Climate Change Scenarios PRECIS
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December 2003 Generating High Resolution Climate Change Scenarios using PRECIS NATIONAL COMMUNICATIONS SUPPORT UNIT WORKBOOK Workbook on generating high resolution climate change scenarios using PRECIS Richard Jones, David Hassell, Debbie Hudson, Simon Wilson, Geoff Jenkins and John Mitchell Hadley Centre for Climate Prediction and Research, Met Office, Bracknell, UK October 2003 Workbook on generating high resolution climate change scenarios using PRECIS 2 Workbook on generating high resolution climate change scenarios using PRECIS Contents 1 Introduction 4 1.1 Background 4 1.2 Objective and Structure of the Workbook 6 2 Constructing climate scenarios for impact studies 7 3 Uncertainties 10 4 Techniques for obtaining regional climate change projections 11 5 What is a Regional Climate Model? 13 5.1 Issues in Regional Climate Modelling 13 5.2 How regional climate models add value to global climate models 15 6 PRECIS 18 6.1 What is PRECIS? 18 6.2 Who should use PRECIS? 18 6.3 Description of PRECIS components 18 6.4 PRECIS User Interface 19 6.5 The PRECIS Regional Climate Model 19 6.6 PRECIS data-processing and graphics software 19 7 Creating regional climate scenarios from PRECIS 20 7.1 Validation of the PRECIS RCM 20 7.2 Generating climate change projections 20 7.3 Providing a wide range of projections of future climates 20 7.4 Creating regional climate change scenarios for use in impacts models 21 7.5 Example: Generating climate change scenarios for the UK from RCM projections 21 8 Further developments 22 Annex I: Description of the PRECIS RCM 23 Annex II: Examples of the Hadley Centre RCM over regions of the world 26 Annex III: Examples of the use of PRECIS RCM-generated scenarios 28 Annex IV: Papers on Hadley Centre RCMs 30 References 31 3 Workbook on generating high resolution climate change scenarios using PRECIS 1 Introduction 1.1 Background change. Assessments of vulnerability are informed by estimates of the impacts of climate change, which in “An increasing body of observations gives a collective turn is often based on scenarios of future climate. picture of a warming world and other changes in the These scenarios are generally derived from climate system.” (IPCC WGI TAR, 2001). These other projections of climate change undertaken by Global changes include the decrease in snow cover and ice Climate Models (GCMs). These GCM projections may extent, rise in sea level, regional variations of be adequate up to a few hundred kilometres or so, precipitation patterns, and changes in extremes of however they do not capture the local detail often weather and climate. These recent regional changes, needed for impact assessments at a national and particularly temperature increases, have already regional level. One widely applicable method for affected many physical and biological systems. The adding this detail to global projections is to use a rising socio-economic costs related to climate-related regional climate model (RCM). Other techniques damage and to regional variations in climate suggest include the use of higher resolution atmospheric global increasing vulnerability to climate change. But what is models and statistical techniques linking climate causing all these changes? “There is new and stronger information at GCM resolution with that at higher evidence that most of the warming observed over the resolution or at point locations. These approaches, last 50 years is attributable to human activities mainly with their strengths and weaknesses, are discussed in brought about through changes in the atmospheric section 4. composition due to the increase in emissions of greenhouse gases and aerosols” (IPCC WGI TAR, The provision of a flexible RCM is thus part of an 2001). What are the projections for the future? Human integrated package of methods, which would also influence will continue to change atmospheric include a range of GCM projections for assisting composition throughout the 21st century and hence countries to generate climate change scenarios and global average temperature and sea level are hence to inform adaptation decisions. The Hadley projected to rise. Centre has developed such a flexible RCM to provide non-Annex I Parties with a practical tool to make their Humans’ actions are starting to interfere with the own projections of national patterns of climate change global climate. Recognising that the problem is global, and hence estimate the possible impacts and assess and in response to a series of International their vulnerability. It must be stressed that the RCM conferences and the work of the Intergovernmental does not replace GCMs, but it is a powerful tool to Panel on Climate Change, the United Nations, in 1990, be used together with the GCMs in order