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 warminggreenhouse 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 PredictionsGCM 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…

CloudCloud• 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.

VegetationVegetation

• 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-AtmosphereOcean-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 MoistureSoil Moisture

(Loaiciga et al, 1995)

GCM Uncertainties

• Miscomprehension of how systems are coupled

• Future GHG emissions and conversion to atmospheric concentrations

• Too Simplistic in Parametrizatione.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 ModelingRegional + 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 IMPACTSof Climate Change on

Groundwater

• Melting of Ice Caps causes Sea Level Rise which leads to Seawater IntrusionsSeawater Intrusions

• Population GrowthPopulation Growth

• Land Use Efficiencies (Urbanization)Land Use Efficiencies (Urbanization)

• DeforestationDeforestation

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• 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 ?