Half a Degree

The report highlights a number of impacts that could be avoided by limiting global warming to 1.5°C compared to 2°C, or more. For instance, by 2100, global sea level rise would be 10cm lower with global warming of 1.5C compared with 2°C. The likelihood of an Arctic Ocean free of sea ice in summer would be once per century with global warming of 1.5°C, compared with at least once per decade with 2°C. Coral reefs would decline by 70-90 per cent with global warming of 1.5°C, whereas virtually all (> 99 percent) would be lost with 2°C.

The IPCC is the leading body for assessing the science related to climate change, its impacts and potential future risks, and possible response options. It assesses the thousands of scientific papers published each year, identifies where there is agreement in the scientific community, where there are differences of opinion, and where further research is needed. It does not conduct its own research and to produce its reports, the IPCC mobilizes hundreds of scientists and officials drawn from diverse backgrounds.

The new report was prepared under the scientific leadership of three working groups. Working Group I assesses the physical science basis of climate change; Working Group II addresses impacts, adaptation and vulnerability; and Working Group III deals with the mitigation of climate change.

More than 6,000 scientific references are cited in the new report, and the IPCC says thousands of expert and government reviewers worldwide have contributed. In addition 91 authors and review editors from 40 countries prepared the report.

If people still question the existence of climate change despite the exhaustive list of professional contributions from around the world, they can still quite easily recognize the physical and mental health benefits of preventing global warming.

The discussion needs to shift away from questioning the existence of climate change and the intelligence of our scientific community. Specific numbers say global net human-caused emissions of carbon dioxide would need to fall by about 45 per cent from 2010 levels by 2030, reaching ‘net zero’ around 2050. This means that any remaining emissions would need to be balanced by removing CO2 from the air.