If the global average temperature rises by 4C it would affect many ecosystems on the whole world, for example:
Marine ecosystems could be fundamentally altered bye oceanacidification which would have an impact on fisheries. This could cause substantial loss in jobs. The loss of coral reef habitats due to acidification may affect many commercial fish species and couldcause a disaster for coastal communities relying on subsistence fishing of reef species.
High forest-fire danger would affect every populated continent. Regions moving into the highdanger category: large areas of the united states, Mexico, south America, east of the Andes, southern and east Africa, Sahel, Australia and Europe.
Maize and wheat yields will be reduced by upto 40% at low latitudes.
Complete disappearance of glaciers from many regions in South America. In Peru’s Cordillera Blanca summer run-off from glaciers reduced by up to 69% asthe glacial area falls bye 75%.
Water resources affected by up 70% reduction in run-off around the Mediterranean, southern Africa and large areas of South America.
Half of all Himalayan glaciers willreduce bye 2050, even at a global average temperature below 4C.
The Indus river basin obtains 70% of its summer flow from glacial melt.
In China, 23% of the population lives in the western regionswhere glacial melt provides the principal dry season water source.
Sea Level Rise:
Greenland Ice Sheet has a 60% likelihood of irreversible decline. This would result in a very long-term sea-levelrise of up to 7 meters globally.
Seal-level rise combined with storm surges could pose a serious threat to people and assets in the Netherlands and south-eastern parts of the UK.
Sea level increasesare likely to be even greater at low latitudes, disproportionately affecting tropical islands and low-lying regions.
If the west Antarctic ice sheet did melt it would contribute a further 3.3 meters...