https://youtu.be/LYdvn2pGyOw Jason Box has been doing some good explainers in recent months, focusing recently on some of the most important indicators of the record El Nino cycle we are living. Above, one suggested cause of current high Atlantic Sea Surface Temps is of some unintended consequences, actually an example of inadvertent geo-engineering.Science: The Atlantic Ocean…
Covid-19 Cut Gases That Warm the Globe But a Drop in Other Pollution Boosted Regional Temperatures
A new study shows how tiny aerosol particles from industrial emissions have an outsized cooling effect.
February 15, 2021
Two Iranian men wearing protective face masks walk along the Azadi (Freedom) Square in western Tehran during a spike in air pollution following the Covid-19 outbreak in Iran, on January 12, 2021. Credit: Morteza Nikoubazl/NurPhoto via Getty Images
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Efforts to slow the Covid-19 pandemic early last year by restricting travel and various forms of commerce pushed greenhouse gas emissions down, at least for a few months. But that didn’t slow global warming, as 2020 tied with 2016 as Earth’s warmest year on record and atmospheric greenhouse gases reached a new high.
February 1, 2021 at 12:00 pm
Among the biggest questions for climate change forecasters is how atmospheric aerosols shape clouds, which can help cool the planet. Now, a new study finds that one promising strategy for understanding how aerosols and clouds interact can overestimate the cooling ability of pollution-generated clouds by up to 200 percent, researchers report in the Jan. 29
Science.
“Clouds in general, and how aerosols interact with the climate, are a big uncertainty in climate models,” says Franziska Glassmeier, an atmospheric scientist at Delft University of Technology in the Netherlands. Scientists know that aerosols — both natural, as from volcanoes, and human-caused, as from pollution — can change a cloud’s thickness, ability to scatter sunlight or how much rainfall it produces. But these complicated physical effects are difficult to simulate, so scientists have sought real-world examples to study these effects.
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IMAGE: Clouds cool the climate system by reflecting incident sunlight. The reflection of sunlight and cooling is stronger in the presence of pollution particles. Pollution also
affects the development of clouds: While... view more
Credit: Glassmeier et al
The impact of atmospheric aerosols on clouds and climate may be different than previously thought. That is the conclusion of cloud researcher Franziska Glassmeier from TU Delft. The results of her study will be published in
Science on Friday, January 29th.
Clouds
Cloud decks cover vast stretches of the subtropical oceans. They cool our planet because they reflect incoming sunlight back to space. Air pollution in the form of aerosols -- particles suspended in the atmosphere -- can increase this cooling effect because it makes clouds brighter. The cooling effect of pollution offsets part of the warming effect of greenhouse gases. How much exactly, is one of the largest uncertainties faced by climate scientists.
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The way exhaust-aerosol particles from ships spur cloud development in "ship tracks" that trail these vessels, and which reflect radiant energy back to space, has been used to understand the effects of atmospheric aerosol particles on cloud reflectivity more broadly. But, according to a new study, ship track-derived data cannot be generalized to estimate anthropogenic aerosols' role in climatological forcing, say the authors; it overstates anthropogenic aerosols' cooling effect. The findings highlight an important bias in current aerosol-cloud forcing estimations as they're currently used to project climate change. By reflecting incoming solar radiation back into space, stratocumulus clouds cool the planet and play an important role in mediating Earth's atmospheric temperatures. Effects of atmospheric aerosol particles on cloud formation and their overall reflectivity represents a major source of uncertainty in understanding and forecasting human impacts on the climate system. Data from studies involving the long, linear stratocumulus clouds formed by the rising exhaust from ships - ship tracks - have been used to estimate the radiative impact of anthropogenic aerosols. Here, Franziska Glassmeier and colleagues argue that this approach cannot be used to estimate the cooling effect of anthropogenic aerosols in the atmosphere. By comparing detailed numerical simulations with satellite analysis, Glassmeier et al. show how data derived from ship-track studies - particularly the effect of aerosols on non-precipitating stratocumulus clouds - leads to an overestimation of their cooling effect by up to 200%. According to the authors, the warming effect of decreasing stratocumulus clouds must be accounted for to constrain anthropogenic aerosol's role in cloud-mediated radiative forcing. Based on their results, they write, "it seems desirable to identify alternatives to ship-track studies that allow for a direct observation of aerosol effects."