Climate Modeling Research & Applications in Wales John Houghton C 3 W conference, Aberystwyth 26 April 2011
Computer Modeling of the Atmosphere & Climate System has revolutionized Weather Forecasting and Research Climate Prediction and Research
Identifies: Computer Modeling of the Atmosphere & Climate System starting conditions for weather or climate Integrates: the dynamical equations of motion the physical equations of state, energy etc algorithms describing all relevant processes NOT based on empirical or statistical information
Solar radiation Thermal radiation Top of atmosphere Density depends on temperature and pressure Atmosphere Motion horizontal and vertical Composition water vapour, carbon dioxide, clouds, etc. Surface Surface exchange of heat, momentum (friction) and water vapour Parameters & Physical Processes included in a Computer Model of the Atmosphere
Horizontal Grids for Global and Regional Models
UK Met Office jp05
Weather shows large variability in space and time Detailed weather forecasting only possible 10 to 30 days ahead Climate (= average weather) also shows large variability Is forecasting of human influence on climate a possibility?
Components of the Climate System Atmosphere Oceans Cryosphere Land Surface Biosphere All these components interact closely
Radiation Atmosphere: Density Motion Water vapour Heat Exchange of: Momentum Water Ocean: Density (incl. salinity) Motion Sea ice Land Parameters & Physical Processes included in a Coupled Atmosphere Ocean Global Climate Model
Changes in the atmosphere: composition, circulation Changes in the hydrological cycle Changes in solar inputs Clouds Atmosphere N 2, O 2, Ar, H 2 O, CO 2, CH 4, N 2 O, O 3, etc. Volcanic activity Atmosphere ice interaction Heat exchange Precipitation evaporation Wind stress Aerosols Terrestrial radiation Human influences Glacier Atmosphere biosphere interaction Ice-sheet Biosphere Sea ice Hydrosphere: ocean Soil biosphere interaction Land surface Ice ocean coupling Hydrosphere: rivers and lakes Changes in the cryosphere: snow, frozen ground, sea ice, ice-sheets, glaciers Changes in the ocean: circulation, sea level, biogeochemistry Changes in/on the land surface: orography, land use, vegetation, ecosystems Schematic of the Climate System from IPCC Report 2007
Computer Modeling of the Climate an essential tool that provides the means to add together all the non-linear processes and effects including positive & negative feedbacks Essential for estimating future climate
~500 km (a) ~500 km (b) Section of model grid in a typical global climate model in 1990 (a) and 2007 (b)
Climate (= average weather) shows large variability from month to month, year to year Global Climate (= patterns of climate averaged over globe) shows clear response to external forcing factors, e.g. Changes in Solar Radiation Volcanoes Greenhouse gases
Anomaly from 1991 ( C) 0.4 0.2 0.0 0.2 0.4 / Observed land surface air temperature and night marine air temperature (relative to April June 1991) Model predictions 0.6 1990 1991 1992 1993 1994 1995 1996 1997 Year Predicted & Observed changes in Global Average Temperature after the eruption of Mount Pinatubo in 1991 from IPCC Report 1996
(a) 1.0 (b) 1.0 Temperature anomaly ( C) 0.5 0.0 0.5 1.0 1900 Pinatubo Santa Maria Agung El Chichón 1920 1940 1960 1980 2000 Year Temperature anomaly ( C) 0.5 0.0 0.5 1.0 1900 Pinatubo Santa Maria Agung El Chichón 1920 1940 1960 1980 2000 Year Changes in Global Mean Temperature in 20 th century as observed (black) as simulated by ensemble of models (red & blue) with natural and anthropogenic forcings (a) - with natural forcings only (b) From IPCC Report 2007
Patterns of Chaos
LORENZ ATTRACTOR A solution of set of three coupled differential equations, dx/dt = σ (y - x), dy/dt = x (ρ - z) - y, dz/dt = x y - β z, that arise in studies of atmospheric convection
Lorenz Attractor distorted by External Forcing (after Palmer 1999)
Future Climate under increased Greenhouse Gas Emissions
S, L = global average values of incoming solar & outgoing long wave radiation at top of atmosphere (a) (b) (c) (d) S 240 L 240 S 240 L 236 S 240 L 240 S 240 L 240 top of atmosphere CO 2 x 2 CO 2 x 2 CO 2 x 2 + feedbacks T s =15 C T s =15 C T s =15+1.2 C T s =15+3 C Earth s surface The enhanced greenhouse effect with doubled CO 2
Some main impacts of climate change More intense heat waves Sea level rise More intense hydrological cycle jp14
Projected changes in annual temperatures for the 2050s The MetOffice. Hadley Center for Climate Prediction and Research.
