Measuring greenhouse gas from ponds improves climate predictions

Date:
June 7, 2023
Source:
Cornell University
Summary:
Shallow lakes and ponds emit significant amounts of greenhouse
gases into the atmosphere, but emissions from these systems vary
considerably and are not well understood.


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FULL STORY ========================================================================== Shallow lakes and ponds emit significant amounts of greenhouse gases
into the atmosphere, but emissions from these systems vary considerably
and are not well understood.

Now, a new Cornell University-led study measures methane and carbon
dioxide emissions from 30 small lakes and ponds (one acre or less) in
temperate areas of Europe and North America, revealing that the smallest
and shallowest bodies of water exhibit the greatest variability over time.

The paper marks an important step toward calibrating climate models so
they better predict emissions from inland waterbodies, and it points to
the need to study small waterbodies more closely.

"This study helps understand both the drivers of greenhouse gas
concentrations, and importantly, what makes some ponds more variable
in their concentrations," said Meredith Holgerson, assistant professor
of ecology and evolutionary biology and senior author of the study,
published in the journal Limnology and Oceanography.

"The paper points to patterns across a broad geographic range, such
that we can actually get in and predict which waterbodies are going to
vary and will be most variable, and it confirms that we need to go out
and sample frequently," said Nicholas Ray, a postdoctoral researcher in Holgerson's lab and the paper's first author.

Holgerson and colleagues have previously estimated that shallow lakes
and ponds may contribute 5% of the global methane emissions to the
atmosphere. But without accurate measurements across many water bodies,
they said, the true number could be as little as half or as much as
twice that percentage.

While some small lakes and ponds emit greenhouse gasses in consistent, predictable amounts, others are highly variable. Understanding these
dynamics is important as carbon dioxide and methane act as greenhouse
gases in the atmosphere, with methane being 25 times more potent at
trapping heat than carbon dioxide.

Each body of water analyzed was sampled over the 2018 and 2019 summers
at three times in three locations, including the deepest point and then
two locations on opposite ends (but not too close to the shore).

"One key result we found was that the smaller the system is, in regard
to surface area, the higher emissions are likely to be," Ray said.

For carbon dioxide, samples were consistent in all parts of the
waterbody, which revealed that researchers likely only needed to
collect a sample from one location to get an accurate prediction of
the whole body of water. Methane, on the other hand, required samples
from multiple locations to get an accurate measure. Also, for methane, shallower systems were more variable, suggesting stratification of the
water column in deeper water may prevent gases from rising to the surface.

For carbon dioxide, the amount of plant life in the water played a large
role in variability over time. For methane, variability was more driven
by the water depth and likely associated with stratification in the
water column.

Among other uses, the study sets the groundwork for informing a New York
state climate mitigation strategy to build more ponds to help farmers
better handle droughts.

"We're working to identify how ponds can be built, or if there are simple management strategies people can employ, to minimize emissions," Ray said.

* RELATED_TOPICS
o Plants_&_Animals
# Ecology_Research # Nature # Drought # Mice
o Earth_&_Climate
# Global_Warming # Water # Climate # Environmental_Issues
* RELATED_TERMS
o Greenhouse_gas o Earth's_atmosphere
o Climate_change_mitigation o
Greenhouse_effect o Climate_engineering
o United_Nations_Framework_Convention_on_Climate_Change o
Methane o Wild_rice

========================================================================== Story Source: Materials provided by Cornell_University. Original written
by Krishna Ramanujan, courtesy of the Cornell Chronicle. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Nicholas E. Ray, Meredith A. Holgerson, Mikkel Rene Andersen,
Jānis
Bikse, Lauren E. Bortolotti, Martyn Futter, Ilga Kokorīte,
Alan Law, Cory McDonald, Jorrit P. Mesman, Mike Peacock, David
C. Richardson, Julien Arsenault, Sheel Bansal, Kaelin Cawley,
McKenzie Kuhn, Amir Reza Shahabinia, Facundo Smufer. Spatial
and temporal variability in summertime dissolved carbon dioxide
and methane in temperate ponds and shallow lakes. Limnology and
Oceanography, 2023; DOI: 10.1002/lno.12362 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/06/230607004112.htm

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