Northwest Wetlands and Climate Change

ESSENTIAL TO BOTH human and natural systems, mountain wetlands are expected to be highly sensitive to climate change. Yet despite their importance and vulnerability, mountain wetlands tend to be understudied. Now, a new research approach from the University of Washington is offering solutions.

The approach, published last month in the journal PLOS ONE, is a new computer modeling technique that allows researchers to develop site-specific hydrologic models for mountain wetlands. The technique is intended to help researchers and resource managers overcome some of the difficulty of studying hard-to-access mountain wetlands by partially substituting computer simulation for in-the-field measurements. The technique will assess how individual sites will fare under climate change. Here’s how it works:

The study’s researchers collected in-the-field data—water depth and size—from 121 mountain wetlands across five Northwest national parks and wilderness areas including North Cascades, Mt. Rainier, Olympic National Parks, and the Willamette and Deschutes National Forests. The researchers then classified the wetlands into four types based on how often they remained wet: ephemeral (0-3 percent), intermediate (3-33 percent), perennial (33-70 percent), and permanent (70-100 percent).

The collected data was then fed into the Variable Infiltration Capacity (VIC) Macroscale Hydrologic Model, which modeled the local hydrologic behavior of the wetlands. This allowed the researchers to establish a baseline by hindcasting historic water levels for their sites for the years 1916-2010. From this the researchers looked at what factors at individual sites were the best predictors of water level. This then informed a larger regression model that was used to forecast climate changes for the middle and end of this century.

Not surprisingly, the researchers found consistent impacts of climate change on all classes of wetlands, with ephemeral and intermediate wetlands showing the most sensitivity to climate change. Some ephemeral wetlands may, essentially, disappear and more than half of intermediate mountain wetlands are projected to become ephemeral by the 2080s according to the researchers.

The wetlands’ vulnerability to climate change is due to that fact that they are dependent on factors related directly to climate, namely precipitation, snowpack, and evaporation. Reduced snowpack, higher evaporation, and extended summer droughts result in more and quicker drying and lower water levels.

A project of the University of Washington’s Climate Impacts Group, this multi-year effort leading up to the PLOS ONE paper began in 2011. It has received funding from two CIRC partners: the Northwest Climate Science Center (NW CSC) and the North Pacific Landscape Conservation Cooperative (NP LCC). The project is expected to aid conservation biologists studying the effects of climate change on mountain frogs and other amphibians as well as researchers interested in mountain wetlands’ role in watersheds. The project was reviewed in detail in Northwest Climate Magazine, a joint publication of CIRC, NW CSC, and NP LCC.


Study: PLOS ONE

Citation: Lee S-Y, Ryan ME, Hamlet AF, Palen WJ, Lawler JJ, et al. (2015) Projecting the Hydrologic Impacts of Climate Change on Montane Wetlands. PLOS ONE 10(9): e0136385. doi: 10.1371/journal.pone.0136385

High and Dry: Northwest Mountain Amphibians and their Changing Wetlands,” Northwest Climate Magazine, Issue 1, May 2015. 

Photo: Researchers conduct fieldwork in mountain wetlands south of Mt. Rainier. (Photo Credit: Maurreen Ryan, University of Washington).


Nathan Gilles is the managing editor of The Climate Circulator, and oversees CIRC’s social media accounts and website. When he’s not writing for CIRC, Nathan works as a freelance science writer. 

 


 

 

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