More rain for some; less rain for others Jun-Jul-Aug changes by 2090s Precipitation increases very likely in high latitudes Precipitation decreases likely in most subtropical land regions From Summary for Policymakers, IPCC WG1 Fourth Assessment Report
Increased global average surface temperature leads on average to: More evaporation of water vapour from oceans More water vapour in atmosphere More average precipitation (as now observed) More latent heat release into atmosphere* More intense hydrological cycle Increase in risk of floods and droughts * from condensation of water vapour - a large source of energy
Proportion of land surface in drought - 3 computer simulations under A2 Emissions Scenario (after E Burke et al, Hadley Centre)
Proportion of land under extreme drought (from Burke 2006) 1980 ~ 1% 2005 ~ 3% 2040 (+2 deg) ~ 8% 2070 (+3 deg) ~ 18%
Some Feedbacks in the Climate System Water-vapour feedback Cloud Radiation feedback Ocean Circulation Feedback Ice Albedo feedback CO 2 fertilization effect Climate/carbon-cycle feedback
Cloud -Radiation Feedback largest contributor to uncertainty in climate sensitivity to increase in greenhouse gases
Condensation Reflection of solar radiation Water/ice Blanketing of thermal radiation Precipitation Evaporation Boundary layer Physical Processes associated with Clouds lead to feedbacks both +ve (high clouds) & -ve (low clouds)
Clouds influence average temperature + 3% High Clouds + 0.3º + 3% Low Clouds 1.0º
Polluted clouds have smaller particles - leading to more reflection of sunlight from the cloud top, less radiation at the surface, less precipitation & longer cloud lifetime
Annual mean net Cloud Radiative Forcing (Mar 2000 - Feb 2001) CERES instrument on NASA Terra satellite from King et al Our Changing Planet
Ocean circulation feedback
Estimates of Heat Transport by the Oceans (terawatts, 1012W ) Note -average solar radiation on 106 km2 ~ 250 terawatts,
How can models be validated? Comparison with Recent Climate Comparison with Past Climates Comparison with particular events
Sources of Climate Data Instruments, in-situ, passive & active remote sensing, mounted on satellites, aircraft, balloons, ships, buoys, land surface etc
Envisat - 2002 Nimbus - 1970s jp02
Instruments on ESA s Earth Observation Satellite, ENVISAT Passive AATSR MIPAS MERIS SCIAMACHY MWR GOMOS Active RA-2 ASAR DORIS
Illustrating Data Overload
Examples of Climate Modeling Research Projects How well can models describe extreme weather? How well can models forecast extreme climate events e.g. floods, droughts, storms etc timing & location? Cloud- Radiation Feedback What is its average sign & size of how do they vary? How well do models describe Ocean-Circulation Feedback on Climate? What are the influences of particles (aerosols) on climate? What is the relative influence of different greenhouse gases? How can human communities adapt to climate change? What model improvements could best help mitigation policy? What can we learn from past climates? How can models represent sub-grid-scale motions more accurately?
Possible Collaborations for C 3 W in Climate Modeling with Met Office with European partners etc