Climate change-boosted disease could endanger China’s food supply

Wheat ear infected with Fusarium ear blight (FEB), giving the ear a pinkish color. The disease could be set to increase in countries like China and the UK with climate change, Bruce Fitt and his teammates have found, suggesting resistant varieties should be developed. Photo credit: CIMMYT.

Wheat ear infected with Fusarium ear blight (FEB), giving the ear a pinkish color. The disease could be set to increase in countries like China and the UK with climate change, Bruce Fitt and his teammates have found, suggesting resistant varieties should be developed. Photo credit: CIMMYT.

As the planet warms, China’s wheat crops will be threatened by more frequent epidemics of ‘fusarium ear blight’ (FEB), scientists in the UK and China have projected. Bruce Fitt from the University of Hertfordshire in Hatfield, UK, and his teammates forecast levels of the disease in the Anhui and Hubei provinces from 2021-2050. Whereas in the worst affected regions in 2001-2010 around one-sixth of all ears were infected, this was the lowest disease level the researchers found in their future scenario. In the worst-hit areas, FEB infected more than a third of all ears. “This has implications for crop breeding because it takes 10-15 years to breed a new cultivar,” Bruce told me. “If you know the disease is going to become more important then you need to get on and start breeding now rather than waiting until the disease hits you.”

Today, over a billion people don’t have enough to eat, and further population growth and climate change are set to put the world’s food supplies under even greater strain. To help ease that pressure, Bruce and other scientists are working to understand and help improve control of crop diseases like FEB. While some crop diseases will worsen in the future, not all will, he stressed. “For example, you might have a disease that is spread by rainsplash in summer and then it’s predicted that there will be far less rainfall in summer,” he explained. “Then you would expect that with climate change the importance of that disease would diminish.” If governments, farmers and seed suppliers know which diseases are likely to get worse, they can prioritise developing strategies to contol them, like breeding disease resistant varieties.

To make useful forecasts for which diseases will worsen, scientists build models that include weather data, how crops grow and how the disease pathogen spreads through the crop. “In this particular instance the wheat is susceptible only at flowering,” Bruce said. “It may be in flower for a few days. If it doesn’t get the pathogen inoculum and the right weather conditions at that time it will not get the disease.” Climate change can both alter flowering times and the chances of warm, wet weather that make infection more likely. When wheat gets infected, even if it can be harvested it is more likely to contain poisonous mycotoxins. “If it’s full of mycotoxins then it can’t be eaten by man or beast, so it’s just wasted,” Bruce added. Read the rest of this entry »

Warming makes flowers change dates, or don skates

Blue Fleabane (Erigeron acer) has only moved its flowering date forward around by 3 days in 50 years, and instead the places where it's found in the UK have moved north by around 9 miles. Image credit: Vlad Proklov, used via Flickr Creative Commons licence.

Blue Fleabane (Erigeron acer) has only moved its flowering date forward around by 3 days in 50 years, and instead the places where it’s found in the UK have moved north by around 9 miles. Image credit: Vlad Proklov, used via Flickr Creative Commons licence.

If plants can’t flower earlier to adapt to global warming they’re probably being driven away from where they used to grow, towards cooler places. That’s what new findings on how these responses are linked from Tatsuya Amano at the University of Cambridge and his teammates suggest. “We believe that the link we’ve revealed will help us understand the complex implications of climate change on biodiversity,” Tatsuya told me. “Many studies have relied on models that only consider species’ spatial responses for projecting the impact of climate change on species. We might be able to generate more realistic projections.”

You could think of regular natural events, such as flowering in plants, as being triggered by an alarm clock – another type of dandelion clock, if you like. The study of when those alarms go off is known as phenology. In 2009, Tim Sparks from Coventry University visited Tatsuya, Bill Sutherland and others in Cambridge to give a talk on changes in when these events were happening. He was helped by notes on plant life many people in the UK had jotted down in their spare time, but that data’s inevitable patchiness caused him problems.

Bill and Tatsuya were working on mathematical models that helped fix similar problems in bird count data, and so they offered to help Tim with his work. They were also joined by Richard Smithers, then in charge of the Nature’s Calendar archive run by the UK’s Woodland Trust. He helped them realise the power of this publicly-accessible record of over 250 years’ worth of data on 405 UK species, nearly 400,000 records in all. Using that information, in 2010 the team showed that UK flowers are now blooming earlier in the year than in any 25-year period since 1760.

