The Guardian, based on IPCC and Met Office data, reports 4th December 2015: Negotiators in Paris are trying to craft a deal at the UN climate talks that will keep global temperature rise below 2°C. But what does that mean in reality — and what difference will a couple of extra degrees really make?
1°C
- 2015 was the first year to reach this level
2°C
- Many species and ecosystems with limited ability to adapt to higher temperatures will be subject to “very high risks” even with 2°C of warming.
- At particular risk are species dependent on Arctic sea ice — such as polar bears and coral reefs.
- Arctic sea ice extent in September falls by 43% in extent against the long-term average.
- 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%.
3°C
- Ocean acidification is much greater, with surface ocean pH decreasing up to 62%.
Above 4°C
- The Arctic is nearly ice-free in summer, as early as 2050.
- Sea levels rise up to 82cm.
- Ocean acidification accelerates hugely, with surface ocean pH decreasing up to 109%.
Sources: IPCC, Met Office
The Guardian, 4th December 2015: For the full details, see www.theguardian.com/environment/2015/dec/04/paris-climate-talks-what-difference-will-temperature-rises-really-make