Pollen production could impact climate change by helping clouds form


Date:
May 8, 2023
Source:
American Chemical Society
Summary:
For millions of people with seasonal allergies, springtime means
runny noses, excessive sneezes and itchy eyes. And, as with many
things, climate change appears to be making allergy season even
worse.

Researchers have now shown that common allergen-producing plants
ryegrass and ragweed emit more smaller, 'subpollen particles'
(SPPs) than once thought, yet climate would likely be most affected
by their intact pollen grains, which can boost cloud formation.


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FULL STORY ==========================================================================
For millions of people with seasonal allergies, springtime means runny
noses, excessive sneezes and itchy eyes. And, as with many things, climate change appears to be making allergy season even worse. Researchers
reporting in ACS Earth and Space Chemistry have shown that common allergen-producing plants ryegrass and ragweed emit more smaller,
"subpollen particles" (SPPs) than once thought, yet climate would likely
be most affected by their intact pollen grains, which can boost cloud formation.

In addition to annoying sinuses, pollen naturally functions as a way
for plants to exchange genetic material and reproduce. When exposed to moisture, these pollen grains can burst into tiny SPPs less than a micron
long. Their smaller size allows them to reach the lower respiratory
system, where they can last longer and cause more inflammation than
their larger counterparts. Both SPPs and whole pollen grains are also
thought to act as ice nucleation sites - - miniature starting points for clouds. But compared to regular clouds, SPPs and pollen form smaller,
more numerous clouds that tend to hold onto their precipitation, helping
trap in radiant heat and contributing to climate change.

In turn, higher temperatures can extend pollen-release periods, further exacerbating the problem. Previously, Brianna Matthews, Alyssa Alsante
and Sarah Brooks studied how oak trees emit SPPs at different humidity
levels. But this time, the team wanted to investigate how two other common allergen- producing plants, ragweed and ryegrass, release SPPs under humid conditions, and how those particles could affect ice cloud formation.

The researchers collected samples of ryegrass and ragweed, then placed
them into a specialized "pollen chamber." There, the samples were exposed
to different humidity levels and bursts of wind over several hours to
simulate real-world conditions.

The group assessed the number of SPPs per pollen grain, as well as the abilities of both to nucleate ice. Surprisingly, the team found that
previous experiments on the same types of plants underestimated the
amount of SPPs by a factor of 10 to 100. This was likely because the
other experiments used a less realistic means of spreading the pollen and generating the SPPs, say the researchers. Ragweed and ryegrass SPPs were
very poor ice-nucleating sites, however -- barely better than plain water
-- while whole pollen grains facilitated cloud growth. The researchers
say that these updated parameters and numbers of emitted pollen grains and particles could ultimately be used to create more-accurate climate models.

* RELATED_TOPICS
o Plants_&_Animals
# Endangered_Plants # Nature # Agriculture_and_Food #
Endangered_Animals
o Earth_&_Climate
# Climate # Global_Warming # Environmental_Awareness
# Ice_Ages
* RELATED_TERMS
o Hypoallergenic o Allergen o
Paleoclimatology o Global_climate_model o
Global_warming_controversy o Kyoto_Protocol o
Consensus_of_scientists_regarding_global_warming o
Temperature_record_of_the_past_1000_years

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


========================================================================== Journal Reference:
1. Brianna H. Matthews, Alyssa N. Alsante, Sarah D. Brooks. Pollen
Emissions
of Subpollen Particles and Ice Nucleating Particles. ACS Earth
and Space Chemistry, 2023; DOI: 10.1021/acsearthspacechem.3c00014 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/05/230508150934.htm

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