ZERO IN ON the remaining carbon budget and decadal warming rates. The CONSTRAIN Project Annual Report 2019

This report is the first in a series that will provide the latest climate science knowledge relevant to the implementation of the Paris Agreement in a digestible and timely manner.

For the duration of the EU-funded CONSTRAIN project (2019-2023), the annual ZERO IN reports will inform on key scientific progress delivered by the project and on crucial scientific elements relevant to the implementation of the Paris Agreement.

Firstly, we ZERO IN on the remaining carbon budget – a concept which is widely used in global and national policy and in campaigning environments, but depends on a number of core assumptions which are not always made clear. We explain the strengths and weaknesses of the concept and its applications, and present our recommended approach to its quantification. Our resulting estimate of the remaining carbon budget will be updated annually in future ZERO IN reports.

Secondly, we ZERO IN on surface warming rates over the next 20 years, and their representation in the new generation of climate models that will inform the IPCC Sixth Assessment Report. Importantly, this demonstrates that we could see unprecedented rates of anthropogenic warming in coming decades.

But the good news is that if we do follow a strong mitigation pathway, we can cut anthropogenic warming rates by half. Therefore, we still have the chance to take meaningful action to avoid dangerous climate change. As with the carbon budget, future ZERO IN reports will update this outlook, taking into account the latest science from the CONSTRAIN project and beyond.