Welcome to the final topic of the MOOC “simulation models for the design of transition paths
towards a sustainable society”. Today, we will learn how to design policy targets and
scenarios in the MEDEAS model. In the first session of the topic we’ll
introduce the energy and climate change policies and scenarios. After that, we’ll go right
to the point and define some scenarios and simulate them in the second session.
Integrated assessment models, or IAMS, are useful for their capability to show us possible
outcomes for the years to come under different circumstances. Uncertainty is the dominant
feature of complex systems, and that’s why scenarios are so important to IAMS, especially
in system dynamics models. Therefore, we need to trace comprehensive storyline pathways
to model complex systems under high uncertainty. Defining a scenario takes a qualitative storyline
to support it. And of course, every storyline has to be grounded in numbers which will be
quantitative inputs to the models. Scenarios are very handy to answer such research questions
as: what would the system’s performance be if population were twice the current population,
or if GDP grew faster or slower than historical projections? It is also useful for assessing
the sensitivity of our endogenous variables to scenarios or exogenous variables.
One of the most popular framework scenarios is the shared socioeconomic pathways, or SSPS,
widely used by the IPCC in their reports. Here you can see the qualitative characteristics
for their 5 scenarios. Basically, SSP1 is a scenario which could be defined as a ‘green
growth’ narrative, where the energy transition goes together with economic development. SSP2
is sometimes also known as a business as usual scenario, where historical trends are followed
and no big efforts on the energy transition are to be expected.
SSP3 is a regionalisation scenario where international cooperation lose strength, with slow economic
development and population growth, higher inequality and also low concerns on climate
action. SSP4 tells a story of adaptation policies rather than mitigation efforts, growing social
conflicts and high technological development, especially in middle and high income countries.
Finally, SSP5 follows a storyline whereby the economy and the energy transitions rely
increasingly in global markets, the belief in growing fossil fuels reserves and high
economic growth. So, demography, economic growth, inequality,
technology, policy efforts and energy mix options are the main drivers of the shared
socioeconomic pathways. Because we are modelling an energy transition
towards sustainability, it makes sense to have a look at the framework set by the current
climate governance to define our own scenarios. The Paris Agreement was reached by the international
community in 2015, and it established as its main objective keeping a global temperature
rise well below 2º and limiting the temperature increase even further than 1.5º over pre-industrial
levels. To meet this goal, each country submitted what was named ‘intended nationally determined
contributions’, where they described the policies that they would implement in their
respective territories. Despite this unilateral approach, we can track some common patterns
which will help us to define scenarios. If we focus on just the 15 top policies put
forward by the different countries, we can see an overwhelming preference for a shift
in the electricity mix towards clean, renewable technologies, but also for measures oriented
towards energy efficiency (both production and consumption-based), electrification, substituting
oil and coal by natural gas, different policies regarding transport such as electrification,
fostering biofuels or changing transport modes. Also recycling, reducing and implementing
ambitious afforestation programmes.