Dear Fridays For Future activists:

I am writing to you as a member of a research group from a Spanish University that has been working on issues of sustainability, energy and climate change for more than ten years. I am doing this because I think that, as you say, it is time for action in the face of the climatic emergency, but I also think that it is necessary to be very clear about what kind of action is necessary.

And so, in that sense, there is one thing that worries me. In your speeches on climate change you can find demands for very ambitious decarbonization objectives proposing, for example, the replacement of all fossil fuels by 2050 or 2100. According to my knowledge and according to the studies we are making in our group, such ambitious goals as these would require very drastic measures which go far beyond the usual proposals such as investment in renewable energy, electric vehicles or energy saving and efficiency.

Therefore, I think we have to be very realistic about the decarbonization objectives and the measures we demand in order to achieve them. If we do not, our leaders can happily silence the protests, by using exclusively technological cosmetic measures that do not solve anything, and the hopes of many young people with good intentions may be frustrated.

The research group which I belong to, although collaborating with the IPCC, is different from other scientific teams which study climate change because we try to address the problems much more systemically than is usual. Not only do we study, for example, greenhouse gas emissions, but also the energy model and the economic system that generate them. We also study the consequences of the transition to renewable energies on the economy and the biosphere because we think all feedback is extremely important and we must not forget that everything is connected.

Four years ago we started working on a European project that aimed to build a model that could advise EU policy makers on the energy transition. The result of the project is the MEDEAS model, which very clearly shows the interactions that arise when trying to make the transition to renewable energy. With the MEDEAS model we can see, for example, what it would take to get world transport emissions to be what the IPCC estimates we need in order to have a 66% chance of keeping the temperature below 2ºC (it requires that emissions in 2050 be 30% of the current ones).

In figure 1 you can see the results we get when we try to achieve these objectives with different scenarios. The “Current Trends” scenario is based on letting things continue as before, the “EV-high” is a radical commitment to the electric vehicle that would make practically all private cars electric in 2050, but would not be able to electrify ships or aeroplanes, and trucks only partially, due to obvious technical difficulties. The “E-bike” scenario is based on a radical replacement of private cars with bicycles and very light electric motorcycles, so that the evolution of private vehicles would be the one seen in Figure 2; a really huge change in the way of moving around.

In spite of how radical all these possible scenarios are, in figure 1 it is evident that they only manage to make emissions from the transport sector stop growing, but are far from achieving the proposed decarbonization objectives. It can also be observed that, even in the scenario in which we do nothing, the “Current Trends”, emissions stop growing. That is because our model takes into account the limits of fossil fuels (such as peak oil), where the economy stagnates, and that causes emissions to moderate, although not enough to achieve the objectives of decarbonization.

In figure 1 you can also see that the decarbonization objectives are only achieved in the scenario we have called “Degrowth”. What is this scenario? It consists of a radical commitment to light mobility such as the “E-bike” scenario, plus a decrease of 85% in the demand for air transport and by sea 60% (a world where you travel less by plane and which is much more local). It is a scenario where, in addition, the world’s governments coordinate to change the current economic model, based on competition and growth, for another system capable of meeting human needs while economic activity decreases.

These results make it clear that the decarbonization we need in order to not exceed 2ºC in temperature cannot be achieved simply by changing our petrol car for an electric car. In addition, our model shows that using electric cars on a large-scale, as in the EV-high scenario, depletes the reserves of certain minerals such as lithium and manganese.

If we use MEDEAS to study the transition to renewable energies within electricity, the results offer us a similar picture. For example, to achieve 100% renewable electricity in 2060 requires that a lot of energy be invested in the creation of all the necessary mills, solar panels or power line infrastructure. This may mean that, in a few years, humanity devotes a third of the energy consumed in the world to building renewable electricity infrastructures. Of course that would be a formidable challenge that would probably make us wonder whether we really needed to consume so much energy or if it might be easier to change to a more austere way of life before embarking on such an expensive renewable transition.

The results obtained from our studies always end up showing a very obvious reality which, somehow or other, we do not see because it is hidden behind a lot of data, other interests and inertia. In fact, it is the same conclusion that the first studies on the limits of growth, in the 1970s, obtained almost 50 years ago: sustainability requires very important changes in the socio-economic model; changes which humanity has resisted. We need to change the present economic system, based on growth, to a system based on stability, and this is not an easy task. This is why the problem of climate change, and ecological problems in general, have been well known for decades, and why decades have passed by without it being fixed.

For all these reasons I encourage you to learn from our models and the publications on our blog, since we have made a special effort to disseminate our results in the most simple language possible. I hope that this message reaches you and that you can make use of the best scientific and global knowledge that we have within our reach right now. Use it to go beyond the call to action in order to be able to propose a viable and really effective path to solving the climate crisis.