Show Your Stripes: Iconic Global Warming Imagery Goes Local

June 21, 2019, 1:58 AM EDT

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Above: Warming stripes for four U.S. states—California, Minnesota, Mississippi, and Maryland—show the differing patterns of a century of warming, as detailed below. Image credit: Climate Central, background image NOAA/NCEI.

The summer solstice arrives on Friday, June 21, and so does the second year of “warming stripes”. Launched in 2018, this growing campaign builds on a set of imagery developed by University of Reading climate scientist Ed Hawkins: colored stripes that portray a century-plus of global warming at a single glance.

This year’s campaign is taking the global trend and drilling down to individual U.S. states and cities. Climate Central has unveiled a website that allows you to generate warming stripes for 160 U.S. cities and all 50 U.S. states. The campaign has also revved up its use of social media, and dozens of broadcast meteorologists around the world will use warming stripes on air and online Friday, bringing home the reality of our warming planet.

“Meteorologists have a unique opportunity as trusted local messengers to educate audiences and help to create transformative change in a very challenging time,” said Jeff Berardelli, who coordinated last year’s effort among weathercasters, Meteorologists United on Climate Change (#MetsUnite on Twitter). After many years as a full-time broadcast meteorologist, Berardelli has shifted gears in the past year, moving to New York to produce climate-oriented segments for CBS News while working on a master's degree focusing on climate and society at Columbia University’s Earth Institute.

“This year there will be a lot more participation as the masses join #MetsUnite to #ShowYourStripes!” said Berardelli. “Through a combined effort from Climate Central and Ed Hawkins, we have made this campaign accessible to everyone who cares about planet Earth.”

“Increasingly, the public is convinced that the climate is changing. However, they don't always know exactly what that means for them, their family, and their community,” said Bernadette Woods Placky, who directs the Climate Matters program at Climate Central. “TV meteorologists are in a unique position to help answer those questions—to connect the dots between climate change and the increase in heavy rain, more coastal flooding, challenges to our food and water systems, longer and stronger pollen seasons, and intensifying heat that takes a toll on the health of outdoor workers and results in rearranging of our kids' camp and sports schedules.”

Four states, four snapshots

The image at top shows that warming across the contiguous U.S.—about 1.9°F from 1895 to 2018, which is fairly close to the global trend—hasn’t played out in the same way everywhere. The common threads are a mostly natural warming in the early 20th century, a mid-century leveling (and cooling in some areas) driven in part by postwar industry and sun-blocking pollution, and a more sustained warming in recent decades as the influence of human-produced greenhouse gases becomes ever more prominent.

All graphs below are from the NOAA National Centers for Environmental Information, with temperatures in degrees F (left) and degrees C (right). Century-scale warming rates are graphed; 30-year warming rates are given at the end of each blurb.

California saw fairly steady warming (with some multidecadal zigs and zags) through the 20th century, but what jumps out the most is a dramatic spike during the severe drought of the early 2010s. Research has shown that California’s droughts are now far more likely to be hot, higher-impact droughts more likely to spawn wildfires. Even during the relative mildness since 2015, California has remained consistently hotter than in any year prior to 2010.

Amount of warming per decade in the last 30 years (1988-2018): 0.6°F

Warming stripes and warming trends for California

Much of the warming in Minnesota to date has taken place in the early and late 20th century, with fairly level temps in the mid-20th century, and little overall change in the last 20 years. It’s been a rocky couple of decades, though, with plenty of year-to-year swings between exceptional warmth and more historically moderate readings. Such swings can play havoc with activities that range from winter festivals to summer planting. Polar-vortex intrusions that could be linked to Arctic sea ice loss led to sharply cold periods in the winters of 2013-14 and again in 2018-19.

Amount of warming per decade in the last 30 years (1988-2018): 0.5°F

Warming stripes and warming trends for Minnesota

Mississippi has one of the nation’s more intriguing warming patterns. A midcentury cooldown was so sharp in this part of the country that it led to what researchers dubbed the “warming hole”, a complex feature with possible links to post–World War II industry and uncontrolled pollution as well as multidecadal oceanic cycles. Whatever's caused it, the Southeast warming hole seems to be on the wane. Mississippi has warmed roughly 1.5°F in the past 30 years, and 2016 was one of the state’s hottest years on record.

Amount of warming per decade in the last 30 years (1988-2018): 0.5°F

Warming stripes and warming trends for Mississippi

Of the four states profiled here, Maryland has the most gradual and most prototypical warming story. The midcentury cool spell and the sustained temperature rise since 1980 are both evident. Warming like this is easier to plan for, but the state has its hands full between aging infrastructure, sea level rise, and intensified precipitation. The Northeast, including Maryland, is seeing the nation’s biggest increase in heavy precipitation events, a process linked to human-produced climate change in many studies.

Amount of warming in the past half century (1968-2018): 0.5°F

Warming stripes and warming trends for Maryland

Making it real

Climate change is a massive global crisis that’s easy to paint in broad strokes, yet it also deserves the detail that localized warming stripes can help convey, just as vividly drawn characters are what help bring an epic novel to life.

As Berardelli puts it, “The local stripe visuals help us tell a nuanced story—the climate is not changing uniformly everywhere. Some areas are warming much faster than others. Climate communicators have the opportunity to engage social media followers with a story of how/why the climate is changing differently locally than it is regionally or globally.”

Placky saw the popularity of warming stripes first hand this month when she attended the American Meteorological Society’s Conference on Broadcast Meteorology in San Diego. “There were warming stripes all over the place,” she said. “TV meteorologists were wearing stripes on their conferences badges, on earrings, and I even spotted a striped t-shirt.

“Climate change is a global issue that's felt personally. So the more we can break it down to the local level, the more we can connect with people personally.”

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

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Bob Henson

Bob Henson is a meteorologist and writer at, where he co-produces the Category 6 news site at Weather Underground. He spent many years at the National Center for Atmospheric Research and is the author of “The Thinking Person’s Guide to Climate Change” and “Weather on the Air: A History of Broadcast Meteorology.”

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