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Warming Winters: U.S. Temperature Trends

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Report Summary

While the U.S. as a whole has seen a warming trend that has raised annual average temperatures by 1.3°F over the past 100 years, warming varies seasonally, and it’s winter that has seen the fastest warming.

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An analysis of data from the U.S. Historical Climatology Network of weather stations shows that the coldest states are warming the fastest, and across the country winter warming since 1970 has been more than four-and-a-half times faster per decade than over the past 100 years. Winter nights across the country have warmed about 30 percent faster than nights over the whole year. Some states cooled or failed to join the warming trend over the past 100 years, but since 1970, every state has shown winter-warming.

To better understand winter warming patterns we analyzed average-daily temperatures and overnight-low temperatures for December through February for the continental 48 states from 1912-2012 and 1970-2012.

We found:

  • Since 1970, winters in the top 5 fastest-warming states — Minnesota, North Dakota, Wisconsin, Vermont and South Dakota — heated up four-and-a-half times faster than winters in the 5 slowest-warming states: Nevada, California, Oregon, Colorado, and Washington. The five fastest-warming states have seen at least 4oF warming in winters since 1970.

Rates of warming (°F per decade) for average winter (Dec.-Feb.), 1970-2012.
Click image to enlarge.

  • Winter warming accelerated almost everywhere since 1970, and all states have warmed since that time. Nationwide since 1970, winters warmed more than four-and-a-half times faster per decade than over the past 100 years.
     
  • In contrast, over the past century, winters in 13 states — 10 in the South — bucked the warming trend and either cooled significantly or exhibited a non-significant slight cooling trend.
  • Winter nights have warmed in all but one of the lower 48 states since 1970. Across the continent, winter nighttime temperatures have warmed about 30 percent faster than nighttime temperatures over the entire year. Since 1970, overnight winter temperatures in Wisconsin, Minnesota and Vermont have warmed faster than 1.29°F per decade, or more than 5°F in just 43 years.
     
  • Since 1912, states with average winter temperatures below 32°F warmed three times faster than states with average temperatures above 32°F. Since 1970, winter warming has accelerated almost everywhere and states that previously cooled began to warm in winter. Yet, the coldest states (below 32°F) have still warmed nearly twice as fast as the rest of the country on average. And during that time, winter nights in the coldest states warmed up to five times faster than those in warm states.
     
  • The pattern of winter warming is different than the pattern of warming throughout the whole year, which was illustrated in Climate Central’s June 2012 analysis of annual temperatures, The Heat is On. Some of the fastest-warming states overall, such as Arizona, New Mexico and Colorado, have had some of the slowest-warming winters, both since 1970 and over the past 100 years.

Comments

By Dave (Basking Ridge, NJ 07920)
on February 21st, 2013

That fits the expected trend. GW raises the average temperature. But it also evens out differences in temperature extremes geographically and in time. So the differences between summer and winter seasons are expected to get smaller, between daytime and nighttime temperatures and also geographically, for instance between the lower latitudes and the polar regions. 

The typically cited extreme example of this is Venus, where the dense atmosphere is mostly comprised of CO2, and the greenhouse effect is extremely aggressive.  Orbiter missions to that planet have measured blistering surface temperatures of about 460 C (860 F) but with no significant detected differences between the light side and the dark side (days and nights are much longer on Venus) or between the poles and the equator.

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By Harry Wiggs
on February 21st, 2013

This map also nicely shows two things:

-That the climate models have been generally and consistently correct for over 20 years;

-That the greater overall increases are towards the Poles.

The climate change deniers are going to run out of any oxygen, and soon. Data don’t lie, but deniers do all the time. sad thing is, their prevarications for the past 30+ years have had an indelible result on he entire planet. We’ve lost time to combat this, and we are quickly running out of options.

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By Andrew Kerber (Blue Springs, MO)
on February 22nd, 2013

Well, this is a good thing.  Warmer winters mean a longer growing season, more food, and an overall higher standard of living.  I am a little dubious though, the US climate record is less than 200 years in most places, and this doesnt mention the rest of the world, so I question if this is a worldwide trend.

