Investigating the implications of net-zero emissions at different global warming levels

Abstract

To stop global warming, humanity needs to achieve close to net-zero greenhouse gas emissions. Many countries are committed to reducing greenhouse gas emissions significantly over the next decade and to reaching net-zero emissions by 2050, in line with the Paris Agreement goal of limiting global warming well below 2°C above pre-industrial levels. This can only be achieved through deep decarbonization and removal of carbon dioxide from the atmosphere. However, many questions remain about the long-term implications of stabilising global temperatures at the Paris Agreement goals or missing this target but stabilising the climate at a higher global warming level.We have run bespoke millennium-length simulations with the Australian Earth System Model, ACCESS-ESM1.5, under net-zero emissions at different global warming levels ranging from about 1.5°C to 3°C. Here, we discuss these simulations and analyse the evolution of temperature, precipitation and carbon budgets. We will present results on the linearity of local climate changes under different stabilised global warming levels and how these compare with local changes in rapidly warming climates. We will also discuss the processes that cause these local non-linearities and raise opportunities for research that these simulations provide.We must gain a better understanding of potential future climates which evolve under near-zero greenhouse gas emissions. Policymaking is based on achieving net-zero emissions and we hope our work and similar analyses can increase understanding of a changing climate under net-zero scenarios.