Food for 10 billion

If everyone around the world sat down to share a meal during the coming holiday season, there would have to be seven billion chairs at a very long table. Some researchers have estimated that based on these figures, by 2100 there will be 10 billion people on the planet. To paraphrase the line from the movie “Jaws,” the world’s going to need a much bigger banquet table for that year’s holiday get-together, not to mention a lot more food.

With the Christmas and New Year festivities approaching, it’s hard not to think about food and how it will fit into the party planning and gift giving. However, in the past 100 years, the global population has more than tripled from an estimated two billion around 1930.

During the decades when the world’s population grew from three billion to six billion people, researchers around the world including those at the International Rice Research Institute worked to significantly boost rice and wheat yields by nearly half again in order to feed more people than before with a single harvest.

Analyses

Faced with an expected population increase of three billion people before the end of this century, a team of American researchers has released an analysis of various methods for significantly boosting crop yields, along with their potential environmental impacts.

“Both land clearing and more intensive use of existing croplands could contribute to the increased crop production needed to meet such demand [for more food to feed a larger population], but the environmental impacts and tradeoffs of these alternative paths of agricultural expansion are unclear,” wrote University of Minnesota researcher David Tilman and his colleagues in their report published online the week of Nov. 21 in the journal Proceedings of the National Academy of Sciences USA.

Using agricultural and population data from the United Nations’ Food and Agricultural Organization, the researchers tracked annual yields of nearly 300 crops currently used for feeding humans, livestock and aquaculture. They noted that the environmental impacts of increasing food production vary depending on factors such as how much land is cleared to plant more crops, what crops are planted and how much fertilizer is applied.

Scenarios

In one of their scenarios, a billion hectares of land is cleared for crops and the greenhouse gas emissions due to agriculture rise by three gigatons (Gt) of carbon annually. For reference, three Gt of carbon is roughly 10 percent of the total amount of global carbon emissions attributed to burning fossil fuels in 2009.

“Agriculture’s greenhouse gas emissions could double by 2050 if current trends in global food production continue,” Tilman said in a statement. “Global agriculture already accounts for a third of all greenhouse gas emissions.”

Another scenario considered by Tilman and his colleagues in their report called for technology transfer from developed countries to developing nations. In this case, they said, less than half a billion hectares of land would be cleared for crops, producing 1.6 Gt of greenhouse gas emissions annually.

Still another scenario they presented further reduces the amount of land cleared to less than a quarter of a billion hectares though the amount of fertilizer put into the soil rises dramatically to boost crop yields, which could in turn have negative impacts on the marine ecosystems that receive the fertilizer runoff from the fields.

Tilman and his colleagues noted in their conclusion that aside from the points used in their analyses, other factors could affect the projections, such as the true impact of climate change on crop yields. In short, they said, “the environmental impacts of escalating crop demand will depend on the trajectory along which global agriculture develops.”

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