The annual ZERO IN reports by the CONSTRAIN project inform on crucial scientific elements relevant to the Paris Agreement in a timely manner, providing background and context on new developments that relate to the science-policy interface.
This first report zeroes in on the remaining carbon budget as well as on projected surface warming rates over the next 20 years. Both topics are crucially important when discussing the implementation of the Paris Agreement. Estimates for these quantities will be updated annually as part of the CONSTRAIN project.
The remaining carbon budget
- Different estimates and assessments of the remaining carbon budget in the recent scientific literature have caused some confusion. Building on the methodology used in the IPCC Special Report on Global Warming of 1.5°C, this report presents a robust framework reconciling different methodological choices and provides a single best estimate for a Paris Agreement compatible remaining carbon budget.
- When using the carbon budget within climate policy, policy-makers need to be aware that it is a value judgement-dependent Earth system characteristic, that is, the concept combines science with value judgements. Value judgements around warming targets and respective probabilities of meeting them, for example, are important considerations for the carbon budget’s quantification and use.
- From the start of 2020, the remaining carbon budget is 985 Gt CO2 for limiting warming to 2.0°C with a 66% probability. To limit warming to 1.5°C with a 50% probability, it is reduced to 395 Gt CO2, and 235 Gt CO2 for a 66% probability.
Decadal warming rates
- If warming continues at its current rate, we are likely to reach 1.5°C between 2030 and mid-century. The rate depends on mitigation efforts, and would likely increase to unprecedented levels if the current Nationally Determined Contributions (NDCs) or stronger mitigation efforts are not delivered. This increase would reduce the timescales available for effective adaptation, in particular for the most vulnerable.
- Conversely, stringent mitigation action could reduce the rate of human-induced near- term 2020-2040 warming by up to half. This underscores the benefits of near-term emission reductions including up to 2030, the timescale of the current NDCs.
- Based on our present best scientific understanding, very high near-term warming rates – double or more of those observed in the recent past – are of low likelihood. However, this does not rule them out as a possibility, emphasising the need for urgent mitigation and action towards net zero emissions to contain this risk.
Unabated: the Carbon Capture and Storage 86 billion tonne carbon bomb aimed at derailing a fossil phase out
The climate talks at COP28 have centred around the need for a fossil fuel phase out. Our analysis quantifies the risk posed by restricting a phase out commitment to only ‘unabated’ fossil fuels.
No change to warming as fossil fuel endgame brings focus onto false solutions
The CAT's annual warming estimate has risen by 0.1˚C to 2.5˚C. The estimate is largely influenced by weak existing targets rather than shifts triggered by updated Nationally Determined Contributions.
When will global greenhouse gas emissions peak?
The IPCC says peaking before 2025 is a critical step to keep the 1.5°C limit within reach. With emissions set to rise in 2023, this leaves limited time to act. To assess if we can meet this milestone, we look at when global emissions might peak, as well as what we can do to get there in time.
Wind and solar benchmarks for a 1.5°C world
This report presents a detailed methodology for determining the amount of wind and solar capacity that is required for a country to align with the Paris Agreement’s 1.5°C temperature goal. While the focus of the report is the method, it includes illustrative benchmarks for Brazil, China, India, Indonesia, Germany, South Africa.
A 1.5°C future is possible: getting fossil fuels out of the Philippine power sector
The Philippines is also one of the fastest-growing developing countries: poverty is in decline, access to energy is rising and, with that, demand for energy services. However, fossil fuels still dominate the energy system, accounting for 78% of power generation in 2022. This report sets out what the Philippines government needs to do to get the country’s power sector onto a 1.5˚C compatible emissions pathway, replacing fossil fuels with renewable energy.
Production Gap Report 2023
Governments, in aggregate, still plan to produce more than double the amount of fossil fuels in 2030 than would be consistent with limiting warming to 1.5°C. The persistence of the global production gap puts a well-managed and equitable energy transition at risk.
Emissions impossible: Unpacking CSIRO GISERA Beetaloo Middle Arm fossil gas emissions estimates
This report provides an independent evaluation of the CSIRO and GISERA assessments of the potential greenhouse gas emissions that would result from the exploitation of the Beetaloo fossil shale gas reserves.
Adjusting 1.5°C climate change mitigation pathways in light of adverse new information
This study uses an integrated assessment model to explore how 1.5°C pathways could adjust in light of new adverse information, such as a reduced 1.5°C carbon budget, or slower-than-expected low-carbon technology deployment.
Railway development: lessons for the EU
This paper analyses how EU railway policy for a low-carbon future can be enhanced, drawing insights from Japan and Switzerland.