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 »

Renewable energy beats ‘clean coal’ on cost in Australia

A part of the extension of the Snowtown Wind Farm in South Australia that added 90 new 3 megawatt turbines. In South Australia wind farms contribute 27% of annual electricity, notes University of New South Wales' Mark Diesendorf. Photo by David Clarke, used via Flickr Creative Commons license.

A part of the extension of the Snowtown Wind Farm in South Australia that added 90 new 3 megawatt turbines. In South Australia wind farms contribute 27% of annual electricity, notes University of New South Wales’ Mark Diesendorf. Photo by David Clarke, used via Flickr Creative Commons license.

It’s unlikely that fossil fuel power stations that capture and store their CO2 emissions could supply eastern Australia’s electricity more cheaply than renewable energy technologies like solar and wind power. That’s according to a study based on hour-by-hour analysis of electricity demand by Ben Elliston, Iain MacGill and Mark Diesendorf from the University of New South Wales in Sydney. Although renewables are often seen as expensive, these findings highlight that they can be competitive after accounting for the impact of burning coal and gas on our climate. “Our studies, and those conducted by other research groups around the world, find that it is possible to operate reliable national and subnational electricity systems on predominantly renewable energy generated by commercially available technologies and that these systems are affordable,” Mark told me.

Ben is a PhD student, supervised by Iain and Mark, and together the three have sought to answer key questions about renewable energy. Is it possible to supply a whole electricity grid’s needs with these technologies, or are some ‘base-load’ coal or gas power stations needed to fall back on? And if it is possible, would it be affordable?

To answer these questions, Ben designed a computer programme to simulate running an electricity supply system. His program can go through a year’s hourly data on electricity demands, wind and sunshine over the region in a fraction of a second. “Everything else follows from this, provided of course one asks the right questions,” Mark noted.

Over the last two years they have published work exploiting that programme, first showing that it’s possible to reliably supply 100% of eastern Australia’s electricity using renewable energy. Wind and solar power supplied most of the electricity, but output from these technologies varies due to changes in weather. But rather than filling gaps with fossil fuels, they showed existing hydroelectric power stations and gas turbines burning biofuels could be used to meet the grid’s reliability standard. Read the rest of this entry »

Could pollution be stopping warming’s impact on rain?

A brown cloud of pollution over Phoenix, Arizona. Brown clouds of aerosol pollutant particles could be overwhelming the expected changes in rainfall arising from increasing greenhouse gas levels in the air. Credit: Flick/Flickr

A brown cloud of pollution over Phoenix, Arizona. Brown clouds of aerosol pollutant particles could be overwhelming the expected changes in rainfall arising from increasing greenhouse gas levels in the air. Credit: Flick/Flickr

Contrary to previous predictions and measurements, rain patterns have got more uniform as the world has warmed over the past 70 years. So say Michael Roderick and his teammates from Australian National University, Canberra, who’ve developed an ‘accounting system’ that looks closely at where and when rain fell. And the reason could be aerosols – clouds of pollutant particles – produced by humans. “The existing dogma is that increasing greenhouse gas concentrations in the atmosphere have raised rainfall variability,” Michael told me. “In that context, our results emphasise the importance of taking a whole system approach in trying to understand how something complex, like rainfall, is changing in different places.”

When scientists want to understand how climate has been changing over large areas, they usually look at maps of long-term average data that ignore patterns of change in time, Michael explained. When they want to look at how it’s changed over time, they usually either look at a single place or a worldwide average, which ignores patterns in where the changes are. But Michael, along with fellow scientists Fubao Sun and Graham Farquhar, wanted to find a way to link place and time.

