The Cnr study showing that 2018 was the hottest year since 1800, published yesterday, has in effect put in writing the existence of ongoing climate change in Italy (as in the rest of the world). All the more so because Michele Brunetti, head of the Historical Climatology Database at the Institute of Atmospheric Sciences and Climate in Bologna and author of the research, specifies that "the 2018 anomaly on its own means little, but seen in the context of the last 220 years of Italy's climate history it is very much significant." Here, then, are a few further explanations.

Read also: Climate: 2018 was the hottest year in Italy since 1800

Your study takes the last 30 years as its reference period: how does it show that the year just gone was truly the hottest since 1800?
What we highlighted is that the average against which all data from 1800 to today are referenced is in strong anomaly compared with the mean temperature of the last 30 years. There has been a rigid shift in all temperatures, of several degrees. And 2018 came in at more than 1.58 degrees above the average of the last three decades, which is already warmer in itself. It is significant that of the 30 hottest years since 1800 to the present day, 25 fall after 1990.

And yet the very first days of 2019 brought what was called a "cold snap" and snowfall in the South, so much so that some people seized on it to play down concerns about global warming.
But this is not an anomalous cold spell — we are fairly within the norm; we must not confuse weather with climate. What we are seeing at this time of year are normal oscillations around the average; it is perfectly normal for there to be heat peaks in summer and cold peaks in winter.

Is it also true that the very melting of the glaciers at the Pole can release cold water into the oceans and, by lowering the temperature of the currents, generate colder or more violent atmospheric phenomena?
What has been observed is that the poles — the North Pole in particular — are warming more than other parts of the Earth, and this reduces the temperature gradient that drives the circulation at our latitudes. This can lead to longer blocking periods and more prolonged spells of bad weather. That said, one cannot claim that the melting of the ice in itself causes cold snaps.

As well as being the hottest year on record, 2018 was also the year of the partial failure of the Cop24 negotiations on reducing atmospheric emissions: is there still time to save the planet?
The alarm raised by the Ipcc report went unheeded. In my view the opportunity to act is still there, but I do not know whether the will to do so exists. Action must be taken to cut emissions; the concentration of CO2 in the air absolutely must be reduced.

What is lacking above all is someone to step forward as a leader on this issue, someone to set an example, now that the United States in particular has decided to distance itself?
It is the industrialised countries that should take the first step, and a helping hand should also be extended to those who, at this point in time, need to grow. Clearly, the action has to start somewhere: China is improving — it is true that it emits more than anyone else, but if we look at per-capita emissions it has reached Europe's level. Trump, unfortunately, is not very keen on the matter, but some of the more industrialised individual states, such as California and New York state, have already decided to do something on their own. There is a glimmer of hope.