Negotiators in Paris are trying to craft a deal at the UN climate talks that will keep global temperature rise below 2C. But what does that mean in reality – and what difference will a couple of extra degrees really make?
Without action, climate scientists have warned that temperatures could rise by nearly 5C above pre-industrial levels by 2100. World leaders meeting in Paris hope to keep average global surface temperature rises below 2C – but their pledges to cut emissions could still see up to 3C according to analyses. While it is very hard to make firm predictions, here are some of the potential impacts. All are for possible temperature rises occurring by 2100.
1C – 2015 was the first year to reach this level
2C
- Many species and ecosystems with limited ability to adapt to higher temperatures will be subject to “very high risks” even with 2C of warming.
- At particular risk are species dependent on Arctic sea ice – such as polar bears – and coral reefs.
- Warming of around this level would see global annual economic losses of 0.2-2% of income, though experts caution that the “global economic impacts from climate change are difficult to estimate”.
- Arctic sea ice extent in September falls by 43% in extent against the long-term average.
- Snow cover in the northern hemisphere spring decreases by 7%.
- Sea levels rise by up to 55cm. They have already risen by around 20cm over the 20th century.
- The oceans get more acidic, with the surface ocean pH decreasing by 15-17%.
- Glaciers decline in global volume by as much as 55% (excludes those on Antarctica’s periphery and the Greenland and Antarctic ice sheets).
- 1.5 billion people exposed to heatwaves each year.
- 30 million people affected by flooding each year.
- 1.5 billion people exposed to increased water stress.
