I think the first and most important point to make is that this is a declaration based on science. The United Nations' Intergovernmental Panel on Climate Change, the pre-eminent scientific body in the world on this matter, has determined that in order to avoid a disastrous 1.5 degree Celsius rise in global temperatures and beyond—a rise that would see increased risk to human health and livelihood, civil unrest, mass drought, disease, loss of lands and homes, increased fires, increased tropical storms, mass human displacement, and globally exhausted resources—we must act with urgency to ensure global emissions fall to net zero by 2050. 