The glut of news reports on the COP26 in Glasgow risks obscuring fundamental considerations that are essential in order to have a true perception of the substance of the problems.
It is undoubtedly difficult to maintain a balance between the risks of dramatizing the climate situation and the expectations of effective solutions, but I believe it is essential to provide substantial elements. While the last IPCC report left open the prospect that there is still room to halt or even reverse the climate crisis, the report of the UN Environment Programme does not seem to provide the necessary clarity. It is certainly important to warn that the benefits of measures taken, even timely ones, will not arrive before 2040, but the comments on the need for “adaptation” conceal, in my opinion, the irreversibility of processes that have not only been triggered a long time ago, but have worsened in unsustainable ways (Giorgio Ferrari, il manifesto, August 12).
It would be out of place to go into the facts regarding the mechanisms of irreversibility in a complex and highly non-linear system such as the Earth’s atmosphere, but a few hints can clarify these aspects. In the last few days, the attention placed on the agreement on deforestation (if it was not merely a reiteration of past agreements already violated, as Correggia wrote in il manifesto on November 3) has omitted the fact that destroyed forests, besides seriously deteriorating the state and permeability of soils, permanently modify heat exchange, evaporation and planetary albedo. Similarly, permanent ice reflects solar radiation much more than the land or sea surface that will remain exposed, which will further increase the warming of the atmosphere.
Global warming is also weakening the Gulf Stream, which could stop (or even reverse), with disastrous consequences that would feed the resulting processes even further: such as a rapid rise in sea level towards the East Coast of the United States, and conversely a cooling of the Atlantic-facing regions of Europe.
Processes like these are called feedbacks, which can be positive (self-reinforcing) or negative: in the first case, which is definitely the most common for the atmosphere, they amplify the change from the starting situation, and can push the Earth’s system towards thresholds that, if exceeded, might prevent climate stabilization altogether and increase warming even if anthropogenic emissions are reduced.
A complex system, which is highly non-linear, has thresholds beyond which the system evolves in an absolutely uncontrollable and unpredictable way.
The mechanisms of this type are innumerable, because the terrestrial environment is a whole, in which all aspects are deeply interconnected. The unstoppable increase of urbanized and cemented areas is profoundly altering the microclimate, generating heat traps and thermal inversions, as well as polarizing production and consumption towards the cities, in particular that of water, causing imbalances throughout the territory. With the unstoppable loss of biodiversity, the biosphere is becoming less and less lively and reactive: authoritative scientists have sounded the alarm that the sixth mass extinction has begun.
There is also the problem of the systematic omission of energy consumption and emissions due to military facilities and wars. The Pentagon alone is the top single consumer and polluter in a ranking that includes nation-states: it exceeds, for example, all the emissions of Sweden.
Such facts should be the basis of environmental education, for a balanced evaluation avoiding both excessive pessimism and unfounded illusions.