Because it is said that the Sahara desert is turning green

This year, an intensification of rainfall in the northern part of the tropical belt that envelops Africa has made the part of the Sahara desert that borders the Sahel greener.

“Lush”, with large green areas that invade the southern strip of one of the hottest and driest deserts in the world.This is what the Sahara, in the north of the African continent, in one satellite photo taken on September 12, 2024 from the Modis satellite of NASA, the United States space agency, and compared with the same day a year ago.This description immediately makes us imagine something positive, also by virtue of the now famous Great Green Wall, a project to restore a degraded area of ​​the Sahel, which we have heard so much about in recent years.Yet, the news of a less arid and more "lush" desert hides a decidedly less fascinating aspect.

In the expansion of lush vegetation towards the north, which overflows the African tropical belt to spill over into the desert, hide extreme meteorological events that have hit some states in western and central Africa this year.The rainfall that led to a “migration of the intertropical convergence zone” – as described by a study published in the scientific journal Nature climate change – they did not occur in the form of a pleasant rain that wet the sand and miraculously made it bloom.No, this precipitation fell to the ground in the form of storms, storms And floods which caused floods and major damage to the population and territories of Nigeria and Cameroon, Niger and Chad, even hitting Sudanese and Libyan soil.

But what is the intertropical convergence zone?This is an area where it remains throughout the year a state of low pressure wrapping the Earth right on the equatorial band.A sort of "belt" where high temperatures and humidity guarantee abundant rainfall, especially on the African continent, following the convergence of large tropical air masses.Depending on how this area moves (Itcz, in the English acronym), drier or wetter seasons are also determined in the areas affected.

This year Itcz appears to have experienced a considerable migration northward with obvious impacts on the tropical climate and on the society of the populations concerned.A migration that seems determined, as often in recent months, by two fundamental factors.The first is the transition from El Niño, which has upset the average global temperature in recent years, a La Nina, which is expected to cause a cooling of ocean surface waters and thus put an end to a period that, by definition, is drier.The other, needless to say, is the global warming.The increase in emissions of CO2 and other greenhouse gases in the atmosphere caused by the use of fossil fuels and the consequent increase in average global temperature seems to push Itcz further north and, according to the study published in Nature climate change, this migration it should become gradually more frequent over the next two decades.

But the consequences are already evident now.In Chad, a country that lies between the Itcz and the Sahara, between two and three centimeters of rain falls between mid-July and early September.This year, however, in the same period a quantity of water between 8 and 20 centimeters fell, causing devastating floods with almost 1.5 million people affected And 340 dead.Same fate suffered by Sudan at the end of August, with at least 132 deaths and more than 12 thousand homes destroyed, and from Nigeria where these days the situation is decidedly out of control.In the state of Borno, in the north-east of the country, the floods were defined by the United Nations High Commissioner for Refugees (UNHCR) as the worst of the last thirty years, impacting the lives of hundreds of thousands of people.Today there are tens of thousands of girls and boys without access to clean water and healthcare, as reported by the NGO Save the Children.Obviously they are not going to school and many of them no longer even have a roof to shelter under.“The situation here is terrible.Half the city has been submerged and the roads are impassable,” he said Chachu Tadicha, deputy director of Save the Children in Nigeria and responsible for humanitarian operations and who is currently in Maiduguri, in the heart of the affected area.

Intertropical Convergence Zone migration is something that needs to be studied thoroughly and carefully.And that he certainly finds its origin in several factors, including global warming, as anticipated.Just as the effects of this phenomenon must be studied in the long term, so as to avoid easy comparisons or - worse - conclusions on the project a green corridor, like that of Great Wall along the Sahel, which started more than fifteen years ago and which, on the contrary, has the aim of stemming the advance of the desert towards the south, thanks to the restoration and cultivation of approximately one hundred million hectares of land.