperatures at fixed times (midnight, 4am), and this data doesn’t exist for more than a few places.
Highly paid climate professionals don’t seem to know that minimum temperatures don’t occur at night, which is symptomatic of the pervasive ignorance of the basics in the realm of the climate

John Michalski

I live in a rural area 8 miles from the nearest town (pop 3200) and drive 55 miles to the nearest large city (pop 200,000). Many mornings on the way to work, the temperature will increase as much as 10 degrees F (according to the temp display on my rearview mirror so not very reliable but close enough). This is all before the sun comes up, so not much can be attributed to direct solar.


Theo Goodwin said:
September 15, 2010 at 5:55 pm
Pardon me for being a broken record, but this startling new information would have been known long ago if meteorologists and climate scientists did not have the absolutely weird habit of recording a contrived temperature for each day and place. What they do is take the average of a daytime and a nighttime reading. Is that weird or what. Folks, we are scientists. Stick with the facts. Record an actual measured temperature for day and another actual measured temperature for night. Do not average them. Do not report an average. The average is worthless to science.
Amen. “Weird habit” is right. This practice makes absolutely no sense. But they then compound it by averaging the averages! The ability to compare these numbers in any statistically meaningful sense is lost. What really matters is heat content, which could be measured using an integrated set of recorded temperatures over time. I have never understood how a daily high (which, in a hypothetical example, might have only been the temperature for a brief period of time) can be averaged with a daily low (when the temperature over 24 hours could hypothetically have been at or near the low for much of that period of time) to generate any meaningful measure of the average temperature for the day. This penchant to produce averages is very peculiar.

Claude Harvey

Is even the opening statement correct? “While it is common knowledge that the summer of 2010 posted record-high temperatures across the United States….” Where? My impression was that while this past summer had its hot moments in the South and East, overall it was relatively moderate. Parts of the west coast felt they had missed summer altogether due to the body of cold Arctic water lurking just off the coast.
Claude Harvey

Dave Worley

Moratorium cities.


savethesharks says:
September 15, 2010 at 7:28 pm
I’d have to agree with you. While I admire the NDRC’s work on overfishing, I’d never give them a dime, for all the reasons you state. It’s a shame that all environmental organizations just won’t let go of their political, ecototalitarian agendas. They still have the good-will of the sheeple, and could do so much good if they focussed on real problems and practical, non-punitive solutions.