Dump fossil fuels for the health of our hearts

Air quality in London on April 3, 2014 fell to a level where it became hard to see normally-visible skyscrapers. Conditions hit a 9/10 risk ranking  thanks to a combination of pollution and dust blown in from the Sahara desert. Tackling such pollution could immediately improve people's health, stresses New York University's George Thurston. Image copyright David Holt, used via Flickr Creative Commons license.

Air quality in London on April 3, 2014 fell to a level where it became hard to see normally-visible skyscrapers. Conditions hit a 9/10 risk ranking thanks to a combination of pollution and dust blown in from the Sahara desert. Tackling such pollution could immediately improve people’s health, stresses New York University’s George Thurston. Image copyright David Holt, used via Flickr Creative Commons license.

Sometimes when I blow my nose and – inevitably – look into my handkerchief, I see that my snot is black. It doesn’t happen when I’m at home, in the small English city of Exeter, only when I’m in London. It’s a clear sign of the extra pollution I’m inhaling when I’m in the capital – one backed up by data published last week by Public Health England. Its striking report says that in 2010 73 deaths per thousand in the London borough of Waltham Forest, where my girlfriend’s sister lives, could be put down to grimy air. For Exeter, the figure was just 42 per 1000. Across the whole of England, pollution killed 25,002 people in 2010, or 56 of every 1000 deaths nationwide.

But wherever you live, air pollution will become even more important as the climate changes, while fighting this scourge could also help the world bring global warming under control. “There’s more than enough rationale for controlling emissions based on the health effects and the benefits that we get as a society from getting off of fossil fuels,” New York University’s George Thurston told me. “Those are the benefits that are going to accrue to the people who do the clean-up – locally and immediately, not fifty years from now.”

Public Health England is trying to draw attention to ‘particulate matter’, or dust, less than 2.5 micrometres in diameter, too small to see with our naked eye. You won’t find this ‘PM2.5’ pollution listed as people’s cause of death – it’s likely to be down as a heart attack or lung cancer. George has run huge studies in the US to help work out exactly how much such dust worsens people’s health. One study for the American Cancer Society followed 1.2 million men and women originally enrolled in 1982. Another, started in 1995, tracked over 500,000 US retirees over the following decade. And he was also a part of a worldwide project that last year showed ‘global particulate matter pollution is a major avoidable risk to the health of humankind’. Read the rest of this entry »

Detailed regional data reduce warming-drought link doubts

Sergio Vicente-Serrano and his team have shown that warming is driving more severe and widespread droughts on the Iberian Peninsula, even in this river plain landscape near Aguilar de Campoo in northern Spain Image Credit: tracX via Flickr Creative Commons license

Sergio Vicente-Serrano and his team have shown that warming is driving more severe and widespread droughts on the Iberian Peninsula, even in this river plain landscape near Aguilar de Campoo in northern Spain Image copyright: tracX, used via Flickr Creative Commons license

Spanish and Portuguese researchers have produced some of the strongest evidence yet that warming climate is making droughts more severe. Sergio Vicente-Serrano from the Pyrenean Institute of Ecology (IPE) in Zaragoza and his colleagues have used detailed data from their countries to overcome uncertainties seen in worldwide studies. They have shown that a local warming of 1.5°C from 1961-2011, and 2.1°C in summer months, and rainfall that has decreased by around a sixth increased drought severity in the region. “Future scenarios in the Iberian Peninsula and southern Europe indicate an increase of temperature even more than 3°C for the 21st century,” Sergio told me. “If we have already observed an important decrease of water resources, you can imagine that in the future water resources in these regions will be at higher risk.”

Air holds and ‘demands’ more water as it gets warmer, which is a fundamental reason for why we might expect both worse droughts and heavier rainfall with climate change. Scientists have already used real-world measurements to look at global changes in drought severity. However, they have disagreed on whether things really have got worse in recent years or not. Sergio stressed that such worldwide research faces important limitations. He emphasised that evapotranspiration – the water released by Earth’s surface and by plants breathing – is important in drought studies. But it has to be worked out from a combination of direct measurements, and the records needed are patchy in areas like Africa or South America.

