Observations confirm that aerosols formed from plant emitted compounds
can make clouds brighter

Date:
September 24, 2021
Source:
University of Eastern Finland
Summary:
An observational study confirms a prevailing theory that volatile
organic compounds emitted by vegetation form atmospheric aerosols
which make clouds more reflective.



FULL STORY ==========================================================================
An observational study by Finnish research groups confirms a prevailing
theory that volatile organic compounds emitted by vegetation form
atmospheric aerosols which make clouds more reflective. Brighter clouds
reduce the amount of solar radiation reaching the Earth's surface, thereby cooling the surface. Emissions of organic compounds from vegetation
increase with increasing temperature, thus having the capability to slow
down climate warming.


========================================================================== Atmospheric aerosols scatter and absorb solar light, and influence the formation of clouds. However, these processes are not yet completely understood, which leads to significant uncertainties when estimating
the role of aerosols in climate change. In order to reliably estimate
the effect of humans on climate change, we need to be able to separate
the effects of natural and anthropogenic aerosols.

The study by Finnish researchers, published in Nature Communications,
estimated the impact of volatile organic compounds emitted by boreal
forests on aerosol concentration and cloud properties. The analysis
was based on aerosol observations at the Hyytia"la" SMEAR II station in
Finland and remote sensing observations of cloud properties over Southern Finland from NASA's spaceborne MODIS instrument. The observations showed
that biogenic aerosols formed from volatile organic compounds reduced
the amount of solar radiation reaching the Earth's surface by scattering
more radiation back to space. Furthermore, these aerosols increased the
amount of cloud droplets and made clouds more reflective. Both processes
become stronger as temperature increases, indicating that these natural aerosols can slow down the warming of climate. The magnitudes of the
radiative effects of these processes are similar and their combined effect
is significant when compared with the radiative effect of anthropogenic aerosols in the boreal region. Therefore, this natural mechanism needs
to be considered in more detail in climate model simulations.

The long-term and versatile observations from the SMEAR network and NASA's comprehensive satellite observations enable this kind of breakthrough
research.

========================================================================== Story Source: Materials provided by University_of_Eastern_Finland. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Yli-Juuti, T., Mielonen, T., Heikkinen, L., Arola, A., Ehn, M.,
Isoka"a"nta", S., Keskinen, H.-M., Kulmala, M., Laakso, A.,
Lipponen, A., Luoma, K., Mikkonen, S., Nieminen, T., Paasonen,
P., Peta"ja", T., Romakkaniemi, S., Tonttila, J., Kokkola, H.,
Virtanen, A. Significance of the organic aerosol driven climate
feedback in the boreal area. Nature Communications, 2021 DOI:
10.1038/s41467-021-25850-7 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/09/210924104251.htm

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