LAGOS, Nigeria – The yellow haze descended across Nigeria, blotting out the sun, canceling airline flights and coating everything with a fine layer of dust.
The sudden storm sparked frightened text messages about supposedly killer acid rain, but meteorologists say the weather comes from the harmattan, a yearly trade wind that brings dust from the Sahara Desert through Nigeria and the rest of West Africa. This year, however, the harmattan has come at an abnormal time, a possible result of global warming. Experts say it may delay the rainy season in Africa’s most populous nation and there are worries it may even throw off future seasonal changes.
“It is part of the changes of the climate,” said Temi Ologunorisa, a professor of climatology at Osun State University. “With the coming of this dust, you cannot have rain.”
The harmattan, caused by shifting weather patterns, means “tears your breath apart” in Twi, a West African language. The harmattan season typically begins in late November, as Nigeria’s dry season begins to end. The winds carry the sands and dust of the Sahara southward, and pick up the loose crop soil of Nigeria’s arid northern Sahel with it.
This year, the harmattan briefly appeared in January. It typically ends by February, said Sampson Wilson, a deputy general manager at the government-run Nigerian Meteorological Agency. But it blew back into Nigeria without warning last weekend, first enveloping the country’s north in dust and dropping visibility to almost zero, according to Wilson, and forcing many airlines to cancel flights in the country of 150 million people.
As it reached south, the storm encased the megacity of Lagos in a yellow fog that made the setting sun give off no more light than the moon.
Northern Nigeria is experiencing growing desertification as rising temperatures allow the edge of the Sahara Desert to creep closer to the country. That additional dust adds fuel for the harmattan winds, said Ologunorisa, an expert on climate change.
“The more dust you have, it shows we have more desertification,” he said.
The harmattan has made it hard to breathe in Lagos, whose air already is polluted by swarms of beat-up cars navigating potholed streets and by electrical generators that provide power during frequent blackouts. Health authorities warned the public to cover faces with wet cloth and stay indoors, but many had to take to the streets to earn a living in a country where most live on less than $1 a day.
Doctors expected the late harmattan to bring colds, flu and asthma attacks, as the kicked-up dust in the air inflames lungs and nostrils.
Changing patterns in the trade winds also affect when the harmattan will arrive, Ologunorisa said. The disruption of those patterns throws off Nigeria’s rainy and dry seasons as well — timing long relied on by farmers to know when to plant across the country’s fertile middle belt.
Forecasters predict this harmattan will slowly lift across the country in the coming week. But fears over Nigeria’s changing weather patterns will linger.