“I’m very critical of the conclusions of these kinds of global studies, not about the methodology, but the input data,” Sergio said. “The problem is the use of highly uncertain variables. There are problems with precipitation data sets in terms of density of observations. The problems for precipitation are much higher for variables that are necessary to estimate the water demand of the atmosphere. Estimating these kinds of variables with confidence is really difficult. Also, there’s no validation in terms of impact on crop production, stream flows, reservoirs, soil moisture, this information is not available. That’s really the approach that must be followed to determine if drought is increasing in severity and impact.” Read the rest of this entry »

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 »

Climate sensitivity wrangles don’t change the big picture on emissions

The sources of data that scientists can use to determine climate sensitivity include ice cores, the cylinders these researchers are holding at the Vostok station in Antarctica. Image credit: Todd Sowers, Columbia University

The sources of data that scientists can use to determine climate sensitivity include ice cores, the cylinders these researchers are holding at the Vostok station in Antarctica. Image credit: Todd Sowers, Columbia University

How much does the world warm up in response to a certain amount of greenhouse gases like CO2 in the atmosphere? It’s a simple question, but its answer depends on whether you mean short-term or long-term warming, and estimates vary according to the methods used. Scientists are currently intensively debating long-term ‘climate sensitivity’, which begs prompts the question: might we be pushing too hard to cut climate CO2 emissions, if this is uncertain?

The answer is no, according to Joeri Rogelj from the Swiss Federal Institute of Technology, ETH Zurich, and his coworkers. They looked at how a range of climate sensitivity values affected their 21st century warming projections in a paper published in Environmental Research Letters last week. “When taking into account all available evidence, the big picture doesn’t change,” Joeri told me. The ‘carbon budget’ of greenhouse gases we could still emit today and in the future is very limited whatever the climate sensitivity, he explained. “Keeping the so-called carbon budget in line with warming below 2°C still requires a decarbonisation of  global society over the first half of this century.”

Climate sensitivity is the measure of how much the world will eventually warm when it reaches equilibrium after a doubling of CO2 in the air. Today, we have upset the normal equilibrium where the Sun’s energy flowing into the atmosphere matches the flow the Earth radiates back out of it. Now more is coming in than leaving, and that’s heating the planet up. Think of the atmosphere as a series of pipes, with energy flowing through them like a liquid. The Earth is a reservoir in the system, filled by an incoming pipe and drained by an outgoing one. CO2 acts like a blockage in the outgoing pipe – it slows the outward energy flow and causes a build-up in the reservoir. When the reservoir gets fuller it can put enough pressure on the blockage for the outward flow through it to again match the incoming flow. Then we’d be at equilibrium, but with a fuller reservoir – a warmer planet. The more CO2 we emit, the worse the blockage gets and the hotter we get before reaching equilibrium. Read the rest of this entry »

Fairness instinct trumps economic expectations on climate costs

ETH Zurich's Robert Gampfer hopes governments can learn from the climate negotiation games he ran. Image credit: ETH Zurich

ETH Zurich’s Robert Gampfer hopes governments can learn from the climate negotiation games he ran. Image credit: ETH Zurich

We care about fairness in sharing climate change costs, although differences in who’s more vulnerable to it can affect our ideas of what exactly is fair. That’s the clear suggestion emerging from a set of climate change negotiation games run by Robert Gampfer from the Swiss Federal Institute of Technology, ETH Zurich. In his experiments, students from Zurich universities took on the role of countries in climate talks trying to agree how costs should be shared. Robert feels this unusual approach provides unique insights into our true attitudes, and could help guide our leaders in responding to them.