To do this Fubao started from a common statistical test called Analysis of Variance or ANOVA. Normally it’s used to compare the effect of different “treatments” – such as a variety of temperatures – on the yield of a crop, for example. In such cases each treatment must be repeated more than once, giving different “replicates”, for the test to be valid. ANOVA can be used to give a value for variance – a measure that shows how spread out an experiment’s measurements are. Read the rest of this entry »

Climate cycles drive civil wars

A child in a rebel camp in the north-eastern Central African Republic, one of the countries where internal conflict has been shown to be twice as likely to occur during a year when the El Niño weather pattern occurs than in La Niña years. Credit: Pierre Holtz/UNICEF CAR/Flickr

A child in a rebel camp in the north-eastern Central African Republic, one of the countries where internal conflict has been shown to be twice as likely to occur during a year when the El Niño weather pattern occurs than in La Niña years. Credit: Pierre Holtz/UNICEF CAR/Flickr

Civil war is much more likely during the warmer phase of a global climate cycle, seemingly as political tensions get literally overheated. That’s according to researchers from Columbia University, New York, who say that conflicts within a single country are twice as likely to occur during warmer El Niño years as cooler La Niña years. This is the first indication that modern societies’ stability relates strongly to climate, though the scientists warn that their findings might not be applicable to human-caused climate change. However some of the more dramatic changes in climate and society during humanity’s history have successfully been tied together. Columbia’s Mark Cane says his team’s latest findings build on those results. “What it shows beyond any doubt is that even in this modern world, climate variations have an impact on the number of civil conflicts,” Cane said Tuesday. “It’s frankly difficult to see why that won’t carry over to a world that is disrupted by global warming.”

Previous studies on whether modern climate has influenced war found only weak links between temperature over long periods, while studies on year-to-year local changes have disagreed and been criticised for having too narrow a focus. Consequently, together with Solomon Hsiang and Kyle Meng, Cane turned to the El Niño-Southern Oscillation, or ENSO, that affects weather patterns where half the world’s people live. El Niño originates from around 1°C warming in the tropical Pacific every three to seven years, bringing hotter, drier weather to the tropics. That alternates with cooler La Niña phases that provide more tropical rain, but can dry out more northern areas, as in East Africa and the southwest US this year. Consequently, the Columbia scientists were working with changes between two states on a worldwide scale that happened relatively regularly. This comes close to the “ideal but impossible” experiment of studying two Earths with different climates, they write in top science journal Nature. Read the rest of this entry »

Vikings’ Greenland demise tells climate tale

Braya Sø, one of the two lakes in Greenland William D'Andrea and colleagues took sediment from to reconstruct 5,600 years of climate history. Credit: Credit: William D'Andrea/Brown University

Braya Sø, one of the two lakes in Greenland William D’Andrea and colleagues took sediment from to reconstruct 5,600 years of climate history. Credit: Credit: William D’Andrea/Brown University

Known as a scourge of Europe through the middle ages, the mighty Vikings disappeared from their Greenland settlements in the face of abruptly changing temperatures. In doing so, they followed the example of the Saqqaq people, whose Greenland existence also ceased in a period of rapid climate change. Climate is probably only one of many factors that led to these upheavals, warns William D’Andrea of University of Massachusetts, Amherst, one of the researchers who has made this link. However, studying past climate changes should help us better anticipate how climate may change in the future.

“Climate is a major factor that influences societies and cultures,” D’Andrea told Simple Climate, “but there are other factors that are social in origin and involve the way that cultures adapt. There have been very large changes in Earth’s climate system both over the last 10,000 and 100,000 years. Now, the globe as a whole is getting warmer and it’s because of greenhouse gases in the atmosphere in very large part. But what we really want to know is how will the places that we’re living in change. We can’t begin to do that unless we understand how the climate system has responded to changes in the past.”

It was the search for that in-depth climate knowledge that originally drove D’Andrea and his colleagues from Brown University, in Providence, Rhode Island, University of Nebraska, Lincoln, and Loughborough University, UK, to Greenland. “The goal of the paleoclimate community is to generate climate records from all over the world,” he explained. “No single site is going to be able to inform us about the climate system. We had identified western Greenland as a site that was interesting to work in because there weren’t many records from there.” Read the rest of this entry »

But, how do we know this is right?

While many reporters cover climate issues - like this one taking notes during a demonstration for the enforcement of Kyoto Protocol - some of them only confuse the issue. Credit: ItzaFineDay

While many reporters cover climate issues - like this one taking notes during a demonstration for the enforcement of Kyoto Protocol - some of them only confuse the issue. Credit: ItzaFineDay

Be careful – the people you trust may be leading you astray. Are they worthy of your faith in them? Does what they say really represent reality?

