Five key findings of stark UN climate change report

More forest fires, heat deaths and water shortages among consequences of temperature overshoot

The United Nations Intergovernmental Panel on Climate Change (IPCC) released a report on Monday; below are its key findings and consequences.

5 Key Findings of ‘1.5 degree’ report:

1. The world has already warmed by 1.1 degrees since pre-industrial times, due to human activity. On current trends, it’s likely to pass the 1.5 degree mark between 2030 and 2052. Land is warming faster than the oceans and the Arctic is warming at two- to three-times the global average rate.

2. Even half a degree will significantly worsen the risks of drought, floods, extreme heat and poverty for hundreds of millions of people.

3. To stabilise temperatures, emissions need to reach net zero and stay there. That means cutting emissions as much as possible and drawing carbon out of the air to balance any remaining emissions. The amount of warming is ultimately determined by how long it takes to get to net zero.

4. To have any chance of limiting global temperature rises to 1.5 degrees by 2100 would mean a greater reliance on techniques such as “carbon capture and storage” – such techniques are unproven at large scale; some may carry significant risks for sustainable development.

5. The Earth is already seeing the consequences of 1.1 degree of global warming in the form of more extreme weather, rising sea levels and diminishing Arctic sea ice.

5 key consequences of ‘temperature overshoot’:

1. At 2 degrees extremely hot days, such as those experienced in the northern hemisphere this summer, would become more severe and common, increasing heat-related deaths and causing more forest fires.

2. At 1.5 degrees, the proportion of the global population exposed to water stress (difficulty obtaining fresh water) could be 50 per cent lower than at 2 degrees.

3. The greatest difference would be to nature: insects, which are vital for pollination of crops and plants are almost twice as likely to lose half their habitat at 2 degrees compared with 1.5 degrees. Corals would be 99 per cent lost at the higher of the two temperatures, but more than 10 per cent have a chance of surviving if the lower target is reached.

4. Sea-level rise would affect 10 million more people by 2100 if the half-degree extra warming brought a forecast 10cm additional on coastlines. Over centuries and millennia, sea levels will continue rising after temperatures have stabilised. The collapse of ice sheets in Greenland and Antarctica could lead to rises of several metres.

5. Biodiversity loss: the proportion of species that will “lose half their geographic range” is striking – out of 105,000 species studied, the rate doubles between 1.5 degrees and 2 degrees warming to 16 per cent for plants and 8 per cent for vertebrates, and triples to 18 per cent for insects.

Kevin O'Sullivan

Kevin O'Sullivan

Kevin O'Sullivan is Environment and Science Editor and former editor of The Irish Times