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Contrails warm the world more than aviation CO2 emissions
THIS WEEK
Contrails heat more than aircraft fuel Michael Marshall
Mario Aurich/airteamimages.com
THE innocuous white vapour trails that criss-cross the sky may not be as harmless as they look. In fact, they might have contributed more to global warming so far than all aircraft greenhouse gas emissions put together. High-altitude clouds like cirrus warm the planet by trapping heat. Contrail “cirrus” does the same thing, but the question is: how much? We know that contrails trap some extra energy in the atmosphere: their radiative forcing trapped 10 milliwatts per square metre (mW/m2) in 2005, according to an estimate by the Intergovernmental Panel on Climate Change (IPCC). That
16 | NewScientist | 2 April 2011
Nerves all fire together in Parkinson’s
Using satellite observations of spreading contrails as a guide, Burkhardt built a model that simulated how they form, spread out and dissipate. Then she embedded it in a global climate TOO much of a good thing can be bad model and watched what compares with 28 mW/m2 happened. She found that contrail for you. The synchronous firing of trapped by all of the carbon neurons is crucial for many ordinary cirrus ended up covering 0.6 per brain functions, but excessive, dioxide released by aircraft cent of Earth’s surface – an area engines since the start of aviation. nine times as great as that covered uncontrolled synchronisation might be behind the symptoms of by line contrails. However, the IPCC estimate Parkinson’s disease. Now a computer Burkhardt then used this only took into account the model has backed up the idea. figure to produce a more relatively fresh, visible vapour Parkinson’s disease has been linked accurate estimate of the total trails which exist for a few hours. to a lack of dopamine, a chemical energy trapped by contrails. After that they spread out and that, among other things, dampens Her calculations suggest a global become indistinguishable the transmission of signals across figure of 31 mW/m2 – higher than from normal cirrus, meaning nerve junctions called synapses. that attributable to aviation CO2 they might trap energy in the Measuring this effect in humans is atmosphere for many more hours. (Nature Climate Change, DOI: not currently possible, so Leonid 10.1038/nclimate1068). “Only a small part of the Rubchinsky and colleagues at Indiana As the first to build contrail problem has been studied,” says University-Purdue University cirrus into a climate model, Ulrike Burkhardt of the Institute Indianapolis turned instead to a Burkhardt’s study is “an for Atmospheric Physics in computer model of neural networks. important leap forward”, says Oberpfaffenhofen, Germany. As they boosted signal strength, With her colleague Bernd Kärcher, Olivier Boucher of the Met Office the network became more prone to Hadley Centre in Exeter, UK. she set out to discover how much switching from non-synchronised to There is a catch, though. heat contrail cirrus traps. synchronised firing. By comparing “[The measurement] says the pattern of neural signals recorded nothing about what will happen from people with Parkinson’s against tomorrow,” says David Lee those predicted by the model, the of Manchester Metropolitan University in the UK. While “The brains of people with a contrail lasts a day, the CO2 released from a plane lingers Parkinson’s readily switch in the atmosphere for hundreds between synchronised and of years. For example, while non-synchronised states” contrails – and their warming team found that in Parkinson’s, the potential – disappeared from brain readily switches between European skies last April when synchronised and non-synchronised an Icelandic volcanic ash cloud behaviour even when it is relaxed. grounded flights, atmospheric CO2 continued to warm the world. This might explain the disease’s motor symptoms. The flip side is that cutting A healthy brain fires synchronously contrails would make an in a brief and controlled way to immediate difference to coordinate motor behaviour and atmospheric warming, whereas perform tasks. The stronger emissions cuts take years to have connections in the brains of people an effect, says Robert Noland of with Parkinson’s mean that attempts Rutgers University in New to coordinate behaviour trigger Brunswick, New Jersey. sustained synchrony, which may make Planes could avoid creating it difficult to end a task or begin a contrails by flying at lower altitudes, he says, or steering clear new one (Physical Review E, in press). “This is a simple and elegant study,” of water-rich patches of air – although such measures could be says Peter Brown of the University of Oxford. “The model beautifully counterproductive if they make flying more inefficient and lead to captures the dynamic behaviour of the system.” Mark Buchanan n –It’s the way they spread out– a greater increase in CO2 levels. n
