The Boreal–Arctic Wetland and Lake Dataset (BAWLD)
<p>Methane emissions from boreal and arctic wetlands, lakes, and rivers are expected to increase in response to warming and associated permafrost thaw. However, the lack of appropriate land cover datasets for scaling field-measured methane emissions to circumpolar scales has contributed to a l...
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| Autores principales: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Copernicus Publications
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/52b5da0f52cb481395efcc6ac1b6641a |
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| Sumario: | <p>Methane emissions from boreal and arctic wetlands, lakes, and rivers are
expected to increase in response to warming and associated permafrost thaw.
However, the lack of appropriate land cover datasets for scaling
field-measured methane emissions to circumpolar scales has contributed to a
large uncertainty for our understanding of present-day and future methane
emissions. Here we present the Boreal–Arctic Wetland and Lake Dataset
(BAWLD), a land cover dataset based on an expert assessment, extrapolated
using random forest modelling from available spatial datasets of climate,
topography, soils, permafrost conditions, vegetation, wetlands, and surface
water extents and dynamics. In BAWLD, we estimate the fractional coverage of
five wetland, seven lake, and three river classes within 0.5 <span class="inline-formula">×</span> 0.5<span class="inline-formula"><sup>∘</sup></span> grid cells that cover the northern boreal and tundra biomes
(17 % of the global land surface). Land cover classes were defined using
criteria that ensured distinct methane emissions among classes, as indicated
by a co-developed comprehensive dataset of methane flux observations. In
BAWLD, wetlands occupied 3.2 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>6</sup></span> km<span class="inline-formula"><sup>2</sup></span> (14 % of domain)
with a 95 % confidence interval between 2.8 and 3.8 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>6</sup></span> km<span class="inline-formula"><sup>2</sup></span>. Bog, fen, and permafrost bog were the most abundant wetland
classes, covering <span class="inline-formula">∼</span> 28 % each of the total wetland area,
while the highest-methane-emitting marsh and tundra wetland classes occupied
5 % and 12 %, respectively. Lakes, defined to include all lentic open-water
ecosystems regardless of size, covered 1.4 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>6</sup></span> km<span class="inline-formula"><sup>2</sup></span>
(6 % of domain). Low-methane-emitting large lakes (<span class="inline-formula">>10</span> km<span class="inline-formula"><sup>2</sup></span>) and glacial lakes jointly represented 78 % of the total lake
area, while high-emitting peatland and yedoma lakes covered 18 % and 4 %,
respectively. Small (<span class="inline-formula"><0.1</span> km<span class="inline-formula"><sup>2</sup></span>) glacial, peatland, and yedoma
lakes combined covered 17 % of the total lake area but contributed
disproportionally to the overall spatial uncertainty in lake area with a
95 % confidence interval between 0.15 and 0.38 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>6</sup></span> km<span class="inline-formula"><sup>2</sup></span>. Rivers and streams were estimated to cover 0.12 <span class="inline-formula">×</span> 10<span class="inline-formula"><sup>6</sup></span> km<span class="inline-formula"><sup>2</sup></span> (0.5 % of domain), of which 8 % was associated with
high-methane-emitting headwaters that drain organic-rich landscapes.
Distinct combinations of spatially co-occurring wetland and lake classes
were identified across the BAWLD domain, allowing for the mapping of
“wetscapes” that have characteristic methane emission magnitudes and
sensitivities to climate change at regional scales. With BAWLD, we provide a
dataset which avoids double-accounting of wetland, lake, and river extents
and which includes confidence intervals for each land cover class. As such,
BAWLD will be suitable for many hydrological and biogeochemical modelling
and upscaling efforts for the northern boreal and arctic region, in
particular those aimed at improving assessments of current and future
methane emissions. Data are freely available at
<a href="https://doi.org/10.18739/A2C824F9X">https://doi.org/10.18739/A2C824F9X</a> (Olefeldt et al., 2021).</p> |
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