Climate change, price shocks and diseases threaten rubber trees around the world, and in order to cope with the crisis, do we need to find alternative rubber sources as soon as possible?
Natural rubber is a unique material that is both soft and tough, as well as highly waterproof. Products made of natural rubber can be found everywhere in our daily lives, such as tires for vehicles, soles for sneakers, sealants used in engines and refrigerators, insulated wires and cables, etc. It is also made into condoms, clothing, sports balls and common elastic bands. Over the past year, rubber has played a key role in the personal protective equipment worn by doctors and nurses around the world.
In fact, rubber is seen as a commodity of global importance and has been included in the EU's list of key raw materials. Unfortunately, there are indications that the world's natural rubber may be running out. Disease, climate change and plummeting global rubber prices have put rubber supplies in crisis. It also prompted scientists to look for a solution before it was too late.
So how did such an important commodity get into this crisis in the first place?
The global supply of natural rubber is about 20 million tons per year, produced almost exclusively by smallholder farmers who cultivate small plots of land in tropical forests. Millions of workers carefully peel off the bark of trees on plantations in Thailand, Indonesia, and West Africa, extract the milky white sap, and then dry it in the sun to form flakes. These farmers provide 85% of the world's natural rubber.
But this fragile supply model is under threat. Rubber trees (scientific name: Hevea brasiliensis) are native to the Brazilian rainforest, and due to the epidemic of leaf blight in South America, rubber trees are no longer commercially cultivated in Brazil. South American leaf blight was a catastrophic plant disease that killed Brazil's rubber industry in the 1930s. For now, the disease is controlled in South America thanks to strict quarantine controls, but an invasion of Asia is almost inevitable.
At the same time, farmers in other parts of the world are also plagued by local pathogens such as white root rot and other leaf blight, which may have come from neighboring oil palm plantations. Climate change has also caused losses in rubber production, such as in Thailand, which has been hit by droughts and floods in recent years, which have further spread pathogenic microorganisms in growing areas.
For farmers, the growth in demand for rubber and the shortage of supply should be good news, because it will make rubber cultivation more profitable. Unfortunately, this is not the case. The price of rubber is determined by futures exchanges far from the source, where middlemen trade commodities such as rubber, gold, aluminum and fuel oil. Halcyon Agri, the supply chain leader in natural rubber, said that rubber's "pricing has nothing to do with production costs." Because of this, the price of rubber per ton can move as much as three times in two months, and has remained at a very low price in recent years.
This situation further jeopardizes the supply of rubber. Smallholder farmers calculate that income equals price multiplied by quantity, and lower prices force farmers to over-mine trees for more rubber, which makes trees more fragile and more susceptible to disease. Low prices have also prevented people from planting new trees to replace those that have reached the end of their lives commercially; on the other hand, many farmers have abandoned plantations altogether. On unit land, oil palm and natural rubber have the same income, but the labor input of rubber is higher, and due to the falling price of rubber, farmers are switching from producing rubber to selling wood for short-term profits, and then switching to oil palm.
Taken together, these factors mean that the current supply of natural rubber in the world does not meet demand. In late 2019, the International Tripartite Rubber Council (ITRC) warned that by 2020, there would be a shortage of 1 million tons of global rubber supply, or about 7% of production. Then, covid-19 broke out.
As countries entered lockdowns, demand for rubber declined. As a key indicator of the final demand for rubber, the mileage of the car has also declined. Rubber soon rebounded, though, with demand beating even the most optimistic forecasts. After the epidemic is basically over, new car sales have increased significantly, and now there is a serious shortage in many places (rubber), and the inventory owned by tire manufacturers is very low.
Although synthetic rubber can be synthesized with petrochemical products, natural rubber has unique properties that these synthetic materials cannot match: natural latex gloves are more tear resistant than nitrile gloves; aircraft tires use natural rubber with high elasticity and heat resistance, which can provide greater friction when landing.
The shortage of rubber supplies is partly due to the fact that migrant workers responsible for collecting rubber still cannot cross the border and therefore cannot harvest rubber trees. In the spring of 2020, many factories that process rubber into usable products shut down for several months. But the bigger problem is that this shortage comes from deep structural problems that are not easily solved. We need to find urgent measures to solve the rubber crisis.
One obvious answer might be to plant more rubber trees. On the other hand, if the price of rubber rises when supply is scarce, farmers will have an incentive to clean up the rainforest and plant more rubber. While oil palm plantations have received more attention, rubber plantations can also lead to biodiversity loss.
