Leila Ousmane and her 10-year-old daughter walk in disbelief atop the crumbling bricks that, until a few days earlier, formed the walls of their family home.

Heavy rains and floods in late September ravaged the Dosseye refugee camp where they live, toppling their house of mud bricks and wooden stumps into rubble. “We went to live with my neighbour,” said Ousmane. “But last night, the storm made their house collapse too.”

Chad, a country already beset by economic and humanitarian crises, faces another looming disaster: climate change. It was ranked as the country most vulnerable to the effects of global warming in a 2016 index compiled by risk consultancy Verisk Maplecroft. The annual ranking combines exposure to climate change with a state’s capacity to respond.

While governments discuss ways to slow climate change at annual UN talks in Bonn from November 6-17, the impacts of a hotter planet are already wreaking havoc in Chad, a landlocked Central African nation with a population of 14 million. In Dosseye camp in the south, thousands of refugees from Central African Republic, chased from their homes by murderous gangs since 2013, have found themselves ousted from their new homes once again – this time by extreme weather, which is predicted to get worse as the planet warms.

Ousmane’s family was one of about 600 whose makeshift dwellings were flooded or destroyed in late September. Across the region, roads and fields were submerged under water, making transport difficult and spoiling harvests. The flood waters also increased the risk of cholera, malaria, dengue fever and other diseases, experts said.

“We see such cases (of flooding) more and more,” said Ferdinand Dana Obo, who works in southern Chad for the Lutheran World Federation (LWF), a religious body that does aid work. In recent years, the rains have come earlier and lasted longer, disrupting local farming and cattle-rearing, Obo said.

The most glaring effects of climate change, however, are seen around Lake Chad, which also borders Nigeria, Niger and Cameroon. Once one of Africa’s largest lakes, its water mass has shrunk by over 90 per cent in the past 50 years.

The reduction in size has disrupted the livelihoods of more than 21 million people who rely on the lake’s resources for their basic needs such as fishing and growing crops. This environmental disaster, coupled with an insurgency by Islamist militant group Boko Haram which has killed tens of thousands and uprooted hundreds of thousands, has left more than 7 million people hungry and in need of food aid across the Lake Chad basin this year, according to the United Nations. Meanwhile in eastern Chad, alternating droughts and floods are making life even tougher for more than 300,000 refugees from Sudan and their Chadian hosts, says the UN refugee agency.

Though Chad is considered to be one of the countries worst affected by climate change, in Africa it is by no means alone. A January study by the Brookings Institute said the continent is home to seven out of ten countries projected to be hit hardest by climate change: Sierra Leone, South Sudan, Nigeria, Chad, Ethiopia, Central African Republic and Eritrea.

With 94 per cent of Africa’s farm produce rain-dependent, climate change is already harming harvests. Crop yields from rain-fed agriculture could decrease by up to 50 per cent by 2020 with severe consequences for food security, the report warned.

Hotter temperatures and heavier rainfall mean malaria, one of the continent’s biggest killers, will also spread to new areas, including the highlands of Ethiopia, Kenya, Rwanda and Burundi, the study noted. Rising sea levels will affect West Africa in particular, where 56 per cent of GDP is generated near the coast, it added.