The Climate Crisis, By The Numbers: Your Guide To Humanity’s Greatest Challenge

Where our planet stands today, how we got to this point, and what we must do to avoid disaster.

In a world regularly hit by supercharged storms, surging seas, deadly heat waves, and intense wildfires, the climate crisis is already a clear and present danger.

The numbers below document global warming and sea level rise since the 1880s, when widespread reliable data became available. They show just how far we have already come — and how little wiggle room we have to avoid a climate catastrophe by the end of this century.

Under the 2015 Paris agreement, the world’s nations agreed to limit global warming to well below 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial temperatures — ideally restricting warming to just 1.5 degrees C (2.7 Fahrenheit).

Less than a decade later, we’re close to blowing past the 1.5-degree target, having so far made little progress in turning things around.


Via NASA/Berkeley Earth/NOAA

The range shown for global warming comes from comparing the average global temperature for the period of 1880–1899 with the average for the most recent five complete years, as measured by two leading studies of historical temperature records that are run by NASA’s Goddard Institute for Space Studies and Berkeley Earth.

The Berkeley Earth project launched in 2010 — funded in part by the conservative-leaning Charles Koch Foundation — to address concerns that observed global warming might result from biases in data collection. But its reanalysis conclusively confirmed the scientific consensus that our planet is heating up. Indeed, the higher 1.3 degrees estimate comes from Berkeley Earth; 1.1 degrees is from NASA’s analysis.

“We already have dangerous climate change,” Michael Wehner, a senior staff scientist at the Lawrence Berkeley National Laboratory, told BuzzFeed News. “It’s just more dangerous for every tenth of a degree.”

As the Earth has warmed, the global average sea level has risen, driven by melting ice and the thermal expansion of seawater. The estimate for sea level rise since 1880 comes from the National Oceanic and Atmospheric Administration (NOAA). It is based on analyses of historical records from tide gauges throughout the world combined in recent decades with measurements of the return time and intensity of radar pulses fired down at the ocean surface from orbiting satellites.

Peter Aldhous / BuzzFeed News / Via Berkeley Earth/NASA

This chart plots the monthly global average temperature calculated by NASA and Berkeley Earth — you can highlight either analysis by tapping or hovering on the legend item. While there is a lot of variation from month to month, there’s a clear warming trend, especially in recent decades. Both projects calculate global temperatures compared to the average from 1951 to 1980, a relatively stable period during which temperature monitoring stations had good coverage across most of the globe.

Peter Aldhous / BuzzFeed News / Via NASA

Not everywhere is heating up at the same speed. Change has been most rapid in the Arctic, which is warming at three times the global rate and causing a decline in Arctic sea ice and melting the Greenland ice sheet. Warming has also been faster over land than over the ocean. You can use this map to view NASA’s historical temperature analysis for any location shown: Click or tap on the map or enter a location into the search box to see the annual chart redraw for that location.

Peter Aldhous / BuzzFeed News / Via CSIRO/U. Hawaii

This chart of average global sea level combines data from two projects: a reconstruction using historical and modern records, which runs from 1880 through 2013, from scientists with CSIRO, Australia’s national research agency, and an ongoing project at the University of Hawaii Sea Level Center. The reference for comparison is the global average sea level from 1993 to 2008, after satellite measurements came into regular use. Since 2006, global average sea level has been rising by about 3.6 millimeters (0.14 inches) per year, according to NOAA.

Even if coastal areas are not completely inundated, rising sea levels make it more likely that unusually high tides or surges caused by powerful storms will trigger flooding, causing major property damage and loss of life.

If we don’t limit warming, sea level rise is expected to accelerate as more and more ice melts from Antarctica’s massive ice sheets. According to a recent study published in the journal Nature, a trajectory that sends the planet toward 3 degrees C of warming could cause an abrupt increase in the pace of Antarctic ice melting after 2060. Compared to a world warmed by 2 degrees C, this would cause an extra 6 centimeters (2.4 inches) of sea level rise by the end of this century and an extra 23 centimeters (9 inches) by the end of the next.

“These results demonstrate the possibility that rapid and unstoppable sea-level rise from Antarctica will be triggered if Paris Agreement targets are exceeded,” the researchers concluded.

That would reshape coastlines worldwide, devastating cities from Amsterdam to Bangkok and triggering massive human migration. It would also wipe some small island nations off the map. And these projections do not include an unpredictable yet catastrophic tipping point like a rapid collapse of one of Antarctica’s enormous ice sheets — an almost unimaginable event that could add several meters to the global average sea level.