In 2011, soaring prices, fueled by growing demand for rubber, led to massive deforestation in Southeast Asia, and governments opened up woodlands for rubber in an attempt to profit from the trend. In Cambodia alone, rubber plantations account for a quarter of total deforestation. However, rubber trees take a long time – up to 7 years to grow – before they can be harvested.
Maybe we can try to get more rubber from existing plantations. Katrina Cornish, a professor of biosativascular materials at Ohio State University in the United States, said: "In Indonesia, there is a great opportunity to increase rubber production. They are growing the same asexual breeders in Thailand and Malaysia, but with much lower yields, so more rational crop management measures can be taken. Existing rubber trees should relieve the current pressure. "One option is to apply ethephon on rubber trees, a chemical that stimulates trees to produce more latex sap, but too much ethylene can kill the trees and make some farmers reluctant to use it."
Another option is to abandon the Brazilian rubber tree altogether. "The increase in production requires the help of new options, not Brazilian rubber trees," Konish said. Her Ohio State University is involved in the Natural Rubber Alternative Choice Excellence Project (PENRA), an industry collaboration dedicated to addressing the rubber crisis, and researchers involved in the project are exploring plants that might replace rubber trees.
One of the plants that has received attention is the rubber grass (Taraxacum kok-saghyz), a small dandelion plant grown in the Soviet Union during World War II when the supply of rubber in Asia was threatened, originating in Kazakhstan.
We can extract the gum by crushing the roots of the rubber grass, which produces only one-tenth of the rubber yield of the rubber tree. However, rubber grass can be harvested in three months and can produce a large number of seeds, making it easy to replant and expand production. Although the chemical composition is similar to that of natural rubber, rubber grass does not contain the protein that causes latex allergies.
The Fraunhofer Institute for Ceramics in Germany has launched a tire called "Biskya", which comes from the German abbreviation meaning "German bionic synthetic rubber". The institute said the rubber is made of rubber from rubber grass and has better wear resistance and tear resistance than ordinary rubber. Scientists are also developing new rubbergrass varieties and cultivation techniques — including hydroponics and vertical farms — to help commercialize the rubber. In this system, rubber grass roots filled with gumy sap can be harvested 5 times a year.
Also notable is Parthenium argentatum, a shrub that grows in the desert on the border between the United States and Mexico. During World War II, due to the lack of rubber, the United States once forced the cultivation of silver gum chrysanthemum. In the Emergency Rubber Project at the time, a group of scientists and workers painstakingly planted 13,000 hectares of silver gum chrysanthemums and soon produced about 400 tons of rubber per month. The shrub takes two years to undergo its first extraction, but can then be pruned and converted to annual extraction. However, after the end of World War II, the project was abandoned as cheap Asian rubber returned to the market.
Today, only two companies use silver chrysanthemum for commercial rubber production, including Yulex, which has partnered with outdoor clothing brand Patagonia to launch wetsuits containing some silver chrysanthemum rubber. Tire manufacturer Bridgestone retained a 114-hectare silver chrysanthemum test field in Arizona and produced its first tires in 2015 from the rubber it produced. The project was assisted by Italian oil giant Eni, which also owns a silver chrysanthemum test field in Sicily.
In the future, attempts such as these will only become more urgent. The global demand for natural rubber will continue to grow, especially as developing countries become richer. Cars are the biggest source of demand in the rubber market, and if every African household ends up owning two cars, that would mean a lot of rubber.
There are already some signs of change: Many big rubber buyers, including Bridgestone, German Continental and Goodyear, have signed agreements with the Global Platform for Sustainable Natural Rubber to ban the purchase of rubber grown on recently cut land in the hope of introducing a fixed minimum price for rubber. Like the Fair Trade scheme for coffee and cocoa, this will safeguard the livelihoods of rubber farmers in developing countries and help ensure a more adequate supply of rubber.
We must support smallholder farmers to do what they can so that they can withstand price shocks, thereby improving productivity systems and being able to replant. Further deforestation to grow these cash crops is bad news for both climate and biodiversity, as well as for humanity, and really needs to be carefully considered.
If South American leaf blight invades Asia, these fears will become even more urgent. Think of aspergidium fir, elm disease, pine beetles – you could lose an entire species, billions of trees, and when all the rubber trees die within a year, you can't immediately find a replacement for 40 million tons.
If at least 10% of the rubber used worldwide comes from alternative sources, then in such an emergency, they can be rapidly scaled up, and the rubber crisis will be a once-in-a-lifetime opportunity to help these alternative sources attract investment. To be sure, if we do not handle the rubber tree crisis well, the consequences will be unimaginable, both for developed and developing countries. (Ren Tian)