- Significant impacts of climate change are projected already for a warming of 1.5°C above pre-industrial levels for all analysed climate changes and impacts, including temperature extremes, extreme precipitation and dry spells, water availability, crop yield reduction risks for major staple crops, coral reef bleaching and sea-level rise. The results add to a growing body of evidence showing that climate risks occur at lower levels than previously thought.
- Projected climate impacts will rise substantially between 1.5°C and 2°C with particularly high increases in heat extremes, the risk of tropical crop yield reductions, coral reef bleaching and subtropical water scarcity.
- Tropical and dry subtropical regions emerge as hot spots in which impacts increase most strongly between 1.5°C and 2°C. In combination with limited adaptive capacity and high exposure of most countries in these regions, this point towards a substantial increase in climate change risks.
- The results support the analysis of the IPCC AR5 which assessed risks for 3 out of 5 Reasons for Concern to be at least moderate-to-high under a 2°C warming. These three include risks for unique and threatened systems such as coral reefs, risks by extreme events and unequal distribution of risks across geographical regions.
The 0.5°C warming difference is critical for vulnerable regions
Our assessment implies that differences in climate impacts between 1.5°C and 2°C are most significant and pronounced for regions with limited adaptive capacity and high exposure.
Under a 2°C warming, coastal tropical regions and islands face the combined effects of a complete loss of tropical coral reefs, which provide coastal protection and are a main source of ecosystem services and livelihoods, on-going sea-level rise faster than today and increased threats from coastal flooding and inundation. Limiting warming to below 1.5°C could reduces this risk, as some coral reefs may remain and the rates and levels of sea-level rise are lowered substantially.
Tropical regions emerge as hot-spots for warming trends and agricultural risks. While extreme temperatures at 1.5°C still remain largely within the upper end of currently experienced climate variations, heat extremes that to date would be highly unusual will become the new normal in tropical regions at 2°C.
Risks of substantial regional crop yield reductions are projected. For wheat and maize, projected median yield reductions of local crop yields over the tropical regions double between 1.5°C and 2°C. If highly uncertain effects of CO2-fertilization on future crop yields are excluded, median reductions of 10% are projected for all crop types already under a 1.5°C warming.
Yield reduction and increasing water scarcity increase significantly between 1.5°C and 2.0°C of warming in subtropical dry regions and especially the Mediterranean. Population growth and urbanization in these regions will greatly increase these regions vulnerability to such climate impacts. In conjunction with other development challenges, the impacts of climate change represent a key risk for regional food security.
The Mediterranean region, including North Africa and the Levant, emerges as a hot-spot for severe reductions in water availability and dry spell increases as warming moves from 1.5°C to 2°C: the already water scarce regions faces reductions in water availability of up to 16% under 1.5°C. This risk doubles to almost 30% of potential reduction at 2.0°C of warming.
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.
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.
The effects of political knowledge use by developing country negotiators in Loss and Damage negotiations
This article traces how developing country negotiators used knowledge to further their interests in loss and damage negotiations from 2003 to 2013.
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.
De la CDN 1.0 à la CDN 2.0: qu'est-ce qui a changé dans les CDN des PMA de l’Afrique de l'Ouest?
La présente étude examine les premières et les secondes Contributions Déterminées au niveau National des onze pays les moins avancés de l’Afrique de l’Ouest à savoir le Bénin, le Burkina Faso, la Gambie, la Guinée, la Guinée Bissau, le Libéria, le Mali, le Niger, le Sénégal, la Sierra Leone et le Togo.
Research agenda for the loss and damage fund
This piece in Nature discusses what research could contribute to the design of the loss and damage fund.
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.