Peter Aldhous / BuzzFeed News / Via NOAA

Warming and sea level rise are driven by the buildup in the atmosphere of greenhouse gases, especially carbon dioxide from burning fossil fuels. These gases act like a glasshouse, trapping the sun’s heat and warming the globe.

Since 1958, we have had accurate measurements of carbon dioxide in the atmosphere from a project started by the late Charles David Keeling of the Scripps Institution of Oceanography. He used infrared sensors to measure the concentration of the gas in air at the Mauna Loa Observatory on the Big Island of Hawaii, a site chosen for its lack of local pollution and sparse vegetation (plants pull carbon dioxide from the air).

The chart above shows records from both Mauna Loa and a composite value compiled by NOAA from measurements at sites across the globe since 1980. Both plots show a regular annual cycle with a dip each spring and summer caused by the plant growing season in the large landmasses of the Northern Hemisphere superimposed over a climb caused mostly by fossil fuel burning.

Peter Aldhous / BuzzFeed News / Via NOAA

Deniers of human-caused climate change sometimes argue that levels of carbon dioxide and global temperatures have varied widely in the past as a consequence of natural long-term cycles — and suggest that something similar is happening today. They are wrong, and scientists have proof of this.

By measuring levels of carbon dioxide trapped in bubbles of air in deep cores taken from the thick cap of Antarctic ice, scientists have been able to reconstruct the atmospheric concentration of the gas going back more than 800,000 years. It’s true that levels of carbon dioxide waxed and waned as the Earth cycled in and out of successive ice ages. However, the final almost vertical line, which includes the modern record shown on the previous chart, shows that nothing like the recent surge has happened in the ice-core record. Humanity’s emissions of carbon dioxide from fossil fuels are clearly to blame, scientists concluded in the latest Intergovernmental Panel on Climate Change report.

Peter Aldhous / BuzzFeed News / Via Our World In Data/Global Carbon Project

This chart ranks the world’s nations by their contribution to those emissions, using data compiled by Our World in Data from the Global Carbon Project. Once released into the atmosphere, carbon dioxide can hang around for hundreds of years. This means that the Earth today is being warmed by the cumulative emissions pumped out over many decades — making the United States, the largest historical emitter, most responsible for the crisis, even though China’s current annual emissions are larger.

The long residence time of carbon dioxide in the atmosphere also means that global warming is a bit like an oil tanker on the high seas: slow to turn around, even if you yank hard on the tiller. The great challenge now facing humanity is that we need to make rapid cuts in our use of fossil fuels. The goal is to quickly bring our emissions down to what’s called “net zero” — where carbon dioxide going into the atmosphere equals the amount being pulled out by natural or technical means — to have any chance of keeping beneath those 2015 Paris targets.

Peter Aldhous / BuzzFeed News / Via Our World In Data/Global Carbon Project

But as this chart shows, at least until the temporary reduction caused in 2020 by the coronavirus pandemic, carbon dioxide emissions have grown, driven in particular by a surge in emissions from Asia in recent decades as China and India flexed their economic muscles.

It is still not too late to turn things around. But if we don’t quickly cut the mountain of carbon dioxide emissions shown on the chart above, a disastrous future awaits.

Peter Aldhous / BuzzFeed News / Via Climate Action Tracker

This chart shows potential future emissions scenarios, released by the Climate Action Tracker during the 2021 climate summit in Glasgow. Emissions over the past three decades are shown as a black line. (The numbers are larger than on the previous chart because they account for all greenhouse gases, not just carbon dioxide.)

According to these projections, current policies will likely see the world warm to up to 2.9 degrees C above preindustrial temperatures. The most ambitious targets to reduce emissions might just keep warming down 1.8 degrees C, but these depend on pledges from some nations to achieve net-zero emissions in the future that give few details on how they will actually be achieved.

A big problem with these targets is that deep cuts do not begin immediately. And it is far from clear whether pledges will actually be met; according to an investigation by the Washington Post, many nations are not even reporting their current emissions accurately.

“It’s all very well for leaders and governments to claim they have a net-zero target but if they don’t have plans on how to get there — their 2030 targets are not aligned with net zero — then frankly these net-zero targets are just paying lip service to real climate action,” Bill Hare, CEO of Climate Analytics, one of the partners behind the projections, said at a press conference.

“One thing is clear: All governments need to reconsider their targets so that we can keep 1.5 degrees alive,” added Claire Stockwell, a senior climate policy analyst with Climate Analytics.

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