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Posted at 10:45 AM ET, 11/18/2009

Record highs vs. lows reveal shifting climate

By Andrew Freedman

* Trending cloudy; showers? Full Forecast | Autumn photos in D.C. *

Each bar shows the proportion of record highs (red) to record lows (blue) by decade, as observed at about 1,800 weather stations in the continental United States from January 1950 through September 2009. In the last 30 years, record highs have become much more common than record lows. Graphic by Mike Shibao, UCAR.

Climate change has long suffered from a perception problem. Studies show that people tend to view it as a long-term phenomenon divorced from their more immediate and pressing concerns, rather than something that is already reshaping the planet in many ways. Part of the explanation for this may have to do with the statistics typically cited when scientists discuss climate change, such as the nearly one degree Fahrenheit increase in globally averaged surface temperature during the past century.

This statistic, while profoundly alarming to many scientists, is at the same time rather lacking, because it is not readily relatable to the local level.

A forthcoming study in the journal Geophysical Research Letters offers an innovative and useful metric to show how climate change is affecting the United States, and it is one that may help people spot the fingerprint of long-term warming when they get their daily weather information, whether it's from this site or elsewhere.

The study examines the changing relationship between record daily high maximum temperatures and record low minimum temperatures across the United States between 1950 and 2006. It finds that record highs are now much more common than record lows, averaged across the country, compared to the middle of the 20th century. The ratio of record highs to record lows has increased from about one to one at the beginning of the period, to two to one in the present decade.

Absent a warming climate, the ratio of record daily highs to lows should be about even, the study states.

The researchers went on to conduct computer model simulations of future climate, which showed that by 2050, record highs would dwarf record lows by a ratio of 20 to one, reaching 50 to one by 2100, as the model's climate warmed in response to increased emissions of greenhouse gases such as carbon dioxide and methane. The simulation assumed emissions would rise according to a roughly "business as usual" scenario.

The study is the result of a joint effort between public- and private-sector scientists, including a Weather Channel meteorologist and a researcher from Climate Central, a nonprofit climate science communications group. ** Disclosure: I am working with Climate Central on a climate science reporting project, but was not involved with this research. **

If you fancy raw numbers rather than ratios, consider this: the study found that between Jan. 1, 2000, and Sept. 30, 2009, the lower 48 states chalked up 291,237 record highs compared with 142,420 record lows.

On a shorter time scale, between the beginning of this year through the end of September, there had been 11,711 record highs compared to 7,449 record lows. This translates to a ratio of just less than two to one. However, the record lows may gain some ground once October is taken into account, since it was the third coolest October on record in the United States.

In a press release, lead author Gerald Meehl of the National Center for Atmospheric Research emphasized that the study translates long-term climate change into daily weather terminology. "Climate change is making itself felt in terms of day-to-day weather in the United States," Meehl said. "The ways these records are being broken show how our climate is already shifting."

The study found that the shift in the ratio between record highs and lows would be extremely unusual under a climate that was not warming. "The behavior of the ratio in recent years is very, very, very unlikely under stationary conditions," said co-author Claudia Tebaldi of Climate Central.

Interestingly, the study found that record cold is becoming a more rare occurrence with time, not that record heat is occurring much more frequently.

However, Tebaldi cautioned that cold snaps are not going to disappear entirely.

"...I think it is important to highlight the fact that record lows still happen here and there, every now and then, which is something people seem to be surprised by and take as a sign that global warming should be doubted," Tebaldi said in an email conversation. "So in a way the study makes global warming relevant on a daily scale, but also explains that on daily scales other counter-intuitive effects can still manifest themselves without necessarily being at odds with the idea of average warming."

The views expressed here are the author's alone and do not represent any position of the Washington Post, its news staff or the Capital Weather Gang.

Other reactions to study:

* More Record Highs and Far Fewer Lows
* U.S. Record Temperatures--A Closer Look
* Record high temperatures far outpace record lows across U.S.
* Comments On Meehl Et Al 2009 On Trends In Record High And Low Temperatures
* A Critique of the October 2009 NCAR Study Regarding Record Maximum to
Minimum Ratios

By Andrew Freedman  | November 18, 2009; 10:45 AM ET
Categories:  Climate Change, Freedman, Science  
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Notice how this "study" conveniently begins in the 1950's. Curious why they didn't plot the 1930's and 1940's? There is a reason. Here is another reaction to this piece of propaganda masquerading as a "study".