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By Randall Field (South Lyon, MI 48178)
on February 22nd, 2013

This is cherry picking.  The fact that Europe is freezing this year and especially last year is ignored in order to feed the climate misinformation machine.  Like it or not, the current warm period has been going on for about 12,000 years now and is about to come to an end when we’ll be plunging into the next ice age which will last 70,000 to 90,000 years as the last four have.  As it is, we’ll be lucky if a bit of warming stalls the onset of the next ice age by a few decades while we scramble to develop fusion energy and attempt to melt the advancing glaciers.

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By Stan Bartsch (Louisville, Ky 40218)
on February 22nd, 2013

WHY 1970?  What is so magical about that arbitrary date?  Do we lose the “warming trend” if we go to 1969?  1940?  1936 anyone?

Global warming wasn’t even on the radar in the 70s.  It was all about….oh wait, that’s right, the 1970’s were on the tail end of the “Global Cooling” scare, when the multi-decade drop in temperatures was ending…..and the warming started again.

I bet that including the temps from before 1970 plays hell with all the pretty “reds” on the chart!

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By Dave (Basking Ridge, NJ 07920)
on February 22nd, 2013

RF:

Personally I see no “cherry picking” or “misinformation” in this report.  It is real data relating to the US. That seems like unfounded criticism to me.

Re the next glacial period, there is in fact no scientific evidence to suggest that we need to be at all concerned about that for a very long time indeed. See for instance: Tzedakis, P.C., et al,  Determining the natural length of the current interglacial, Nature Geoscience, 5, 138-41, 2012.

AK:

If you want to think globally, then the Arctic is about as far North as you can go and it is clearly the fastest warming place on the planet. It is also a very large place. So that is certainly a basic and indisputable global trend and a very clear signal of global warming.

To your point though, by comparison, as far as I can see many of the detailed temperature trends in Europe and Asia are also obviously somewhat less linear in this context than the current US data shown here. In the North Atlantic region for instance, it is certainly known that there is a complex interplay between the impact of climate change on components of multiple heat transport mechanisms comprising both wind and ocean heat transport, such as the North Atlantic Oscillation and the Atlantic MOC. These also represent areas of research. Nevertheless, although counterintuitive, climate predictions also indicate that some land regions may experience temporary cold periods while the overall global mean temperature rises on a decadal scale.  Lucky for you indeed if you happen to be in a climate privileged area that is seeing a current benefit from climate change.  Unfortunately, that has not been the case so far for a lot of other people…

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By john mcnally (Portland, Oregon 97210)
on February 22nd, 2013

I FIND IT CURIOUS THAT ALL THE PHD ANALYSTS WITH CREDENTIALS IN STATISTICS WHO DID THIS STUDY
WOULD BELIEVE IT’S LEGITIMATE TO COMPARE….“AVERAGE DAILY TEMPERATURES TO AVERAGE LOW
TEMPERATURES”.....THE FIRST BEING AN AVERAGE OF NUMEROUS DAILY TEMPERATURE POINTS TO A SINGLE
LOW TEMPERATURE FOR EACH DAY.  AS THEY SAY…“STATISTICS DON’T LIE BUT…..(YOU KNOW THE REST).

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By Dick Smith (Madison WI 53726)
on February 23rd, 2013

Mr. Bartosh’s comment about the 1970’s is not accurate.  Here is the “basic” response at Skeptical Science.  (Note: there are more advanced responses at the website if you’re interested).

The vast majority of climate papers in the 1970s predicted warming.

In the thirty years leading up to the 1970s, available temperature recordings suggested that there was a cooling trend. As a result some scientists suggested that the current inter-glacial period could rapidly draw to a close, which might result in the Earth plunging into a new ice age over the next few centuries. This idea could have been reinforced by the knowledge that the smog that climatologists call ‘aerosols’ – emitted by human activities into the atmosphere – also caused cooling. In fact, as temperature recording has improved in coverage, it’s become apparent that the cooling trend was most pronounced in northern land areas and that global temperature trends were in fact relatively steady during the period prior to 1970.

At the same time as some scientists were suggesting we might be facing another ice age, a greater number published contradicting studies. Their papers showed that the growing amount of greenhouse gasses that humans were putting into the atmosphere would cause much greater warming – warming that would a much greater influence on global temperature than any possible natural or human-caused cooling effects.

