A number of the latest generation climate models (CMIP6) project greater future warming than previously assessed, but drawing conclusions about the implications for emission reduction targets is premature.
The higher warming these new models project is due to higher climate sensitivity, which might be partly explained by how these models incorporate new knowledge about the interactions between clouds and the climate.
A growing number of studies suggest that CMIP6 model sensitivities might lead to overestimating future warming. More importantly however, the change in the quantity in CMIP6 models, which is relevant for calculating carbon budgets - the transient climate response to emissions (TCRE) - may be smaller than the potential increase in long-term equilibrium warming.
Preliminary results based on a limited set of models suggest that even TCRE estimates from more sensitive CMIP6 models, if proven correct, would only reduce the best estimate for the 1.5°C carbon budget by a few percent. These differences are very small compared with the uncertainties surrounding these carbon budget estimates, and do not allow for any robust conclusions. If anything they only re-emphasise the need for stringent near-term emission reductions to achieve the Paris Agreement goal.
The world is 1°C warmer than pre-industrial levels and continues to warm at about 0.2°C per decade. Slowing down warming over the next decades is crucial to limit warming to 1.5°C. Stringent emission reductions, as implied by Paris Agreement compatible pathways, can reduce near-term warming rates by up to 50%. Near-term emissions reductions are key to keep the Paris Agreement’s long-term temperature goal in sight.
The Intergovernmental Panel on Climate Change (IPCC), the United Nations body for assessing the latest climate change science, will release its 6th Assessment Report (AR6) in 2021. A great deal of the findings in AR6 will be based on the latest generation of climate models from the 6th phase of the Coupled Model Intercomparison Project (CMIP6). Therefore, it is crucial to assess whether these models provide a better representation of the climate system and offer more realistic projections of global warming than their predecessors.
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.
2030 targets aligned to 1.5°C: evidence from the latest global pathways
Our new method applies sustainability limits and minimises the need for carbon dioxide removal to set key 2030 global targets for renewables, fossil fuels and emissions.
The deployment length of solar radiation modification: an interplay of mitigation, net-negative emissions and climate uncertainty
Here, we investigate the deployment timescales of solar radiation modification and how they are affected by different levels of mitigation, net-negative emissions and climate uncertainty.
Uncompensated claims to fair emission space risk putting Paris Agreement goals out of reach
Only halving emissions by 2030 can minimise risks of crossing cryosphere thresholds
How can the EU transform its economy to meet the 1.5°C goal?
What does the 1.5°C goal require from EU climate policy? This 4i-TRACTION policy brief analyses the latest 1.5°C-aligned scenarios and spells out what they imply for EU climate policy.
Institutional decarbonisation scenarios evaluated against the Paris Agreement 1.5°C goal
This study analyses six institutional decarbonisation scenarios published between 2020 and mid 2021 (including four from the oil majors and two from the International Energy Agency. It finds that most of the scenarios would be classified as inconsistent with the Paris Agreement as they fail to limit warming to ‘well below 2 ̊C, let alone 1.5 ̊C, and would exceed the 1.5 ̊C warming limit by a significant margin.
An emission pathway classification reflecting the Paris Agreement climate objectives
When categorising pathways in line with the Paris Agreement, the focus has been put on the temperature outcome. Here we propose a pathway based on emission reduction objectives that reflect the climate criteria set out in the Paris Agreement.
No time for complacency: without closing the 2030 gap, net zero targets cannot prevent severe climate impacts
Fossil gas: a bridge to nowhere
This report assesses how fast fossil gas power generation must be phased out in different parts of the world to keep the Paris Agreement’s 1.5°C temperature goal in reach.