Yesterday I read a number of news stories about the new IPCC's (International Panel on Climate Change) report regarding the current state of global warming. It reported that we are on track for hitting their safety threshold for global warming, namely an increase of 1.5 °C average temperatures since pre-industrial times. A number of reports are made, such as for example:
- Maintaining the goal of 1.5 degrees instead of 2 degrees will result in 10cm lower sea levels by the year 2100.
However it's the report on the effect on coral reefs that really shocked me. At the moment our level is 1 degree above pre-industrial levels. The report predicts that if the level is allowed to rise to 1.5 degrees (which is supposedly going to happen in 2030 at this rate), that 70 to 90 per cent of coral reefs will be destroyed. Further, if this metric rises to 2 degrees, that we can expect over 99% of coral reefs to be destroyed. This pretty much sounds to me that they will all but be destroyed if we allow up to a 2 degree increase.
I'm pretty naive on the subject, so I'm wondering why such a temperature increase of half a degree can have such a marked effect on coral reefs in particular.