Transcript Slide 1

Climate Change
UnderGround
Cynthia Valle
OUTLINE
What is Climate Change?
Where does Groundwater fall?
How do GCMs contribute?
What are there setbacks?
How does regional modeling assist?
climate change global warming
greenhouse warming
Svante Arrhenius
(1896) was first
scientist to study
effect of increased
[CO2] on surface
Temperatures.
GLOBAL CIRCULATION MODELS
Formulated to simulate climate sensitivity to increased
concentrations of greenhouse gases, primarily carbon
dioxide .
GCM Predictions
Precipitation by 2080s:
• Increases in Winter Precipitation, +15% to +62%
• Divergence in Summer Precipitation, -36% to +54%
• Precipitation Extremes during late Summer & through Winter
Evaporation by 2080s:
• Increases in Winter by +3% to +9%
• Increases in Summer by +5% to +16%
Temperature by 2080s:
• Increase of 2-4 degrees Celsius
UnEqual Distribution of Climate
Change’s Effects
- Areas where precipitation unaffected…
Increased evapotranspiration…
Reduced watershed yields.
- In Tropical Latitudes, mean temperatures will
remain relatively high and uniform throughout
the year…
water resources will not be affected due to
the assumption of increased hurricane activity.
FEEDBACKS
GCM predictions based on feedbacks
derived from simulations…
Cloud
• Global mean net cloud forcing = -16 Wm-2
– Negative Forcing
– Causing a 10ºC to 15ºC cooling effect at surface
• Doubling CO2 to 600 ppm…
– Positive Forcing = 4 Wm-2
– 2ºC to 4ºC increase in surface temperature
• Cloud Cover Reduction
Surface Albedo
• Warmer Climates:
- Melting of Ice…
- Lower Planetary mean Albedo…
- Increase in Incoming Solar Radiation…
- Increase in Surface Temperature.
Vegetation
• Plant Growth and Respiration critically
depends on atmospheric and land
variables
– CO2 Concentrations, Temperature
– Soil Moisture
• Warmer Climates Causes:
– Change in Vegetation
– Rise in Surface Albedo
Ocean-Atmosphere
• Warmer Climate:
- Increased Precipitation…
- Greater Fresh-Sea Water Mixing…
- Lower Ocean Density…
- Decreased Ocean Circulation
- Decrease in Temperatures
at High Latitudes:
- Decreased Evaporation
- Reduced Salinity
(Loaiciga et al, 1995)
Soil Moisture
(Loaiciga et al, 1995)
GCM Uncertainties
• Miscomprehension of how systems are
coupled
• Future GHG emissions and conversion to
atmospheric concentrations
• Too Simplistic in Parametrization
e.g. Cloud Feedback: Not address possible diurnal/seasonal cloud shifts,
changes in latitudinal cloud cover, cloud cover shifts from albedo
variations, changes in cloud optical thickness
• Difference in Measuring Scales of Atmosphere
(days) and Oceans (up to 1000 yrs)
GCM Limitations
• Predictions can not be confirmed until mid
21st century since Climate is so Sensitive
and Variable
• Affects are not Distributed Equally
• Lack of Data
– Leads to paleoclimatic reconstructions which allow for more
uncertainity
• Buttefly Effect
• Anthropogenic Influences
Multi-Scale Modeling
Regional + Macro
Vorosmarty et al, 2000)
CLASP II
•
Uses GCM outputs for watershed scale simulations
•
Nests groundwater models (i.e. MODFLOW) within watershed scale
system…
– Allows for focus on aquifer-stream interaction in physically-based
manner
•
Classified as an aquifer-vegetation-atmosphere model
•
Distinct from other Models:
– Decadal Timescale…can study impacts of global climate change on
watersheds
– Converted to represent Long-Term Groundwater
Feedbacks…appropriate to infer Groundwater Implications on Climate
Change…
• Done by Studying Change and Interaction between Water Table and
Latent Heat Fluxes
• Must be Simplified to get long-term timescale
CLASP II Predictions
(York et al, 2001)
Compared to Other Simulations
(York et al, 2001)
• Clasp II simulation including an aquifer compared to one excluding
an aquifer, proves how groundwater has an effect on climate change
and/or vice-a-versa.
CLASP II Limitations
• Characterizes atmosphere as a single column
– Denies horizontal heterogeneities
• Abundance of fixed variables
– Aquifer surface and base elevation, hydraulic conductivity,
storage coefficient, and soil density and heat capacity
• Hydraulic head is set to be constant
• Homogeneous vegetation cover
• Climatic feedbacks may distort hydrological
systems, in turn altering parametrization
• Limited to inaccuracies of the larger scale model
INDIRECT IMPACTS
of Climate Change on Groundwater
• Melting of Ice Caps causes Sea Level
Rise which leads to Seawater Intrusions
• Population Growth
• Land Use Efficiencies (Urbanization)
• Deforestation
STRESS TODAY
(Ranjan et al, 2006)
(Ranjan et al, 2006)
CONCLUSION
Models having taken a multiple-scale
approach by nesting a subgrid model
within a GCM, allow for more realistic
insight on how hydrological processes
are affected as a function of climate
change.
Models also open our eyes to how much
we have yet to understand about the
interactions in coupled systems.
References
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Bloomfield, J.P., Williams, R.J., Gooddy, D.C., Cape, J.N., and P. Guha. (2006) Impacts of climate
change on the fate and behavior of pesticides in surface and groundwater- a UK perspective.
Science of Total Environment: 369, 163-177.
Holman, I.P. (2006) Climate change impacts on groundwater recharge- uncertainity, shortcomings,
and the way forward? Hydrogeology Journal: 14, 637-647.
Karl, T.R. and Kevin E. Trenberth. (2003) Modern climate change. Science: 302, 1719-1723.
Liang, X. and Zhenghui Xie. (2002) Important factors in land-atmosphere interactions: surface
generations and interactions between surface and groundwater. Global and Planetary Change:
38, 101-114.
Loaiciga, H.A., Valdes, J.B., Vogel, R., Garvey, J., and Harry Scwarz. (1995) Global Warming and
the hydrological cycle. Journal of Hydrology: 174, 83-127.
Ranjan, P., Kazama, S., and Masaki Sawamoto. (2006) Effects of climate change on coastal fresh
groundwater resources. Global Environmental Change: 16, 388-399.
Vorosmarty, C.J., Green, P., Salisbury, J., and Richard B. Lammers. (2000) Global water
resources: Vulnerability from climate change and population growth. Science: 289, 284-288.
Wilby, R.L., Whitehead, P.G., Wade, A.J., Butterfield, D., Davis, R.J., and G. Watts. (2006)
Integrated modeling of climate change impacts on water resources and quality in lowland
catchment: River Kennet, UK. Journal of Hydrology: 330, 204-220.
York, J.P., Person, M., Gutowski, W.J., and Thomas C. Winter. (2001) Putting aquifers into
atmospheric simulation models: an example from the Mill Creek Watershed, northeastern Kansas.
Advances in Water Resources: 25, 221-238.
? QUESTIONS ?