In November 2024, the winners of Prince William’s Earthshot Prize, which aims to “search for and scale the most innovative solutions to the world’s greatest environmental challenges,” were announced on a stage in Cape Town, South Africa.¹ Among the five recipients were a team of Kenyan entrepreneurs who had designed a solar-powered refrigeration system, dubbed “Keep it Cool,” for farmers and fishing communities. This was the latest in a spate of awards for cooling technologies in Africa, in competitions whose sponsors included the World Bank, the Ikea Foundation, and an international trade association for the cooling industry.

Cold storage facilities for food are quintessential climate interiors. Without them, supply chains for perishable goods risk collapse, with potentially devastating financial impacts for producers, regional economies, and food security. These novel interiors are celebrated for helping to keep products fresh for longer as they move from fields, farms, and fishing nets to markets and mouths. UN agencies, charities, businesses, and investors in Africa frame new cooling technologies as solutions to the logistical and public health challenges posed by a steadily warming environment. They also see such technologies as a means of bringing farmers on the continent into global markets—both as food producers and as paying clients of the companies that build, sell, lease, or rent these digital and solar devices.

In all the talk about the potential of new cooling devices to open markets, there is surprisingly little mention of the microbes that cause food spoilage or food-borne disease. Technologies for cold storage of food are also technologies for managing the growth of fungi and bacteria. Yet the policy documents, corporate presentations, and marketing materials that present artificial cooling as a new development technology are silent about the microbial life inside these refrigerated worlds.

The production of new climate interiors for the African continent’s food is also, fundamentally, about mold—or rather, efforts to control, manage, and live with mold. Refrigerated interiors provide a graphic illustration of the ways that human futures are entwined with those of microbes in a warming world.

Mold is a generic, non-scientific term for over a hundred thousand species of multicellular, filamentous fungi that live all around the globe. Mold spores are ubiquitous in air, water, and soil. When vegetables, fruit, or meats are placed inside a refrigerated unit, they carry spores into this new environment. Inside these dark, cold spaces, spores absorb moisture and gradually create the long, branching, microscopic filaments that biologists call hyphae. These threads eventually become visible to the human eye as they overlap into a complex network, the mycelium.

Molds are dangerous because they produce toxic by-products, or mycotoxins, that can have harmful effects on human health when they are inhaled or ingested, particularly by people with preexisting vulnerabilities. The current consensus among environmental scientists, agronomists, and mycologists is that rising temperatures across Africa will increase the susceptibility of crops to mold and lead to an increase in mycotoxin contamination.

Over three hundred known species of mold belong to the genus Aspergillus. Aspergillus molds offer a distinctive entry point for studying climate interiors. They can be found inside damp and poorly insulated housing for refugees and students in the UK, where they provoke increased political interest in the quality and safety of low-cost rental housing. And they can be found in almost every food crop across the African continent.

Biology and food science journals contain detailed, country-specific studies—from Nigeria to India—documenting the risks of human exposure to Aspergillus from cereals, nuts, fruits, vegetables, and spices and seeds, as well as every meat and dairy product derived from animals that consume these crops as feed. The mycotoxins produced by Aspergillus molds as they convert organic matter into energy have been linked to lung disease, respiratory disease, and cancer.

A longstanding method of controlling pathogenic mold is the use of biochemical treatments, or fungicides, to eradicate spores. Fungicides destroy mold spores from the inside, breaking down their cellular structure. But a growing number of studies indicate that climate change is blunting the efficacy of some of the most common fungicides on the African market. Extreme heat, it seems, can increase the fungicide resistance of Aspergillus spores.

By contrast, cold chains are technologies of preservation. They keep microbes alive, even as they afford humans greater control over them. Unlike freezers for seeds or embryos that operate at sub-zero temperatures, refrigerators do not keep mold spores in a dormant state of cryogenic suspension. Instead, operating between 3ºC and 6ºC (between 38ºF and 42ºF), they simply slow the rate at which molds absorb moisture.

Of course, temperature is not the only factor controlling mold growth inside the fridge. Some foods—like those that are rich in proteins, carbohydrates, and fats—provide additional protection from the cold for microbial cells. Meanwhile, every time the door is opened, the rush of air causes spores to circulate, crossing between foods and adhering to rubber seals and plastic surfaces. Neither is temperature itself a given. Constant cooling inside an electrically powered refrigerator depends on a steady energy supply and ongoing maintenance. Such challenges are driving innovation in cold chains.

