![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
. | ![]() |
. |
![]() by Karen Smith | University of Toronto Toronto, Canada (The Conversation) Feb 26, 2020
One of the earliest climate model predictions of how human-made climate change would affect our planet showed that the Arctic would warm about two to three times more than the global average. Forty years later, this "Arctic amplification" has been observed firsthand. Record-breaking Arctic warming and the dramatic decline of sea ice are having severe consequences on sensitive ecosystems in the region. But why has the Arctic warmed more than the tropics and the mid-latitudes? We now know that this is due, in part, to tiny concentrations of very powerful greenhouse gases - ozone-depleting substances such as chlorofluorocarbons (CFCs).
A wonder gas? These chemicals were invented in the 1920s. They were touted as "wonder gases" used as refrigerants, solvents and propellants, in refrigerators, air conditioners and packing materials. It wasn't until the 1980s when scientists discovered a hole in the ozone layer above Antarctica that they realized the full extent of the ozone-depleting nature of these chemicals. In 1987, 197 countries agreed to phase out their use of ozone-depleting substances by ratifying the Montreal Protocol. The success of this historic international agreement has reduced the emissions of CFCs to nearly zero; however, the recovery of the ozone hole has been slower as CFCs remain in the atmosphere for decades. Due to the effect of ozone-depleting substances on the ozone layer, climate scientists who study these chemicals and their climate impacts have been focused on the consequences of ozone depletion. The climate impact of ozone-depleting substances themselves has been typically considered small given the very tiny concentrations of these gases in the atmosphere, and has been largely unexplored.
Experimenting with climate models One way that climate scientists approach problems like this one is to use computer models of the Earth to understand what the effects of different phenomena, such as volcanic eruptions, and greenhouse gases, such as methane, might have on air temperatures, ocean circulation patterns, rainfall and so on. To explore the contribution of ozone-depleting substances to late-20th century warming, we ran a climate model over the period from 1955 to 2005. One of the simulations incorporated all of the various historical climate drivers - those that warm the climate, like carbon dioxide, methane, nitrous oxide and ozone-depleting substances, and those that cool the climate, like volcanic particulate matter. The second simulation had all the historical climate drivers, except the ozone-depleting substances. This is one of the first times the role of ozone-depleting substances had been isolated. Typically, climate model experiments that examine the roles of different climate drivers will lump all greenhouses gases together. Comparing the two model simulations revealed that global warming was reduced by one-third and Arctic warming by one-half when the ozone-depleting substances were not included in our simulation.
Arctic amplification Finally, when it comes to Arctic amplification, we know that this phenomenon arises from feedbacks within the climate system that act to enhance warming, and this is exactly what we find in our model simulations. In the simulation without ozone-depleting substances, the climate feedbacks were weaker than in the simulation with them, resulting in less Arctic amplification. Understanding why the feedbacks differ is the aim of our future research but, in the meantime, our work clearly demonstrates the significant impact of ozone-depleting substances on Arctic climate. Thirty years ago, those who signed the Montreal Protocol were not thinking about climate change. Yet, research such as ours underscores the important role this agreement will play in mitigating future warming as the concentrations of ozone-depleting substances decline over time. That said, without massive reductions in carbon dioxide emissions in the coming decades, the gains we will achieve through the Montreal Protocol will be quickly overwhelmed. Further action is needed to protect the Arctic - and our planet.
![]() ![]() Another reason to reduce man-made ozone: To cool a warming planet Bethlehem, PA (SPX) Jan 28, 2020 While elected officials in the U.S. debate a proposed "Green New Deal" and U.S. President Donald Trump derides "prophets of doom" in Davos, environmental scientists continue to gather evidence about how changes to industry could mitigate the harms of climate change. In a News and Views article in Nature Climate Change ("Cleaner Air is a Win-Win," 10.1038/s41558-019-0685-4) Lehigh University Professor of Earth and Environmental Science, Benjamin S. Felzer, highlights the importance of a new analysi ... read more
![]() |
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |