Temperatures in Africa are projected to rise faster than the global average, with estimates ranging from increases of 0.2℃ per decade at the lower end to more than 0.5℃ per decade at the upper end. Some climate change skeptics and politicians, such as Lamar Smith, a former Republican representative from Texas and chairman of the House Science Committee until he retired in 2018 to become a lobbyist, have argued that crop yields might actually increase in the far north and south, offsetting weakness in Africa, India and other regions, warming.
Not so fast. There is no doubt that climate change will alter crop yields around the world. Models used by scientists and other organizations such as the Intergovernmental Panel on Climate Change (IPCC) predict that if the current rate of climate change continues, crop yields at low latitudes will decline, while those at higher latitudes will rise. As NASA puts it, higher CO2 levels increase crop yields by “increasing the rate of photosynthesis, which stimulates growth, and reduces the amount of water lost.”
Long-term negative effects on crops from rising temperatures?
But whatever benefits warming may confer in some regions, they will soon fade with further warming. It is assumed that extreme heat, changing precipitation, and other impacts of climate change will make it difficult to grow staple crops in more productive agricultural regions such as the United States as soon as 2020 is possible, and many studies claiming positive effects ignore the little-studied phenomenon that accompanies changes in climate — changes The types and prevalence of crop diseases.
Researchers from the Universities of Exeter and Utrecht looked at crop climate models and took into account crop pest risks. Paper 2021 in The nature of climate change They found that by looking at rising temperatures, they could track how 80 fungal pathogens have reduced yields in 12 major crops over the century.
They found that the benefits of yield gains could be reduced — and in some cases eliminated — by simultaneous increases in crop diseases on farms located at higher latitudes. According to the researchers:
Crop disease burden can follow crop responses, increasing at higher latitudes where climate change is a project to increase yields. Moreover, the range of crop diseases faced by farmers in some of the world’s most productive regions will change dramatically. … Agriculture must prepare accordingly if we are to realize any potential benefits of climate change on crop yields.
What tools can be deployed?
According to the Broad Institute’s Science Alliance, gene editing could be a powerful answer by modifying the genes of crops to make them more resistant to the effects of climate change:
- Disease management – As we have indicated so far, higher temperatures mean an increase in disease. Meanwhile, Kenyan researchers have applied CRISPR technology to inactivate the banana streak virus, which is activated by drought and extreme heat.
- Drought Tolerant – Dry soils and less precipitation will increase under climate change scenarios, particularly in low latitudes (but higher latitudes are not immune). With target genes that can potentiate the effects of these stresses, CRISPR-Cas gene modification can disrupt these genes and enable stronger crop growth in the face of drought.
- Increase Yields – Traditional breeding techniques, applied strategically, can increase crop yields. In addition, CRISPR-Cas9 produced rice with an 11 to 68 percent increase in yield, increased tomato size and created more cattle muscle mass.
- Survival in Salty Soils – Salinity is a symptom of climate change, and severely hinders plant growth. Poor quality watering is likely to exacerbate the problem. In response, CRISPR has been used to increase salinity tolerance in tomato and, in China, eliminate a rice gene to improve tolerance to high soil salts.
- Fend Off Weeds – Enemy number one of crop growers, weeds can reduce crop yields by more than 30 percent. There is no doubt that increased carbon dioxide concentrations and changes in precipitation and temperature will lead to faster growth of weeds. While the new chemicals could help stop weed growth, the CRISPR modification introduced a herbicide-tolerant genetic variation (allele) into rice, which could allow farmers to practice no-till farming that itself reduces greenhouse gas emissions.
How do pathogens make their way to higher latitude plants?
