Climate change explained to my students

This is a written version of something I said a few days ago to my students of a class for of the "Economic Development  and International Cooperation" school (SECI) of the University of Florence.

The question: Professor, but did I hear correctly what you said? You say that climate change will bring problems for us in decades? Now, I knew that scientists were talking about centuries or even longer times. How can that be possible?

My answer.  You got it right: I said "decades", not centuries and I might as well have said "years" - although perhaps decades is a more correct time scale for the troubles awaiting us - and you in particular, since you are so young. Now, I also understand why you were under the impression that climate change is a question of centuries; something to be dealt with by future generations. This is an unfortunate result of the way some data are presented; in particular by the intergovernmental panel on climate change, the IPCC. They are very cautious, they try to avoid giving the impression of being "catastrophists" and the result is that climate change, according to the way they discuss it, looks very smooth and gradual that goes on for centuries. That's not necessarily the case.

The time scale of climate change depends on what we are considering. Some effects are very slow: if we think, for instance, to the Antarctica ice cap melting and disappearing, well, that will take centuries or even millennia. But if you consider the Arctic ice cap, you see that it is melting down fast and it is melting now! And the consequence is a major change in the weather patterns in the Northern Hemisphere - it is something we are all seeing in terms of droughts, hurricanes, snowstorms and the like.

But it is also true that we won't die because of bad weather and your probability of being drowned by a major hurricane is rather small, especially if you live in Italy. Your question is more specific and I understand it very well: what will be the importance of climate change for people like you, who are now in their 20s?

Let me rephrase the question to make it clearer. I could say that from my personal viewpoint - I am now 61 - I could organize my life on the bet that climate change won't affect me too much for the time I still have to walk on this planet. It is probably a reasonable bet for me (but it IS a bet!). The question is, then, is it reasonable for you to bet in the same way? I think not at all and let me explain to you why.

Let's see.... the life expectancy at birth in Italy is of about 80 years, so you have more than half a century to go, in principle. But let's say that you don't care about getting stricken by the Alzheimer disease. You just want to get, say, to 70 in good health. Then you still have more than 40 years to go; that the time range you should care about, supposing, of course, that you don't care at all about your children and grandchildren - which seems to be the standard way of thinking around us: after all, what did my descendants do for me? Given these assumptions, how is climate change relevant for you?

If you look at the nice and tame IPCC scenarios, you'll see that in 40 years from now we are talking of about 1-2 degrees C of temperature increase. So stated, it looks like a very minor effect. What difference does a degree and half make? Just a minor nuisance. In Summer we'll turn on our air conditioners and in Winter we'll save a lot of money on heating. The same is true for sea level rise: the IPCC is talking of about 20 cm for mid 21st century and what are 20 cm? We can build a 20 cm wall to keep the water out in no time. So, nothing to worry about too much? I am afraid that things are not so simple.

The real problem has to do with the resilience of our society. You may have heard the term "resilience" in various contexts - basically it means the capability of a system to resist changes, in particular rapid or even violent changes. The opposite of resilient is, "fragile". For instance, a glass is hard, but not very resilient, of course; it is fragile. The trick when discussing resilience is that it is often the result of a compromise with performance. If you want to have high performance - say -  for a sport car; then your car will be more prone to breakdowns: think of using a Ferrari F1 for going to the supermarket to buy your groceries.

This kind of problem exists also for much bigger things: the way our world works; say, industry, commerce, transportation, and agriculture. And now that I said that, think of how fragile is modern agriculture. You have probably heard of the "Green Revolution", the new way of producing food that's feeding more than seven billion people on this planet. It is true; there has been such a revolution in the second half of the 20th century. It has been based on hybridizing plants in such a way to obtain higher and higher performance. The grain which is cultivated today has a yield at least ten times higher than the grain which was cultivated one or two centuries ago. It is truly the Ferrari of crops.

Unfortunately, the fact that the new generation of grain is such a wonder doesn't mean it is also resilient. Actually, it is not. As all engineered varieties of crops, it is made to grow in very specific conditions. It needs water, it needs fertilizers, and it needs mechanization. Which is fine; so far we have been able to supply agriculture with all that and in this way we are able to feed seven billion people. Well, not really seven billion. Despite the wonder crops we have, a lot of people are going hungry every day, I read that it the number is around 850 million, which means that more than one person in ten, today, doesn't have enough to eat. In a sense, it is a success because years ago the situation was worse but during the past few years this number has not been going down - the success of the Green Revolution seems to have tapered out. Nevertheless, the problem today is more a question of distribution than of production. In principle, our agriculture would be perfectly able to feed seven billion people - probably even more than that, although we seem to be getting close to the physical limits of what can be produced on a certain area of land.

So, what's the problem? It is that high performance normally comes with low resilience and this is true also for agriculture. The wonder crops of our age are high performance but low resilience. They have been developed for a situation in which climate was relatively stable, now that it has become unstable, it is another matter. Periodic droughts and floods are obviously very bad for agriculture and even a wonder crop is useless without water; it is like a Ferrari without good tires. And think of how floods wash away the fertile soil needed by plants, to say nothing about the damage done by fires.

Don't take me for an agronomist; I am not one. Food production is a complex matter and lots of things may happen that improve (or worsen) the situation. I am just noting that climate change may strongly impact the - almost literally - soft belly of humankind: agriculture. But that's not the only case. Think of infectious diseases, often transmitted by insects such as mosquitoes whose distribution depends on small temperature changes. Think of the mass migrations created by desertification of large swats of land. Then, couple climate change with the other great problem we have, resource depletion, and you'll see that the two problems reinforce each other. We said that a couple of degrees C is nothing if you have air conditioning; fine, but in order to have air conditioning you need energy and that energy - today - comes from fossil fuels. But fossil fuels are fast depleting: will you have enough energy for air conditioning in 30-40 years from now? Maybe, but I wouldn't bet on that.

So, let's go back to the initial question. I was telling you that you have much to be worried about because of climate change during your life expectancy of about 40-50 years. It doesn't mean that you won't arrive to my age; but that it is not obvious that you will. I said before that there are about 850 million malnourished people on this planet and I wouldn't be surprised if they were to become a larger fraction of the total population in the near future. Your problem, in this case, is whether or not you'll be part of that fraction.

As I said, acting in view of the future is like betting on something. If I were you, I wouldn't bet on the fact that the future will be like the past (it never is, actually). So, I think it would be a bad idea for you to plan to pass on the next generation the troubles that will come because of climate change; just like my generation has been doing with you. At some moment, someone has to be left out in the cold (actually, in the heat) and I am afraid that there are good chances that it will be your generation.

That brings the question of what to do to avoid becoming a malnutrition statistics (if possible, avoiding that anyone becomes such a statistics) but this is a long story that we'll discuss in another occasion. For the time being, let me just say that this discussion reminded me of something that Marcus Aurelius said. Citing from memory, it was something like "Everyone lives only in the fleeting moment and you could live many thousand years and that would make no difference to this fact  (*)" So, don't worry too much about how many years of life you have left. You can't know. But you know that you have a lot of work to do if you want to do something useful for you and for everyone else. So, you'd better start doing it now. 





(*) Remember that even if you were to live for three thousand years, or thirty thousand, you could not lose any other life than the one you have, and there will be no other life after it. So the longest and the shortest lives are the same. The present moment is shared by all living creatures, but the time that is past is gone forever. No one can lose the past or the future, for if they don't belong to you, how can they be taken from you? Marcus Aurelius (121-180)