Mr. Q.

Posted by: Mr_Q | November 18, 2009 11:28 AM | Report abuse

Does this account for the "urban heat island effect". I imagine a lot of weather stations that were once located in a corn-field now are in the middle of an urban heat island. Yes, those are warmer and in some ways reflect (or cause) climate change.

But is it meaningful to broader climate change to know that there are fewer record lows in Central Park or at Reagan National Airport?

Posted by: ah___ | November 18, 2009 11:37 AM | Report abuse

Second question: The bars all appear to be the same length, but shouldn't there be fewer records of either type the longer we go (you pointed this out in a previous blog post). From this it appears we're setting more record highs than ever, but is that really the case?

Posted by: ah___ | November 18, 2009 11:39 AM | Report abuse

ah_, I agree, it could be misleading, but since what is being plotted is just a ratio, a bar of a given length is used to display the percentages of one vs. the other, not the direct values.

Posted by: Brian-CapitalWeatherGang | November 18, 2009 11:47 AM | Report abuse

It is difficult to have confidence in the comparison between the number record lows vs record highs, when you are aware of incidents like this -

All time low temperature record for Illinois called into question by NWS, citing lack of confidence in equipment.

I don't believe that if the record being set was a record high, they would a similar "lack of confidence" in the equipment. Does anyone have an example of a lack of confidence in the equipment on a record high?

Mr. Q.

Posted by: Mr_Q | November 18, 2009 12:04 PM | Report abuse

Mr. Q - Im not certain how citing to a self described skeptic's website that just so happens to fit your own personal belief set does anything to enrich the conversation.

Everyone who visits this site understands your position. Your core point has been made (again - on top of again - and on top of again).

Clearly you've staked out a position on climate change. You're welcome to it - but for those of us more interested in constructive dialogue and discussion - do you not realize how little you're actually contributing?

Posted by: hrc2211 | November 18, 2009 1:15 PM | Report abuse

I guess I still fail to understand the significance of data over 50 years when the earth is 5 billion years old. Seems like a small sample size to use and predict future weather trends. Can't this 50 years be a blip on the 5 billion year old screen that has nothing to do with what humans are doing? And was the data obtained the same exact way in 1955 as it was in 1995, or as one poster mentioned, could the instruments have been influenced by a change in location or surrounding local environment? Just things I wonder out loud whenever I read about global warming studies.

Posted by: dave09 | November 18, 2009 1:21 PM | Report abuse

dave09 wrote, "... could the instruments have been influenced by a change in location or surrounding local environment?"

Go to this link and scroll half way down and look at the graphic that depicts a 4 degree change in the reported temperature when the sensor was temporarily moved from the northern end of an airfield to the southern end. It is the ASOS located at the Reno Nevada airport. It is unbelievable.

Mr. Q.

Posted by: Mr_Q | November 18, 2009 1:41 PM | Report abuse

All the same, we're getting fewer heavy snow events around here in recent years and more thunderstorm days...possible signs of a warming climate. Heat island effects could be responsible for some of the warming...this would continue if more lanes are added to I-66 at the expense of Arlington County green space.

Posted by: Bombo47jea | November 18, 2009 1:46 PM | Report abuse

My thoughts: 1. Climate is always changing, always has always will.2. No one can predict with 100% certainy what will happen in the future, & all the arguements pro or con r nothing more than guesses. Who is right, only time will tell & I doubt many of us will b around 2 c who's right.3. I know it is warmer, 4 the most part, in the winters with less snow in this area now than in the 50's, 60's & 70's. May be a result of climate change or not.4. Political beliefs should play no role in the debate, but that doesn't seem 2 b the case. Maybe, if people on both sides of the political fence put their beliefs aside a consenses could be reached.
5. Arguing the issue is like trying 2 change a persons religous belief, it isn't going 2 happen.

Posted by: VaTechBob | November 18, 2009 2:44 PM | Report abuse

ah__: Re: your question about the urban heat island, the study relies on the National Climatic Data Center (NCDC) to perform quality control of the data, including adjusting for the effects of urban heat islands as well as the issue of changing weather station locations and temperature sensors. Keep in mind that the study looks at temperature records from about 2,000 weather stations, rather than smooth temperature trends.

Posted by: Andrew-CapitalWeatherGang | November 18, 2009 2:57 PM | Report abuse

To eliminate the influence of the heat island effect, change in instrument location and/or technology, quality control of surace data, etc., consider the relevant satellite MSU global measurements.

