4000 scenarios for the climate change
With an extensive computer simulation of the climate, global economy and global energy system, PSI researchers, together with colleagues from the USA, China, Ireland, Finland and Sweden, have analysed different possibilities for a climate change.
Mankind currently emits 42 billion tonnes of carbon dioxide per year. According to calculations by the Intergovernmental Panel on Climate Change (IPCC), only around 300 to 600 billion tonnes may be added since 2020, otherwise the goal of limiting global warming to 1.5 degrees Celsius will hardly be achievable. Evangelos Panos from the PSI’s Laboratory for Energy System Analysis agrees with this conclusion: “It could be close, because in 70 per cent of our scenarios the world will exceed the 1.5 degree Celsius mark in the next five years.”
Which climate measures have the greatest success?
Against the backdrop of climate change, numerous political, economic and social decisions have to be made. However, these are subject to numerous uncertainties. It is understandable that those responsible are looking for reliable bases for one of the central questions, for example: Which measures have the greatest effect and are also economically advantageous in order to achieve the net zero emissions target, as Switzerland has set itself, for example? Answers are now provided by a large computer simulation that was developed on this topic. It couples climate models with economic models and 1200 technologies for the provision and use of energy and for the reduction of greenhouse gas emissions. As part of the study, a supercomputer calculated 4000 scenarios for 15 regions of the Earth, taking into account possible developments in ten-year steps up to the year 2100 in each case. “This requires sophisticated data analysis and visualisation techniques,” adds co-author James Glynn, head of the analysis platform for modelling energy systems at Columbia University in the USA. The final file is 700 gigabytes. The research article on it has now been published in the trade medium Energy Policy.
What makes the work of Evangelos Panos and the co-authors so special: For the first time, their integrated assessment models take into account many of the uncertainties inherent in the models. Previous scenarios usually assume that all parameters for the future are known, such as when which technologies will be available and what they will cost, or how large the expansion potential for renewable energies is. Moreover, IPCC calculations focus solely on technology options, i.e. on the question of what effects the choice of certain technologies will have on the climate. The uncertainties in climate models and how the climate reacts to economic growth are left out of the equation, as are many other uncertainties, for example regarding population development or political measures. “The most important contribution of our research is that it enables policy makers to make concrete decisions about climate action with full knowledge of the existing uncertainties,” emphasises co-author Brian Ó Gallachóir from University College Cork.
18 uncertainty factors and 72 000 variables
When researchers want to calculate scenarios that contain many variables and uncertainties, they often resort to the so-called Monte Carlo method. The Monte Carlo method does not predict the future. “Rather, it lays out a kind of data map with what-if decision paths,” says Evangelos Panos. This was also the case in the current study: the team varied 72 000 variables for each scenario. “We considered 18 uncertainty factors, including population and economic growth, climate sensitivity, resource potential, the impact of changes in agriculture and forestry, the cost of energy technologies and the decoupling of energy demand and economic development,” explains James Glynn of Columbia University.
Sound basis for national paths to energy transition
In order to break down individual scenarios focusing on political and economic issues to the different national paths to energy transition, additional, national-specific parameters must be taken into account. “An energy system that enables the transition to a carbon-free economy is capital intensive and requires the mobilisation of resources from all actors,” Panos sums up. This requires tailor-made analyses at the national level: “Our study provides a sound basis for this.”