Physical and biogeochemical impacts of RCP8.5 scenario in the Peru upwelling system
<p>The northern Humboldt Current system (NHCS or Peru upwelling system) sustains the world's largest small pelagic fishery. While a nearshore surface cooling has been observed off southern Peru in recent decades, there is still considerable debate on the impact of climate change on the re...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-07-01
|
| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/17/3317/2020/bg-17-3317-2020.pdf |
| Summary: | <p>The northern Humboldt Current system (NHCS or Peru upwelling system)
sustains the world's largest small pelagic fishery. While a nearshore
surface cooling has been observed off southern Peru in recent decades, there
is still considerable debate on the impact of climate change on the regional
ecosystem. This calls for more accurate regional climate projections of the
21st century, using adapted tools such as regional eddy-resolving
coupled biophysical models. In this study three coarse-grid Earth system
models (ESMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5) are
selected based on their biogeochemical biases upstream of the NHCS, and
simulations for the RCP8.5 climate scenario are dynamically downscaled at
<span class="inline-formula">∼12</span> km resolution in the NHCS. The impact of regional climate
change on temperature, coastal upwelling, nutrient content, deoxygenation,
and the planktonic ecosystem is documented. We find that the downscaling
approach allows us to correct major physical and biogeochemical biases of the
ESMs. All regional simulations display a surface warming regardless of the
coastal upwelling trends. Contrasted evolutions of the NHCS oxygen minimum
zone and enhanced stratification of phytoplankton are found in the coastal
region. Whereas trends of downscaled physical parameters are consistent with
ESM trends, downscaled biogeochemical trends differ markedly. These results
suggest that more realism of the ESM circulation, nutrient, and dissolved
oxygen fields is needed in the eastern equatorial Pacific to gain robustness
in the projection of regional trends in the NHCS.</p> |
|---|---|
| ISSN: | 1726-4170 1726-4189 |