Why is there a focus on limiting global warming to 1.5°C above pre-industrial levels?

The focus on limiting global warming to 1.5°C above pre-industrial levels is to prevent catastrophic environmental and societal impacts.

The 1.5°C target was established by the Paris Agreement, an international treaty aimed at combating climate change. This target is based on scientific research suggesting that a global temperature increase of more than 1.5°C could lead to irreversible changes in our climate system. These changes could include more frequent and severe weather events, such as hurricanes and droughts, rising sea levels, and significant loss of biodiversity.

The Intergovernmental Panel on Climate Change (IPCC) has warned that exceeding this temperature increase could push many ecosystems beyond their ability to adapt. For instance, coral reefs, which are vital for marine biodiversity, are expected to decline by 70-90% with a 1.5°C increase, and would be virtually wiped out with a 2°C increase. Similarly, the Arctic region is expected to experience ice-free summers once every century with a 1.5°C increase, but this would occur once every decade with a 2°C increase.

Moreover, the societal impacts of exceeding the 1.5°C target could be devastating. Rising sea levels could displace millions of people living in coastal areas, while changes in weather patterns could disrupt agriculture, leading to food shortages and increased poverty. The World Health Organisation has also warned that climate change could lead to an additional 250,000 deaths per year between 2030 and 2050 due to malnutrition, malaria, diarrhoea and heat stress.

Limiting global warming to 1.5°C is therefore seen as critical for preventing these catastrophic environmental and societal impacts. However, achieving this target will require significant reductions in greenhouse gas emissions. According to the IPCC, global net human-caused emissions of carbon dioxide would need to fall by about 45% from 2010 levels by 2030, and reach 'net zero' around 2050. This will require a major transformation of our energy, transport and industrial systems, as well as changes in our lifestyles and consumption patterns.