Science Assessment
and Analysis

Climate science is highly complex and the policy implications are not always clear. We make the latest climate science easily accessible for stakeholders in the international climate change arena.

 ©Sarah Depper, CC BY 2.0
©Sarah Depper, CC BY 2.0

We synthesise and advance scientific knowledge in the area of climate change science, policy and impacts to make it easily accessible for stakeholders in the international climate change arena. This includes conducting our own research (for example, to evaluate the uncertainties in climate science associated with potential mitigation pathways, project sea-level rise or evaluate impacts and risks at different levels of warming) as well as bringing together and communicating the findings of the available scientific literature and providing the context needed to understand their implications. Projections of future climate change are subject to uncertainty, as they depend on a range of developments that cannot be foreseen (e.g. emission pathways). Also, there remain important limitations in the understanding and the modeling of some key processes of the climate system. Much of our work therefore focused on understanding these key process and the probabilities associated with climate impact projections.

Latest

COP23 briefing - Limiting warming to 1.5°C is of paramount importance to protect the oceans. This briefing provides an overview of the latest science on key risks for ocean systems including from sea- level rise, ocean acidification and impacts on coral reefs and other marine and coastal ecosystems.  
We can only limit sea level rise to around half a meter by 2100 if cumulative carbon emissions stay below 850 gigatonnes and coal is nearly phased out by 2050. If emissions continue unchecked, oceans could rise 55 per cent more than previously thought – by around 130cm in 2100, according to a paper published in Environmental Research Letters today.  
Coastal cities around the world could be devastated by 1.3m of sea level rise this century unless coal-generated electricity is virtually eliminated by 2050, according to a new paper that combines the latest understanding of Antarctica’s contribution to sea level rise and the latest emissions projection scenarios.  
Climate change could lead to sea level rises that are larger, and happen more rapidly, than previously thought, according to a trio of new studies that reflect mounting concerns about the stability of polar ice. In one case, the research suggests that previous high end projections for sea level rise by the year 2100 — a little over three feet — could be too low, substituting numbers as high as six feet at the extreme if the world continues to burn large volumes of fossil fuels throughout the century.  

Publications

There have been proposals for the UNFCCC to adopt a dual-term greenhouse gas accounting standard: 20-year GWPs alongside the presently accepted 100-year GWPs. It is argued that the advantage of such a change would be to more rapidly reduce short term warming and buy time for CO2 reductions. This briefing shows why these changes would be counterproductive and the benefits overstated.  
This paper incorporates latest findings on Antarctic ice sheet dynamics into new sea level rise modelling, and pairs it with the new generation of scenarios – Shared Socioeconomic Pathways (SSPs) and compares them with outcomes for the previous generation of scenarios - Representative Concentration Pathways (RCPs), used in the last IPCC Assessment (AR5). It finds that without any mitigation, sea levels could rise by an average of 132 cm in 2100 relative to the 1986-2005 mean.  
The adoption of the 1.5°C long-term warming limit in the Paris Agreement made 1.5°C a ‘hot topic’ in the scientific community, with researchers eager to address this issue. Long-term warming limits have a decades-long history in international policy. To effectively inform the climate policy debate, geoscience research hence needs a core understanding of their legal and policy context. This article describes this context in detail, and illustrates its importance by showing the impact it can have on global carbon budget estimates.  
This commentary in journal Nature Climate Change discusses how evidence from the observational climate record provides useful guidance in discriminating the climate impacts of half-degree warming increments, which is high on the science agenda since the adoption of the 1.5°C temperature limit in Paris Agreement.  
The Intergovernmental Panel on Climate Change (IPCC) has accepted the invitation from the UNFCCC to provide a special report on the impacts of global warming of 1.5 °C above pre-industrial levels and on related global greenhouse-gas emission pathways. Many current experiments in, for example, the Coupled Model Inter-comparison Project (CMIP), are not specifically designed for informing this report. This article documents the design of the half a degree additional warming, projections, prognosis and impacts (HAPPI) experiment. HAPPI provides a framework for the generation of climate data describing how the climate, and in particular extreme weather, might differ from the present day in worlds that are 1.5 and 2.0 °C warmer than pre-industrial conditions.  
The Paris Agreement long-term global temperature goal refers to two global warming levels: well below 2°C and 1.5°C above preindustrial. Regional climate signals at specific global warming levels, and especially the differences between 1.5°C and 2°C, are not well constrained, however. In particular, methodological challenges related to the assessment of such differences have received limited attention. This article reviews alternative approaches for identifying regional climate signals associated with global temperature limits, and evaluates the extent to which they constitute a sound basis for impacts analysis.  

Projects

IMPACT is a cross-cutting, multi-faceted project that aims to strengthen the connections between the scientific assessments of climate impacts, vulnerability and adaptation to help enable access to finance and help Small Island Developing States (SIDS) and Least Developed Countries (LDCs) implement concrete projects.  
The ISIpedia project is an effort to bridge a gap between the modellers from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) studying the global and regional impacts of climate change on natural and human systems, and stakeholders who may need this knowledge to identify appropriate policies. By creating channels of cooperation between modellers and stakeholders, ISIpedia aims at facilitating the co-production and knowledge transfer of climate impact information. The end-product of ISIpedia will be a user-friendly, freely accessible online encyclopaedia for consistent impacts projections across sectors.  
The "Climate Action Tracker" is an independent science-based assessment, which tracks the emission commitments and actions of countries.  
Science and policy to assist and support SIDSs and LDCs to negotiate a strong international climate regime, enabling low carbon development and supporting adaptation needs.  
This project aims to establish a scientifically robust and transparent link between the latest climate-economic science data and the Climate Bonds Initiative’s project universe. The Framework's goal is to ensure that project categories certified under the Climate Bond Standards represent mitigation actions that current climate science finds most relevant in order to keep global warming below 2° C. Project period: 2015 - 2016.