to add set up a Committee to draft a Framework Convention fine-scale detail to their broad-scale projections. on Climate Change. The Convention was adopted in 1992 and received 155 signatures at the June 1992 This new regional modelling system, PRECIS United Nations Conference on Environment and (Providing Regional Climates for Impacts Studies, Development (known as the Rio Earth Summit). The pronounced pray-sea, i.e. as in French), has been objective of the Convention is the “stabilization of developed at the Hadley Centre and is sponsored by greenhouse gas concentrations in the atmosphere at a the UK Department for Environment, Food and Rural level that would prevent dangerous anthropogenic Affairs (DEFRA), the UK Department for International interference with the climate system. Such a level Development (DFID) and the United Nations should be achieved within a time-frame sufficient to Development Programme (UNDP). PRECIS runs on a allow ecosystems to adapt naturally to climate change, PC and comprises: to ensure that food production is not threatened and to • An RCM that can be applied easily to any area of enable economic development to proceed in a the globe to generate detailed climate change sustainable manner.” (Article 2, UNFCCC: projections, http://www.unfccc.de). • A simple user interface to allow the user to set up and run the RCM, and Under Article 4.1 and 4.8 of the UN Framework • A visualisation and data-processing package to Convention on Climate Change (UNFCCC), all Parties allow display and manipulation of RCM output. have the requirement to assess their national A sample display of PRECIS configured for a region vulnerability to climate change and to submit National over New Zealand is provided in Figure 1. Communications. To this effect, the National Communications Support Unit (NCSU) is developing an integrated package of methods to assist developing countries to develop adaptation measures to climate 4 Workbook on generating high resolution climate change scenarios using PRECIS Figure 1: Example output monitoring the PRECIS RCM running over New Zealand, showing (from top left, clockwise) maps of rainfall (shaded) and mean sea level pressure isobars (contoured) at 6 hourly intervals for three successive days of a model integration. PRECIS is freely available for use by developing valuable local knowledge, for example in checking the country scientists, especially those involved in validity of models against observations from the region vulnerability and adaptation studies conducted by their of interest. By encouraging and facilitating the use of governments which are to be reported in National regional climate models, it is hoped that PRECIS will Communications to the UNFCCC. Section 6.2 contribute to technology transfer and capacity building, summarises the resources required when using important aspects of Article 4 of the UNFCCC. PRECIS and its applicability. It is important that adaptation decisions are based on a range of climate Whilst projections from regional climate models are scenarios accounting for the many uncertainties undoubtedly very powerful aids to planning and associated with projecting future climate (section 3). adaptation, uncritical use of their output could lead to These are most conveniently derived by groups of misinterpretation, and it is important that prospective neighbouring countries working together over a certain users understand the limitations of all methods for region. National climate change scenarios can then be generating climate scenarios, as well as their created locally for use in impact and vulnerability advantages. To address this, the Hadley Centre has studies using local knowledge and expertise. Carrying prepared a comprehensive workshop for prospective out the work at regional level will lead to much more users of PRECIS. It provides background on the effective dissemination of scientific expertise and science of climate change, global and regional awareness of climate change impacts than could be modelling of the climate system and explains about achieved by simply handing out results generated from other methods for obtaining high resolution climate models run in developed countries. It will also tap into change information, so that users are aware of these. 5 Workbook on generating high resolution climate change scenarios using PRECIS It provides in depth training on the installation and use Detailed technical information describing the of PRECIS, including hands-on work. It provides installation and use of PRECIS is contained within a opportunities for users to discuss and plan separate technical manual. collaborative work. Finally, examples are given of how climate scenarios may be produced and used. The Workbook is structured as follows. The next section describes the general steps