Weather extremes take twin crop and disease toll

Using MODIS data of red and infra-red emissions from the Earth's surface Assaf Anyamba and his colleagues can track conditions including temperature and levels of plant growth. In this shot the Normalized Difference Vegetation Index (NDVI) for southeast Australia from September to November 2010 shows that plants were thriving after a bout of extremely cool, wet weather. Image copyright: PLOSone, used via Creative Commons license, see reference below.

Using MODIS data of red and infra-red emissions from the Earth’s surface Assaf Anyamba and his colleagues can track conditions including temperature and levels of plant growth. In this shot the Normalized Difference Vegetation Index (NDVI) for southeast Australia from September to November 2010 shows that plants were thriving after a bout of extremely cool, wet weather. Image copyright: PLOSone, used via Creative Commons license, see reference below.

The wet and dry weather extremes the world felt between 2010 and 2012 caused wild variations in farm output and encouraged serious diseases spread by insects like mosquitoes. That’s according to scientists from NASA and the US Department of Agriculture (USDA) who studied severe droughts and rainfall that happened in six places during this period. Harvests in the four drought-stricken regions fell to as little as one-fifth of normal levels, but grew dramatically in the two rain-soaked areas, almost doubling in one case. But wet or dry, extreme conditions favoured certain species of mosquitoes (also known as vectors) that went on to cause outbreaks of illnesses like the potentially-fatal Rift Valley Fever. “Extreme weather events can have both negative and positive impacts,” observed NASA’s Assaf Anyamba. “For example eastern Australia and South Africa had bumper harvests of some crops but at the same time had outbreaks of vector-borne disease.”

Assaf and his coworkers help provide ways for the US government to closely monitor the whole world to see where droughts or wet periods might be happening. One way Assaf does this is with a pair of ‘eyes in the sky’ – NASA’s Terra and Aqua satellites. Each carries a Moderate Resolution Imaging Spectroradiometer, or MODIS, which precisely records the colours of the Earth’s atmosphere and surface, including those we can see and reaching far beyond. Scientists use the infra-red data it collects to track surface temperatures, while a combination of red and infra-red can tell them how leafy places are. From these, NASA makes this awesome ‘NDVI’ map of how well vegetated crop-growing regions across the world are, while the USDA includes them in monthly Rift Valley Fever risk reports.

While it’s important to know the impacts of extreme weather, not all countries are able to measure them. But from 2010 to 2012, the MODIS records captured the most intense set of weather they had recorded since Terra’s launch in 1999. The US, Russia, east Africa and southwest Australia endured droughts, and rain drenched South Africa and southeast Australia. Assaf and his team noticed that this weather was influencing both farming and disease in these cases, and decided to look at ‘the big picture’. “We wanted to showcase this connectedness as an example of the mixed bag of impacts anomalous weather conditions impose on society at large,” he explained. Read the rest of this entry »

The climate challenges that my morning toast poses

Britain's wheatfields could become even more productive as the world warms - but that will have implications for further greenhouse gas emissions and fairness to countries less well positioned. Image credit: Tim Gage used via Flickr Creative Commons license

Britain’s wheatfields could become even more productive as the world warms – but that will have implications for further greenhouse gas emissions and fairness to countries less well positioned. Image credit: Tim Gage used via Flickr Creative Commons license

It may seem that nothing could be simpler than toast, but next time I see a slice pop up I’ll also see an emblem of the world’s future. That’s thanks to a UK study exploring the problems surrounding growing enough wheat for flour and other foods as the world warms and has ever more people in it. The issue is especially tangled, Mirjam Röder and her University of Manchester teammates show, as adapting farming for the future will likely increase greenhouse gas emissions, driving further warming. “Climate change and food security are two issues which can’t be decoupled,” Mirjam told me. “The same applies for mitigation and adaptation.”