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Worse extreme temperature effects urge farming precautions

Stanford University's Sharon Gourdji talks about her study on increasing extreme heat during sensitive crop flowering periods. Credit: IOP Publishing, via Creative Commons license, see citation below.

Since 1980, maize and wheat crops in many places have been increasingly exposed to extreme heat during sensitive flowering phases that can damage them and cause harvests to fail. That’s according to scientists at Stanford University, California, who predict that this problem will increase for these crops, and also hit rice. In fact, the area of maize and rice hit by such deadly heat is set to expand more quickly through to the 2050s. “Crop breeders need to think carefully about how to incorporate heat tolerance, particularly during the flowering period, into wheat, maize and rice,” Stanford’s Sharon Gourdji told me.

Our warming climate affects farming in many ways. For example higher temperatures, and the higher CO2 levels that are primarily responsible for them, can speed up the photosynthesis process that makes plants grow. Meanwhile, shifting rainfall patterns are set to have serious impacts on important farming areas. In 2011, Sharon’s teammate David Lobell and other scientists showed that overall crop production growth worldwide has been held back by such changes in the last three decades. But they didn’t discuss how environmental changes might influence future food availability.

“The net impact of all these factors is the golden question, but notoriously difficult to model,” Sharon explained. “Also, the most relevant of these factors, and the associated adaptation measures, differ by location and crop. Therefore most modelling studies to date look at net impacts on just a given region, or type of cropping system.” To make worldwide predictions that could help secure our future food supply, Sharon’s team had to concentrate on a smaller, simpler issue. “We focused on extreme heat during flowering,” Sharon said. “This is one aspect of global environmental change that could be particularly risky for crops regardless of other more gradual changes that are taking place simultaneously.”

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Iconic authors help reveal record early flowering

"When I wrote the following pages, or rather the bulk of them, I lived alone, in the woods, a mile from any neighbor, in a house which I had built myself, on the shore of Walden Pond, in Concord, Massachusetts, and earned my living by the labor of my hands only." Those are the famous opening lines to Henry David Thoreau's Walden. Now, scientists have used Thoreau's notes on his surroundings to show how much earlier global warming has pushed plant flowering. Credit: Tim Hettler, via Flickr

“When I wrote the following pages, or rather the bulk of them, I lived alone, in the woods, a mile from any neighbor, in a house which I had built myself, on the shore of Walden Pond, in Concord, Massachusetts, and earned my living by the labor of my hands only.” Those are the famous opening lines to Henry David Thoreau’s Walden. Now, scientists have used Thoreau’s notes on his surroundings to show how much earlier global warming has pushed plant flowering. Credit: Tim Hettler, via Flickr

Notes from the last 150 years made by two environmental pioneers have helped show that the speed at which global warming is pushing spring events forward is not slowing. Boston University’s Libby Ellwood and her teammates compared flowering times recorded by Henry David Thoreau and Aldo Leopold to spring 2010 and 2012, the warmest and second warmest on record.  “Plants flowered earlier than ever before in these recent record warm years,” Libby told me. That advance is so closely linked to the warming our world’s experiencing, the researchers showed that they can predict flowering time from temperature. This knowledge could help predict climate change’s impact on crops.

“There will likely be winners and losers with climate change,” Libby said. “It is quite possible that some species will be able to use the warmer temperatures and longer growing season to their advantage. The risk for plants that begin growing as soon as the weather is warm though, is that the new spring growth and flowers are susceptible to late season frosts, and this can set back plant growth and reproduction.”

To understand what global warming is doing to other organisms, scientists have to find records about them from times when fossil fuel burning wasn’t as widespread as today. Thoreau and Leopold are best known as authors of books that lay the foundations of modern environmentalism. Both Thoreau’s Walden and Leopold’s A Sand County Almanac, published in 1854 and 1949 respectively, hold powerful ideas on the relationship between humans and nature. But both authors also studied phenology – the cycle of biological events such as plant flowering throughout the year. Read the rest of this entry »

If you question the numbers, ask the plants

The 2012 Plant Hardiness Zone Map unveiled by the US Department of Agriculture this week shows average annual extreme minimum temperatures based on data from 1976-2005.This version is modified to use the same colour code as 1990. See the end of the entry for original image and link to USDA interactive map. Credit: US Department of Agriculture/Friend of the Earth

