Contrails from aeroplanes warm the planet – here's how new low-soot fuels can help

A blue sky with a contrail line and wispy cirrus clouds. Contrails track the flight paths of aeroplanes, but can also spread out to form cirrus clouds. Daniel Albach/Shutterstock

While aviation accounts for 2.4% of all emissions from fossil fuel use globally, two-thirds of the sector’s warming effect depends on something other than its CO₂ emissions. And one of the most significant ways aviation contributes to global warming is through the clouds aeroplanes create in the upper atmosphere.

But, in a new study, researchers have shown that alternative fuels to the kerosene that aeroplanes typically burn can help.

At cruising altitudes where the atmosphere is cold and humid enough, contrails (short for condensation trails) form in the wake of aircraft. These are clouds made of ice crystals that are initially produced from the plane engine’s soot and water emissions – you’ll probably have seen them as white, puffy streaks in the sky on a clear day. When the atmosphere is especially cold and humid at high altitudes, these line-shaped contrails can last for many hours and spread to form vast webs of cirrus clouds, which look like white wisps of hair.

These clouds reflect the sun’s radiation back to space, cooling the atmosphere, but they can also trap infrared radiation reflected from the Earth. This process ultimately warms the atmosphere, as the warming effect exceeds the cooling. This is calculated to be aviation’s largest current warming effect – nearly double that from historic CO₂ emissions.

Reducing aviation’s climate impacts from contrails will depend on minimising soot particles from aeroplane exhausts. Aircraft exhaust plumes used to be smoky, as they contained a lot of soot. Modern engines are designed to reduce the heaviness of soot emissions, but the size and number of ice crystals that form depends on the large number soot of particles. There’s only so much more that can be achieved by cleaning aeroplane exhausts – future efforts must focus on the fuel itself.

Impurities such as napthalene, which are naturally present in aircraft fossil fuels like kerosene, are called aromatic compounds. These are carbon ring-shaped chemical structures that form the building blocks of soot particles. Biofuels made from crops and waste vegetable oils, and synthetic fuels made using renewable electricity, hydrogen and CO₂, are designed to reduce the carbon footprint of flying.

There are no aromatic impurities in these fuels, meaning fewer soot particles are generated when they’re burned. In the new study, the researchers found that they also generate fewer (but larger) ice crystals in the atmosphere during flight. This, in turn, makes the contrails and the cirrus clouds they form warm the Earth less.

The future of flying

Currently, aeroplanes can only fuel up with kerosene or kerosene-biofuel blends. The authors of the new paper found that blends of fuels with low aromatic impurities cut ice crystal formation by between 50 and 70%. In another paper, researchers predicted that would equate to a reduction in the overall warming effect of contrails by approximately 20%-50%. Flights are likely to be permitted to run on pure biofuels at some point in the future, so the potential reduction in the warming caused by aviation could be even greater.

The new study’s findings suggest that sustainable fuel blends offer a win-win situation for lowering aviation’s CO₂ output and its production of contrail cirrus clouds.

Other solutions, such as electric flight, are only likely to be possible for very short routes. Even hydrogen-fuelled aircraft may only be developed to manage medium distances. Both technologies will take more than a decade to mature before they can be introduced into the global aircraft fleet. Long-haul aviation is likely to depend on liquid kerosene-type fuels for the foreseeable future.

Another option is for pilots to avoid parts of the atmosphere where contrails are more likely to form. On a flight-by-flight basis though, navigating to avoid these regions would almost certainly increase the flight’s CO₂ emissions. Weather models also cannot predict the areas where contrails will form with enough accuracy.

Of course, the financial costs of developing and distributing biofuels and synthetic fuels at sufficient scale will probably be large, and may increase the costs of flying. In all likelihood, governments will need to mandate a phase-out of fossil-based kerosene and provide large incentives for airlines to switch. But time is running short to decarbonise flying, and this is an effective option that airlines can develop straight away to reduce the industry’s overall climate impact.

About The Author

David Simon Lee, Professor of atmospheric science, Aviation and Climate Research Group Leader, Manchester Metropolitan University

Related Books

Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming

by Paul Hawken and Tom Steyer
9780143130444In the face of widespread fear and apathy, an international coalition of researchers, professionals, and scientists have come together to offer a set of realistic and bold solutions to climate change. One hundred techniques and practices are described here—some are well known; some you may have never heard of. They range from clean energy to educating girls in lower-income countries to land use practices that pull carbon out of the air. The solutions exist, are economically viable, and communities throughout the world are currently enacting them with skill and determination. Available On Amazon

Designing Climate Solutions: A Policy Guide for Low-Carbon Energy

by Hal Harvey, Robbie Orvis, Jeffrey Rissman
1610919564With the effects of climate change already upon us, the need to cut global greenhouse gas emissions is nothing less than urgent. It’s a daunting challenge, but the technologies and strategies to meet it exist today. A small set of energy policies, designed and implemented well, can put us on the path to a low carbon future. Energy systems are large and complex, so energy policy must be focused and cost-effective. One-size-fits-all approaches simply won’t get the job done. Policymakers need a clear, comprehensive resource that outlines the energy policies that will have the biggest impact on our climate future, and describes how to design these policies well. Available On Amazon