In October 2024, a trade fair for the off-grid solar industry took place in the Kenyan capital, Nairobi. The fair featured a raft of new appliances designed to help people living in low- and middle-income countries meet their needs for cooling without creating new carbon emissions. Products on display ranged from fans to refrigerators to evaporative air coolers, from milk chilling units to vaccine refrigerators—all powered by renewable off-grid solar energy.

These kinds of trade fairs have their roots in nineteenth-century commercial exhibitions held across the colonial tropics, which showcased technologies for storing and transporting ice, and opened up new markets for cold drinks and foods.² From South Asia to the Pacific, markets for cooling were defined by the thermal imaginaries of settler colonialists, who saw the heat of the tropics as an environmental force capable of shaping bodies and minds—both those they sought to subject to new rule, as well as those in power. In the early twentieth century, research into mold from food imported from Britain’s colonies in Africa led mycologists to advocate for new methods to control temperature and humidity in cold-stored meats. Such arguments provided a basis for mass investments in artificial refrigeration.

At trade fairs like the one in Nairobi, marketing for novel cooling technologies promotes prospects for the increased economic productivity and viability of exported goods. The solutions suggested in these spaces of techno-optimism present a familiar narrative of freedom from scarcity through technology. For farmers who have limited access to electricity and thus a high risk of food spoilage and exposure to dangerous mycotoxins, it would seem, the answer is solar-powered.

Off-grid, solar-powered cooling technology now makes up one of the fastest-growing segments of investment and innovation in renewable energy across Africa.³ New companies like Keep it Cool or Sure Chill appeal to international investors and policymakers on several registers. They materialize a teleology of clean energy transition; they offer scalable solutions, apparently capable of achieving the same results regardless of geography; their products vary in size, from small solar-powered refrigerators and freezers to large cold storage facilities or cold rooms capable of cooling cubic tons of food.

Aspergillus spores provide the rationale for investment in the continent’s new climate-controlled interiors, and in the companies that build them. These spores traverse supply chains for grains, cereals, fruit, and vegetables. In response, the threat of mold is leveraged across other supply chains, increasing demand for the imported silicon-based materials, metals, electronics, batteries, and plastics that are used to encase and insulate Africa’s food products from a warming world.

The aspirations and ambitions for climate-controlled storage facilities in Africa have shifted in recent years. Ten years ago, business models promised to focus on local manufacturing and construction, and promised job creation. Today, they tout smart devices, assembled largely outside the continent, with sensors to monitor temperature and humidity, microprocessors to collect and store user data, and SIM cards that allow for mobile connectivity. In this new model, customers do not pay an upfront cost for cooling technology, but they sign a long-term pay-as-you-go agreement.

According to one nongovernmental alliance established to promote this model, “clients benefit from high quality cooling at better prices, and don’t need to distract any budget to acquire the system. Technology providers benefit from a continuous income stream and can establish long-term relationships with their clients.”⁴ “Cooling as a service” is also cooling as a twenty-first-century surveillance system. Smart fridges and freezers allow companies to harvest data on real-time cooling practices. They also create a structure for carbon trading schemes, in which traders offset the use of high-emitting cooling technology in high-polluting markets with the use of clean technology in low-polluting ones.

The emergence of this new market-based intervention is just the latest chapter in a “biology of history,” a century-long story of food scares and market-making that is written inside the cell walls of mold spores.⁵ Today, ethically motivated entrepreneurs are helping to design new interior infrastructures for food storage on an irrevocably changing planet. As Rebeca Ibáñez Martín notes in this issue of Limn, the basics of these infrastructures are quite familiar: the modern greenhouse is built upon a nineteenth-century template, just as the twenty-first-century solar refrigerator echoes decades of anxiety about the effects of tropical air and humidity on food safety.

The refrigerated interiors being rolled out across the African continent promise to further integrate farmers into global markets. Knowingly or not, they also promise to rearrange the Earth’s moldy ecology. ⦿

1. “The Earthshot Prize: Our Vision and Mission,” The Earthshot Prize, accessed March 22, 2025, https://earthshotprize.org/our-vision-mission/. ↩︎
2. H. I. J. K. Hobart, Cooling the Tropics: Ice, Indigeneity, and Hawaiian Refreshment (Duke University Press, 2023). ↩︎
3. Off Grid Solar Market Trends Report (World Bank, International Bank for Reconstruction and Development, 2024). ↩︎
4. “Cooling as a Service Initiative: How it Works,” Basel Agency for Sustainable Energy, accessed March 22, 2025, https://www.caas-initiative.org/how-it-works/. ↩︎
5. Hannah Landecker, “Antibiotic Resistance and the Biology of History.” Body & Society 22, no. 4 (2016): 19–52. https://doi.org/10.1177/1357034X14561341. ↩︎