Dubai, United Arab Emirates—"The North Star of the COP28 Presidency is to keep 1.5°C within reach," has been the frequent refrain of Sultan Ahmed Al Jaber, the COP28 president overseeing the current U.N. climate change negotiations in Dubai. Al Jaber is reflecting the oft-chanted activist slogan "Keep 1.5 Alive!" The idea is that humanity must reduce its emissions of globe-warming greenhouse gases from burning fossil fuels sufficiently to keep the planet from warming more than 1.5 degrees Celsius above the pre-industrial baseline (1850-1900).
It is worth tracing the history of where the 1.5 C "North Star" originated and what the consequences of breaching it would likely be. The 1.5 C threshold was officially enshrined as a goal under the United Nations Framework Convention on Climate Change with the adoption of the Paris Climate Change Agreement in 2015. Article 2 in the Paris Agreement commits signatories to strengthening the global response to the threat of climate change by "holding the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change."