This Changes Everything: Capitalism vs. The Climate

by Naomi Klein
1451697392In This Changes Everything Naomi Klein argues that climate change isn’t just another issue to be neatly filed between taxes and health care. It’s an alarm that calls us to fix an economic system that is already failing us in many ways. Klein meticulously builds the case for how massively reducing our greenhouse emissions is our best chance to simultaneously reduce gaping inequalities, re-imagine our broken democracies, and rebuild our gutted local economies. She exposes the ideological desperation of the climate-change deniers, the messianic delusions of the would-be geoengineers, and the tragic defeatism of too many mainstream green initiatives. And she demonstrates precisely why the market has not—and cannot—fix the climate crisis but will instead make things worse, with ever more extreme and ecologically damaging extraction methods, accompanied by rampant disaster capitalism. Available On Amazon

From The Publisher:
Purchases on Amazon go to defray the cost of bringing you InnerSelf.comelf.com, MightyNatural.com, and ClimateImpactNews.com at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.

 

This article originally appeared on The Conversation

YOU MAY ALSO LIKE

enafarzh-CNzh-TWdanltlfifrdeiwhihuiditjakomsnofaplptruesswsvthtrukurvi

follow InnerSelf on

facebook icontwitter iconyoutube iconinstagram iconpintrest iconrss icon

 Get The Latest By Email

Weekly Magazine Daily Inspiration

LATEST VIDEOS

The Great Climate Migration Has Begun
The Great Climate Migration Has Begun
by Super User
The climate crisis is forcing thousands around the world to flee as their homes become increasingly uninhabitable.
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
by Alan N Williams, et al
The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that without a substantial decrease…
Earth Has Stayed Habitable For Billions Of Years – Exactly How Lucky Did We Get?
Earth Has Stayed Habitable For Billions Of Years – Exactly How Lucky Did We Get?
by Toby Tyrrell
It took evolution 3 or 4 billion years to produce Homo sapiens. If the climate had completely failed just once in that…
How Mapping The Weather 12,000 Years Ago Can Help Predict Future Climate Change
How Mapping The Weather 12,000 Years Ago Can Help Predict Future Climate Change
by Brice Rea
The end of the last ice age, around 12,000 years ago, was characterised by a final cold phase called the Younger Dryas.…
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
by Frank Wesselingh and Matteo Lattuada
Imagine you are on the coast, looking out to sea. In front of you lies 100 metres of barren sand that looks like a…
Venus Was Once More Earth-like, But Climate Change Made It Uninhabitable
Venus Was Once More Earth-like, But Climate Change Made It Uninhabitable
by Richard Ernst
We can learn a lot about climate change from Venus, our sister planet. Venus currently has a surface temperature of…
Five Climate Disbeliefs: A Crash Course In Climate Misinformation
The Five Climate Disbeliefs: A Crash Course In Climate Misinformation
by John Cook
This video is a crash course in climate misinformation, summarizing the key arguments used to cast doubt on the reality…
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
by Julie Brigham-Grette and Steve Petsch
Every year, sea ice cover in the Arctic Ocean shrinks to a low point in mid-September. This year it measures just 1.44…

LATEST ARTICLES

bright light from under small building light terraced rice fields under starry sky
Hot nights mess up rice’s internal clock
by Matt Shipman-NC State
New research clarifies how hot nights are curbing crop yields for rice.
A polar bear on a large mound of ice and snow
Climate change threatens the Arctic’s Last Ice Area
by Hannah Hickey-U. Washington
Parts of an Arctic region called the Last Ice Area are already showing a decline in summer sea ice, researchers report.
corn cob and leaves on ground
To sequester carbon, leave crop leftovers to rot?
by Ida Eriksen-U. Copenhagen
Plant materials that lie to rot in soil makes good compost and play a key role in sequestering carbon, research finds.
image
Trees are dying of thirst in the Western drought – here’s what’s going on inside their veins
by Daniel Johnson, Assistant Professor of Tree Physiology and Forest Ecology, University of Georgia
Like humans, trees need water to survive on hot, dry days, and they can survive for only short times under extreme heat…
image
Climate explained: how the IPCC reaches scientific consensus on climate change
by Rebecca Harris, Senior Lecturer in Climatology, Director, Climate Futures Program, University of Tasmania
When we say there’s a scientific consensus that human-produced greenhouse gases are causing climate change, what does…
Climate heat is changing Earth’s water cycle
by Tim Radford
Humans have begun to alter Earth’s water cycle, and not in a good way: expect later monsoon rains and thirstier…
Climate change: as mountain regions warm, hydroelectric power plants may be vulnerable
Climate change: as mountain regions warm, hydroelectric power plants may be vulnerable
by Simon Cook, Senior Lecturer in Environmental Change, University of Dundee
Around 27 million cubic metres of rock and glacier ice collapsed from Ronti Peak in the northern Indian Himalayas on…
Nuclear legacy is a costly headache for the future
by Paul Brown
How do you safely store spent nuclear waste? No-one knows. It’ll be a costly headache for our descendants.

 Get The Latest By Email

Weekly Magazine Daily Inspiration

New Attitudes - New Possibilities

InnerSelf.comClimateImpactNews.com | InnerPower.net
MightyNatural.com | WholisticPolitics.com | InnerSelf Market
Copyright ©1985 - 2021 InnerSelf Publications. All Rights Reserved.