Contrails heat more than aircraft fuel Michael Marshall
Mario Aurich/airteamimages.com
THE innocuous white vapour trails that criss-cross the sky may not be as harmless as they look. In fact, they might have contributed more to global warming so far than all aircraft greenhouse gas emissions put together. High-altitude clouds like cirrus warm the planet by trapping heat. Contrail “cirrus” does the same thing, but the question is: how much? We know that contrails trap some extra energy in the atmosphere: their radiative forcing trapped 10 milliwatts per square metre (mW/m2) in 2005, according to an estimate by the Intergovernmental Panel on Climate Change (IPCC). That
16 | NewScientist | 2 April 2011
Nerves all fire together in Parkinson’s
Using satellite observations of spreading contrails as a guide, Burkhardt built a model that simulated how they form, spread out and dissipate. Then she embedded it in a global climate TOO much of a good thing can be bad model and watched what compares with 28 mW/m2 happened. She found that contrail for you. The synchronous firing of trapped by all of the carbon neurons is crucial for many ordinary cirrus ended up covering 0.6 per brain functions, but excessive, dioxide released by aircraft cent of Earth’s surface – an area engines since the start of aviation. nine times as great as that covered uncontrolled synchronisation might be behind the symptoms of by line contrails. However, the IPCC estimate Parkinson’s disease. Now a computer Burkhardt then used this only took into account the model has backed up the idea. figure to produce a more relatively fresh, visible vapour Parkinson’s disease has been linked accurate estimate of the total trails which exist for a few hours. to a lack of dopamine, a chemical energy trapped by contrails. After that they spread out and that, among other things, dampens Her calculations suggest a global become indistinguishable the transmission of signals across figure of 31 mW/m2 – higher than from normal cirrus, meaning nerve junctions called synapses. that attributable to aviation CO2 they might trap energy in the Measuring this effect in humans is atmosphere for many more hours. (Nature Climate Change, DOI: not currently possible, so Leonid 10.1038/nclimate1068). “Only a small part of the Rubchinsky and colleagues at Indiana As the first to build contrail problem has been studied,” says University-Purdue University cirrus into a climate model, Ulrike Burkhardt of the Institute Indianapolis turned instead to a Burkhardt’s study is “an for Atmospheric Physics in computer model of neural networks. important leap forward”, says Oberpfaffenhofen, Germany. As they boosted signal strength, With her colleague Bernd Kärcher, Olivier Boucher of the Met Office the network became more prone to Hadley Centre in Exeter, UK. she set out to discover how much switching from non-synchronised to There is a catch, though. heat contrail cirrus traps. synchronised firing. By comparing “[The measurement] says the pattern of neural signals recorded nothing about what will happen from people with Parkinson’s against tomorrow,” says David Lee those predicted by the model, the of Manchester Metropolitan University in the UK. While “The brains of people with a contrail lasts a day, the CO2 released from a plane lingers Parkinson’s readily switch in the atmosphere for hundreds between synchronised and of years. For example, while non-synchronised states” contrails – and their warming team found that in Parkinson’s, the potential – disappeared from brain readily switches between European skies last April when synchronised and non-synchronised an Icelandic volcanic ash cloud behaviour even when it is relaxed. grounded flights, atmospheric CO2 continued to warm the world. This might explain the disease’s motor symptoms. The flip side is that cutting A healthy brain fires synchronously contrails would make an in a brief and controlled way to immediate difference to coordinate motor behaviour and atmospheric warming, whereas perform tasks. The stronger emissions cuts take years to have connections in the brains of people an effect, says Robert Noland of with Parkinson’s mean that attempts Rutgers University in New to coordinate behaviour trigger Brunswick, New Jersey. sustained synchrony, which may make Planes could avoid creating it difficult to end a task or begin a contrails by flying at lower altitudes, he says, or steering clear new one (Physical Review E, in press). “This is a simple and elegant study,” of water-rich patches of air – although such measures could be says Peter Brown of the University of Oxford. “The model beautifully counterproductive if they make flying more inefficient and lead to captures the dynamic behaviour of the system.” Mark Buchanan n –It’s the way they spread out– a greater increase in CO2 levels. n