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The Climate CIRCulator is brought to you by The Pacific Northwest Climate Impacts Research Consortium (CIRC)
and The Oregon Climate Change Research Institute (OCCRI).
In this Issue:
Featured Researcher: Dr. Shaun Marcott
The Impact of Beetle-Induced Tree Mortality on
Water Quality
Featured Researcher
Reconstructing 11,300 Years of Temperature Data
to Study Warming
Dr. Shaun Marcott is a postdoctoral scholar
in the College of Earth, Ocean, and
Atmospheric Sciences at Oregon State
University. His research interests span a
broad range of geological and climatological
questions that primarily encompass the past
100,000 years. Specifically, his expertise is
in the fields of glacial geology and
paleoclimatology with a firm rooting in
geological and geochemical techniques. Dr.
Marcott works with a number of paleoclimate
archives including glacial deposits, marine
sediment cores, and ice cores, as well as
with statistical models. His work is primarily
focused on understanding the interplay
between climate and glaciers of the past,
and is useful in placing modern climateglacier interactions into a historical context
for understanding future changes. National Climate Assessment Northwest Regional
Town Hall
The Effect of Climate Sensitivity on Ocean
Acidification
Evidence of Increasing Frequency of Intense
Precipitation in the Olympic Peninsula
The Rain-Shadow Effect in the Washington
Cascades
The Impact of BeetleInduced Tree Mortality on
RSS
Water Quality
Large scale tree die-offs, such as those
caused by Mountain Pine Beetle (MPB)
infestations, can alter physical, hydrological,
and biogeochemical processes in the
affected watersheds. For instance, large dieoffs may enhance the leaching of natural
organic matter into ground and surface
waters. In turn, the increased concentration
of certain organic compounds in water being
treated for human consumption can lead to
an increase in the formation of harmful
disinfection by-products (DBPs) (these byproducts form as a result of reactions
between the chlorine used as a disinfectant
and several naturally occurring organic
compounds). This study examined waterquality data sets for eight years (2004–2011)
from a number of water treatment facilities in
Colorado for perturbations due to tree
mortality. MPB-impacted watersheds
exhibited higher overall DBP concentrations
and altered timing of peak DBP
concentrations as compared to the controls.
These results suggest that forest mortality
due to MPB infestation induces unique
changes to the forest carbon cycle. In
particular, these results suggest that the
relative abundance of the organic
compounds involved in the formation of
harmful DPBs is being altered in these
systems.
Mikkelson, K.M., E.R.V. Dickenson, R.M. Maxwell,
J.E McCray, and J.O. Sharp. 2013. Water-quality
impacts from climate-induced forest die-off. Nature
Climate Change Vol. 3, 218-222. doi:
10.1038/nclimate1724.
Photo Credit: Wikimedia Commons, Forest Beetle
Kill
Reconstructing 11,300
Years of Temperature Data
to Study Warming
Marcott et al. reconstructed a dataset of
surface temperature anomalies using 73
distributed temperature records that were
derived largely from marine archives.
Previous reconstructions of the past
millennium relied mostly on land-based
records. This study provides a broader
perspective of temperature over the last
11,300 years. The authors compared their
findings with the observational temperature
record. The last 1,500–200 years before
present of the 11,300-year temperature
reconstruction are indistinguishable from
previous studies. The coolest temperatures
of this period were found 200 years ago, in a
period also known as the Little Ice Age.
Global climate model projections show that
global temperature is likely to exceed the full
distribution of warmth presented in this paper
by the year 2100.
Marcott, S.A., J.D. Shakun, P.U. Clark, and A.C.
Mix. 2013. A Reconstruction of Regional and Global
Temperature for the Past 11,300 Years. Science Vol.
339 (6124), 1198-1201. doi:
10.1126/science.1228026.
Photo Credit: Creative Commons, flickr.com/photos
NCA Northwest Regional
Town Hall
The National Climate Assessment (NCA)
Northwest Regional Town Hall took place
March 12, 2013 at Portland State University.
This one-day meeting brought together over
100 climate change experts and users of
climate change information to learn about
the NCA process and how to use and
contribute to the Third NCA Report (to be
released in 2014). Participants were from
academia, government agencies, non-profit
organizations, private sectors, and the
general public. After presentations on draft
findings from the report, current climate
activities in the region, and a panel session
on building assessment capacity, participants
broke into small groups for discussion based
on different sectors such as water resources,
forestry, and society’s response to climate
change. Each group discussed and identified
concrete actions that are (or could be) taking
place on the regional, sectoral, and national
levels; what data, information, and chapters
of the NCA were most relevant and
interesting; and what was missing and
should be included in the subsequent reports
through the sustained assessment process.
In addition, the groups discussed what
capacities already exist and are still needed,
and how to develop them in the future. You
can view and download individual
presentations from the town hall here.
