Struggles of the world’s ‘second lung’ put one of the most beloved crops at risk

On Nov 18, 2025

It is not only the Amazon rainforest, at the epicentre of UN climate talks this week, being disrupted by human activity. The degradation of the vast Congo Basin, known as the world’s “second lung”, is taking a toll across the African continent and threatening one of the world’s most traded and beloved crops: cocoa.

Stretching across six Central African countries, the world’s second-largest tropical rainforest is a critical carbon sink. It shapes weather patterns as far away as Ivory Coast, a distance greater than that from Dublin to Moscow.

The Congo has drawn fresh funding during the COP30 summit, as France aims to raise $2.5bn to deal with the ramifications of deforestation being felt far beyond the local ecosystems to a wide belt of neighbouring nations.

As trees in the basin are being felled at an accelerating pace, rainfall farther away in West Africa is already being severely affected, according to a study by Zero Carbon Analytics.

This has put at risk one of the region’s most valuable commodities, central to export revenues.

“This rainfall system has been supporting the global cocoa industry for decades and now that environmental service is breaking down,” said Joanne Bentley, a molecular ecologist and the study’s author.

The effects were wide ranging, she added. “Carbon storage, biodiversity, water, services, heat protection, temperature regulation — these are all things that drive real economic risk if they are lost.”

While the Amazon’s climatic influence has long been studied, the research is among the first to quantify the Congo Basin’s transcontinental climate effects.

There was a “fairly live academic debate about how you model” these effects, said Dominic Moran, professor of agricultural and resource economics at the University of Edinburgh, noting that the new study helped fill a vacuum in research on the Congo Basin rainforest.

The study combined deforestation trends, regional climate models and crop-response data to assess how declining rainfall could disrupt cocoa production across nine producing countries.

Its findings suggest that clearing these forests could cut rainfall in West Africa’s cocoa belt by as much as 20 per cent during critical growing seasons, threatening the yields that underpin three-quarters of global cocoa supply.

Cocoa prices have soared in the past few years as disease outbreaks and adverse weather, driven by climate change in Ivory Coast and Ghana, have crushed yields.

As prices hit record highs — with the price of a 100g bar of chocolate rising by 35 per cent in parts of Europe — consumer demand has softened.

Rainforests regulate rainfall through evapotranspiration: trees draw groundwater up through their roots and release it through their leaves, creating clouds and sustaining a self-reinforcing cycle of rainfall.

The Congo Basin’s trees generate up to 83 per cent of local rainfall — more than in the Amazon — keeping the forest humid and sustaining continuous precipitation. Seasonal winds then carry this moisture westward, supplying almost a fifth of the rainfall in West Africa, including over Ivory Coast and Ghana, the heart of the world’s cocoa belt.

When forests are cleared, that “rain pump” weakens. Deforestation not only cuts moisture production, it also alters regional wind patterns, weakening West Africa’s monsoon flows.

The Congo Basin has already lost around 10 per cent of its tree cover since 2000 and deforestation is now accelerating, driven by small-scale agriculture, logging and charcoal production.

More than half of its trees lie within the Democratic Republic of Congo, which lost more than 1.2mn hectares of forest cover in 2024 alone. If current rates continue, 27 per cent of the forest could be destroyed by 2050 — a level scientists warn could push the region past a critical tipping point, leading to persistently drier conditions both locally and across West Africa.

Cocoa is among the most rainfall-dependent crops in the tropics. Grown almost entirely by smallholders in humid equatorial zones, African production relies on rainfall rather than irrigation, and yields collapse when drought sets in.

Zero Carbon Analytics projects by 2050, cumulative losses could reach 1.6mn tonnes in Ivory Coast — about 80 per cent of current output — and a further 866,000 tonnes in Ghana, 377,000 in Nigeria and 205,000 in Cameroon.

Cocoa makes up roughly one-third of export earnings in Ivory Coast and more than half of agricultural exports in its neighbours, leaving their economies highly exposed.

The price impact would be global. The study estimates cocoa could reach $68.10 per kilogramme by 2050, almost six times the 2030 level, with deforestation accounting for about 40 per cent of the increase. Without further forest loss, the 2050 price would be closer to $41.

Europe, the world’s biggest cocoa importer, would bear much of the cost, the study found. If shipment volumes remained unchanged, deforestation alone could add $33.8bn a year to EU import bills by 2050.

The Netherlands, Belgium and Germany would see annual increases of $13.1bn, $6bn and $4.4bn, respectively, pushing cumulative extra costs to about $256bn compared to 2025 — almost double the global industry’s 2024 market value.

Not all researchers agree on the scale of those risks. Moran said such estimates might overlook how farmers and the cocoa industry could adapt in the face of a changing climate. “The approach they take is that the crop is where it is, the crop gets hammered because of drought and there’s no substitution effect,” he said. “That’s questionable, because most crops will get grown in other places. Farmers themselves will diversify.”

Some major chocolate makers have already started adjusting their strategies. High-quality chocolate and cocoa product maker Barry Callebaut, which lost 20 per cent of its market value last year during the cocoa crisis, is investing in new areas outside West Africa, particularly in Latin America, where rainfall is more stable and yields are less volatile.

Researchers at Zero Carbon Analytics argue that the larger threat lies in timing. Their analysis indicates impacts remain manageable through the early 2030s but accelerate sharply after 2040, as rainfall systems degrade and the Congo Basin’s role as a regional moisture source collapses. They also find that prevention would be far cheaper than inaction.