The 2012 Plant Hardiness Zone Map unveiled by the US Department of Agriculture this week shows average annual extreme minimum temperatures based on data from 1976-2005.This version is modified to use the same colour code as 1990. See the end of the entry for original image and link to USDA interactive map. Credit: US Department of Agriculture/Friend of the Earth

You may have heard of dandelion clocks, but have you ever thought of looking at plants to check the temperature? It may not give you a precise reading, but changes in where plants can live in the US and when they grow in China have clearly demonstrated global warming this month. They reinforce the recently reported worldwide average surface temperature for 2011, providing a real world example of the climate change shown in scientists’ graphs.

Much of the US was one 5°F (2.8°C) half-zone colder in the 1990 Plant Hardiness Zone Map compared to the latest version. Credit: US Department of Agriculture

Much of the US was one 5°F (2.8°C) half-zone colder in the 1990 Plant Hardiness Zone Map compared to the latest version. Credit: US Department of Agriculture

On Wednesday, the US Department of Agriculture (USDA) unveiled its latest map of planting zones, which has been redrawn to reflect warming seen since the last version was published in 1990. The Plant Hardiness Zone Map shows zones representing average annual extreme minimum temperatures. The old map was based on temperatures from 1974-1986, but updating it to include temperatures from 1976-2005 has shifted many zone boundaries. Though that’s in part due to new technology and better weather data, across much of the US the map is one 5°F (2.8°C) half-zone warmer.

And while the USDA says that the map is “not a good instrument” to assess climate change, David Wolfe, professor of plant and soil ecology in Cornell University’s Department of Horticulture says it’s being too cautious. “At a time when the ‘normal’ climate has become a moving target, this revision of the hardiness zone map gives us a clear picture of the ‘new normal,’ and will be an essential tool for gardeners, farmers, and natural resource managers as they begin to cope with rapid climate change,” he told Associated Press reporter Seth Borenstein. Read the rest of this entry »

Climate-driven species creep hangs in the balance

Studies of moss campions in North America have demonstrated that climate change may create tipping points in populations. Credit: Daniel Doak

Studies of moss campions in North America have demonstrated that climate change may create tipping points in populations. Credit: Daniel Doak

There is overwhelming evidence that many species have shifted the geographical ranges they live in over recent decades, with some actually becoming more widespread. However, adverse effects of climate change could still await these species, say University of Wyoming’s Daniel Doak and William Morris at Duke University in Durham, North Carolina.

Their research shows competing influences are holding the southern range limit of two Arctic and alpine plants in place, while warming forces the northern limit further north. However, their temperature-driven spread may ultimately prove short-lived, Doak warns. “Up to a point we may see little effect of warming for many organisms,” he says. “But past a climatic tipping point, the balance of opposing effects of warming will likely cease, leading to subsequent rapid declines in populations.” Read the rest of this entry »

Rapid climate change poses ecological questions

A male Liolaemus tenuis, an egg-laying lizard species broadly distributed in Central-Southern Chile. Many lizards are ectothermic, or cold-blooded, and those that live in the tropics have had their metabolic rates affected more by increased global temperatures since 1960 than those in colder regions. Credit: P. Victoriano

A male Liolaemus tenuis, an egg-laying lizard species broadly distributed in Central-Southern Chile. Many lizards are ectothermic, or cold-blooded, and those that live in the tropics have had their metabolic rates affected more by increased global temperatures since 1960 than those in colder regions. Credit: P. Victoriano

Although climate changes have happened throughout the Earth’s history, and species have either evolved to cope or perished, the rate of the current changes could now pose a particular problem. So says George Wang, a researcher at the Max Planck Institute for Developmental Biology in Tübingen, Germany, who has been studying global warming’s effects on ectotherms, better known as “cold-blooded creatures”.

“The most worrying aspect of recent climate change is its speed,” Wang told Simple Climate. “Climate changes in the past have generally been much slower than what we see in the last 50 years, so it’s unknown how natural populations will cope. For my field – physiological ecology – the most striking impact of climate change has been to expose just how little we know about how short to mid-term temperature variability will effect populations.” Read the rest of this entry »