Half of global croplands could see a drop in suitable crops at 2C of warming

More than half of global cropland areas could see a decline in the number of suitable crops under a warming scenario of 2C, new research finds. 

The study, published in Nature Food, projects how climate change will modify the areas suited for growing 30 major crops under four scenarios, ranging from 1.5 to 4C of global warming.

It finds that under just 1.5C of warming, more than half of the studied crops would suffer from an overall loss of potential suitable cropland, compared to the current climate.

While warming would decrease crop diversity in the tropics, it would increase in areas far from the equator, “offering opportunities for climate change adaptation”, the authors write.

One scientist, who was not involved in the study, tells Carbon Brief that expanding research beyond just staple crops is “essential to understand[ing] the full impact of climate change on agriculture”, adding that “it is exciting to see more work in this space”.

Declining ‘safe’ space for crops

Cultivating a diverse range of crops contributes to a more stable and diverse food supply. 

For example, having a wide variety of crops allows farmers to select the crops that will be most resilient to extreme events, such as drought.

In order to understand how climate change will affect future potential crop diversity, the researchers identify the “safe climatic space” – or climate “niche” – for 30 major crops. This approach “maps the current climatic space of the major production areas of each crop”, based on annual rainfall, biotemperature and aridity.

(Biotemperature is the average of monthly average temperatures above 0C and below 30C, and is a method of considering both temperature and growing season.)

Using the “safe climatic space” approach, the authors calculate crop diversity by counting the number of crops that could be grown in a specific area in the future. 

Then, the researchers project how these areas would change under the four future warming scenarios of 1.5C, 2C, 3C and 4C above pre-industrial levels, compared to the current climate (1990-2020). 

The study finds that under a 1.5C warming scenario, more than half of the 30 crops analysed would see a net decrease in their global potential cropland area. The most affected crops are wheat, barley, soya beans, lentils and potatoes.

Beyond 2C warming, the declines in suitable areas for the 30 crops become more pronounced – in some cases approaching and passing 50%, the study notes.

In a 3C scenario, all of the 30 crops studied would have their suitable cropland area reduced.

The chart below shows the percentage changes in global potential cropland area for all the crops under the four warming scenarios examined. Each colour represents a level of global warming.

The 30 crops were classified into five groups: cereals, fruits and vegetables, oil crops, pulses and starchy roots.

Dr Dale Rankine is an applied climate scientist at the University of the West Indies. The expert, not involved in the study, tells Carbon Brief that the wide range of crops analysed in the research is “commendable” and that the findings are largely in line with previous work.

Dr José Clavijo Michelangeli, chief product officer at Praedictus Climate Solutions, an agricultural data and forecasting company, notes that most studies on agriculture and climate change only focus on the impacts to main staple crops, such as maize, wheat, rice and soya beans. Clavijo Michelangeli, who was also not involved in the study, tells Carbon Brief:

“Studies expanding to other crops are essential to understand the full impact of climate change on agriculture and it is exciting to see more work in this space.”

He points out that although the findings are consistent with previous understanding of the impacts of climate change on cropping systems, the climate data used to define the “safe climatic spaces” may not “align” with the responses to temperature of the crops currently grown there. He tells Carbon Brief: 

“This has the potential to over or underestimate the potential change in suitability of the crop in that region.”

Unequal impacts

The study also reveals that climate change impacts on crop production and diversity will vary across regions. 

Regions near the equator, such as sub-Saharan Africa and south Asia, would see the greatest declines in potential crop diversity – decreasing “on more than 70% of the cropland area if global warming exceeds 2C”, according to the study.

By contrast, global warming could increase the diversity of crops in other regions – such as North America, Europe, central Asia and Latin America. In these regions, crop diversity would increase – or see no change – on more than half of the cropland area under warming levels of up to 3C, the study says.

The map below shows the potential changes in crop diversity at 2C of warming. The inset charts show crop-diversity changes divided by regions and global warming levels, with the x-axis of the charts representing the four warming scenarios. Areas in brown represent places where crop diversity is projected to decrease, while those in blue are areas where crop diversity is projected to increase.

Adaptation opportunity

For areas that could see an increase in crop diversity, this creates “opportunities for climate change adaptation”, the authors say.

Clavijo Michelangeli says that the overall pattern of where the highest or lowest risks lie is in line with prior research. He adds:

“It is very likely that warming temperatures will not only increase diversification – which is in fact already happening – but also productivity of higher-latitude systems. 

“The work is also very important in continuing to emphasise the need to do more research in tropical systems.” 

Rankine warns that the benefits of increased crop production in temperate climates should not come at the expense of working to adapt agriculture in tropical climates. He argues that if future production centers on temperate countries, it could result in “a disinterest in tropical crops”. 

He tells Carbon Brief that an uptick of extreme events in temperate areas in the future could endanger global food security: 

“If [temperate regions] become the hub for food production, this could lead to global food shortages…This would amount to maladaptation, the opposite of diversity.” 

The study calls to limit global warming to 2C “to avoid detrimental impacts on food production”, especially in the tropics, where many of the world’s most-vulnerable nations are located.

Sara Heikonen, the study’s lead author and a doctoral researcher at Finland’s Aalto University, says that any negative effect on agriculture in these regions would impact global food networks. Therefore, she says, “international collaboration and support for countries that need help with adaptation” will be critical for “developing new agricultural practices to adapt to these difficult conditions”.