Mirjam is part of the “Climate change mitigation and adaptation in the UK food system” project, led by Alice Bows-Larkin and backed by Manchester’s Sustainable Consumption Institute. One concern the project reflects is that without adaptation farming will probably be the industry worst hit by climate change, with worldwide productivity falling as temperatures rise. Meanwhile, farming also releases about one-tenth of the greenhouse gases we humans emit overall. “These are largely emissions other than CO2, such as nitrous oxide and methane, mainly occurring from natural processes,” Mirjam said. “They are much harder to reduce and control. Then of course global society is challenged by increasing global food demand. So we face a triad of challenges in the food system: we need to reduce emissions, while food demand is increasing and the sector is impacted by climate change.”

Alice and Mirjam’s team looked at wheat because it makes up almost a third of all cereals grown in the world. “Global wheat demand is projected to increase by about 30% by 2050,” Mirjam. “If we don’t find methods to reduce them, total emissions from producing more wheat will rise.” As well as gases released directly by bacteria and other soil microorganisms, emissions from wheat farming arise from the energy needed to produce nitrogen fertiliser. Whether growing more wheat or dealing with rising temperatures, farmers will need more fertiliser, driving more emissions and therefore further warming. Read the rest of this entry »

Heat drives Pakistani migration

Shahdadpur, Sanghar district, Pakistan: Residents collecting their belongings on a higher ground outside village during floods. Though they may be displaced temporarily, Valerie Mueller from the International Food Policy Research Institute (IFPRI) in Washington DC and her team find high temperatures are more likely to drive permanent migration. Image credit: Oxfam International

Shahdadpur, Sanghar district, Pakistan: Residents collecting their belongings on a higher ground outside village during floods. Though they may be displaced temporarily, Valerie Mueller from the International Food Policy Research Institute (IFPRI) in Washington DC and her team find high temperatures are more likely to drive permanent migration. Image credit: Oxfam International

Excessive rainfall rarely drives Pakistanis to permanently leave their villages, even when it causes hardship like the flooding that hit around a fifth of the country in 2010. Yet they do consistently move in response to extreme temperatures, Valerie Mueller from the International Food Policy Research Institute (IFPRI) in Washington DC and her colleagues have found. She says the finding is a first stage in establishing if, how, and why people’s choices are affected by climate and climate change. “This is a useful step in order to be able to predict migration flows and inform local governments how might they better prepare in terms of the delivery of resources and investing in infrastructure given the occurrence of extreme weather events,” she told me.

There are few efforts collecting information about who has migrated and why over long periods of time, especially in areas where extreme weather occurs. But IFPRI has a long history of evaluating questions linked to food security in countries across the world, including Pakistan. From 1986-1991 its Pakistan Rural Household Survey questioned 800 households about how they lived and farmed, and it has tracked those households ever since. “Local collaborators found the original households in 2001 and 2012 and asked the head of household or an otherwise knowledgeable person what happened to each household member who resided with them in 1991,” Valerie said. “Our study is one of the first to quantify long-term migration patterns over a long period of time.”

The follow-ups recorded the long-term movements and fortunes of 4,428 people from 583 households. The researchers combined these answers with temperature and rainfall data in one ‘logit’ and one ‘multinomial logit’ model designed to let them measure the odds that people moved. “The first model allows us to answer: What are the odds of a person moving out of the household in response to extreme temperature or rainfall?” Valerie explained. “The second model allows us to distinguish moves by location and allows us to answer the following questions: What are the odds of a person moving out of the household but within the village in response to extreme temperature or rainfall? What are the odds of a person moving out of the household but out of the village in response to extreme temperature or rainfall?” Read the rest of this entry »

Fossil fuels are more than just a bad habit

The benefits fossil fuels bring make them probably the hardest addiction ever to kick. Credit: Don Hankins, via Flickr Creative Commons licence

The benefits fossil fuels bring make them probably the hardest addiction ever to kick. Credit: Don Hankins, via Flickr Creative Commons licence

I’m increasingly realising how much of a creature of habit I am. I have the same bizarre sticky brown yeast extract goo on toast for breakfast each morning. I watch films in my lounge most evenings. And I wonder: How much of my personality is just a collection of habits? What about yours, and all of ours? Could our whole society just be a giant collage of habits? And most relevant to this blog: how much of the human greenhouse gas emissions that are driving global warming come from our habits?

