Even as drought and the effects of climate change grew visible across this land, the Kariba Dam was always a steady, and seemingly limitless, source of something rare in Africa: electricity so cheap and plentiful that Zambia could export some to its neighbors.

The power generated from the Kariba — one of the world’s largest hydroelectric dams, in one of the world’s largest artificial lakes — contributed to Zambia’s political stability and helped turn its economy into one of the fastest growing on the continent.

But today, as a severe drought magnified by climate change has cut water levels to record lows, the Kariba is generating so little juice that blackouts have crippled the nation’s already hurting businesses. After a decade of being heralded as a vanguard of African growth, Zambia, in a quick, mortifying letdown, is now struggling to pay its own civil servants and has reached out to the International Monetary Fund for help.

“The Kariba Dam was a big eye-opener, sort of a confirmation that, yes, there could be this problem of climate change,” said David Kaluba, national coordinator of the government’s Interim Climate Change Secretariat.

On a continent especially vulnerable to the effects of climate change, Zambia’s rapid fall shows how the phenomenon threatens economic development across Africa, and how easily it can contribute to wiping out the fragile gains made in recent years.

While the global drop in commodities prices has devastated Africa, drought and other weather patterns related to climate change over decades have also undermined some of the biggest economies across the continent, from Nigeria in the West to Ethiopia in the Horn of Africa to South Africa at its bottom tip.

Over the next decades, Africa is expected to warm up faster than the global average, according to the Intergovernmental Panel on Climate Change. Despite an agreement reached in Paris in December, which committed nearly every country in the world to lowering greenhouse gas emissions, it is far from clear how much money African nations will have to mitigate climate change and adapt to it.

Zambia remains largely dependent on foreign assistance to manage climate change, and has been slow to plan for the consequences on its own.

“Unfortunately, what is going in Zambia is pretty much what is going on in the rest of Africa,” said Danny Simatele, a climate change expert at the University of the Witwatersrand in Johannesburg.

To many in Zambia, the current power crisis has focused attention on climate change in a way that changes over years and decades, like rising temperatures and irregular rainfall patterns, had not. People across the nation now track Kariba’s water level — it was 13 percent of capacity on a recent visit, up from a low of 11 percent in January — as closely as they follow their favorite soccer teams.

At the J.S. Butchery in the capital, Lusaka, the light had just come back on after an unscheduled, eight-hour blackout, hardly ideal for the food sitting in its glass refrigerator. Joe Mulenga, a 28-year-old butcher, said he had first learned about climate change on television about a year ago and then did an Internet search about it.

 

“Now it’s here, we started experiencing it, it’s real,” he said. “I’m very worried.”

Francis Ndilila, who leads the energy committee at the Zambia Chamber of Commerce and Industry, said that climate change had had the direct “effect already of slowing down our economic development.”

Projections for growth in Zambia, which averaged more than 7 percent for the decade up to 2015, have been cut in half.

The problems at the dam here stem from an El Niño weather pattern that has brought the worst drought in decades to parts of Africa. Farmers, who rely on rain and lack irrigation facilities, have been hit hard.

But so have countries dependent on hydroelectricity, like Zambia, Zimbabwe, Mozambique, Tanzania and Malawi. In Zambia, hydropower accounts for 95 percent of the electricity. Production at Kariba Dam, which usually generates more than 40 percent of the nation’s power, has fallen to about a quarter of capacity.

On a recent morning, not a drop came out of the dam’s sluices. Rocky patches on the riverbed that feeds Lake Kariba lay exposed, and sections of the dam’s walls, usually submerged, were discolored. The rains had come late to Zambia this season, and then only in small quantities, though recent strong rains up north have given officials some hope.

“Once the inflow reaches us in a few weeks, we expect some fair rise, not much,” said Pherry Mwiinga, a hydrologist at the Zambezi River Authority, which manages the dam.

Between 1960 and 2003, Zambia’s average annual temperature rose by 1.3 degrees Celsius, and rainfall has decreased by 2.3 percent each decade. The rainy season has become shorter, marked by more frequent droughts. When rains fall, they do so with greater intensity and tend to cause floods.

African governments say that big investments are needed to build irrigation facilities, canals and other climate-resilient infrastructure, in addition to developing renewable energy sources.

In the climate deal reached in Paris in December, wealthy nations, which are the biggest emitters of greenhouses gases, pledged $100 billion a year starting in 2020 to developing nations to help deal with climate change. But the amount is not legally binding, and terms were left vague.

“It’s very unclear,” said Mr. Kaluba of Zambia’s climate secretariat. “We see $100 billion scattered all over documents, but what it means has not hit the ground.”

Robert Chimambo, an environmental activist at the Zambia Climate Change Network, a private group, said that “the government could do a lot of things without the help of donors.”

Zambia’s reliance on hydropower has compounded its problems. The price of copper, its main export, fell because of decreasing demand from China. As the lack of rains led to low water levels here, Zambia was forced to carry out scheduled — and often unscheduled — blackouts. As the blackouts increased production costs, copper miners laid off thousands of workers.

In a country accustomed to a secure supply of power, the drought and the resulting blackouts immediately affected businesses big and small.

For Good Time Steel in Lusaka, the nation’s biggest steel maker, the power cuts meant losing a third of its production capacity and frequent breakdowns in its machinery. Unable to meet production deadlines, the company became unprofitable for the first time last year.

Good Time Steel was established in Zambia a decade ago, part of a big wave of Chinese investments in the country and elsewhere in Africa. At the time, Chinese businessmen did not weigh a government’s response to climate change as part of their investment decision making, said Jacky Huang, the manager of Good Time Steel, which employs 600 Zambians and 60 Chinese.

“Now we consider what the government is doing about climate change,” Mr. Huang said, adding that his company had recently abandoned an expansion plan because of the erratic power supply. “It’s a factor we have to consider.” 

In an area in Lusaka called Kalingalinga, small informal businesses also complained of losing customers and money. Many business owners now sleep when the power goes off and work when it comes back on.

The only thriving business appeared to be rentals of diesel generators, a popular source of power — and pollution — in many African nations without enough electricity.

At one such place, business has been so brisk that its five employees had not had a single day off since opening more than three months ago.

“We don’t go to church,” said Sheila Kandala, 20. “It’s not fair. Sunday, we’re supposed to rest.”