In this report, we explore several lines of evidence about the sensitivity of our climate to greenhouse gases. That evidence is consistent with the range for climate sensitivity estimated by the Intergovernmental Panel on Climate Change (IPCC), but it points to a risk that the actual sensitivity of our climate might be towards the top end of that range. If climate sensitivity is higher than expected we have underestimated the rate of future warming, with catastrophic warming levels of over 2°C before 2050 now likely, unless we change course.

These findings show that net zero carbon budgets will not limit temperatures to 1.5°C. This is a classic model risk situation, with strong parallels to the global financial crisis, where financial models could Parasol Lost: Recovery plan needed January 2026 not see the interconnected nature of the global financial system, leading to complacency and a failure to mitigate systemic risk. Emergency action was required to stabilise the system, which would have been unimaginable without the crisis. Following this, significant work took place to enhance financial services risk management practices.