"Global warming is certain, but it does not depend only on man and does not endanger his survival". In these days of great heat (although so far the data seem to indicate - at least in Italy - a less torrid summer compared to the peaks of recent years) FIRSTonline consulted an authoritative counter-current expert such as Ernesto Pedrocchi, Emeritus Professor of Energy at the Milan Polytechnic and which in 2019 published a volume entitled “The global climate changes. How much fault does man have?”. The answer, according to the data and the calculations made by the teacher, goes in a direction that may seem denial but which actually looks at the phenomenon in a broader way. However, casting shadows on the future and on the solution to the problem: "The average global temperature will continue to vary according to nature and man can do very little about it".
Professor, let's start from the basics: can we confirm that global warming really exists and is it a serious problem for the survival of the human species?
“Global warming is certain. Over the entire globe, the average increase in global mean temperature (Tgm) since 1850 is about 1°C. The northern hemisphere has warmed more than the southern one, in particular the Arctic area has warmed up more. Certainly, however, it is not a problem for man, who lived in warmer climates, for example in the period of Roman civilization and about 1.000 years ago, when there was the medieval warm period testified by countless findings".
But in the Arctic area the ice is melting visibly. Isn't that a problem?
“It is true that it is happening and it is consistent with the increase in global temperatures, but in the past, with humans already alive on the planet, the glaciers have retracted much more. For example, in the Alps a thousand years ago the glaciers occupied a much smaller surface than they do now, and it is documented. Finally, I would like to remind you that 90% of the ice on Earth is found in Antarctica, which is almost intact”.
How much of the phenomenon of global warming is really, according to your considerations, attributable to man and his activities?
“In my opinion the ongoing global climate change is mainly due to natural factors and only to a small extent due to human activities. At the local level, in highly anthropised areas, there is instead an important sign of anthropic activities, but it concerns less than 3% of the planet's surface, if we consider that 71% is water and of the remaining 29% a good part is occupied by deserts, glacial zones, forests and uninhabited tundras”.
It is often confused between climate-altering factors and polluting factors. Can you explain to us precisely which activities have the greatest impact on climate change, distinguishing them from those that generate air pollution?
“This is a serious misunderstanding. The use of fossil fuels, the main defendants, involves emissions of H into the atmosphere2O and CO2, which are physiological combustion waste and both potentially climate-altering greenhouse gases. But fossil fuels can also emit pollutants such as sulfur oxides, nitrogen oxides, unburnt products and particulates due to impurities present in the fuels and the way they are burned. Pollutants are harmful to human health and have an effect essentially on the local climate, and every effort should be made to reduce them as much as possible. The best current technologies allow it, albeit by increasing the cost of the energy produced. h2O and CO2 instead they are not pollutants, but as greenhouse gases they could contribute to climate change. The water vapor produced by fossil fuels is completely irrelevant compared to the contribution coming from evaporation from the seas, lakes and wetlands. The CO2 coming from fossil fuels now constitutes about 5% of all emissions of this gas into the atmosphere”.
The concentration of CO2 however, it has greatly increased in recent times.
“The concentration of CO2 in the atmosphere it began to increase from the beginning of 1700, well before there were significant anthropogenic emissions and since then it has always increased from about 280 to 415 ppm. I believe that it grows mainly due to natural causes such as the concomitant warming of the oceans. Furthermore, since the end of the last ice age there is now no evidence of an effect of the change in CO concentration2 on the Tgm. The opposite link is more often evident: the variations in temperature precede those in the concentration of CO2. Carbon dioxide it is the basic element for the production of carbohydrates essential for every form of life on earth. There have been periods in the history of the Earth with concentrations of CO2 significantly higher than current values.
This year, the global lockdown meant that CO emissions in the spring2, according to Nature, have decreased by 9% (although projected for the entire year, with the recovery of activities from the summer onwards, the decrease will be much smaller). In your opinion, would such a drop be sufficient, if confirmed, to achieve the objectives of the Paris agreements?
“The drop in anthropogenic emissions due to the lockdown is completely irrelevant compared to the total CO emissions2 in the atmosphere. The Paris agreement was formalized in containing the increase in Tgm to 1,5/2,0°C which I believe, on the basis of what has been said above, is not a goal within man's reach”.
This year, in Italy, we've been having a very hot summer in the last few weeks, after a milder and rainier first phase, especially in the North, than usual. How do you evaluate this trend?
“Italy's climate is a non-significant local data, the only significant parameter is that of the Tgm, the average global temperature, and the data available up to the month of July tell us that this summer was less hot than the peaks reached in 2016 (the warmest year since 1850) and 2019”.
Is it possible that an initially less torrid summer was a direct effect of the lockdown, or is it just a coincidence?
"It's just a coincidence."
When we talk about global warming we refer to a period that goes from the mid-nineteenth century onwards, since it has been able to measure it more precisely. But does it make sense in your opinion to talk about "norm" or does the planet's climatic history tell us something else?
“There is no “norm” climate. The Earth went from markedly warmer times with no ice on the planet to times when it was an ice ball. Man has been on Earth for a relatively short time and survived a glaciation, a much more anomalous period than now”.
But how is heat measured today? And how much does the "heat island" effect affect big cities?
“As I said, by far the most important parameter for characterizing the global climate is the Tgm which includes the snow-glacial cover and the sea level. Obviously, but erroneously, man is led to evaluate the global climate with the climate he feels. There is no doubt that highly anthropized areas, i.e. large cities, are certainly heat islands that can reach temperatures a few °C higher than non-anthropized neighboring areas”.
If you had to name just one, what would be the first climate-changing activity you would eliminate or drastically reduce?
“Reduce as much as possible the production of pollutants in the use of fossil fuels. Fossil fuels now cover about 80% of the world's energy needs, it is unthinkable to give up their use. It is said that by 2050 they will no longer be used, but conservatively assuming that the energy requirement then is equal to the current one, the replacement for example with wind energy would require the commissioning between now and then of 6.000 large wind turbines every day " .
In short, it seems to understand that in your opinion we do not have much chance of containing CO emissions2 and the increase in atmospheric temperature as prefixed by international agreements.
“CO emissions2 consequent the use of fossil fuels will depend only on their availability, the TGM will vary according to nature and man can do very little about it”.
Some of the data cited in this interview are publicly available on the site climate4you.
