hydrologic effects of climate change in the...
TRANSCRIPT
![Page 1: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/1.jpg)
Hydrologic Effects of Climate Change in the Sierra-Nevada
Knowles, Noah (1); Dettinger, Michael (2); and Cayan, Daniel (2)
(1) USGS, Menlo Park, CA
(2) USGS; Scripps Institution of Oceanography, La Jolla, CA
1. Observed hydrologic changes
a. Snowpack
b. Runoff timing
c. Snowfall versus Rain
2. Projected hydrologic changes
a. Snowpack, snow-covered area
b. Runoff timing, flow peaks
c. Interannual variability
d. Soil moisture
Funded by the USGS NRC and Hydroclimatology Programs, NOAA OGP, DOE, the California Energy
Commission’s Public Interest Energy Research Program (PIER) through the California Climate Change Center at
Scripps Institution of Oceanography, and by the CALFED Science Program through the USGS CASCaDE Project.
![Page 2: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/2.jpg)
1. Observed Hydrologic Changes
![Page 3: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/3.jpg)
Mote et al., BAMS 2005
Snowpacks across the western U.S. and Canada have been declining.
TRENDS (1950-97) in
April 1 snow water content at
western snow measurement sites
![Page 4: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/4.jpg)
Stewart et al., 2005
Spring-pulse dates
Centers of Mass
Also, western streamflow has been
arriving earlier in the year
in recent decades.
Also: Dettinger and Cayan, 1995; Cayan et al., 2001
![Page 5: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/5.jpg)
Trends in ratio of winter (Nov-Mar) snowfall water equivalent (SFE) to total winter
precipitation (rain plus snow) for the period WY1949-2004. Circles represent significant
(p<0.05) trends, squares represent less significant trends.
MORE RAIN, LESS SNOW
LESS RAIN, MORE SNOW
Trends in Precipitation Form (1949-2004)
A west-wide shift from snowfall to rainfall has taken place
Knowles, N., M.D. Dettinger, and D.R. Cayan 2006. Trends in Snowfall versus Rainfall in the Western United States. Journal of Climate, 19(18), 4545–4559.
![Page 6: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/6.jpg)
Temperature Trends
Temperature changes have driven these trends
Trends in Precipitation Form
![Page 7: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/7.jpg)
If the warming continues, where should we expect the largest changes in warm-storm flooding to be manifested?
“Warm-storm flooding”
Less change More change
Computed from UW’s VIC model daily INPUTS (ala Bales et al, 2006)
How many
historical storms
> 1"/day were
just below
freezing?
10-yr avg
Linear trend
![Page 8: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/8.jpg)
By comparing Western U.S. temperature, snowpack, and streamflow
timing from observations and from “naturally” and “anthropogenically”
forced GCMs, Barnett et al (Science, 2008) showed:
• Trends in all quantities are detectable (beyond natural variability).
• ~60% of 1949-1999 “trends” in these quantities are attributable to
anthropogenic forcings (greenhouse gases, ozone, sulfate aerosols).
More than half of the regional trend is anthropogenic.
Barnett, T. P., D. W. Pierce, H. G. Hidalgo, C. Bonfils, B. D. Santer, T.Das, G. Bala, A. W. Wood, T. Nozawa, A. A. Mirin, D. R. Cayan, and M. D.Dettinger, 2008: Human-induced changes in the hydrology of the westernUnited States. Science, 319, 1080-1083.
![Page 9: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/9.jpg)
2. Projected Hydrologic Changes
![Page 10: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/10.jpg)
…and most climate models
yield a fairly narrow range of
precipitation changes in
California.
Dettinger, 2005
19 of 23 in this range
cm
/month
cm
/month
20 of 23 in this range
Under projected greenhouse
forcings, all climate models
yield warmer futures for
California…
![Page 11: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/11.jpg)
Pb: Not so much warmer
No ppt change
Pa: Medium warmer
Small ppt decrease
Gb: Medium warmer
Drier
Ga: Much warmer
Drier
Cayan et al., 2006, Report to
Governor
From amongst the most recent ensemble of climate-change
projections, we have chosen four scenarios to consider:
![Page 12: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/12.jpg)
Modeling Sequence
Watershed Model
![Page 13: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/13.jpg)
GFDL-A2 GFDL-B1
PCM-A2 PCM-B1
Avg 2070-2099 Snow Water Equivalent as percentage of 2001-2030 avg
![Page 14: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/14.jpg)
Peak Snowpack as a Fraction of Total Annual Runoff
Northern Southern
GFDL-A2 -95% -58%
GFDL-B1 -80% -50%
PCM-A2 -74% -31%
PCM-B1 -61% -33%
GFDL-A2
![Page 15: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/15.jpg)
Annual Maximum Snow-Covered Area
Northern Southern
GFDL-A2 -52% -23%
GFDL-B1 -46% -19%
PCM-A2 -37% -12%
PCM-B1 -26% -11%
GFDL-A2
![Page 16: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/16.jpg)
post-April fraction of annual runoff
Northern Southern
GFDL-A2 -21% -34%
GFDL-B1 -08% -19%
PCM-A2 -23% -18%
PCM-B1 -10% -14%
GFDL-A2
![Page 17: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/17.jpg)
Reduces snowpack leads to earlier runoff, resulting in more water being
managed as a hazard.
water
managed
as hazard
water
managed as
resource
water
managed
as hazard
water
managed as
resource
![Page 18: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/18.jpg)
GFDL-A2 GFDL-B1 PCM-A2 PCM-B1
Changes in peak flows driven by…?
![Page 19: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/19.jpg)
Changes in peak precipitation events
GFDL-A2 GFDL-B1 PCM-A2 PCM-B1
![Page 20: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/20.jpg)
![Page 21: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/21.jpg)
NOT A PREDICTION
![Page 22: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/22.jpg)
Changes in mean annual cycles for GFDL-A2:
2070-2099 (red) vs. 2001-2030 (blue)
![Page 23: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/23.jpg)
Reduced Soil Moisture, esp in Spring-Summer in S. Sierra
![Page 24: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/24.jpg)
Due to reduced snowmelt and warmer air temps, stream temps also rise.
See http://cascade.wr.usgs.gov for more.
![Page 25: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/25.jpg)
![Page 26: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/26.jpg)
GFDL-A2 GFDL-B1 PCM-A2 PCM-B1
Precipitation Trends
![Page 27: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/27.jpg)
GFDL-A2 GFDL-B1
PCM-A2 PCM-B1
Precipitation Trends
![Page 28: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/28.jpg)
Globally, since ~1970, natural climate variability has been
augmented by warming trends associated with increases in the
global greenhouse effect…
Climate-model simulations of global-average temperature
Meehl et al., 2004
Observed
Natural forcings suffice
Greenhouse emissions
required
![Page 29: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/29.jpg)
PCM-A2
![Page 30: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/30.jpg)
GFDL-B1
![Page 31: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/31.jpg)
PCM-B1
![Page 32: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/32.jpg)
GFDL-A2
![Page 33: Hydrologic Effects of Climate Change in the Sierra-Nevadacecentralsierra.ucanr.edu/files/101800.pdf · 2011. 6. 6. · Hydrologic Effects of Climate Change in the Sierra-Nevada Knowles,](https://reader036.vdocuments.mx/reader036/viewer/2022070112/60532657a4779319f57a236e/html5/thumbnails/33.jpg)
GFDL-A2 Reservoir Storage