Graphic by Prof. Ed Hawkins (National Centre for Atmospheric Science, University of Reading).
June 21st is Show Your Stripes Day!
Show Your Stripes Day is a global moment to share our concern about how the climate is changing and the need for urgent action.
University of Reading
What Is It?
In 2018, Prof. Ed Hawkins, a climate scientist at the University of Reading, UK, published a graphic he called “warming stripes.” Designed as a visual representation of temperature change over time, with cool temperatures in shades of blue and warm temperatures in shades of red, the graphic is a powerful statement of climate change over decades. The warming stripes graphic below shows global average annual temperatures for 1850 through 2024. Based on a reference temperature of the 1961-2010 average, cooler temperatures are shown in blue stripes, while shades of red indicate warmer temperatures than the reference average.
Graphic by Prof. Ed Hawkins (National Centre for Atmospheric Science, University of Reading).
The result is an instantly understandable statement of global climate change. The annual event of Show Your Stripes Day on June 21st provides a simple, but powerful platform to communicate the reality of climate change. Show Your Stripes Day has been the occasion to display the warming stripes in prominent public spaces, including Times Square in New York City and the Tate Modern museum in London, UK.
2023 ShowYourStripes Day. Warming Stripes beamed onto “the chimney” of the Tate Modern Museum in London, UK. Credit: University of Reading
The University of Reading hosts the #ShowYourStripes website, where you can generate a variety of Warming Stripes graphics for individual cities, countries or the globe, with annual stripes ranging from 1850 through 2024. Climate Central supports a collection of Warming Stripes for U.S. cities and states. The graphic below shows Climate Central’s Warming Stripes for Sarasota, Florida, the location of the Climate Adaptation Center’s headquarters.
Climate Central version of warming stripes for Sarasota, Florida. Note that the reference temperature between cool/blue and warm/red is the average of the full range: 1911-2010 average. Highly localized data like this shows greater variability than the global averages of the previous graphic. Nonetheless, the overall rising temperatures are clearly visible in recent years.
2024 was the warmest year ever recorded. Extreme weather events are occurring more frequently around the world, most recently in June 2025 both the rapid intensification of Hurricane Erick which struck the Pacific coast of Mexico, and an extreme heat dome building across the U.S. The need to address climate change is increasingly urgent.
Back in Time
Climate change skeptics often say “it’s been warm in the past, too,” suggesting that the current global heat isn’t anything unusual. Well, warming stripes for the last 2,024 years show that today’s global climate is certainly unprecedented over more than 20 centuries.
How do we know this? Through the efforts of the PAGES (Past Global Changes) project, an international effort coordinating past global change research. The PAGES2K Global Temperature Proxy database covers the period from year 1 to year 2000, sourced from a variety of proxy data sources, including tree rings, pollen, corals, lake and marine sediments, glacier ice, speleothems, and historical documents. Coupled with the temperature measurement data of the current industrial period, scientists can produce the accurate results in the warming stripes graphic below.
Graphic by Prof. Ed Hawkins (National Centre for Atmospheric Science, University of Reading). Data from PAGES2K, and the Hadley Centre (UK Met Office)/Climatic Research Unit – Temperature (University of East Anglia)
The principal cause of this warming is the growing emissions of greenhouse gases (predominantly CO2) — predominantly the result of our burning of fossil fuels. PAGES records show that CO2 levels in the atmosphere today are the highest they have been in at least 3 million years; and climate warming was faster in the last 50 years than at any time in the last 2,000 years. The following graphic combines the global temperature record with the CO2 record over the last 2,024 years. (Annual temperatures are shown relative to the 1901-2000 average.) The result speaks for itself.
Note that the reference period defining the transition between cool/blue and warm/red colors is the 1901-2000 average. Credit: Hawkins et al (2025) Bulletin of the American Meteorological Society 106, 5; 10.1175/BAMS-D-24-0212.1
Of course, the distribution of that warming isn’t evenly distributed across the earth’s surface — land areas warmed much faster than the oceans. The map below shows that the northern hemisphere land masses have warmed most rapidly, with Arctic amplification resulting in the far North warming at nearly 4 times the rate of lower latitudes.
Credit: Prof. Ed Hawkins (National Centre for Atmospheric Science, University of Reading), Ed Hawkins/climate visuals
The Future
Warming Stripes can also bring home the impact of today’s climate warming on the future climate. The graphic below shows the global average temperature record from 1850 through 2024, and two possible climate warming scenarios for 2025 through 2090.
Warming Stripes, combining observations of global average temperature (1850–2024) and two different future emission scenario choices for the next several decades (2025–90). Future projections are based on U.N. Intergovernmental Panel on Climate Change (IPCC) pathways SSP1–1.9 (Rapid Action) and SSP2–4.5 (Delayed Action), with random noise added to generate annual stripes. Credit: Hawkins et al (2025) Bulletin of the American Meteorological Society 106, 5; 10.1175/BAMS-D-24-0212.1
The “Delayed Action” scenario shows a “3°C world” derived from an IPCC “middle-of-the-road” scenario, where greenhouse gas emissions gradually decrease but do not reach net zero by 2100. This is the outcome described in a recent CAC article “A Hotter World Is Inevitable” in which we conclude that “Planning for a 3°C world is now a necessity.” In the later years of this scenario, the 2024 record year would be considered a “cold” year.
The “Rapid Action” scenario imagines an outcome in which we attain global net zero emissions by 2050. Unfortunately, in 2025 greenhouse gas emissions are increasing, not decreasing. As the saying goes, “You can’t get there from here.” The graphic brings home the reality that even if we succeed in reducing emissions to net zero, we will be living in a world hotter than today (albeit not much hotter) for the next century.
A recent article by Matthew Collins and colleagues highlights regional impacts of climate change that we could expect to develop later this century in the Delayed Action/Rapid Action time frame. The key findings of their study include:
- increasing monsoon rainfall
- potential strengthening of the storm track into northwestern Europe and an increase in land-falling extreme storms (For an example, see CAC’s article on Cyclone Ciarán)
- rainfall will become a larger component of precipitation in the Arctic and Antarctic, affecting ice melt and adding to sea level rise
- in the near future we can expect an increase in the frequency and intensity of El Niño Southern Oscillation (ENSO) events, coupled with changes in ENSO impacts on North America and Europe
- an increase in the frequency of dangerously hot and humid extreme weather.
Research such as this is increasingly important, given the likely trajectory of climate warming in the not too distant future. A recent report by S&P Global, a financial information and analytics company, reinforces that message: “… the projected financial costs of climate physical risks are substantial due to the amount of warming that has already occurred. That reality makes adaptation and resilience central to addressing the physical risks of climate change now and over the years to come.” [emphasis added]