Climate Modeling Elissa Lynn SCRO August 27, 28/ 2013

Why are climate models important for DWR?

What is a model?

Mathematical representation on a computer

Building a Global Climate Model National Earth Science Teachers Association

NASA Climate Essentials…Many good videos NASA Earth Observatory introduction to global climate models Global temperature change National Center for Atmospheric Research Global temperature change projection (older) National Geophysical Fluid Dynamics Laboratory Videos for office/home viewing Selected videos are on the class website as well

IPCC 1990 IPCC 1995 IPCC 2007 IPCC 2001 IPCC = Intergovernmental Panel on Climate Change Climate Change Assessment reports IPCC 1990 IPCC 1995 IPCC 2001 IPCC 2007

Processes in Climate Models Image from National Center for Atmospheric Research

 Future Uncertainty  Data collection  Computer model variability  Feedback mechanisms  Spatial Resolution Why so hard to do? Trivia Time: How long does it take a modern global climate model to simulate 150 years?

Climate models are used to explore possible future changes in climate Climate models don’t predict future changes in climate

Weather Modeling vs Climate Modeling Weather Forecasting What will the weather be on a specific day in a specific place Short term (7-10 days) Future Climate Simulations What will the climate trends be in a region in the future Long term (100 years)

Climate models are used to explore possible future changes in climate Climate models don’t predict future changes in climate Scientists & planners use information from many models to make decisions

Mercury Venus Earth Mars Which planet is the warmest?

How will these greenhouse gases change in the future?

Green House Gases in Climate Models Actual greenhouse gas emissions were higher than future scenarios used in 2007 IPCC studies Colored lines – greenhouse gas emissions scenarios Black dots – actual greenhouse gas emissions Future greenhouse gas concentrations cover a higher range in 2013 IPCC studies -Called RCP or Representative Concentration Pathway -Number at end indicates radiative forcing value at the end of the century 2.6, 4.5, 6.0, and 8.5 W/m 2 in 2100 Concentration CO 2 equivalent from all greenhouse gases RCP8.5 RCP6 RCP4.5 RCP2.6 Fossil Fuel CO 2 Emissions IPCC = Intergovernmental Panel on Climate Change, RCP = Representative Concentration Pathway

Green House Gases in Climate Models IPCC = Intergovernmental Panel on Climate Change RCP = Representative Concentration Pathway for future greenhouse gas concentrations RCP overview: RCP4.5 Incoming solar radiation Atmosphere with changing greenhouse gas concentrations traps and re-emits radiation Radiation emitted to space Radiative forcing is the change in the radiation balance due to changes in greenhouse gas concentrations Increased radiation leads to warming

Green House Gases in Climate Models IPCC = Intergovernmental Panel on Climate Change RCP = Representative Concentration Pathway for future greenhouse gas concentrations RCP overview: IPCC 2013 is using greenhouse gas concentrations called “Representative Concentration Pathways” Scenarios reflect a range of future radiative forcings change in radiation balance at the surface of the troposphere due to changes in greenhouse gas concentrations Names refer to forcing values in the year , 4.5, 6.0, and 8.5 W/m 2, respectively RCP8.5 RCP6 RCP4.5 RCP2.6 Concentration CO 2 equivalent from all greenhouse gases Incoming solar radiation Atmosphere with changing greenhouse gas concentrations traps and re-emits radiation Radiation emitted to space Radiative forcing is the change in the radiation balance due to changes in greenhouse gas concentrations Increased radiation leads to warming

Climate models are used to explore possible future changes in climate. Global Climate ModelEstimate of Future Greenhouse Gases

Climate Change Scenario Activity 4 volunteers needed

Available Climate Change Scenarios From 2007 IPCC [CMIP3] 112 available scenarios (GCM x Greenhouse Gas) Subset of 12 scenarios recommended by California’s Climate Action Team From 2013 IPCC [CMIP5] More available scenarios More variables available Higher spatial and temporal resolution Models include improved representations of processes Regional impacts in California are similar to CMIP3 IPCC=Intergovernmental Panel on Climate Change, CMIP=Coupled Model Intercomparison Project

Downscaling Converting Global model output into Regional or Local information into Regional or Local information More specific, Higher resolution, More useful Images from Mike Dettinger, Scripps/USGS Demonstration: Climate Modeling and Legos

Website for Downscaled Climate Change Scenarios

July Temperature Change 14 GCMs X 3 RCP emissions Scenarios IPCC 5 th Assessment (CMIP5) models Warming is substantial in climate projections Cayan et al. Scripps/USGS 2013

Climate Change Temperatures  OBSERVED Summer warming higher than winter Interior warming greater than coastal/marine Nighttime warming has exceeded daytime in last few decades  PROJECTED Heat wave incidence: more frequent, intense, durable Precipitation change uncertain  Probably will remain extremely variable  Consensus of newest models shows little change in Northern Cal  Continued potential for extremely heavy events CLIMATE CHANGE

Climate scientists and modelers explore possible future climate conditions DWR staff assess potential impacts and risks that those climate change conditions could have on California’s water resources

Decision-Makers: “Keep it simple.” Climate Information Providers: “Here’s the info… use it wisely.” Modelers and Data Analyzers: “Keep it manageable.” Adapted from Levi Brekke USBR Climate Change Information Who is involved? What do they want? Decision Requirements Emission Scenarios Climate Simulations Spatial Downscaling Modeling to support Decision Making Land Cover Changes Societal Changes

Building Coalitions SCRIPPS Institute of Oceanography U.S. Geological Survey California Energy Commission UC Berkeley Lawrence Livermore Lab Santa Clara University Lawrence Berkeley Lab UC Davis

Building Coalitions SCRIPPS Institute of Oceanography U.S. Geological Survey California Energy Commission UC Berkeley Lawrence Livermore Lab Santa Clara University Lawrence Berkeley Lab UC Davis

What Climate Change Scenarios/Models Should We Use? Bookends scenarios that represent high/middle/low changes Ensemble - Use information from a group of models/scenarios - One way to address variability and uncertainty Other?

UNCERTAINTY Climate Projections Converting global data to local/regional scales Changes in societal values $$$$ Ecosystem response Water cycle changes Future water demands Sea level rise Adaptation Strategies Population Land use changes

Take Home Message Global climate models explore possible future climate conditions, they don’t predict future climate conditions DWR uses results from global climate models to evaluate possible impacts of climate change on California’s water resources

Extra Slides

What model best represents California’s historical climate? Figure 19. Relative error of the ensemble mean of each metric for each CMIP5 GCM. Models are ordered from least (left) to most (right) total relative error, where total relative error is the sum of relative errors from all metrics, excluding the diurnal temperature range (DTR) metrics. For 7 GCMs, the diurnal temperature range (DTR) metrics were not calculated (white squares). Ranking Global Climate Models by Rupp and Mote using a multi-factor historical climate evaluation scheme for the Evaluation Parameter Climate Models Relative Error High relative error in SW United States No clear best model, depends on criteria Models that didn’t perform well in SW US may be excluded in future analysis Low relative error in SW United States Least total relative error  Most total relative error Adapted from Cayan 2013 Southwestern United States