At 1.5 degrees of warming, the IPCC predicts that higher ocean temperatures would drive some marine species toward higher latitudes where they could potentially survive but which could then cause major disruptions in existing ecosystems. And, of course, not all species can simply move away. For instance, between 70 and 90 percent of tropical coral reefs would likely die, imperiling the $11 trillion in ecosystem services they currently provide annually in the form of fisheries, tourism, coastal protection, and more. Climate projections also have both heavy rains and droughts growing in frequency and intensity, along with increasing poverty levels.
And that half degree of warming would not look the same everywhere. Over the past 40 years, the Arctic has been heating up about four times faster than the rest of the world, and Europe appears to be the fastest-warming continent. The effects of climate change are not uniform, but what happens in one place can have cascading effects elsewhere. The melting of polar ice sheets, for instance, affects sea level rise elsewhere. Rising seas are already destroying the coastlines and freshwater supplies of many low-lying small island nations in the Pacific Ocean, some of which could soon become uninhabitable or even disappear completely under the waves.
There’s no doubt that climate change is taking a heavier toll on low-income countries, particularly in the Global South, but wealthier countries, many of which are responsible for inordinate amounts of historic carbon emissions, are also face-to-face with the climate emergency. Over the past 10 years or so, wildfires in the western United States have not only destroyed homes and lives but also halted or reversed decades-long improvements in air quality. When record-breaking wildfires raged in Canada last summer, toxic smoke engulfed major cities on the East Coast, including New York City and Washington, D.C., which had rarely experienced this particular type of air pollution. Intensifying wildfires, droughts, floods, hurricanes, storm surges, algal blooms, invasive species, vector-borne diseases, crop failure, economic hardship—suffice to say, we’ve already gotten a real taste of what 1.5 degrees of warming would feel like.
Have we hit 1.5 degrees of warming already?
Yes and no—it’s complicated. Climate scientists agree that the planet has already warmed at least 1.1 degrees Celsius. There is debate, however, about how to best gauge global temperature rise.
Because temperatures naturally fluctuate year to year, the IPCC doesn’t just look at the most recent data to make its assessment. Instead, it calculates average temperatures over the past 20 years. While this method ensures a better scientific picture of climate patterns over time, the world doesn’t have the luxury of waiting an extra decade or two to run the numbers before taking preventative action.
Some climate scientists therefore suggest a new approach, one that would look at temperatures over just the past 10 years plus the projected temperatures for the next decade, and then take an average. This would allow policymakers to more quickly assess whether their current emissions-fighting efforts are up to snuff.