Human impact on global land four times greater than previously thought, new research reveals

Forests have dwindled around the world while cropland and pasture have expanded since 1960

Harry Cockburn
Tuesday 11 May 2021 18:47
One third of the earth’s land surface has changed usage over last 60 years
One third of the earth’s land surface has changed usage over last 60 years

Humanity’s impact on the surface of our planet is four times greater than previous estimations, alarming new research has revealed.

From deforestation to agricultural expansion, and from land abandonment to urbanisation, over the last 60 years 43 million sq km of land has changed use, affecting 32 per cent of our entire planet’s land surface, according to researchers in Germany and the Netherlands.

Understanding human impact on the land is “critical for being able to tackle challenges such as food security, climate change and biodiversity loss”, the research team said.

The extent of human activity means that on average, an area of land twice the size of Germany has changed use every year since 1960.

“This ‘human footprint’ is greater in extent and shows more dynamics than previously estimated,” lead author Karina Winkler of Wageningen University told The Independent.

“Humans have shaped the land surface for many centuries,” she said. “In fact, around three quarters of the global land surface has undergone some kind of human management. In our study, we focus on the last 60 years (1960-2019) and find that land use change has affected nearly a third of the land surface in this period.”

“Land use change is the second largest contributor to greenhouse gas emissions and plays an important role in tackling climate change and biodiversity loss.”

Asked how concerning the findings were, Ms Winkler said: “We should be concerned about it - especially when we aim to achieve sustainable land use in the future.”

But she said “not all changes are harmful for the environment and land use change, for example reforestation, can also contribute to mitigating climate change”.

The analysis identified that overall there has been a global net loss of forest area of 0.8 million sq km whereas croplands and pastures have expanded by 1.0 and 0.9 million sq km,respectively. 

Afforestation and cropland abandonment has increased in the global north, but deforestation and agricultural expansion have risen in the global south over the period.

Ms Winkler said one of the key reasons previous estimates had not accounted for such a great level of change was because areas that have changed in use several times have largely been overlooked.

“These areas of high land use dynamics include agricultural change such as changes between cropland and pasture, or forestry,” she said.

“They are mostly located in the developed countries of the global north, [such as] in the EU and the US, but also in population-rich countries with rapidly growing economies like India and Nigeria.”

She added: “Land use change has many different faces - urban expansion, mountain pastures, forestry, mining, or reforestation - it’s all around us. Most surprising to me is that we can reveal its dynamics, identify its spatial patterns across the globe and track its speed over time with the help of high-resolution data.”

The researchers found over the last sixty years phase of accelerating land use change, from around 1960 until 2005, followed by deceleration thereafter, which they said can be explained by the effects of global trade on agricultural production.

The overall impact is both alarming and encouraging, said Ms Winkler.

“On the one hand, we see an alarming rate of deforestation and agricultural expansion into natural areas in the tropics. On the other hand, we observe reforestation incentives and forest expansion in the Northern Hemisphere.

“We find indications of drivers that have accelerated land use change, like global trade, but also the slowing down effect that an economic crisis can have on land use change.

She suggested the coronavirus crisis could also be a catalyst in helping us “rethink our way of production and the role of global supply chains”.

“Maybe, we are at a point of steering land use in a more sustainable direction. Yes, land use has been a problem for the environment, but it can also be part of the solution.”

The research is published in the journal Nature.

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