Crops are already seeing losses from heat and drought. Can genetic diversity – a return to foods’ origins – help combat the climate challenges ahead?

Climate crisis will make traditionally coffee-growing regions much less suitable for the crop. Composite: The Guardian

The industrialization of agriculture in the last century boosted production around the world – but that success also made our food systems much more vulnerable to the growing climate crisis.

Modern agriculture depends on high-yield monocrops from a narrow genetic base that needs lots of fertilisers, chemicals and irrigation.

But why does this matter?

Because a richer genetic diversity of foods, like we had in the past, will help make our crops more resilient to higher temperatures and changing rainfall patterns.

Like an investor with stocks, savings and real estate, diversity in the field spreads the risk: so if an early season drought wipes out one crop, there will be others which mature later or are naturally more drought tolerant, so farmers aren’t left with nothing.

Here are five key graphics from our recent special report on the precariousness of our modern food system.

1. Once there were hundreds of different types of corn

Maize or corn is now grown in greater volume than any crop in history, and is still the staple food for about 1.2 billion people in Latin America, the Caribbean and sub-Saharan Africa.

Historically, it spread around the world because of its ability to evolve and adapt to different climates, altitudes and day lengths, and people enjoyed purple, blue, black and orange varieties which all tasted a bit different.

Scientists in the 20th century then discovered they could take a locally adapted variety of corn, called landraces or heirlooms, and self-pollinate the plant, creating a genetically identical inbred. And if they did this several times its characteristics would change – perhaps the plant would be taller or have a big ear of corn.

These inbreds were then crossed with each other, again and again, to create hybrids.

Guardian graphic. Source: Corn Genetics: The History of Maize by Sherry Flint-Garcia, USDA.

Hybrid seeds, which farmers have to replace every year, contributed to a huge increase in yield but at the expense of genetic diversity and qualities such as taste, nutrition and climate adaptability. In the blink of an evolutionary eye, Mexico lost 80% of its varieties, and 99% of corn grown in the US today is from hybrid seeds.

2. Food production losses due to climate are already happening

The threat to food from climate crisis is not just a fear, it’s happening now. In Asia, rice fields are being flooded with saltwater; cyclones have wiped out vanilla crops in Madagascar; in Central America higher temperatures ripen coffee too quickly; drought in sub–Saharan Africa is withering chickpea crops; and rising ocean acidity is killing oysters and scallops in American waters.

By the end of the century, the worst-case scenario for crop yield loss would be a disaster, but even the best-case scenario would be devastating for the world’s most important crops.

Guardian graphic. Source: Temperature increase reduces global yields of major crops in four independent estimates by Zhao et al. The worst-case scenario is the RCP8.5 pathway, the intermediate scenarios are RCP6.0 to RCP4.5 and the best-case scenario is RCP2.6.

3. Diets in different countries started out different. Now they overlap

In 1961, this is how many calories people in the United States consumed from various food items each day.

Meanwhile, people in China ate some of the same foods. But the overlap between the two countries’ diets was small.

Guardian graphic. Source: Food and Agriculture Organization of the United Nations. We filtered for food items that account for 20 or more calories per day in a given country.

But around 40 years ago something else started happening: from country to country, the overlap in our diets started to grow.

Over the next half-century, this list got longer. People began eating a larger variety of foods across the world.

Guardian graphic. Source: Food and Agriculture Organization of the United Nations. We filtered for food items that account for 20 or more calories per day in a given country.

4. Uniformity now rules – reducing resilience

Let’s take wheat, the world’s most widely consumed grain which is grown in every continent (apart from the Antarctic) to make bread, chapattis, pasta, noodles, pizza and biscuits.

It feeds billions but it is vulnerable to climate changes. Last year prices for durum (pasta) wheat soared by 90% after widespread drought and unprecedented heatwaves in Canada, one of the world’s biggest grain producers, followed a few months later by record rainfall. Over the last century, Canadian farmers have increasingly relied on genetically similar high yield wheat varieties, elbowing out crucial diversity.

Canadian wheat varieties have been getting more genetically similar over the last century.

Guardian graphic. Source: Genome-Wide Reduction of Genetic Diversity in Wheat Breeding by Fu et al. This data is of Hard Red Spring wheat, a common variety.

5. Our favorite coffee is threatened by drought and hurricanes

Then there’s one of the world’s favorite stimulants. Whether you prefer espresso or instant, our coffee comes from just two species: arabica and robusta. Smooth tasting, high quality arabica accounts for about two-thirds of consumption and is struggling to cope with the changing climate. Robusta, which is hardier with more caffeine and higher yields, has a bitter, grainy flavor.

Wild arabica coffee is native to the forested mountains of Ethiopia and South Sudan, but the coffee we enjoy in our lattes and flat whites today can be traced back to just two sets of arabica plants snuck out of Yemen in the early 17th century.

Its future now hangs in the balance.

Arabica grows at 1,300 to 2,000 meters (4,200 to 6,500 ft) above sea level and is very fussy about temperature, rainfall and humidity. When it’s too hot and dry, coffee ripens too quickly which diminishes yield and quality. Our arabica doesn’t like it to be too wet or too windy either – which is a major problem for coffee growing regions prone to hurricanes such as the Caribbean, Hawaii and Vietnam.

As the climate rapidly changes, higher temperatures, erratic rainfall and more aggressive pathogens could render 50% of current arabica growing regions unsuitable by 2050.

Guardian graphic. Source: Projected Shifts in Coffea arabica Suitability among Major Global Producing Regions Due to Climate Change by Ovalle-Rivera et al.

6. The race to save genetic diversity – all is not lost

As the clock ticks, the private sector is forging ahead with developing biotech solutions such as gene editing and transgenics, which rely on genetic resources in publicly funded gene banks and naturally occurring biodiversity to provide the raw material. Just four agrochemical companies control 60% of the global seed market (and 75% of the pesticides market), and so have a vested interest in making farmers dependent on them for the full shebang.

Not all is lost.

As the Green Revolution fueled the erosion of genetic biodiversity, it also triggered an organized global effort to find and conserve diversity in gene or seed banks.

In the end, though, we need to see greater diversity in farmers’ fields, where old varieties can once again be part of the evolutionary story.

Source: The Guardian

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