These may sound like strange ramblings, but if we all answered truthfully we might better understand the major causes of the current debate on climate change. Everyone in the world depends on their own set of sources of information. We share many of them, like television programs and newspapers, with others. We also have some sources that others don’t, like our friends, or maybe an obscure little website. But, as Australian psychologist Ben Newell and climate change researcher Andrew Pitman warned earlier this month, we often don’t realise when these sources are biased. Read the rest of this entry »

Emitting CO2 puts seas in double trouble

Ove Hoegh-Guldberg, director of the Global Change Institute at the University of Queensland Credit: Ove Hoegh-Guldberg, Global Change Institute, University of Queensland

Ove Hoegh-Guldberg, director of the Global Change Institute at the University of Queensland Credit: Ove Hoegh-Guldberg, Global Change Institute, University of Queensland

Humanity relies heavily on the ocean and its inhabitants, who man in turn is putting at risk by changing the climate. That’s according to Ove Hoegh-Guldberg, director of the Global Change Institute at the University of Queensland, who points out that global warming and ocean acidification pose “serious threats to life in the ocean”. “Both of those are having profound effects on the biology of the ocean and on the ocean services which are important to human well-being,” he told Simple Climate.

In fact, some of these effects have happened so fast that Hoegh-Guldberg has seen them unfold during the course of his career. For example, corals are normally highly coloured, but have been turning white and dying as they lose the microorganisms that inhabit them and provide them with energy and food. “When I started my PhD in the early 1980s, mass coral bleaching events were just beginning to occur across tropical regions,” he explained. “We now know that those are being driven by warmer than normal sea temperatures and that they are slowly removing coral dominated communities from tropical reefs, at the rate of 1-2% per year. Given that this is the most biologically diverse ecosystem on the planet, I think that these rates are striking.”

Read the rest of this entry »

Saturday round-up: Southwest Western Australia suffering unrivalled drought?

Tas van Ommen collecting an ice core at Law Dome in Antarctica Credit: Joel Pedro

Tas van Ommen collecting an ice core at Law Dome in Antarctica Credit: Joel Pedro

Australian researchers say that snowfall records in Antarctica show that the current drought south of Perth is unlikely to have been matched in 750 years, and possibly even longer. To reach this conclusion, Tas van Ommen and Vin Morgan used measurements of cylindrical samples of ice drilled from the Law Dome. This small icecap on the coast of East Antarctica is south of the south-west Western Australia (SWWA) region that has been affected by a 15-20% decline in winter rainfall since 1970. It’s hard to understand the drought’s full historical significance, due to the relatively small amount of direct rainfall information, say van Ommen and Morgan in a Nature Geoscience paper published online last Sunday. “Local records commence only around the start of the twentieth century,” they write.

Analysing ice core information to give weather patterns showed that declining rainfall in SWWA corresponded with increasing snowfall at the Law Dome. There is also a clear link between smaller changes in rain and snow at the two locations, the Australian Antarctic Division and Antarctic Climate and Ecosystems Cooperative Research Centre scientists say. So, the ice core data can tell us how unusual the SWWA weather is. The increase in snowfall at the Law Dome during the period of the drought is the largest in 750 years, van Ommen and Morgan find. They calculate that if environmental conditions had stayed the same, such a change in rain and snowfall should happen just once in at least 5,400 years. “The recent post-1970 anomaly in Law Dome precipitation lies outside the envelope of natural variability and supports the hypothesis of [man-made climate change],” the scientists write.

Meanwhile, amid controversy about how fast glaciers are receding elsewhere, another Nature Geoscience paper, published in the February issue, gives an improved estimate of the status of glaciers in Alaska. The collaboration of scientists from France, the USA and Canada suggests they are melting more slowly than previously thought, contributing around a third less to sea level rises than previously estimated. They say that thinning in other glacial regions could have been been overestimated by a similar amount.

The team’s calculations are based on the height of the glaciers, comparing data from 1962 maps with satellite maps from 2006. They say that using satellite data, rather than manual surveys as other groups have, gives them a more detailed picture of the situation. It also shows that if glaciers are covered with debris, they melt more slowly, as they are insulated from the warmth of the atmosphere. This is a factor overlooked by previous studies, they write. Their estimates suggest that between 1962 and 2006, Alaskan glaciers lost around 42 cubic kilometres of water per year, which raised sea levels by around 0.12 mm per year.