Climate change threatens food but microscopic algae offer answers

In 2021, the Intergovernmental Panel on Climate Change published the first volume of its latest authoritative report on climate change. The UN secretary-general called his findings a “code red for humanity”.

Emerging and projected impacts on agriculture and food supply are severe, according to the panel. For example, heat waves, drought and increasing rainfall variability could affect crop yields and livestock productivity. This, in turn, could lead to problems with the availability and nutritional quality of food, as well as risks of malnutrition and hunger.

Some parts of the world bear this burden disproportionately: more than three billion people are currently considered highly vulnerable to climate change, most of them in Africa, South Asia and Latin America. Small farmers and herders are particularly at risk.

The need for climate action is now clear, but finding viable pathways can be difficult. Yet effective climate actions can reduce climate-related risks while promoting sustainability. “Climate-smart” agricultural technologies offer various proven climate actions, such as agroforestry or drought-resistant seeds. These technologies have the potential to increase agricultural productivity while mitigating (i.e. combating) climate change or helping farmers adapt to it, or both.

Microalgae are a diverse group of microscopic aquatic organisms. Like plants, they generally generate energy from sunlight through photosynthesis. But they differ from plants in fundamental ways. For example, they grow in water rather than on land and absorb nutrients directly rather than through roots. While some microalgae are considered harmful, others provide useful products.

Consumers, businesses and researchers have shown increasing interest in microalgae in recent years. An example is the use of Arthrospira platensis (spirulina) as a dietary supplement. Others include how microalgae can be used as crop support tools, bioplastics, or biofuels.

A question that has remained largely unexplored, however, is whether “agrifood” applications of microalgae could offer promising options for mitigating or adapting to climate change.

A new academic paper has set out to provide tentative answers. He reviewed the available evidence on microalgae as dietary supplements, livestock feed, biofertilizers, biostimulants, and biochar feedstocks. She then assessed the potential of these five microalgae applications to serve as a basis for climate action.

Microalgae have been used as traditional foods in various countries where suitable species occur naturally, such as Mexico and Chad.

Nowadays, food supplements based on microalgae are mainly consumed by health-conscious consumers. Yet they can also be used to fight malnutrition and improve health in places with poor diets. As foods, microalgae can be powerful sources of nutrients, including high-quality proteins, fats, and vitamins.

The production of microalgae has characteristics that clearly distinguish it from plant or animal production. It does not require fertile soil. It is largely independent of local weather conditions and could potentially recycle water. It has high productivity and continuous harvest possibilities.

This technological profile is well suited to cope with climatic shocks, so the production of microalgae can be climate resilient. The delivery of microalgae biomass for food or other purposes can therefore also be climate resilient.

New feeds like microalgae, algae and insects offer options to improve the sustainability of animal production by providing protein-rich supplements to staple foods like grasses and forage crops. Microalgae feeds have been tested on cattle, goats, sheep, pigs, poultry and fish. The results have generally included improved productivity, better nutritional quality of products, or both. Microalgae could also provide a safe source of food in places where climate change-related livestock deaths are a growing concern.

Global agricultural production continues to rely heavily on chemical fertilizers to boost crop productivity. However, these products can sometimes harm agricultural sustainability or not cope well with the impacts of climate change.

Biofertilizers and biostimulants are natural alternatives to boost agricultural production. Biofertilizers provide nutrients to plants. Biostimulants promote plant growth by stimulating biological or chemical processes in plants or root-associated microbes.

Early studies on biofertilizers and microalgae-based biostimulants suggest they can boost productivity while building crop resilience to climate-related stresses like high temperatures, water scarcity, and soil salinity. Treated corn plants, for example, showed more root development than untreated plants. This results in better resistance to drought.

Microalgae could also support agricultural production by using algal biomass to make biochar or carbonized biomass. Application of biochar to fields can improve soil fertility and enhance its ability to retain water. Such effects could help crops cope with the impacts of climate change like erratic rainfall and extreme weather events.

Biochar was a traditional soil management tool in some crops, and treated fields sometimes remain distinct. For example, fields treated centuries ago in South America contained up to 9% carbon, compared to 0.5% in neighboring fields. In addition, their productivity was twice as high as that of the untreated fields. Early studies of biochar made from microalgae suggested it could be an effective soil amendment.

Together, these five agri-food applications of microalgae could be considered as possible ways to improve the climate resilience of food production, and therefore as climate change adaptation measures. Concretely, they provide options to help secure both food supplies and agricultural livelihoods despite climate change.

These five applications have also proven to offer possible ways to mitigate climate change, whether by reducing greenhouse gas emissions or by transforming these gases into physical form. One example is partially replacing an imported livestock feed like soybean meal—associated with transportation emissions and tropical deforestation—with microalgae-based feeds that require relatively little land and could be sourced locally. Another example is the use of microalgae-based biochar to accumulate soil organic carbon in a stable form.

In the future, such mitigation measures could perhaps be supported by carbon markets. These markets provide mechanisms to pay for projects that mitigate climate change. In theory, this could provide cash flow to participating stakeholders, including farmers. Such projects could also be attractive to potential players given the sharp rise in the price of carbon credits in recent years, even if these initiatives have sometimes proved disappointing in the past. However, several institutional changes would be necessary to make this possible.

The five microalgae applications reviewed show promise, both as means to foster climate-resilient food production and as climate change mitigation measures. These applications could thus be framed as climate actions. But further research is needed to explore and verify this potential, and to examine issues such as consumer acceptance and managing possible contamination risks.

In the meantime, these five microalgae technologies deserve greater attention from consumers, farmers, and governments as timely and hopeful innovations.

(This story has not been edited by the Devdiscourse team and is auto-generated from a syndicated feed.)

Teresa H. Sadler