Global timber supply threatened by climate change shifting cultivated land north

Climate change will shift and shrink land suitable for growing food and timber, putting the production of these two vital resources in direct competition, a new study finds.

The presence of vineyards in Britain is becoming increasingly common as warmer summers create increasingly favourable conditions for growing grapes. But behind this success lies a worrying fact: climate change is changing the regions of the world that are suitable for growing grapes.

Researchers at the University of Cambridge have discovered a looming problem: as the land suitable for growing our food moves north, it will reduce the land we need to grow trees. The wood these trees produce is the basis for much of modern life, from paper and cardboard to furniture and buildings.

The increasing competition between land for timber and food production due to climate change has been overlooked until now, but is set to become an emerging issue as our demand for both continues to increase.

In a worst-case climate change scenario, where no action is taken to decarbonise society, the study finds that more than a quarter of existing forest land – around 320 million hectares, equivalent to the size of India – will become suitable for agriculture by the end of the century.

Most of the forests designated for timber production are currently located in the Northern Hemisphere, in the United States, Canada, China and Russia. The study found that 90% of all current forest land that will become productive for agriculture by 2100 will be in these four countries.

In particular, tens of millions of hectares of timber-producing land in Russia will become suitable for agriculture again – more than the United States, Canada and China combined – and conditions will become favorable for growing potatoes, soybeans and wheat.

“There is only a limited amount of land on the planet suitable for producing food and timber, two essential resources for society. As climate change worsens and agriculture is forced to expand northwards, pressure on timber production will increase,” said Dr Oscar Morton, a research fellow in the Department of Plant Sciences at the University of Cambridge, who co-led the study.

“We need to look 50 years ahead because if we want timber in the future, we need to plant it now. The trees that will be cut down by the end of the century are already in the ground, and their growth cycles are much slower than those of food crops,” said Dr Chris Bousfield, a postdoctoral researcher in the Department of Plant Sciences at the University of Cambridge and co-leader of the study.

Global food demand is expected to double by 2050, driven by population growth and rising incomes. Global demand for wood is also expected to double over the same period, largely because it is a low-carbon alternative to concrete and steel in construction.

Moving timber production to boreal or tropical forests is not a viable option, as trees in these regions have remained intact for thousands of years and logging them would release huge amounts of carbon and threaten biodiversity.

“One of the major environmental risks associated with increasing competition between agriculture and forestry for land is that timber production will shift to remaining areas of primary forest in tropical or boreal zones. These areas are the epicentres of the world’s last wilderness areas, and intact tropical forests are the most biodiverse places on the planet. It is essential to prevent further expansion,” said David Edwards, professor of plant ecology in the Department of Plant Sciences at the University of Cambridge and lead author of the study.

To obtain their results, the researchers took satellite data showing intensive logging across the world and overlaid it with projections of agricultural land suitable for the world’s major crops – including rice, wheat, corn, soybeans and potatoes – in the future under various climate change scenarios.

Even in a best-case scenario, where the world reaches net-zero emissions targets, researchers say there will still be significant future changes in regions suitable for timber and crop production.

The study is published in the journal Nature Climate change.

Timber production contributes more than $1.5 trillion annually to national economies around the world. Heatwaves and resulting wildfires have recently caused massive forest losses around the world. Climate change is also fueling the spread of pests such as the bark beetle, which attacks trees.

Climate change is expected to make some tropical regions too hot and inhospitable for growing food, and large areas of southern Europe much less suitable for food and timber production.

“Climate change is already causing problems for timber production. Now we’re going to add increased pressure from agriculture, which is going to create a real storm of problems,” Bousfield said.

“Securing our future wood supply may not seem as urgent as securing the food we need to eat and survive. But wood is just as much a part of our daily lives and we need to develop strategies to ensure both food security and wood security in the future,” Morton said.