Recently, I’ve been keeping track of how long I spend doing things, which has been helping me swap what I think are bad habits for better ones. It’s tempting to suggest fighting climate change in a similar way. Many people talk about how we burn fossil fuels to propel our cars or run our gadgets as a bad habit, and even an addiction. But it’s more complicated than other addictions. Fossil fuels have been to our society more like food and a salary are to us individually – they’ve helped produce many of the healthiest aspects of the modern world. They’ve powered more than a century of rapid social and technological progress, and given many countries their current rich, well-fed figures.

For an article I’m writing about employment prospects in the UK’s chemical industry, I recently spotted the table below. It shows ‘gross value added’ (GVA), a measure of the money contributed to the economy, per person across the country’s different industries. It was striking to me that while bankers may get all the headlines for their wealth, the energy industry has the greatest earning power per head in the UK.

Oil and gas extraction help the "Mining and Quarry; Energy & water" sector make the largest contribution per head to the UK economy, as they employ relatively few people relative to their large economic output . Credit: Office for National Statistics

Oil and gas extraction help the “Mining and Quarry; Energy & water” sector make the largest contribution per head to the UK economy, as they employ relatively few people relative to their large economic output. The ‘total’ figure is the overall GVA for the UK, averaged across all industries. Credit: Office for National Statistics

Much like I’d quickly struggle without food or money, today sharply taking fossil fuel energy away from our societies would immediately threaten our existence. In fact, some think even the small changes already happening taste bad. Again in the UK chemical industry, there are worries that higher costs from clean energy are making it less competitive with other countries. Part of the way it would like to avoid this issue is through unconventional natural gas supplies, presumably extracted through controversial ‘fracking’ methods. Read the rest of this entry »

Continuing the fight for CO2 monitoring

  • This is part two of a two-part post. Read part one here.
Dave Keeling had to balance his work measuring CO2's rise in the air and tracking its movements through the Earth's systems with fighting to get the money to fund his work. Credit: Scripps Institution of Oceanography

Dave Keeling had to balance his work measuring CO2′s rise in the air and tracking its movements through the Earth’s systems with fighting to get the money to fund his work. Credit: Scripps Institution of Oceanography

By 1963, having directly measured a steady increase in CO2 levels over five years, Dave Keeling felt he had clearly shown the value of such non-stop monitoring. But that message hadn’t reached government decision makers. And so Dave swung into the first battle in the war to continue tracking the key greenhouse gas that has flared up repeatedly in the following decades.

Thanks to four new instruments called spectrophotometers, Dave had been able to use the same molecular movements that allow CO2 to absorb heat to measure it. Though his most famous site was at Mauna Loa in Hawaii, one was also installed in Antarctica. Another sailed on a ship and the final one stayed at Dave’s lab at Scripps Institution of Oceanography analysing samples collected in vacuum-filled five litre flasks from aircraft and elsewhere. Thanks to funds from 1957-1958’s International Geophysical Year a team of scientists was busy collecting a “snapshot” of CO2 data that Dave’s boss at Scripps, Roger Revelle, wanted.

So in 1961, Dave moved his family to Sweden for a year to work out exactly what the measurements were showing. He took a fellowship at the Meteorological Institute, University of Stockholm working with its new director Bert Bolin, who had earlier worked on the first computerised weather forecast. With measurements ongoing, annual ‘breathing’ cycles of rising and falling CO2 and the increasing trend underlying them became ever clearer.

Together, Dave and Bert found CO2 concentrations were going up by 0.06 ppm per month on average. Bert also undertook a series of complex calculations by hand to work out CO2 movement and cycles in its levels. In doing so he was showing how oceans, plants on land, and human fossil fuel burning contributed to the patterns that would later need computer models for fuller analysis. This, Dave felt, clearly showed why non-stop CO2 monitoring was needed rather than just snapshots. But by 1963 the shipboard spectrophotometer had come home, and Dave had also called back the one in Antarctica. And with funding cuts biting at the Weather Bureau, now part of the National Oceanic and Atmospheric Administration (NOAA), the staff at Mauna Loa fell from eight to three. And soon afterwards, a problem with Dave’s equipment proved too much for the overstretched team to fix.

