GC51D-0770
In PRISM data, Sierra Nevada warmed only 1°C in the
David R. Conklin and Jeremiah D. Osborne-Gowey, Conservation Biology Institute
th
20
century
Contact Information: david.conklin@consbio.org, 136 SW Washington Avenue, Suite 202, Corvallis, OR, 97333 USA
Methods
Mean Temperature
Legend
Geographic quadrants:
relative to the Sierra crest
NW
NE
NW
NE
SW
SE
1906-35
1979-2008
Temperature (°C)
Several published reports
assert that temperatures in
the Sierra Nevada (USA)
range increased by 3°C in the
20th century1,2,3,4. However,
20th century climate maps
produced by the PRISM
model5 show warming of only
about 1°C. Increases in mean
annual temperatures were
larger south of Lake Tahoe
(39°N), while increases in
winter temperatures were
larger north of Lake Tahoe.
Interdecadal variability is
more pronounced than are
long term trends.
39°N
Year
SE
Change from 1906-35 to 1979-2008
NW
NE
SW
SE
Coldest Month
+0.9°C
+1.1°C
+0.7°C
+0.8°C
Mean Temperature
+0.2°C
+0.3°C
+0.6°C
+0.6°C
mean temperature
• 2009 edition, PRISM US800m
SW
no
Warmest Month
conterminous US climate dataset
+0.1°C
+0.4°C
+0.5°C
mean temperature
change
• Mean monthly values for gridcells
at a grain of 30 arc-seconds, for the
Annual
+12cm
+7cm
+8cm
+3cm
years 1895-2008
Precipitation
• Variables include total monthly
precipitation, monthly averages of
LITERATURE CITED
1) daily minimum and 2) daily maximum temperature, and mean monthly dewpoint temperature
1. Millar C et al. (2004). Response of Subalpine Conifers in the Sierra Nevada, California, USA, to 20th-Century
Warming and Decadal Climate Variability. Arctic, Antarctic, and Alpine Research 36: 181-200.
• Used the study area from the Sierra Carnivore project at the Conservation Biology Institute
2. Moritz C et al. (2008). Impact of a Century of Climate Change on Small-Mammal Communities in Yosemite
National Park, USA. Science 322: 261-264.
• Divided the study area into geographic quadrants, using 39°N to separate northern/southern portions, and the crest
3. Panek J, Conklin D et al. (2009). Projected Vegetation Changes Over the 21st Century in Yosemite National Park
of the Sierra Nevada to separate western/eastern portions (quadrants color-coded in the map and table)
Under Three Climate Change and CO2 Emission Scenarios. Report to the National Park Service under task
agreement #J8R07070021.
• Constructed gridded climatologies from the monthly PRISM data for two 30-yr periods, one from the early 20th
4. Perlman D (2010). Trees shift upward as climate warms, data show. S.F. Chronicle, 6/12/2010, p. C-1.
th
century (1906-35) and one primarily from the latter part of the 20 century (1979-2008)
5. Daly C et al. (2008). Physiographically sensitive mapping of climatological temperature and precipitation across
the conterminous United States. International Journal of Climatology 28: 2031-2064.
Extra material to work with – DELETE SLIDE WHEN FINALIZED!!!
David R. Conklin1,2, Jeremiah D. Osborne-Gowey2, Others?3
FIGURE 1. Sierra Nevada study region of California, USA.
Results cont.:
• TMMIN - range of change: -0.7 to +1.9°C, average for area
shown: +0.8°C
• TMMAX - range of change: -1.5 to +1.8°C
• average for area shown: +0.2°C
TABLE 1. Change in climate from 1906-1935 to 1979-2008.
o
NW
NE
39°N
SW
Discussion and Conclusions:
1906-35
1979-2008
SE
• Expected species range shifts through physiological tolerances
• PRISM
• PRISM climate map results indicate climate change in the Sierra
Nevada in the last 100 years not as large as previously suggested
• Precipitation increasing througout the Sierra Nevada
• Mean minimum and maximum temperatures increasing
throughout the Sierra Nevada
• Southern portion of the Sierra Nevada experienced larger change
in mean temperature between the beginning/end of the 20th
century than northern portion
• Mean change in precipitation in SE portion of the study area 3-5X
smaller than in other three regions
• Change in continentality index beginning/end of the 20th century
3-4 times larger east of the Sierra crest than west