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FACTS: FUZZY ASSESSMENT AND CONTROL FOR TEMPERATURE STABILIZATION
- WHAT IS IT?
FACTS is a software that generates pathways of CO2 emissions that would stabilize the global average temperature around 2ºC.
- HOW DOES IT WORKS?
FACTS uses a simple climate model and an inner controlling system in order to find the adequate changes in emissions that would lead to temperature stabilization.
- HOW TO USE IT?
First you should choose a baseline emission scenario (RCPs, INDCs or your own data) under which the climate model will run until the control activates. Then, choose a year for the control activation. Finally you just need to wait and see how a stabilization scenario would look like.
Figure 1. FACTS interface
- SIMULATION OF THE PARIS AGREEMENT
FACTS was designed to be able to simulate a real-world situation now that the Paris Agreement had enter into force. For example, let’s say that we have the final INDCs from 2020 to 2025 (see Figure 2a), so we could project the average global temperature until that moment (2025) and ask the fuzzy controller to start finding the stabilization pathway from there on (Figure 2b). In that situation, FACTS would give us the ideal aggregation of the global INDCs (Figure 2c) that the parties should be looking forward to accomplish in order to stabilize the global temperature. In that simulation we would have over 5 years to create national plans that lead us to accomplish the goal (Figure 2d).
Figure 2. Simulation for finding ideal INDCs
- THE CONTROLLING SYSTEM
FACTS has an inner fuzzy control which evaluates the climate parameters of certain year i and computes what would be the change in the future emissions of the year i+1 in order to stabilize the temperature.
The fuzzy controllers were constructed with two different methodologies:
Simple Mamdani was constructed with intuitive-empirical rules using only two parameters: the change in the temperature (whether the temperature was increasing or decreasing) and the closeness to the stabilization point, 2ºC.
First, it is evaluated the membership degree of the parameters value to some preconceived fuzzy sets: [decreasing temperature, stable temperature, increasing temperature] and [far low from 2ºC, middle low from 2ºC, close low…, stable, close high…, middle high…, far high…].
Finally, the intuitive- empirical rules are applied, those rules are just intuitive responses to the temperatures parameters, for example, if the temperature is decreasing and far low 2ºC, then the emissions can highly increase. Another rule would be: if the temperature is increasing and stable in 2ºC then decrease the emissions. All the rules are described in Figure 3 as the intersection of the two parameters’ fuzzy sets.
How much is high decrement and how much is high increment? For defining this, we divided into five fuzzy sets (high decrement, low decrement, equal, low increment, high increment) the domain given by the extreme values of the highest increment in emissions of all the RCP scenarios and the highest decrement in emissions. For further details of this system look at the references below, please.
Figure 3. Simple mamdani fuzzy sets and rules
This fuzzy controller was created by an optimization process that uses artificial neural networks that learn from emission pathways proposed in the literature that successfully manage to stabilize the temperature around 2ºC.
The parameters that this controller evaluates are: level of CO2 emissions, level of CO2 concentration, temperature and temperature change. Based on them, the fuzzy controller gives the optimal amount of CO2 reduction or increment in order to stabilize the temperature. For further details of this system look at the references below, please.
- DYNAMIC ASSESSMENT
Another feature of FACTS is that it presents another way of describing the climate beyond just the average global surface temperature. FACTS shows de membership degree of the climate parameters to the climate fuzzy sets at every year. So you can notice in the colorful cells of the right bottom how the climate is changing by observing the intensification according to the colorbar.
In the central bottom of the interface there is a static assessment of the climate at 2100 under the different RCPs and INDCs only for reference purpose. As you can see in the case of RCP3 the emissions are completely defined as low, the CO2 atmospheric concentration it’s a little bit medium but also high, the temperature could be defined as medium-high and the temperature change could be taken as null. Now as an exercise you could analyze the RCP8.5.
Important: the INDCs are only valid from 2020 to 2030, the emissions beyond that are made up by a random constant increment every year, so it doesn’t make sense to analyze the assessment of the INDCs at year 2100.
Figure 4. FACTS Assessment
Bastien, B. & Gay, C. (2016). FACTS: Fuzzy Assessment and Control for Temperature Stabilization ‘Regulating global carbon emissions with a fuzzy approach to climate projections’. Proceedings of the 6th International Conference on Simulation and Modeling Methodologies, Technologies and Applications, Portugal.
Gay, C. & Bastien, B. (2015). Stabilizing Global Temperature through a Fuzzy Control on CO2 Emissions. Proceedings of the 5th International Conference on Simulation and Modeling Methodologies, Technologies and Applications, France.