Declining yields in some parts of the world have created a perception that global food reserves are stagnating. But in fact over the last six decades, the calorific output of global croplands has steadily grown, nearly quadrupling since 1961, according to a recent study. The researchers calculate that this growth is equivalent to an annual increase of 33 kilograms of wheat per hectare.

However these findings come with a stark warning: we will need to innovate to maintain these yields under the effects of climate change, and also share these agricultural spoils more evenly across the globe, parts of which experience deep food insecurity despite this abundance.

Unlike other yield studies that measure global crop productivity by weight, this new study took a different approach, and instead converted annual crop production into a calorie estimate. Weight estimates don’t allow for aggregation across different commodities because the measures are too variable. But using calories creates a standardized measure that allows exactly that. 

Using this approach, the researchers looked at the yields of 144 crops, a huge variety that covers 98% of global cropland area, counting their yields over a 60 year period between 1961 and 2021. With each crop’s annual yields converted into a calorie estimate, those could all be aggregated into a single productivity measure for the entire globe each year. 

From this analysis, the first most striking takeaway emerged: “Global yield growth—a key measure of agricultural productivity—has remained steady over the past six decades. While some crops, regions, or countries may have experienced slower growth, these have been offset by gains elsewhere,” explains Xiaoli Etienne, a researcher in agricultural economics at the University of Idaho, and lead author on the new study. 

Interestingly, the majority of this global growth occurred through greater productivity of crops on the field—and only a minority occurred through the expansion of farmland. This highlights the role that technological developments and increased production efficiency have played in generating such global abundance. In fact, the study shows that calorific yield per hectare has increased by 158% since 1961, rising from 4,330 kilocalories per hectare in 1961 to almost 11,000 in 2021. That means croplands today produce on average 2.5 times more calories per hectare than they did 60 years ago. 

The researchers also showed that this 158% increase closely matches the 152% population increase over that time, suggesting that increasing production generally tracks with global demand. 

One of the most notable findings is that the majority of the global yield increase was driven by four major crops: wheat, maize, rice and soybeans. Dubbed the ‘Big-4’, these accounted for 60% of the yield growth, with their calorie output almost tripling from 4,826 KCal/ha in 1961, to over 14,000 in 2021. Compared to these four, the yields of the remaining 140 crops the researchers surveyed grew by less than 100%, together providing just half the calorie output of the Big-4 in 2021.

Overall, this picture runs counter to the prevailing narrative that the world’s croplands are slowly failing. However that doesn’t mean we can rest on our laurels, the researchers say. 

Firstly, abundant global supply doesn’t equal abundant access. Many parts of the world, typically low-income countries, still deal with huge food insecurity. The authors suggest recalibrating global trade policies to ease the flow of food to places where it’s needed most, and getting a handle on food loss and waste which destines a huge amount of edible to the bin each year.

What’s more, continuously growing food yields aren’t a given under climate change. The effects of extreme weather, heat and drought will likely worsen yields in already food-insecure nations, but this will also be true across the planet. To tackle this we need innovation, the authors say: more research and investment is required to fuel the development of new climate-resilient cultivars, for instance. 

Such innovation will be especially important for the ‘Big-4’ crops that prop up the majority of global nutrition. “This dependency is risky, as climate change is increasing the frequency and severity of extreme weather events, making crops more vulnerable to diseases,” says Etienne.

The authors also say we need to bear in mind that food production may need to keep rising to meet the appetites of a growing world population—some estimates say by a third. And achieving that without wrecking the planet may require changing how we farm, to carefully marry production with sustainability and protect the ecosystems on which our food systems depend.  

Ultimately, despite the bonus finding that our food systems aren’t in decline, the study seems to show that food productivity is neither a given, nor a solution in itself. The way we manage it will determine how food-secure our future turns out to be. 

Baffes and Etienne. “Yield growth patterns of food commodities: Insights and challenges.” PLOS One. 2024.

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