“Suddenly there were no precise measurements being made of atmospheric CO2 anywhere,” he recalled. “I had seen the budget cut coming early in 1963 and had tried to prevent its terminating the CO2 program at Mauna Loa Observatory. I even went to Washington to plead for supplemental funding. This had no tangible effect, however, until the cessation of measurements actually occurred. The National Science Foundation (NSF) then found funds to pay for an additional technician at Mauna Loa. I learned a lesson that environmental time-series programs have no particular priority in the funding world, even if their main value lies in maintaining long-term continuity of measurements.” Read the rest of this entry »

Climate change can make us more violent

Civil wars, like the one in Somalia that destroyed this tank, could become more common as the world warms. Image taken by Charles Roffey, used via Flickr CreativeCommons license.

Civil wars, like the one in Somalia that destroyed this tank, could become more common as the world warms. Image taken by Charles Roffey, used via Flickr CreativeCommons license.

US economists have drawn together 45 sets of evidence spanning 10,000 years to show that warmer temperatures and more extreme rainfall can cause greater human conflict. University of California, Berkeley’s Ted Miguel says this “could have critical implications for understanding the impact of future climate change on human societies”.

“Many global climate models project global temperature increases of at least 2°C over the next half century,” Ted told me. “Our findings suggest that global temperature rise of 2°C could increase the rate of intergroup conflicts, such as civil wars, by over 50% in many parts of the world, especially in tropical regions where such conflicts are most common.”

Scientists have long puzzled over whether data backs climate as a cause of violent events such as the fall of the Roman empire. Global warming has brought an ‘explosion’ of interest from researchers, from archaeologists to psychologists, in climate-linked violence. And the types of conflict vary from fights between two people to civil wars and collapse of whole civilisations. But some studies see political, economic and geographical factors as more important than climate.

How researchers assess their data in these studies could introduce problems. For example, it can often be argued that ‘correlation does not imply causation’, meaning that links between two data sets might be caused by other factors. For example, reading ability might seem to improve as shoe size does, but one doesn’t cause the other – getting older causes both. To find any real, bizarre, link between shoe size and reading ability, you would need to look at people with the same age – or ‘control for’ age.

So Ted and his Berkeley teammates only brought together data that could be used to find causal links, although not all the original studies they started from had done this. Bringing together data from many different studies, collected all over the world, considering different types of violence, gives their findings stronger backing than each lone study. They called on records collected in many places that had taken measurements repeatedly in each place, and analysed them from scratch to reach their own conclusions. Read the rest of this entry »

Speeding poor countries’ progress could halve farming emission growth

Improving agricultural productivity - particularly without increasing fertiliser use - could help cut greenhouse gas emissions from agriculture. Credit: IIASA

Improving agricultural productivity – particularly without increasing fertiliser use – could help cut greenhouse gas emissions from agriculture. Credit: IIASA

If the world’s poorer countries progress faster towards farming like richer ones the improved food availability could help fight climate change. That’s according to Austrian and Australian scientists who say that they have looked at climate change’s links to both animal and crop farming in the most depth yet.

Hugo Valin from the International Institute for Applied Systems Analysis (IIASA) in Laxenburg, Austria, and his colleagues studied cutting the gaps between farming output in rich and poor countries. They say halving this ‘yield gap’ for crops, and reducing it by a quarter for animals, could halve the increase in worldwide greenhouse gas emissions from farming between 2000 and 2050. But they have also found that improved farming methods could raise how much food people eat, meaning that emission reductions aren’t as much as they would be otherwise.

“The widespread idea is that intensifying crop farming is beneficial to the environment because it spares land,” Hugo told me. “We show that it is more complex than this. Intensification also stimulates consumption because it allows farmers to supply more food at affordable prices.”