Photo Credit: Mount Rainier from Tipsoo Lake,
Dudley Chelton
The Effect of Climate
Sensitivity on Ocean
Acidification
As the oceans absorb rising amounts of CO2
from the atmosphere, they are becoming
more acidic and consequently may become
less hospitable to some organisms. Through
the use of numerical modeling, this study
examines the response of the ocean to
various degrees of global warming (the
“climate sensitivity;” a higher climate
sensitivity leads to greater warming for the
same amount of CO2). The climate
sensitivity impacts the ocean’s response by
affecting upper-ocean stratification, and
because CO2 is less soluble in warmer
water. The authors found that increased
climate sensitivity caused unexpected
responses in the ocean. For instance, they
found whole-ocean acidification is smallest
when warming is greatest, due to a spatial
decoupling in acidification between the
surface mixed layer and subsurface layers.
These findings highlight the need for a better
understanding of the biological effects of
ocean acidification, as well as the spatial
extents of those organisms that will be most
impacted.
Matsumoto, K., and B. McNeil. 2013. Decoupled
Response of Ocean Acidification to Variations in
Climate Sensitivity. J. Climate Vol. 26 (5). doi:
10.1175/JCLI-D-12-00290.1.
Photo Credit: Beach near Tofino on Vancouver
Island, Dudley Chelton
Evidence of Increasing
Frequency of Intense
Precipitation in the
Olympic Peninsula
Anthropogenic greenhouse gases may lead
to changes in the frequency and severity of
large storms. Though many previous studies
have looked to the observed record for
evidence of such change already occuring,
Muschinski and Katz (2013) have taken a
new look at statistics of hourly precipitation
observations, focusing on 13 stations
scattered across the contiguous US. In
particular, they examined trends in the
decadal averages of the normalized variance
of hourly precipitation. After accounting for
interannual variability, they concluded that
only one station showed statistically
significant changes: Aberdeen, WA, at the
southern end of the Olympic Peninsula,
where the normalized variance increased by
6.5% per decade over the last 50 years. The
results for Aberdeen are not spurious, the
study’s authors argue, but arise from how
precipitation generally forms in the region. At
most of the stations studied, peak 1-hour
precipitation amounts occur during
convective storms, which are statistically
more "noisy" than hourly precipitation during
typical large-scale northwest winter storms.
At Aberdeen, therefore, it should be easier to
separate the slow additive signal due to
anthropogenic greenhouse gases from the
noise.
Muschinski, T., and J.I. Katz. 2013. Trends in hourly
rainfall statistics in the United States under a
warming climate. Nature Climate Change. doi:
10.1038/nclimate1828.
The Rain-Shadow Effect in
the Washington Cascades
The rain-shadow effect is a dominant feature
in Pacific Northwest climate, and the
Cascade Range provides one of the best
examples in the world. Annual precipitation is
as much as 10 times higher on the windward
side as on the lee side of the north-south
oriented Washington Cascades. The physical
mechanisms behind a rain shadow are wellunderstood: with prevailing winds typically
from the west, rising air expands and cools
on west/windward slopes, condenses, and
produces precipitation. On the east/lee side,
warming air descends and cloud particles
evaporate. To help explain the strength of
the rain shadow, the authors used an eastwest transect of six SNOTEL stations
through the central Cascades. They used
winter (December, January, and February)
precipitation from the SNOTEL sites to
calculate a total precipitation and rainshadow index. They found that the rain
shadow is strongly influenced by a
teleconnection pattern associated with the El
Niño Southern Oscillation (ENSO). El Niño is
associated with a weaker rain-shadow effect
because the southern storm track brings
more warm fronts through the range. La Niña
tends to exhibit a stronger rain-shadow
effect, with a more northern storm track.
Streamflow data from eastern and western
Washington watersheds support
interpretation of SNOTEL data.
Siler, N., G. Roe, and D. Durran. 2013. On the
Dynamical Causes of Variability in the Rain-Shadow
Photo Credit: Cape of the Arches, Dudley Chelton
Effect: A Case Study of the Washington Cascades.
J. Hydrometeor Vol. 14, 122-139. doi: 10.1175/JHMD-12-045.1.
Photo Credit: Summer solstice sunset over Broken
Top, 21 June 2011, Dudley Chelton
Photo Credit: Marys Peak from Pyramid Peak in the
Oregon Cascades on an Exceptionally Clear Day (at
top) and Crater Lake in Winter, Dudley Chelton.
The Climate CIRCulator is brought to you by The Pacific Northwest Climate Impacts Research
Consortium (CIRC). CIRC delivers science, information, and tools to decision makers responsible for the
management of resources and services in a changing climate. Our team consists of experts from Oregon
State University, the University of Oregon, the University of Idaho, Boise State University, and the
University of Washington. CIRC is funded by the National Oceanic and Atmospheric Administration
(NOAA) and housed in the Oregon Climate Change Research Institute (OCCRI) at Oregon State
University. The OCCRI brochure can be downloaded here.
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The Climate CIRCulator, April, 2013, Issue 4.
Copyright © 2012,
The PNW Climate Impacts Research Consortium.
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