Key crops face major shifts in response to global warming

The BBC has reported the results of a new study which finds the parts of the world suitable for growing coffee, cashews and avocados will change dramatically as the world heats up.

On the other hand, New Zealand is among the countries where growing areas will become more suitable for coffee.

The research has been published in the journal Plos One.

Key coffee regions in Brazil, Indonesia, Vietnam and Colombia will all “drastically decrease” by around 50 per cent by 2050.

Suitable areas for cashews and avocados will increase but most will be far from current sites of production.

The authors say that greater efforts must be made to help farmers adapt. Continue reading

Climate change will increase crop disease risk

Crops like wheat and soybeans could become more productive in a changing climate, with warming temperatures unlocking more land to grow and harvest them from.

However researchers have found those gains could also be thwarted by climate change, with temperature-sensitive plant pathogens moving into new environments too.

In a linked Nature News & Views piece, a plant disease expert says this is troubling news for the regions most at risk because it could lead to more epidemics like the Irish potato famine of the 1840s.

According to a study published in Nature Climate Change, climate change could lead to greater crop yields at high latitudes, but the gains may be offset by an increased risk of crop infection by pathogens

Food security is a continuous concern as the global population expands, arable land is reduced and the threat of climate change increases.

Climate change-induced losses to global crop production can occur either directly, for example as a result of drought, or indirectly, including via the impact of plant pathogens.

Plant pathogens represent a major threat to crop production, but little is known about how climate change will impact their distribution and abundance.

Daniel Bebber and colleagues model the production of four major commodity crops (maize, wheat, soybean and rice), as well as eight additional temperate and tropical crops, under future climate scenarios over the 21st century.

The authors predict that, overall, the yield of most of these crops will increase at high latitudes, such as in North America and parts of Eurasia.

They also suggest, however, that temperature-dependent infection risk from 80 fungal and oomycete (fungi-like) plant pathogens will increase at high latitudes. Major shifts in species composition within pathogen communities may additionally occur in some regions, such as the United States, Europe and China.

The authors conclude that potential increases in pathogen burden highlight a potential major risk to food security, reinforcing the need for careful crop management.

Link to research (DOI): 10.1038/s41558-021-01104-8

Source:  Scimex

How a change in peatland farming could reduce global carbon emissions

Reducing drainage depths in agricultural peatlands by 50% could reduce greenhouse gas emissions by the equivalent of over 1% of global anthropogenic emissions, suggests a paper in Nature this week.

Complete restoration of peatland remains the most sustainable option, but where it is not feasible to end drainage-based agriculture, partially raising the water table in peatlands could reduce emissions without halting their productivity.

Draining peatlands can provide fertile land for growing crops, because removing water triggers the release of nutrients through decomposition.

But crops grown on peat have some of the highest greenhouse gas emissions per crop calorie in the world. The equivalent of around 3% of global anthropogenic greenhouse gases are emitted from drained peatland. Continue reading

Climate-driven farming shifts threaten biodiversity and water quality

A warming world will unlock new areas for growing crops, opening the way for farming in regions that were previously unsuitable for agriculture.  But this could significantly impact biodiversity, water resources, and greenhouse gas emissions worldwide, the authors of a new global analysis warn.

Unchecked expansion of farmland into new areas will increase CO2 emissions, reduce biodiversity, and lead to a loss of water quality for hundreds of millions of people, the authors report. They say these frontiers will need careful management to avoid negative environmental consequences.

Lee Hannah, of Conservation International’s Betty and Gordon Moore Center for Science in Arlington, Virginia, and colleagues present a new analysis of these risks in the open access journal PLOS ONE (see  HERE)  Continue reading

US study finds 11 per cent of disappearing groundwater is used to grow globally traded food

A new study by researchers at the University College London and NASA’s Goddard Institute of Space Studies in New York City shows that 11 per cent of the global non-renewable groundwater drawn up for irrigation goes to produce crops that are then traded on the international market.  Two-thirds of the exported crops that depend on non-renewable groundwater are produced in Pakistan (29 per cent), the United States (27 per cent), and India (12 per cent).

The analysis is the first to determine which specific crops come from groundwater reservoirs that can’t quickly be replenished and where they are consumed.

Some underground aquifers replenish so slowly that they are essentially a non-renewable resource.

Countries that export and import these crops may be at risk of losing the crops (and economic benefits)  produced with non-renewable groundwater.  Importers may need to find alternative sources, possibly at a higher cost.

The results were published in Nature on March 30 (see HERE).

“When people consume certain imported foods, they should be aware that they can have an impact on the environment elsewhere,” said lead author Carole Dalin, of the University College London.

Dalin and her colleagues used trade data on countries’ agricultural commodities from the United Nations Food and Agriculture Organisation. They then combined it with a global hydrologic model — validated with ground information and NASA satellite data — to trace the sources of water used to produce 26 specific crop classes from their country of origin to their final destination.

Co-author Michael Puma, of NASA’s Goddard Institute for Space Studies and Columbia University, explained conjectured on how the data might be used.

“Say I’m in Japan, and I’m importing corn from the United States.  It’s important from Japan’s perspective to know whether that corn is being produced with a sustainable source of water, because you can imagine in the long term if groundwater declines too much, the United States will have difficulty producing that crop.”

Globally, 18 per cent of all crops are traded internationally. The remaining 82 per cent stays in country for the domestic market.  But the amounts of various exported crops produced using unsustainable groundwater rose significantly between 2000 and 2010.

In India, for example, exports of groundwater-depleting crops doubled in that period while Pakistan’s increased by 70 per cent and the United States’ rose by 57 percent.

Major importers of crops raised with non-renewable groundwater include the United States, Iran, Mexico, Japan, Saudi Arabia, Canada, Bangladesh, the United Kingdom, Iraq, and China, which went from a net exporter in 2000 to a net importer in 2010. Countries on both lists often export different commodities than they import.

Wheat, rice, sugar, cotton and maize are among the essential internationally traded crops in the global economy.  To produce them many countries rely on irrigated agriculture that accounts for about 70 per cent of global freshwater withdrawals, according to the United Nations Water programme.

Aquifers form when water accumulates in the ground over time, sometimes over hundreds or thousands of years. Non-renewable aquifers are those that do not accumulate rainfall fast enough to replace what is drawn out to the surface, either naturally to lakes and rivers or in this case by people via pumping.

Dalin explained that once the groundwater is depleted, it will effectively be gone for good on the scale of a human life-time, and will no longer be available for relief during crises such as droughts.

Drawdowns in aquifers worldwide have been observed over the last 15 years by NASA’s Gravity Recovery and Climate Experiment, a pair of satellites that detect changes in Earth’s gravity field to see the movement of masses such as ice sheets and, in this case, underground water.

“What’s innovative about this study is it connects groundwater depletion estimates with country level data,” said NASA hydrologist Matt Rodell at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who was not involved in the study.

More research was needed to consider population growth, changing diets, climate change, the implementation of irrigation technology and policy changes to understand when these aquifers may begin to run dry, he said.

Dalin said the absolute amount of water in many of these aquifers is difficult to quantify, though experts in many regions are already looking at better methods to determine how much water remains and how long it may last.  Now and in the future, decision-makers and local farmers will need to decide on a strategy for using this non-renewable water that balances the needs of short-term production versus long-term sustainability, she said.