When yet another drought wiped out his flock five years ago, Toro, a Fulani shepherd in Niger, decided to migrate to the capital Niamey, where he found work selling cell phones instead.

"Without water or grass, my oxen and sheep died, one by one," the lanky man in his 40s said, adjusting a white turban that protects him against the searing heat.

But now, living in the city "without my animals, I've lost my identity," he says.

Climate change has wreaked havoc in Niger, bringing floods, droughts, spikes in temperature and food shortages -- buffeting the lives and livelihoods of millions of farmers in the west African nation.

Farmers flee to cities, while those who stay in rural areas are vulnerable to bloody conflicts over land, livestock or water.

Flooding in the vast sandy nation in 2012 alone killed 102 people, affected more than half a million Nigeriens and caused some 135 million euros ($145 million) worth of damage, according to Mahaman Goni Boulama of the disaster prevention office.

Niger's some 18 million inhabitants are no strangers to hardship, with the landlocked former French colony already one of the world's least developed countries, ranking 187th on the UN Human Development Index.

- Digging deep for water -

Global warming is only worsening the problems, with the steadily encroaching desert now covering three-quarters of the country -- a reality experts and authorities have warned about for three decades.

Temperatures top 50 degrees Celsius (122 Fahrenheit) in the dusty desert north, while the mercury tends to hover between 30 and 45 degrees in the shade for the rest of the country.

The country's water supplies are dwindling relentlessly, with wells, reservoirs and waterways drying up.

"You have to dig several hundred metres to reach water," says Issa Amoumoune, whose home area Tanout in the centre of the country was once its breadbasket but now faces being engulfed by the sands of the Sahara.

The United Nations says two in three people regularly drink polluted water.

The desert sands are encroaching on the Niger River itself, threatening the survival of more than 100 million people living in its basin -- a vast swathe from Guinea to Nigeria, the nine-country Niger Basin Authority warns.

Fish can no longer breed and boats can no longer ply parts of Africa's third largest river as aquatic weeds clog up some of the waterways.

Humans contribute to desertification by cutting down trees for firewood, since they have no electricity for cooking.

The environment ministry says households consume around 200,000 tonnes of wood per year, which translates to 100,000 hectares (250,000 acres) of destroyed forest.

- 'Everything has vanished' -

Just one percent of Niger's land receives an average of 600 millimetres (24 inches) of rain during the rainy season, which lasts three or four months.

Everywhere else is lucky to get between 150 and 300 mm.

"Everything has vanished," said Albert Wright, a Nigerian civil solar engineer, recalling when Niger was an abundant producer of figs and cashews.

Today, Niger can no longer feed the bulk of its people, a situation that is only getting worse because of a population explosion.

Agricultural output is increasing by two percent per year, while the population is growing at nearly twice that rate, says Manou Bague, head of Niger's farmers' union SNAN.

With one of the world's highest birthrates of 7.6 children per woman, the population may reach 50 million by 2050, authorities warn.

Aid groups say 13.3 percent of children under age five suffer serious malnutrition, well above the 10 percent critical threshold set by the UN World Health Organization.

Many Nigerians decide to flee their country -- but they do so at their great peril. In 2013, 92 migrants, mainly women and children fleeing poor harvests, died of thirst while crossing the Sahara to reach Algeria.

Last year, Algiers turned back more than 3,700 migrants from Niger including some 900 children.