By 1980 the predictions about ice ages had ceased, due to the overwhelming evidence contained in an increasing number of reports that warned of global warming. Unfortunately, the small number of predictions of an ice age appeared to be much more interesting than those of global warming, so it was those sensational ‘Ice Age’ stories in the press that so many people tend to remember.

The fact is that around 1970 there were 6 times as many scientists predicting a warming rather than a cooling planet. Today, with 30+years more data to analyse, we’ve reached a clear scientific consensus: 97% of working climate scientists agree with the view that human beings are causing global warming.

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By Judy (12106)
on February 23rd, 2013

How about sharing this with Forbes?

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By Steve Goddard (Fort Collins Colorado 80525)
on February 23rd, 2013

The 1970s had the coldest winters in US history, with the winter of 1978-1979 being the coldest. Cherry-picking a start date of 1970 is remarkably deceptive.

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By MARK NABAVI (20176)
on February 23rd, 2013

The global temperature is part of the nature. It goes on, regardless of our desire or approval. We are simply impotent to halt the progression of the nature. And as far as the nature is concerned, we are no more desirable than, say for example the dinosaurs. In fact we have been more wasteful and toxic to the nature than any living organism on this planet.. So !! Just let’s do the good, and hope for the best, but don’t let us get sucked into the illusion that, if we can fly airplane, or, dive in the submarine, then we shall be able to alter the nature. True !! We can only worsen the natral processes,just a little bit, but halting it ??  Is another matter.

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By Billy P (Pine Bush/NY/12566)
on February 23rd, 2013

This is one of the worst cases of cherry picking I’ve seen. While I do believe that there is an anthropogenic component to climate change, nonsense like this article is designed to do nothing more than deceive people.  1970 was one of the coldest winters in the last 100 years.  It occurred during a period of natural cooling, because the AMO and PDO were both in cold phases.  This entire piece is no different than if I said since 1998 the global temps have dropped.  The last 2 decades are the warmest on record, there are plenty of REAL examples of warming to use, stop creating fraudulent charts that look catastrophic, just to put people in a state of panic.

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By Ice Cold Troll
on February 23rd, 2013

OK, we all know that 1970 was record cold, and the era that saw dire prophecies of a new Ice Age, right? OF COURSE we’re seeing warming since then!

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By Facing Reality
on February 24th, 2013

Do any of you claiming cherry picking even bother to check the data before posting?  It’s really not that hard, if you care about such things.  Go here: http://www.ncdc.noaa.gov/cag/time-series .  For “time scale,” select 3 months, and for “month,” choose February.  That way, you’ll get data for the three winter months.  Now, click the “plot” button, and watch your claims of cherry picking go up in smoke.  1970 was only slightly colder than average; anyone wanting to cherry pick would choose 1978-79, as that was the record-setter, or perhaps the also-cold previous two winters; and the overall trend shows how completely unnecessary it would be to cherry pick, anyway: anyone who is not blind can see the trend.

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By Michael J. Schmitz (PACIFIC COUNTY, 98586)
on March 3rd, 2013

SNOW STORM, 28 TO 49 DEGREES THIS WINTER.

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By J. Fish (Wilmington NY, 12997)
on April 12th, 2013

Speaking of cherry picking how about the comment that for the last 12,000 years we have been warming, choosing that time being one of the coolest time periods in recent history would not be considered cherry picking? Funny how deniers use the very methods that they claim climate change scientists are using…

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By rennie davis (Lyons, Colorado 80540)
on February 22nd, 2014

Thanks for the information. A small circle of scientists now believe that after the warming up comes a cooling donw—that the event of our time will not be global warming but an ice age redefining the human future. I have concluded that climate change has now gone past the point of no return—there are no piece meal solutions—and any human future will require a new way of living. I’m developing projects to engage millions of people in their 20s—as I did in the 1960s—to re-script the human future out of a great turning in ourselves. If you would like to join in or learn more, visit our campaign at http://www.indiegogo.com/projects/rennie-davis-a-story-to-change-the-world/x/5903161
Thanks, Rennie Davis (Chicago 7)

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