June 12, 2012 | 5:10 PM | By

Mapping the Patchwork of U.S. Warming Trends

FILED UNDER: The Science, Temperature

The Southwest and Northeast have warmed the most. California is, well, average

They call it “global warming” but where you fall on the warming scale depends a lot on where you live. Not everywhere has warmed the same amount (or at all), and it certainly hasn’t happened at the same rate.

A new analysis from Climate Central, a climate education organization (and content partner with Climate Watch), breaks down the warming trends in the continental U.S., state by state.

Some states show an increase in average temperatures (Minnesota, Maine, Arizona and New Mexico, for instance), and some show nearly none (Florida, Alabama, Georgia). California ends up pretty much in the middle of the pack. One reason is its size: California is big and geographically diverse.

“We are pushing the system more and more, so what has happened in the past is not a very good sign of what is going to happen in the future.”
“It may well be there are areas warming more or less within California,” Claudia Tebaldi, a research scientist at Climate Central, a visiting scientist at the National Center for Atmospheric Research and one of the report’s authors told me. “And I’m sure the very coastal areas are going to have much less warming than the interior” (a trend we first wrote about back in 2008). Tebaldi said the influence of the ocean and natural patterns and variations — for instance, El Niño — may have an effect, too.

Though states have experienced different amounts of warming, the report finds that beginning in the 1970s, the pace of warming has accelerated across the country.

Tebaldi stressed that while the overall warming trend is consistent with what scientists expect the effects of greenhouse gas emissions to be, this study isn’t about causation. “It’s really not possible to [determine that] at this geographic scale of states,” she explained. This study also doesn’t project what’s to come. “The problem with future projections is we are pushing the system more and more, so what has happened in the past is not a very good sign of what is going to happen in the future,” she said.

Tebaldi and her co-authors used temperature data from the United States Historical Climatology Network, which has temperature records from more than 1,200 weather stations around the continental U.S. That allowed them to get more specific, and to go beyond national or regional trends.

“My interest in doing this as a scientist is to communicate the diversity in the behavior of climate at the local level,” she said. “But also to invite people to have a larger view of what’s going on, and not be bogged down by the fact that the Southeast is not warming. Because the bigger picture is one of warming, especially when you look at the most recent acceleration of the trends.”

About the author

Molly Samuel joined KQED as an intern in 2007, and since then has worked here as a reporter, producer, director and blogger. Before becoming KQED Science’s Multimedia Producer, she was a producer for Climate Watch. Molly has also reported for NPR, KALW and High Country News, and has produced audio stories for The Encyclopedia of Life and the Oakland Museum of California. She was a fellow with the Middlebury Fellowships in Environmental Journalism and a journalist-in-residence at the National Evolutionary Synthesis Center. Molly has a degree in Ancient Greek from Oberlin College and is a co-founder of the record label True Panther Sounds. View all posts by Molly Samuel →

  • Anonymous

    We would be shocked if they mapped from 1921 which was a real pivot point. Many states warmed from 1895 to 1921 and have never got that warm again.

    https://sunshinehours.files.wordpress.com/2012/04/alabama_19211.png

  • James Mayeau

    Here’s the thing. Co2 rises monotonically. That is to say, just because you have a freeway over here, with lots of cars equipped with smog control, efficiently converting CO into Co2, doesn’t mean you get more Co2 than that rural place over there.  It all rises together uniformly. This is because the largest Co2 reservoir is the ocean, which out gasses and uptakes many times the amount of co2 we humans do. 

    As Co2 rises monotonically, as the theory goes, each of these individual Co2 molecules absorbs a quantum of infrared light. That’s a rule of chemistry, and you can’t break that rule of chemistry as it suits you, or to convenience balky regional temperature measurements that don’t fit the theory. 

  • Russell Steele

    Cherry Picking

    Climate Central is up to their typical cherry picking tricks. The later part of the 1970 started a warm phase PDO which ended about 2002.  If they had started their data in 1950, rather than 1970 there was not significan warming.  Steven Goddard has the details:

    The graph below plots Hansen’s 2006 temperatures for the five states which have warmed the fastest (in the map above) since 1970 – Arizona, Minnesota, Wisconsin, Michigan and Vermont. The 1970s was one of the coldest decades in US history. By starting in 1970, Climate Central is intentionally defrauding their readers. Had they started in 1950, there would be almost no warming shown.

    Detail here: http://stevengoddard.wordpress.com/2012/06/12/cheating-for-dollars-at-climate-central/

    • James Mayeau

      Also there’s the question of cherry picking Hansen’s 2006 temperatures, rather then the current product. 

      For readers who only visit links provided on the KQED blog roll,  the 1970′s used to be much cooler before GISS, NOAA,  and NCDC,  started “adjusting” the numbers ~ 2008.

        http://wattsupwiththat.com/2009/06/28/nasa-giss-adjustments-galore-rewriting-climate-history/#more-8991

      http://jennifermarohasy.com/2009/06/how-the-us-temperature-record-is-adjusted/