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Meanwhile, ice is melting at both poles, with Antarctica losing ice mass to the tune of about 150 billion tons per year and Greenland losing roughly 280 billion tons annually. And summer Arctic sea ice extent is shrinking by 12.6% per decade.
All that melting ice contributes to sea level rise, threatening coastal communities and low-lying islands globally. Longtime residents of the Isles de Jean Charles in Louisiana, for example, have already had to abandon their homes for higher ground, due to a combination of sinking land and sea level rise.
Meanwhile, the last decade was the ocean’s warmest since at least the 1800s, with 2021 the warmest on record. Water expands as it gets warmer, so warming oceans are responsible for between one-third and one-half of sea level rise, whose rates of rise NASA calls “unprecedented” over the last 2,500-plus years.
That’s just from one degree Celsius of change.
And impacts will only intensify as the temperature continues to tick up. A 2022 Intergovernmental Panel on Climate Change report notes that even the most ambitious plan of limiting warming to 1.5 C/2.7 F includes “unavoidable multiple climate hazards over the next two decades.”
These risks include threats of sea level rise to infrastructure and low-lying coastal communities, as well as more extreme weather, drought, and related health impacts.
What difference does a degree of change make? Ask the humans of 2100.
In a world that’s 1.5 C/2.7 F warmer than in pre-industrial times, storms, heat waves, and droughts will be even more extreme than they are today. More homes will be lost to sea level rise and wildfire. And more people are likely to suffer from heat-related illnesses, infectious diseases, and starvation.
Life in the 2020s already looks different. With every additional degree — and each fraction of a degree — of warming, the consequences will become yet more palpable in 2100.
Let’s say, for instance, that people manage to keep warming below 1.5 C/2.7 F. Today’s young children could live to see nearly four times the number of extreme storms they see now, according to the Intergovernmental Panel on Climate Change research. And that’s just with an additional 0.5 C of warming from where we are today. With 3 C/5.4 F of warming, however, today’s kids would inherit a world with five times the likelihood of hurricanes and other severe storms.
The following are other examples of the difference a degree or two could make in terms of real-world harm:
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