CORDEX: The science that underpins future climate change policy
The Conference of Parties (COP) 21 in Paris in December 2015 agreed on a global effort to limit global warming to below 2°C compared to pre-industrial levels. Decision makers want to know the potential impacts of a 2°C global warming for different regions of the globe and different economic sectors. When planning for adaptation, policy makers need to understand the difference between global warming of 2°C and other climate change scenarios? Governments want to know what potential impacts can be prevented if global warming is limited to 2°C? There is a need for climate science to produce reliable and easy-to-understand information to specifically answer these questions.
Predicting future climate change is a complex task, requiring sophisticated numerical models and large teams of experts across many different disciplines. Every year significant improvements are made in high-resolution earth system modelling, to multi-model ensembles of both climate and impact projections and, particularly, in the bias correction of downscaled climate data. The WCRP Coordinated Regional Climate Downscaling Experiment (CORDEX) (https://cordex.org/) is working to address science-driven questions related to regional climate projection; identifying, quantifying and delivering high quality, reliable and accessible regional climate information.
impact2impact2ccCORDEX information feeds directly into policy-driven research. Take, for example, the IMPACT2C Project, which is a multi-disciplinary and international project providing information and evidence on the impacts of 2°C global warming. IMPACT2C includes model data from high-resolution (12.5 km) Euro-CORDEX (European branch of CORDEX) simulations. One of its outputs is the IMPACT2C web-atlas, which tells visual stories of the potential impacts of climate change with 2°C global warming for key sectors – energy, water, tourism, health, agriculture, ecosystems and forestry, as well as coastal and low-lying areas – at both the pan-European level and for some of the most vulnerable regions of the world to climate change.
IMPACT2C delivers a few key messages regarding our future with global warming of 2°C:
There will be large increases in extreme events for Europe, with much larger increases in daily maximum temperature over parts of Southern and South-Eastern, as well as increases in heavy precipitation across all of Europe.
It is expected that a global warming of 1.5°C (relative to pre-industrial levels) will be exceeded around or before 2040. In addition, almost all scenarios indicate that 2°C global warming is expected to be exceeded around or earlier than 2060.
Rates of climate change are likely to increase in the near future. Historical rates have averaged at just over 0.1°C per decade, but this could potentially increase to between 0.3°C and 0.7°C per decade over the next few decades. As much of Europe warms at a faster rate than the global average, this will mean even higher rates of change for some regions of Europe.
The project also considers the 2°C global warming benchmark as a precautionary level, which is likely to avoid the occurrence of extreme and potentially catastrophic events. These are referred to as tipping points or vulnerability hot spots and key examples are abrupt ice loss from the West Antarctic Ice Sheet or large-scale disintegration of the Greenland Ice Sheet.
The conclusions of IMPACT2C have major implications for possible adaptation strategies on national and international scales. This is the information that governments need to plan for the future and it would not be possible without the science that necessarily underpins it. To find out more about the application of CORDEX information see Daniela Jacob and Claas Teichmann’s presentation on ‘Climate Services in the frame of CORDEX’ (14.00 CEST, Session D1), streamed live (http://www.icrc-cordex2016.org) from Stockholm at the International Conference on Regional Climate (ICRC)-CORDEX 2016.