This is one of the clearest visualizations of global warming I've ever seen. Ed Hawkins, a climate scientist at the University of Reading, recently made this mesmerizing (and now-viral) GIF showing world temperatures spiraling upward over time between 1850 and 2016:
Each point on the spiral shows how a given month’s average temperature deviates from the long-term average between 1850 and 1900 (the period before industrial activity really took off in the 20th century).
Global warming isn’t a smooth process, and there are fluctuations from year to year due to internal variability (e.g., changes in the sun’s intensity, volcanic eruptions, or shifts in the amount of heat stored in deeper layers of the ocean). But as we keep adding greenhouse gases to the atmosphere and keep trapping extra heat on Earth, that effect eventually dominates, pushing overall temperatures higher and higher. The spiral moves outward.
The line for 2016 is especially striking. Global warming, along with a powerful El Niño in the Pacific Ocean, have combined to make every single month since August 2015 the hottest — by far — in the thermometer record. Once El Niño dies down later this year, the spiral may cool off a bit, as more heat is transferred back to deeper layers of the ocean. But so long as we keep burning vast amounts of oil, gas, and coal, temperatures will keep getting hotter.
Hawkins also created some great graphics deconstructing the spiral. Here’s one showing each year as a line — which, again, makes clear how staggeringly, anomalously warm 2015 and 2016 have been:
The chart below breaks things down by month. This one makes even clearer the dips and spikes over time. In the mid-20th century, aerosol pollution likely suppressed global warming temporarily, and El Niño usually has a short-term warming effect while La Niña has a short-term cooling effect. But, again, the big picture is obvious:
The other thing to note about the spiral is that we’re edging ever closer to the 1.5°C mark — that is, the point at which global average temperatures are 1.5°C (or 2.7°F) above preindustrial levels.
At the Paris climate conference last year, the world’s nations pledged to hold overall global warming below this mark. But short of an immediate and drastic plunge in carbon-dioxide emissions (along with an unprecedented effort to suck CO2 back out of the atmosphere), we’re almost certain to spiral past 1.5°C. And without major changes in energy use, we’ll likely push past 2°C — a threshold policymakers have often considered “dangerous” — sometime in the 21st century as well.
What happens at 2°C? The short answer: we barrel into the unknown. For most of the time human civilization has existed — the past 13,000 years or so — global average temperatures have never really soared that high. The changes are expected to be dramatic: rapid sea level rise could reshape our coastlines and force cities to retreat. Vital coral reefs could die off. Agriculture could suffer as extreme heat and drought start to wilt crops. We’ve reached the point where, no matter what else happens with emissions, we’ll need to think very seriously about how to adapt civilization to these risks — a messy and arduous task.
Hawkins’ spiral can’t possibly capture every last aspect of climate change, but it’s a stunningly elegant way to illustrate one of the largest challenges humanity faces this century.