Basically, higher latitude plants will be no less immune to pathogenic infection than crops at lower latitudes. Diseases are mostly controlled by temperature, light and water. Sunlight increases the accumulation of phytoxins (which fight parasites) and protective pigments in pathogens. Water can, of course, allow physical diffusion as well as aid in reproduction and promote the development of some pathogens (however, others can survive better in drier conditions). Then, temperature can increase susceptibility to rust, and increase the presence of bacteria. Changes in climate, according to a team of plant biologists at the University of Kashmir:
…may lead to geographic distribution, increased wintering, changes in population growth rates, increases in the number of generations, extension of the growing season, changes in synchronization of crops and pests in phenology, changes in interactions between species, and increased risk of invasion by migratory pests.
However, these changes may not rise in a straight line by increasing with each degree of temperature rise. Princeton University researchers modeled the effects of climate change on the fungus “flax rust” (Melampsora Lenny) and the host plant, flax lois, a subalpine wildflower. their studies in Scientific reports showed that climate change will first slow transmission of flax rust, but that the pathogen will re-emerge and spread as temperatures continue to rise. How will this happen? The researchers believe that the warmer temperatures first will inhibit plant growth, which could cause the disease’s prevalence to decrease, at least temporarily.
“This will lead to a reduction in the risk of infection due to a lower spread of spores and a reduced odds of the plant becoming infected when encountering fungal spores,” they wrote. But, they added, “a recovery in plant growth, evolution of infection severity, infection risk, and epidemic pace is expected after the initial slowdown.”
Crop biotech naysayers argue against technology-based solutions
While many environmental groups advocate the deployment of biotechnology to address climate change perturbations in crops, many environmental groups reject the scientific consensus that GMOs or gene editing can play any role in stabilizing crop yields. In one of many dismissive “reports,” the Non-GMO Project, whose revenues depend on the demonization of crop biotechnology, argued in a blog post soliciting donations that the potential benefits of GMOs and genetically modified crops to help address the disruptions of agricultural climate change was one of the ” environmentally friendly claims” in the biotechnology industry.
We hear again and again that #GMOs are needed to feed a growing population on a warming planet, but does the evidence hold? not exactly. At #ClimateWeek, we’re reblogging debunking some of biotech’s biggest, greenest claims. In recent decades, a truly astounding amount of money has been spent under the banner of philanthropy and international aid. Programs such as AGRA (Africa’s Green Revolution) offer hybrid seeds and fertilizers, while WEMA (Water Efficient Corn Project for Africa) provides high-yielding corn (or maize) seeds and, more recently, GMOs.
Despite these and other programs, success remains elusive. … We believe the best solutions are based on local and indigenous knowledge, and developed with the participation of small farmers. These solutions emerge with deep respect for the social and economic implications of both action and inaction, they prioritize justice and autonomy, and value food sovereignty over profit.
Science does not support this fantasy. As science journalist Cameron English reports, “According to the Consultative Group on International Agricultural Research (CGIAR), more than 100 varieties of drought-tolerant maize have been released in 13 African countries since 2006. Field trials have shown that these crops can increase yields by as much as 35 percent.Two million farmers in sub-Saharan Africa currently grow these varieties of maize, and the results, the study reported, are impressive:
Farmers have reported yields 20-30% higher than they would get from their traditional varieties, even under mild drought conditions. If farmers continue to embrace the technology, the project has the potential to reap nearly $1 billion in benefits for farmers and consumers.
As stated by another study focused on Zambia, the benefits of increased food security will go mostly to the poorest of the poor:
DT [drought tolerant] Maize seed generates an additional income of US$ 240/ha [hectare] or more than nine months of food at no additional cost. This has enormous implications in reducing food insecurity while at the same time saving huge amounts of resources at the household and national levels…
Mainstream scientists and ecologists continue to advocate for a comprehensive approach to addressing climate change, and its pathological effects on high-latitude yields. This means we need all the help we can get – and that includes advanced agricultural techniques.
Andrew Porterfield is a writer, editor, and contributing agricultural editor to the Genetic Literacy Project. He has worked with many academic institutions, corporations, and non-profit organizations in the field of life sciences. Biography. Follow him on Twitter @employee