There is a strong case for investing in climate mitigation and adaptation based on the severe economic consequences alone. Mitigation is the most cost-effective means of reducing the economic damages of climate change; it can return as much as 5 to 14 times the original investment. At the same time, adaptation is critical to minimising damages, particularly in the next couple of decades. 

To limit global warming to 2°C by 2100, mitigation investments must increase ninefold and adaptation thirteenfold by 2050. The challenge lies in the timing of climate investments – 60% must be committed before 2050, while 95% of the economic damage from inaction would occur after that point. This report estimates the net cost of inaction is equivalent to 11% to 27% of cumulative GDP by 2100. Annual investment in mitigation and adaptation of 1% to 2% of cumulative GDP is required to avoid this but the world is currently falling well short. 

The report identifies priority levers to address the barriers to taking the necessary action, including:

• reframing the debate on the costs of climate change
• creating transparency on the net cost of inaction across all actors
• strengthening national climate policies to accelerate mitigation and adaptation
• reinvigorating international cooperation on climate change
• advancing our understanding of the net cost of inaction.