The Climate System – The Attempt of an Overview

1. The Climate System –The Attempt of an Overview Miriam S. Andres Carbonate Research & Development Team ETC-Chevron, San Ramon 5th November 2011

2. The Geologic Record – A Matter of Time Scales The very Big and Long Picture

3. The Geologic Record – The Cool and Hot Stuff in-between • Observations • Major warm and cold periods, alternating • No run-away climate (yet). • The younger the more squiggles • Questions • Who are the climate players? • Climate change causes? • Are they always the same? • Why is there no run-away scenario? • What will happen in the future? • Example Time Intervals • Cretaceaus – super Greenhouse • PETM – rapid mega warming • Younger Dryas – back into the ice age • Holocene, the Anthropocene and the Future – Humans and Climate (this afternoon)

4. The Players Courtesy of Richard Sedlock, San Jose State Univ.

5. The Climate System - Causes Ruddiman « Earth’s climate : past and future »

6. The Climate System – Causes-Players-Response William F. Ruddiman « Earth’s climate : past and future » W.H. Freeman and company, New York, 2002 http://www.whfreeman.com/ruddiman/

7. The Climate System – Causes-Players-Response No human influence nor control Ruddiman « Earth’s climate : past and future »

8. Earth’s Orbital Parameters Gravitational Interactions: Control amount and locus of incoming solar radiation! Distance to the sun (=Eccentricity) Tilt of the Earth’s axis (=Obliquity) Wobbling of the tilt (=Precession) 1. Distance to the sun ≈ Eccentricity (deviation of ellipse from circularity) Varies between 0 and 0.05; today at 0.0167 (quasi circular) Frequency: every 100’00 and 400’00 years Effect: amount of radiation, locus of radiation closer farther 2 Tilt of Earth’s axis ≈ Obliquity : today at 23 degrees Frequency: quite regular every 41’000 years Effect: no tilt -> no seasons Small tilt -> mild summers, mild winters Today: significant seasons, esp. at mid- to high latitudes 3. Wobble of the tilt caused by tidal forces exerted by moon-sun system onto solid Earth Frequency: ~ every 26’000 years Effect: axis pointing towards sun -> one hemisphere with great seasonal difference, the other with milder seasons. At present: southern hemisphere seasons somewhat more extreme than ours. Ruddiman « Earth’s climate : past and future »

9. ‘Natural’ Greenhouse Gases and Greenhouse Effect H2O CO2 CH4 Ozone N2O Ruddiman « Earth’s climate : past and future » • Sunlight brings energy into the climate system; most of it is absorbed by the oceans and land. • Heat (infrared energy) radiates outward from the warmed surface of the Earth. Some of the infrared energy is absorbed by greenhouse gases in the atmosphere, which re-emit the energy in all directions. Some of the infrared energy further warms the Earth. Some of the infrared energy is emitted into space. • Higher concentrations of CO2 and other "greenhouse" gases trap more infrared energy in the • atmosphere than occurs naturally. The additional heat further warms the atmosphere and • Earth’s surface. Water vapor = earth’s biggest GHG • Albedo: White (ice/snow-covered surfaces reflect, black (ocean/land) surfaces absorb radiation

10. Plate Tectonics – Volcanoes – Mt. Building • Plate tectonics • Distribution of continents • and oceans, esp. shallow • seas • Plate collisions cause mountain building and volcanism Paleomap Project, Scotese, www.scotese.com Ruddiman « Earth’s climate : past and future » • Mountain Building • Immediate weathering of rocks • Transport in rivers to oceans • Deposition of Silica and Carbonates in the ocean Yosemite NP • Volcanic Eruptions • emitting of ash, aerosols (SO2), water vapor, CO2, HCl, HF into stratosphere (16-32 km) • -> heating of the stratosphere but cooling of the troposphere • -> SO2 turns into Sulfuric acid which condenses to • sulfate aerosol, • which increase • the earths albedo, • thus cooling the • troposphere. www.nps.gov/yose/ Mt St Helens, 1980 www.wikipedia.org USGS, R. Kimmel www.wikipedia.org

11. The Climate System – Causes-Players-Response No human influence nor control Ruddiman « Earth’s climate : past and future »

12. The Geologic Record – The Cool and Hot Stuff in-between • Observations • Major warm and cold periods, alternating • No run-away climate (yet). • The younger the more squiggles • Questions • Who are the climate players? • Climate change causes? • Are they always the same? • Why is there no run-away scenario? • What will happen in the future? • Example Time Intervals • Cretaceaus – super Greenhouse • PETM – rapid mega warming • Younger Dryas – back into the ice age • Holocene, the Anthropocene and the Future – Humans and Climate (this afternoon)

13. The Climate System– No runaway? Why Venus ‘Snowball Earth’ Ruddiman « Earth’s climate : past and future »

14. Geologic Evidence in The Cretaceous Super Greenhouse 2000-1000 ppm; 8x pre-industrial levels 2009 (385 pp) High sea level; abundant inundated shallow shelf areas. one-third of Earth's present land area was submerged Ruddiman « Earth’s climate : past and future »

15. The Cretaceous – Super Greenhouse Climate Why did it not get warmer and warmer? Earth’s Self-regulation Ruddiman « Earth’s climate : past and future »

16. The Geologic Record – The Cool and Hot Stuff in-between • Observations • Major warm and cold periods, alternating • No run-away climate (yet). • The younger the more squiggles • Questions • Who are the climate players? • Climate change causes? • Are they always the same? • Why is there no run-away scenario? • What will happen in the future? • Example Time Intervals • Cretaceaus – super Greenhouse • PETM – rapid mega warming • Younger Dryas – back into the ice age • Holocene, the Anthropocene and the Future – Humans and Climate (this afternoon)

17. Earth’s long-term climate future

18. Key Points on the Climate System ● Earth’s climate: nothing as constant as change; on all time scales and in all areas ● The Major Players: The Major External Causes: ● ‘Natural’ Greenhouse: critical to life on Earth ● Greenhouse: amount of incoming solar radiation albedo effect: fraction of solar radiation that is reflected amount of IR radiation that escapes to space ● No run-away scenario because of positive and negative feedback loops evidenced multiple times in the geologic record

19. The Climate System – Causes-Players-Response William F. Ruddiman « Earth’s climate : past and future » W.H. Freeman and company, New York, 2002 http://www.whfreeman.com/ruddiman/

20. Ocean Response • Earth’s Oceans • cover 75% of the globe • absorb most of the rheat • adsorb most of the CO2 • precipitation of weathered ions, critical to climatic self-regulation • moisture balance • …. Ocean Currents = Coriolis effect + tides + shoreline + depth contours + wind + temperature + salt density-driven thermo-haline circulation www.wikipedia.org Wind-driven circulation affects surface (upper 100–400 m) currents only. Density-driven circulation affects the entire ocean, include deep water. The world ocean is a vast heat reservoir, storing more heat in its upper few meters than the entire atmosphere does. Thus, changes in ocean circulation have significant, complex effects on climate.

21. Thermohaline circulation – THC-> Great Ocean Conveyor Belt www.cleanet.org www.wikipedia.org • Thermohaline circulation driven by differences in density = fct (temp+salt) • The THC is a concept and most images and idealized version • Main driver is cooling of surface water at high latitudes • The THC and wind-driven circulation mix the world ocean setting up ‘the great • ocean conveyor belt’ or ‘Meridional Overturning Circulation’ (MOC). • The MOC is complex, difficult to measure but widely accepted by scientists.

22. Make your own THC! www.cleanet.org www.wikipedia.org Photo: Miriam Andres