Identification and modelling of the processes that govern climate on multi-decadal to centennial time-scale

Identification and modelling of the processes that govern climate on multi-decadal to centennial time-scales; quantification and reduction of the uncertainty in predictions for the next century

Climate change on centennial time scales is a major scientific, societal and policy issue. The work here is geared to addressing the key science questions and providing information for evidence-based decision making to the relevant stakeholders, including government departments (Defra and DECC). It will feed into the international research and policy arenas through contribution to IPCC and WMO/UNEP assessments. It will be closely aligned to the Joint Weather & Climate Research Programme, and will involve wide collaboration with the Met Office.

Background

The evolution of climate on multi-decadal to centennial time-scales is influenced both by the response of the physical climate system (atmosphere, ocean, land, cryosphere) to anthropogenic forcing and also by a wide range of feedbacks involving interactions between the marine and terrestrial biosphere and changing atmospheric composition.

For example, changes in climate cause changes in tropospheric and stratospheric ozone concentrations directly, through the influence of temperature and winds, and indirectly, e.g. by modifying the biogenic emissions of ozone precursors. Equally, ozone is a climate gas and its changes impact the climate system directly, via radiative transfer, and indirectly, e.g. by damaging the terrestrial biosphere and thereby affecting carbon uptake.

Such “Earth system feedbacks” have the potential to amplify, or damp, significantly the rate of climate change, and they are a major uncertainty in projections of climate for the twenty-first century. Improved knowledge of these feedbacks is urgently needed to guide the formulation of policies to mitigate climate change, since the impact of any reductions in emissions of greenhouse gases is felt primarily on multi-decadal and longer time-scales.

We urgently need improved quantitative knowledge about feedbacks involving, for example: composition and aerosols; the depletion and recovery of the ozone layer, the uptake and transport of heat by the ocean; the uptake and emission of carbon compounds; clouds and water vapour.

Developing the appropriate models with the increased complexity to address these issues is a major challenge; exploiting the models of process studies, using new data from satellites, from long-term measurement stations and from focused field campaigns, is a major opportunity.

Through a large modelling programme, including model development and exploitation we will:

• Advance capability for coupled modelling of the physical climate system and of interactions between climate and atmospheric composition.
• Identify the role of atmospheric processes in Earth system feedbacks that have the potential to influence global climate on multi-decadal to centennial time-scales.
• Improve model representation of Earth system feedbacks.
• Exploit existing and new observations to test Earth system models at a process level and to quantify the relative importance of different feedbacks.
• Play a leading role within the NERC community in the development of climate modelling.
• Contribute to addressing science questions relevant to climate mitigation policy, including underpinning research required to assess proposed geo-engineering schemes.
• Play a leading role in major international assessments of global change (IPCC, WMO/UNEP)
• Provide key policy-relevant information to DECC and Defra
• Be a focus for scientific training, including PhD and postdoctoral training, summer schools and specialised courses

Expected outcomes

We will enhance UK capability in earth system science and in studies of global change in centennial time scales. Our legacy will be:

• new earth system models, which will maintain the UK’s position as a leader in international climate science research
• a new generation of scientific experts.

The programme will play a leading role within the NERC community in the development of climate modelling and lead to increased understanding and application of UK numerical models by the international community.

The programme will allow the UK to play a major role in international scientific assessments (IPCC; the WMO/UNEP assessment of the state of the ozone layer). Scientists working in this programme will be directly involved, at a variety of levels, in production of the assessments.

The assessments, and our direct advice to government departments (Defra, DECC), are a crucial input to policy.  We will also respond to science questions relevant to climate mitigation policy, including conducting underpinning research required to assess proposed geo-engineering schemes.

Likely beneficiaries and stakeholders

Policy makers

Emissions policy for global change questions needs to be science-based. Our results will be a key component of the science base which is required by UK government departments (Defra, DECC, etc.). They support our involvement in these activities. We will take every opportunity to provide information through formal and informal channels.  We will work to develop formal mechanisms for communicating our findings to policy partners.

Industry

We will continue to provide advice to industry, e.g., the national and international chemical manufacturing industry, the aviation industry, etc.

Communication

Media: the press (national, international and local) and television and radio all come to us for information and science articles. We will continue to play an active role in translating complex science for these outlets.

The general public: we will engage in communication with the public on global change issues, in a variety of ways, to disseminate and promote the public understanding of this complex field.