Impacts of climate change
- Today, 0.8% of global land is too hot for human existence. On a pathway to 3°C net warming, 19% of global land would be too hot for human existence (i.e., home to a third of humanity).
- Temperatures have risen faster on land than in the ocean, which is warming most near its surface.
- Roughly 1 billion people will be displaced for every 1°C of warming.
The latest report from the IPCC, AR6 (summary PDF), states that sea levels rose 0.2 meters between 1901 and 2018—and that the rate of sea level rise is also accelerating. The report says it's possible sea levels could rise 2 meters by 2100, or 5 meters by 2150.
A warmer atmosphere can hold more water. Over the last four decades, extreme precipitation events have gotten more likely. 1
In recent decades "the magnitude of heat extremes significantly increased," while "multiple successive temperature extreme events" became more commonplace. 2
Reduced food security
Climate change has reduced agricultural productivity by about 21 percent since 1961. 3
The ocean is warming most near its surface.
Climate change is also causing oceans to become more acidic. This impacts the ecosystem of oceans, as well as communities and economies that depend on them.
Climate change could also possibly slow ocean currents:
At issue is the Atlantic Meridional Overturning Circulation, also called AMOC. This system carries warm water from the equator to the North Atlantic, where water cools and gets denser before flowing back south. But with more fresh water flowing in, the water there becomes less salty and dense, meaning it won't flow back south as fast. 4
While the slowing of ocean currents is expected to be a slower change, the impact is fairly unknown, and could represent a "tipping point" for climate change. As the IPCC AR6 report puts it:
The Atlantic Meridional Overturning Circulation is very likely to weaken over the 21st century for all emission scenarios. While there is high confidence in the 21st century decline, there is only low confidence in the magnitude of the trend. There is medium confidence that there will not be an abrupt collapse before 2100. If such a collapse were to occur, it would very likely cause abrupt shifts in regional weather patterns and water cycle, such as a southward shift in the tropical rain belt, weakening of the African and Asian monsoons and strengthening of Southern Hemisphere monsoons, and drying in Europe.
- A heatwave in March 2022 shattered records with temperatures 38°C above average.
The Arctic has warmed almost four time faster than the rest of the world since 1979. 5 This phenomenon has been called "Arctic amplification". Arctic sea ice has shrunk markedly—and in some scenarios, the Arctic could be ice-free within the next few decades.
Less snow and ice means lower albedo, i.e. the Arctic reflects less sunlight back to space. The warmer atmosphere also holds more moisture, which ends up transporting more heat to the poles.
- Rain fell on the peak of Greenland's ice sheet for the first time ever recorded in August 2021.
- In recent decades Himalayan ice sheets have been melting at an "exceptional" rate compared to previous centuries. This will impact agriculture and the water supply for millions of people in South Asia.
Constraining the increased frequency of global precipitation extremes under warming | Nature Climate Change ↩
Growing prevalence of heat over cold extremes with overall milder extremes and multiple successive events | Communications Earth & Environment ↩
Anthropogenic climate change has slowed global agricultural productivity growth ↩
Terra.do coursework. ↩
The Arctic has warmed nearly four times faster than the globe since 1979 | Communications Earth & Environment ↩