In the hit documentary ‘Kiss the Ground’, Woody Harrelson warns of the perils of desertification, describing how there are only “60 harvests left” due to soil erosion. Is this the wakeup call we need in the fight against climate change? Or is this an exaggeratory statement, unnecessary when describing something already so sinister?

Though the term ‘desertification’ may conjure images of the undulating orange sand dunes of the Sahara, the reality is nothing as magnificent, though nonetheless formidable.

Desertification describes the process of once arable land turning into desert as the quality of the soil declines. Overgrazing, deforestation, climate change, urbanisation and tillage practices in agriculture all contribute to desertification by making soils more vulnerable to erosion. Land which is managed in this way is unable to retain water or regrow plants, animals cannot graze, and the land becomes inhospitable. It becomes desert.

The areas hit hardest by soil degradation are those with low or variable rainfall, known as drylands. According to the Intergovernmental Panel on Climate Change (IPCC), drylands cover about 46% of the Earth’s land area. This includes as much as 60% of Africa, though the United States and Northern Europe are also threatened (40% and 33.8% dryland cover, respectively). These drylands are home to around 2 billion people. It is estimated that as a result of desertification, 50 million people living on vulnerable drylands could be displaced by 2030. Desertification is a global issue, which will see people on all continents directly impacted by the end of the decade.

In 2014, the UN Food and Agriculture Organisation (FAO) reported that global soils were degrading so quickly that the world’s remaining topsoil will be gone in 60 years. In other words, due to progressing desertification, we have only “60 Harvests Left”.

Actor Woody Harrelson refers to this statement, whilst narrating the 2020 documentary Kiss the Ground. Warning of the dangers of soil erosion, Harrelson paints a dystopian picture of a near future not dissimilar to the dustbowl Earth in Interstellar (2014).

However, like Interstellar, this definitive claim that there are “60 Harvests Left” may not be much more than science fiction.

I scoured Google for answers as to how accurate this statement is, and whether it is based on any reliable research. The short answer is no, it is not. But this hasn’t stopped newspapers and politicians from declaring an agricultural Armageddon of 100, 60, and even 30 Harvests Left.

The main conclusion of scientists seems to be that desertification is a formidable threat, but it is almost impossible to predict exactly how many harvests are left. In fact, nobody really seems to know where these claims even came from.

In a 2019 article written for New Scientist, botanist James Wong attempted to find out where exactly these predictions originated.

Wong explains that only one peer reviewed paper has ever been cited as evidence for a “final harvest”. The study is one conducted by the University of Sheffield in 2014, comparing the soil quality of allotments to agricultural and urban areas. Now here’s where it gets interesting. Nowhere in this entire study was there any calculation, prediction or even passing reference to the number of harvests left. So where is the evidence behind these headlines?

Determined to find out if there is any truth to these claims, Wong contacted leading soil scientists to ask if they had ever come across such a prediction. Not a single one had.

It is possible that “60 Harvests Left” is a worst-case scenario. Research published in 2020 found that 16% of soils are estimated to have a lifespan of less than 100 years. So, it is not impossible that in 60 years’ time some of the Earth may be little more than dust. In fact, there are examples of soils with life spans shorter than a century on all continents. So desertification is a threat that we need to take seriously.

However, the same study also showed that 90% of soils have a lifespan greater than 60 years, and half of all soils have a lifespan greater than 1000 years. Some soils were even thickening, rather than eroding. Which suggests that the “60 Harvests Left” claim is simply not true.

There is no way of calculating exactly how many harvests the world has left. The threat of desertification varies across the globe and the speed of soil degradation depends greatly on our response to climate change and the actions we take over the coming decades to protect our soil.

The threat of desertification is real, and exaggeratory statements such as “60 Harvests Left” may not be as useful outside of the cinema as Harrelson thinks. We need to use evidence when discussing desertification. This is not a Sci-Fi film – it is real life.

Despite this box-office worthy statement, Kiss the Ground does make one very important point. We need to change the way we treat the soil if we want to save ourselves from desertification.

Planting more trees, reducing grazing through sustainable farming, and improving water management are all solutions offering hope to those who are at risk of losing their homes and their livelihoods to the desert.

Across the world, efforts are already underway to slow the spread of this sinister phenomenon throughout vulnerable drylands.

In Africa, the United Nations Convention to Combat Desertification (UNCCD) is promoting the Great Green Wall Initiative. This project aims to create a band of vegetation across the Sahel region of Africa. Once complete, the Great Green Wall will be the largest living structure on the planet, three times the size of the Great Barrier Reef.

This wall will work to prevent the spread of the Sahara desert and provide food security, climate resilience and income opportunities for the communities living in the region.

A similar effort is also underway in China, in attempts to prevent the expansion of the Gobi desert - though scientists are uncertain whether this will be an effective solution to combat desertification in the region.

As the threat of desertification is exacerbated by climate change, this is a problem that needs global cooperation if we are to solve it. It is also one which needs effective and truthful reporting.

This year, the 17th June marks UNCCD Desertification and Drought Day. This day serves as an important reminder that reversing soil degradation is achievable through problem solving and co-operation at all levels.

We can prevent the dystopian scenes of dust and famine that the “60 Harvests Left” claim portrays, but only if we understand the true threat of desertification and the actions we should take to stop it. We need to distinguish science from science fiction.

Evie White

Evie Is a Biological Sciences BSc graduate from the University of Exeter, and a self-proclaimed member of the Chris Packham fan club. She is passionate about ecology and conservation and believe that biology and sustainability go hand in hand. Evie is particularly interested in the value of citizen science and individual action as a way to make positive environmental change. In her spare time, she loves scuba diving, cooking and painting.

You can find her on Instagram @eview_.

Desertification – The Science Fiction of “60 Harvests Left”

Evie White