The display shown here shows the 20 year daily (Jan 1 - Dec 31) satellite based global average mid-tropospheric temperature along with record high and low temperatures . It's obvious from just eyeball examination that the deviation from average of highs exceeds that for lows through August. For the balance of the year, for some reason, they are about the same. On balance, though, its clear that over the full year the highs exceed the lows.

Unfortunately, the available data covers only the last last 20 years, so there is no basis for comparison with earlier periods with this data set. However, as Andrew correctly notes, it's difficult to explain why there should be more record highs than lows other than in an overall warming scenario.


Posted by: SteveT-CapitalWeatherGang | November 18, 2009 9:50 PM | Report abuse

I appreciate the disclosure of the association with Climate Central, but the disclosure needs to go futher. My understanding is that Climate Central is an advocacy organization on behalf of Human Control of Climate Change and not an impartial, fair source of information. All the folks associated with it are known advocates. I would appreciate a clarification on this point. If my undertanding is correct than Andrew Freedman should stop reporting on their output. If I am wrong than everything is fine.

Posted by: 123andy | November 19, 2009 6:41 PM | Report abuse

CRU was hacked. Emails have been exposed.

It is quite damaging and confirms EVERYTHING that I suspected.

--begin quote--
From: Phil Jones
To: ray bradley ,,
Subject: Diagram for WMO Statement
Date: Tue, 16 Nov 1999 13:31:15 +0000
Cc: k.briffa@xxx.xx.xx,

Dear Ray, Mike and Malcolm,
Once Tim’s got a diagram here we’ll send that either later today or
first thing tomorrow.
I’ve just completed Mike’s Nature trick of adding in the real temps
to each series for the last 20 years (ie from 1981 onwards) amd from
1961 for Keith’s to hide the decline. Mike’s series got the annual
land and marine values while the other two got April-Sept for NH land
N of 20N. The latter two are real for 1999, while the estimate for 1999
for NH combined is +0.44C wrt 61-90. The Global estimate for 1999 with
data through Oct is +0.35C cf. 0.57 for 1998.
Thanks for the comments, Ray.


Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) xxxxx
School of Environmental Sciences Fax +44 (0) xxxx
University of East Anglia
Norwich Email
--end quote--

Notice the "I’ve just completed Mike’s Nature trick of adding in the real temps
to each series for the last 20 years (ie from 1981 onwards) amd from
1961 for Keith’s to hide the decline."

But seriously - the fact that Dr. "we didn't save the raw data" Jones has been deceiving people all along was PAINFULLY obvious to anyone who wasn't an ideologue.

CRU acknowledges the emails look genuine.

Now ask yourself how many studies have used or built upon Dr. Jones' work?

How many climate computer models have used data/work from Dr. Jones?

It has all been a house of cards built upon a lie. There is no catastrophic, man caused global warming. There never was. And we may one day, when the truth finally comes out, find out that there wasn't that much warming.

And like I said from the very beginning, the people who will ultimately suffer from this giant scam are the scientists and journalists. Their reputations will be mud. And that truly stinks. We need good scientists and journalists.

"Journalists" need to ditch their ideology and focus on the truth. Let the chips fall where they may. Or kiss their reputations goodbye.

Mr. Q.

Posted by: Mr_Q | November 20, 2009 2:21 PM | Report abuse

Wow- I wonder if the washington post or Andrew will report on this.

From a post I saw. I doubt these items below will raise any red flags at the WP while they are busy "investigating" Sara Palin's book and Oprah's career change.
1. Conspiracy
2. Government Fraud
3. Computer Fraud
4. Obstruction of Justice
5. Environmental Law Violations (Falsifying lab data pertaining to environmental regulations)
6. Suppression of evidence
7. Tampering with evidence
8. Public Corruption
9. Bribery

Posted by: Tom8 | November 20, 2009 6:48 PM | Report abuse


This is your big chance. Go here and take a LONG, hard look at the lies, deception, and coordinated suppression of dissent. This is your opportunity to recognize that you have been deceived. This is your opportunity to come out publicly and announce your disappointment in those that sought to and successfully deceived you and many others.

Don't be the last guy defending this group and their discredited hypothesis. There will be one person who defiantly insists that the evidence against them and AGW is wrong. There always is that one person. The last guy to catch a clue. Don't be that guy.

Mr. Q.

Posted by: Mr_Q | November 22, 2009 11:20 AM | Report abuse

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