The current measures used by the United Nations in the aviation industry’s goal to reach net zero CO2 emissions by 2050 do not account for the total climate impact of emissions from aircraft, new research shows.
A more comprehensive analysis shows that, even if the aviation industry succeeds in its most ambitious plans for CO2 cuts, current efforts will only limit the sector’s contribution to global warming and not eliminate it, say researchers.
With the help of efficiency improvements, new types of fuel and technological advances, the United Nations International Civil Aviation Organization (ICAO) currently expects to reach the goal of net zero CO2 emissions by 2050.
However, researchers have shown that it isn’t only CO2 that causes air traffic to affect the climate.
Aircraft can also be the cause of emissions of water vapor and small particles in the air that affect both clouds and solar radiation, which also contribute to global warming.
The new study from researchers at the Center for International Climate Research (CICERO) in Norway and Manchester Metropolitan University in the UK – published in the prestigious scientific journal One Earth – has used a new model to measure the impact of aviation on the climate, which accounts for nitrogen oxides (NOx), sulfur dioxide (SO2), water vapor and soot as well as CO2.
David Lee, Professor of Atmospheric Science at Manchester Metropolitan University, said: “International aviation has high ambitions to cut CO2 emissions. But even if the plans succeed, our study shows that air traffic will still lead to increased global warming towards 2070.
“Even with alternative fuels such as hydrogen and biofuels, some CO2 emissions from production will remain and direct emissions of CO2 are not eliminated quickly enough.”
The new study examines the effect of contrails, which are the long, white trails that can be seen in the sky caused by aircraft exhausts.
Researchers explain how particles and water vapor from contrails form clouds, which affect solar radiation and contribute to global warming, effectively acting like a blanket that warms the globe.
Borgar Aamaas, Senior Researcher at CICERO, said: “Our research shows that we need more knowledge about the effect of emissions that are not CO2. This will be crucial for creating effective emission measures.
“Achieving truly climate-friendly air traffic requires not only the phasing out of fossil fuels, but that all types of emissions are taken into account when determining future climate measures.”
Global temperatures have increased by just over one degree since pre-industrial times, with 4% of the causes coming from aviation.
In 2042, airlines are expected to transport 19.5 billion passengers, twice as many as 2024. Despite this strong growth, the ICAO has set ambitious goals to cut CO2.
Through the scenarios proposed in the new study, researchers say that continued growth will see aviation’s share of future global warming become even greater.
Professor Lee said: “At the heart of this issue is growth, driven by demand. Flying is the most carbon intensive activity an individual can undertake– one return flight to New York from London results in an additional 12% of an average UK individual’s CO2 emissions.”
Bethan Owen, Professor of Aviation and Environment at Manchester Metropolitan University, added: “Our study shows that it is critical to phase out the fossil fuel used in the sector as fast as possible and find alternative fuel and technology solutions.”
