How does climate change impact agriculture? Our Agrisciences group will be hosting an event on 6 March to look at just that!
Not only does climate change have a significant impact on agriculture, and the future of food security, but agricultural practices also directly contribute to climate change. Scientists, farmers and policy makers are coming together to find dynamic solutions to the problems caused by climate change in agriculture.
Agriculture provides food. Comprising of a variety of different farming systems, from crops to livestock, agriculture exists in almost every part of the world. Agriculture relies on knowing your geography – its soil properties, local pests and wildlife – but most importantly, the local climate. When these factors start to change, farming becomes a challenge.
We are already experiencing the effects of climate change, and turbulent or extreme weather is becoming more of the norm. As much as environmentalists can try to combat the development of these problems, agriscientists and farmers need to work together to overcome problems.
Consequences of climate change
One of the main consequences of climate change is a temperature increase. Even a slight temperature change can result in a significant effect on crop yields. Further to that, temperature change can result in drought, which affects the soil and plants alike, and lead to a change in pest numbers. An increase in atmospheric CO2 can also affect crops and livestock. Crops that thrive in higher CO2 levels will do better, but others may be negatively affected.
Not only will crop growth be affected directly by the weather, we could see a change in the diversity and number of pests. Image: Pixabay
Extreme weather events are also rapidly increasing in frequency. These include tornadoes, floods, heat waves, all of which can have quickly detrimental effect on farms. The 2018 British summer heat wave significantly affected crop farming in the UK.
As well as being affected by it, agriculture itself contributes to climate change. An estimated 10-20% of greenhouse gases are produced by agriculture, mainly from livestock.
Addressing the challenge
It is easy to consider that the impact of climate change on agriculture is something which can feel beyond our control. However, it is a dynamic challenge, and brings together scientists, academics, farmers, industry and policy makers, to overcome the negative impacts that a changing climate can have on agricultural systems.
Firstly, scientists can work to breed crops that are more resilient to these changes. They can identify genes for traits like heat and drought tolerance, pest resistance and stability under extreme conditions.
Solutions include plant breeding, GM crops, smart crop protection, policy changes and large collaborations across sectors. Image: Pixabay
Livestock farmers can help to curb climate change by introducing new diets that produce less overall methane. Other farmers can make shifts in their farming systems to more sustainable practices.
Policy makers can help with reducing the impact of climate change on agriculture. Not only by supporting environmental policies that potentially reduce the effects of climate change, they can also encourage scientific developments and relevant legislation relating to pest control, GM plants and other key areas.
Alterations to consumer practices can also reduce the impact of agriculture on climate change, and changes need to be made at all levels of the farming and supply chain.
How does climate change affect agriculture? Source: Syngenta
Overall, many parties need to collaborate to help to reduce the impact of agriculture on climate change, and help to overcome the problems that the future might hold, ensuring food security through a changing climate.
Blue dye, in this cross-section of a maize cob, highlights the rice gene that controls T6P in the kernels’ phloem. Image: Rothamsted Research
Through the introduction of a rice gene, scientists have produced a maize plant that harvests more kernels per plant – even in periods of drought.
The rice gene expressed depresses levels of a natural chemical, trehalose 6 -phosphate (T6P), in the phloem of the transgenic maize plant. T6P is responsible for the distribution of sucrose in the plant.
Lowering levels of T6P in the phloem, an essential track in the plant’s transportation system, allows more sucrose to be channelled to the developing kernels of the plant. As a result of increased levels of sucrose in this area of the maize plant, more kernels are produced.
Drought is an increasing problem in countries such as Uganda. Image: Hannah Longhole
‘These structures are particularly sensitive to drought – female kernels will abort,’ said Matthew Paul, team leader and plant biochemist at Rothamsted Research, UK. ‘Keeping sucrose flowing within the structures prevents this abortion.’
The transatlantic team, from Rothamsted and biotechnology company Syngenta in the US, built on field tests published three years ago that demonstrated increased productivity of the same genetically-modified maize.
‘This is a first-in-its-kind study that shows the technology operating effectively both in the field and in the laboratory,’ said Paul.