“Proposals that are perceived as very unfair are likely to meet public resistance, and governments will therefore be unlikely to agree to them in the international negotiations,” he told me. “But the experiment also showed that participants who were richer or more responsible for climate change often acted rather fairly, even if this meant higher costs for them. This is quite a far-reaching conclusion, but maybe governments of developed countries could actually sell costly climate agreements to their citizens if they perceive some fairness obligation to accept them.”

This study builds on a realisation Robert made when looking into possible topics for his climate politics PhD, which he’s now writing the final thesis for. “A lot of surveys on climate change and climate policies ask only very broad questions – whether you would support your country reducing its emissions or not, for example,” he observed. “But we know very little about how specific aspects of global climate politics influence people’s opinion, for example the debate on burden-sharing fairness. In a standard survey it is easy to be in favour of emission reductions, because stating this does not cost you anything. Real emission reductions probably would have some cost, for example through higher energy prices.”

In seeking deeper insights, Robert realised that political science and economic experiments hadn’t addressed fairness much either. “This might be because many think people’s fairness preferences are not important for an international climate agreement,” he said. “I find this quite surprising: in the negotiations, governments use fairness arguments very often. And they probably do this, among other reasons, because they will receive domestic support from their citizens for adopting such negotiating positions.” Read the rest of this entry »

Real-world grounding could cool 21st century outlook

The world's surface air temperature change ("anomaly"), relative to the world's mean temperature of 58° F or 14.5° C, averaged over land and oceans from 1975 to 2008. Inset are two periods of no warming or cooling within this overall warming trend. Copyright 2009 American Geophysical Union. Reproduced/modified by permission of American Geophysical Union.

The world’s surface air temperature change (“anomaly”), relative to the world’s mean temperature of 58° F or 14.5° C, averaged over land and oceans from 1975 to 2008. Inset are two periods of no warming or cooling within this overall warming trend. Copyright 2009 American Geophysical Union. Reproduced/modified by permission of Wiley/American Geophysical Union, see citation below.

Starting climate models from measured data helps simulate the early-2000s global warming hiatus better, and reduces projections for warming through to 2035. Jerry Meehl and Haiyan Teng have compared such ‘initialised’ model runs against more common ‘uninitialised’ ones starting without real-life conditions. The scientists, from the US National Centre for Atmospheric Research (NCAR) in Boulder, Colorado, find initialised runs get closer to modelling that hiatus and surprisingly rapid warming in the 1970s. Using the same approach, admittedly rough 30-year predictions for Earth’s surface air temperature initialised in 2006 are about one-sixth less than uninitialised projections. “We have evidence that if we would have had this methodology in the 1990s, we could have predicted the early-2000s hiatus,” Jerry told me.

The hiatus Jerry and Haiyan studied – an easing off in the rate of global warming since 1998 – is perhaps the aspect of climate change most hotly debated today. But hiatus is a slippery word, whose meaning depends on who is highlighting what points on which graph. Climate skeptics will often infer that it’s evidence that global warming is not a problem, or that it shows we know too little to act on climate change. The UN Intergovernmental Panel on Climate Change puts it in plain numbers: the rate of warming from 1998-2012 was 0.05°C per decade; from 1951 to 2012, it was 0.12°C per decade. “In addition to robust multi-decadal warming, global mean surface temperature exhibits substantial decadal and interannual variability,” it adds.  “Due to natural variability, trends based on short records are very sensitive to the beginning and end dates and do not in general reflect long-term climate trends.”

In a paper published online in the journal Geophysical Research Letters last week, Jerry and Haiyan touch on the current best explanations of the let-up. These include the chilling effect of recent volcano eruptions, but mostly focus on cooling in the Pacific as part of a natural cycle. Called the Interdecadal Pacific Oscillation (IPO), this regular wobble in sea surface temperatures has likely partly masked greenhouse-gas driven warming. The IPO has also been linked to a larger warming than might have been expected from greenhouse gases alone in the 1970s, the NCAR researchers add. 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 »

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