Human activities are already estimated to have caused approximately 1.0ºC of global warming above pre-industrial levels. Global warming is likely to reach 1.5ºC between 2030 and 2052 if it continues to increase at the current rate.
According to the IPCC, limiting global average temperature rise to the relatively safer level of 1.5ºC (versus 2º or more) is still possible, but it will require rapid technological transitions at “unprecedented” scale, including the transition of energy systems to low or zero carbon sources by 2050.
The risks of global warming greater than 1.5ºC include negative impacts on human health, infrastructure, agriculture, and marine ecosystems. For example, coral reefs are projected to decline by an additional 70–90% at 1.5°C with larger losses (>99%) at 2ºC.
The Special Report involved 91 authors from 40 countries, 133 contributing authors, over 6,000 cited references, and 42,001 expert and government review comments.