Maize growing on world’s oldest experiment, Broadbalk field at Rothamsted Research. Image: Rothamsted Research
Drought is becoming an increasing problem for developing countries, where the economic and social impacts are most evident.
Maize, also known as corn, and other cereals are relied on heavily across these nations due to their low cost and high nutritional value, with rice, maize, and wheat used for 60% of the global food energy intake.
The results of these trials are promising, and the team believe this work could be transferred to wheat and rice plants, as well as other cereals, said Paul.
On average, 10% of all crop production is lost annually to drought and extreme heat, with the situation getting worse year on year. Heat stress happens over short-time periods, but drought happens over longer timescales and is linked to drier soils. Maize and wheat are especially hard hit, with yields falling by up to 50% if drought hits.
On the High Plains, the largest US wheat-growing region, drought is a possibility every season. ‘Drought stress can be a key concern, especially in dry lands, but even in irrigated areas we can’t expect the same levels of water in future and farmers face restrictions,’ says Chris Souder at Monsanto.
So, this is not simply a developing world problem. Pedram Rowhani, University of Sussex, UK, found cereals in more technically developed agricultural systems of North America, Europe, and Australia suffered most from droughts. Yield losses due to drought were 19.9% in the US compared to almost no effect in Latin America.
Crop breeders in the past paid a great deal of attention to yield, but not enough to resilience to extreme events such as drought, Rowhani says, but this is changing. Growers increasingly want built-in drought resilience and plant scientists are looking for novel solutions. New, unconventional approaches based on novel insights from basic science might be necessary.
Hundreds of genes and proteins are involved in the complex trait of drought resistance. Plants avoid drought stress by shortening their life cycle with accelerated flowering, or cut down water loss by closing leaf pores called stomata. One approach by breeders is to target specific traits by crossing individual plants that perform best under drought conditions.
Stomata are found of the underside of leaves and are used for gas exchange. Image: Pixabay
‘About 97% of plant water loss occurs through the stomata. If you want to regulate the amount of water a plant uses, regulate the stomata,’ says Julie Gray, University of Sheffield, UK. Gray has been genetically tweaking wheat, barley, and rice plants so they have fewer of these pores.
She believes rising CO2 levels in the atmosphere means that they do not suffer from less carbon dioxide from opening their stomata. ‘CO2 levels have gone up 40% over the last 200 years. It’s quite possible they are producing more stomata than they need,’ says Gray.
Power plant in Tihange, Belgium. CO2emissions continue to increase. Image: Hullie@Wikimedia Commons
Gray reports that plants grown at 450ppm CO2 with reduced stomatal density, but increased stomatal size, had larger biomass and increased growth tolerance when water was limited. ‘Plants can operate with perhaps half as many stomata before you see significant effects on photosynthesis, so you can definitely reduce water loss this way,’ says Gray.
Root of the issue
At the other end of the plant plumbing system are roots. Susannah Tringe, Joint Genome Institute, UK, is seeking microbes that can gift stress-tolerance to their plant hosts. ‘The microbes associated with plants are likely to be just as important for plant growth and health as the microbiome of humans,’ says Tringe.
Though a lot of work has focused on finding the ‘magic microbe,’ Tringe believes whole communities will be necessary in real field conditions, whereas a single strain could be out-muscled by competitors.
Regular bouts of drought are leading to famine in developing countries. Video: Food and Agriculture Organization of the United Nations
Sugar and drought
‘Drought is probably the most widespread abiotic stress that limits food production worldwide. There is always need to improve drought tolerance,’ says Matthew Paul, Rothamsted Research Institute, UK.
‘Sucrose is produced in photosynthesis,’ Paul explains. ‘During drought conditions, plants will withhold sucrose from the grain, as a survival mechanism’. This can terminate reproductive structures and abort seed formation, even if drought is short-lived, greatly compromising yield.
A plant scientist studying rice plants. Image: IRRI Photos@Flickr
Rothamsted researchers have looked at modifying plants so sugar keeps flowing. ‘If you can get more sugar going to where you want it […] then this could improve yields and yield resilience,’ enthuses Paul. Field studies show that GM maize improved yields from 31 to 123% under severe drought, when compared with non-transgenic maize plants.