Even small changes in temperature can have massive impacts on crop productivity. In the United States, a single degree of warming is expected to decrease corn yield by 10 percent. Worldwide, one degree of warming is expected to decrease crop productivity by 3-7 percent. Making matters worse, at the same time as crop yields are expected to decrease, the global population will continue to rise. If we do nothing to slow the effects of climate change, we risk a global food shortage that will affect us all.
Deep cuts to greenhouse gas emissions could do a lot to stave off disaster. But many researchers predict that even if we stopped all emissions tomorrow, we'd still experience some degree of future warming due to past emissions. So, even if we prevent additional damage, we'll still have to adapt to the changes in climate that are already underway.
If we want to feed our growing population, we’ll have to tackle the problem of adapting agriculture to climate change head-on. Right now, one of our best hopes for adapting to a warming climate is a controversial one: genetically engineering our crops to survive better in higher temperatures.
Genetic engineering, the process of directly modifying an organism's DNA, strikes many people as an arrogant, unsafe intrusion on the natural world. The debate over GMOs (genetically modified organisms) has raged for decades, with opponents arguing that our capacity to tinker with nature has outpaced our understanding of the risks.
Concerns about the safety and ethics of genetic engineering are absolutely valid, but we should also realize that, in some cases, our ethical intuition may lead us astray. If you have ever grown a tomato plant, and you live somewhere other than the Andean region of South America, you have selected a plant with mutations that allow it grow somewhere it wouldn’t naturally do so. When we domesticated the tomato plant, we picked out mutant plants that were able to thrive in different areas of the globe. The difference between that process and genetic engineering is that scientists don't have to search for a rare mutant; they can create it themselves.
CRISPR/Cas9 genome editing tools have made modifying DNA much easier. Using CRISPR/Cas9, scientists can create a DNA break in a specific place in the genome. They provide a strand of DNA that has a new sequence and the cell copies from that strand when it repairs the break, creating a genetic change.
Crops made using this technique are not, strictly speaking, GMOs, because they contain no foreign DNA. A wild tomato plant that was modified using CRISPR/Cas9 to be able to grow further north would be indistinguishable from the mutant plants that arose naturally, right down to the molecular level. And yet if engineers use genome editing to make that same change, it strikes many people as dangerous, even though the plants are completely identical.
Our food sources have already benefited from past forays into genetic engineering. Researchers' past efforts were focused on creating crops that are resistant to pests and disease. This is an important part of feeding the world – we could feed 8.5 percent of all the people on Earth with the crops lost to fungal pathogens alone. Climate change is making this problem worse: as warmer temperatures have spread toward the poles, so has disease.
But disease isn’t the sole consequence of climate change: the overall yield of food will likely drop because the areas where crops grow will no longer have the right weather for them to thrive.
Expanding crop-growing regions
One solution to this problem is to move heat-sensitive crops closer to the poles. But it’s not that simple: the seasonal cue that tells many plants when to flower is day length, and day length depends on latitude. That means you can’t take a plant that requires short days, move it further north, and expect it to produce fruit, even if it’s at the right temperature.
Recently, researchers discovered the gene that represses flowering in tomato plants in response to long days. It's thanks to the variation in this gene that we're able to grow tomatoes further from the equator. These researchers used CRISPR to show that disrupting this gene results in plants that flower rapidly, regardless of day length. That means that if we want crops to grow at different latitudes, we won't have to find a rare mutant. By zeroing in on the genes that control day-length-sensitive flowering, we can create those crops within months.
And when it comes to boosting crop productivity, one option is to create plants that convert sunlight into food more efficiently. That’s the goal of the RIPE (Realizing Increased Photosynthetic Efficiency) project, an international group working to increase crop yield by improving photosynthesis through genetic engineering.
Surprisingly, photosynthesis isn’t as efficient as it could be. Plants don’t adapt as quickly as they could to transitions between sunlight and shade. When there’s too much sunlight, plants protect themselves by releasing excess light as heat. But if a cloud passes in front of the sun, the protective mechanism lingers, which means less photosynthesis and lower yield. By speeding up the process of adaptation, RIPE scientists have shown that they can increase crop yield by 15 percent.
Although producing enough food to feed the world is crucial, genetic engineering isn't a cure-all. As long as we fail to confront the problems of war and unequal distribution of wealth, people will starve no matter how much food we produce. But adapting agriculture to climate change is unquestionably part of the equation, and genetic modification allows us to produce those changes quickly, easily, and safely.
Critiques of genetic engineering often focus on the most ethically questionable and unsettling research, but many scientists are doing work that could save the lives of millions. Keeping a closed mind risks demonizing a technology that may help us to survive.