Farming produces about a third of all ‘man-made’ greenhouse gas emissions, though a lot of them are actually from farm animals’ belches and farts and manure. The rest come from chemical reactions of fertiliser used on crops in soil, and also gases released from soil, plants and trees when forests are converted into farmland. Four-fifths of these emissions happen in developing countries. The world’s population is set to grow from around 7 billion people today to between 8.3 and 10.9 billion by 2050. We need more food for those extra people, which will add to the greenhouse gases farming puts into the air each year. Read the rest of this entry »

Extra climate targets urge faster CO2 cuts

University of Bern's Marco Steinacher has helped show that setting limits on different aspects of damage from climate change will likely limit CO2 emissions more than just temperature alone. Credit: University of Bern

University of Bern’s Marco Steinacher has helped show that setting limits on different aspects of damage from climate change will likely limit CO2 emissions more than just temperature alone. Credit: University of Bern

To give the world a chance of restricting damage caused by climate change, we need more than just a single temperature target, Swiss researchers have found. Marco Steinacher and his teammates at the University of Bern worked out the chances that climate change can be kept within harmful limits in six different areas. “Considering multiple targets reduces the allowable carbon emissions compared to temperature targets alone, and thus CO2 emissions have to be reduced more quickly and strongly,” Marco told me.

In December 2009, world leaders agreed the non-binding Copenhagen Accord, which ‘recognises’ that scientists think world temperature increases beyond 2°C above the pre-industrial average from 1850-1899 would be dangerous. It also mentions sea level rise, protecting ecosystems and food production. And as climate talks have continued since the 1990s, specific new dangers of CO2 emissions have been found. One serious impact that has been realised in the last decade comes from the fact that oceans absorb CO2 from the air, which makes the seas more acidic. That can make it harder for sea creatures’ shells to form, and together with warmer seas can damage coral, and in turn reduce fish numbers available for food. “Traditional climate targets have not addressed this effect,” Marco said.

It might seem reasonable to assume that negotiating climate deals on temperature limits alone could protect against other dangers. But until recently only very simple ‘Earth system’ models were available to test this against the idea of having several targets. They couldn’t simulate regional effects on quantities such as ocean acidification or farming productions, Marco said. “Climate targets that aim at limiting such regional changes can only be investigated with a model that has a certain amount of complexity,” he explained. Read the rest of this entry »

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.”

Read the rest of this entry »

The well-qualified amateur who threw the spotlight back on CO2

Guy Callendar in 1934, about the time he turned his attention to the CO2-climate question

Guy Callendar in 1934, about the time he turned his attention to the CO2-climate question

In April 1938, a brave outsider stood up and showed a room full of sceptical experts evidence that would drive a revolution in climate science. Guy Callendar had pulled together temperature data from many parts of the world that clearly revealed global warming for the first time. Though few in the audience believed that humans could influence a planet-spanning system like climate, that’s just what Guy told them we were doing, by producing CO2.

But when better-known audience members at the Royal Meteorological Society meeting in London challenged his results, Guy fought back with a lifetime of scientific experience. He had followed in the footsteps of his father, physicist Hugh Callendar, making science the ‘family business’. But in 1938 the major part of that business so far for Guy – fully exploring the properties of steam – was nearing an end. And though climate science remained largely a hobby for him, Guy’s contributions are fundamental to our understanding of the global warming that is still ongoing today.

Guy was born in Montreal, Canada, in 1898 when his father, a pioneer in X-ray and steam physics, was a professor at McGill University. Hugh, his wife, and their three children returned to their native UK before Guy was one, when Hugh took up a position at University College, London. He then moved on to Imperial College London, where he chaired the physics department from 1908-1929. Beyond X-rays and steam, Hugh invented equipment to accurately measure and record air temperatures, wind speeds, and the Sun’s radiation. Perhaps it was these tools that inspired Guy to collect weather data, which he called his ‘figs.’, through much of his life. He took measurements so accurate that at one point they were used to form the official temperature records for central England.

In 1905, Hugh’s professorial salary and inventions bought a four story, 22-room house in Ealing. Life wasn’t entirely idyllic however, as by then Guy had been accidentally blinded in one eye with a pin by his brother Leslie. Further danger followed partly from Hugh’s encouragement of his children’s interest in science. He converted a greenhouse in Ealing into a laboratory, only for Leslie to destroy it while trying to make TNT. With his partial blindness preventing him from fighting in the First World War, Guy left school in 1915 to join his father’s laboratory. He performed X-ray tests, such as looking for cracks and other faults in aircraft engines, introducing him to the science of energy carried in waves. Read the rest of this entry »

Follow

Get every new post delivered to your Inbox.

Join 160 other followers