1. SOAR 2005 Past Climates and Current Changes

2. Past Climate Records Instrumental  18 th – 21 st centuries with increasing accuracy  Best in Europe, N. America, Australia  Very little data over oceans, 70% of surface  Keening Curve: 1957 - present  CO 2 in air over Mauna Loa, Hawaii Instrumental  18 th – 21 st centuries with increasing accuracy  Best in Europe, N. America, Australia  Very little data over oceans, 70% of surface  Keening Curve: 1957 - present  CO 2 in air over Mauna Loa, Hawaii Northern Summer: Plants absorb CO 2 Northern Winter: CO 2 builds up from decay. This simple curve started the whole damn controversy!!

3. Anecdotal Records  Written records of planting, blooming, harvests  Frozen Dutch canals in art  Archeological sites  Vikings in Greenland and Labrador Anecdotal Records  Written records of planting, blooming, harvests  Frozen Dutch canals in art  Archeological sites  Vikings in Greenland and Labrador Past Climate Records

4. Proxy (indirect natural) Records  Tree rings  Temperature, precipitation, fire, insects, other stresses  Depends on area, species level of stress  best near stress limit  Back to ~1000 years (bristlecone pine in CA)  plus overlapping with structures Proxy (indirect natural) Records  Tree rings  Temperature, precipitation, fire, insects, other stresses  Depends on area, species level of stress  best near stress limit  Back to ~1000 years (bristlecone pine in CA)  plus overlapping with structures

5. Past Climate Records Proxy (indirect natural) Records  Tree rings  Fossil forests in the arctic … 60 million years old! Proxy (indirect natural) Records  Tree rings  Fossil forests in the arctic … 60 million years old!

6. Past Climates Proxy (indirect natural) Records  Palynology (pollen) from sediments  Accumulated in peat bogs & lakes  Must be independently dated (cross-matched or 12 C)  Local influences complicate records  eg. Fire, flood, etc.  Types of pollen vary in uniqueness  eg. Pine pollen everywhere … even ice caps! Proxy (indirect natural) Records  Palynology (pollen) from sediments  Accumulated in peat bogs & lakes  Must be independently dated (cross-matched or 12 C)  Local influences complicate records  eg. Fire, flood, etc.  Types of pollen vary in uniqueness  eg. Pine pollen everywhere … even ice caps! birch spruce shrub Pine sedge oak

7. Past Climates Collecting sediment samples in Canada Lake sediments Peatland cores Dr. Steve Robinson, SLU Geology

8. Past Climate Records Proxy (indirect natural) Records  Ice Cores  Alpine glaciers  Greenland ice sheet  Antarctic ice sheet Proxy (indirect natural) Records  Ice Cores  Alpine glaciers  Greenland ice sheet  Antarctic ice sheet Greenland ice sheet at 10,400 feet = 1.98 miles

9. Past Climate Records Vostok & Greenland Ice Cores  Show annual* variations of atmosphere  Bubbles of air contain old atmosphere  Variations in CO 2, CH 4 Give  Comparisons to today,  Correlations with temperature  Ice crystals vary in composition  Different Isotopes of Oxygen, Hydrogen, etc.  Dust  Volcanos, Impacts, Winds, Organic Matter Vostok & Greenland Ice Cores  Show annual* variations of atmosphere  Bubbles of air contain old atmosphere  Variations in CO 2, CH 4 Give  Comparisons to today,  Correlations with temperature  Ice crystals vary in composition  Different Isotopes of Oxygen, Hydrogen, etc.  Dust  Volcanos, Impacts, Winds, Organic Matter *Where annual layers unclear, chronology is reconstructed from other annual variables (eg. Berillium in

10. Isotopes Number of neutrons in nuclei varies  eg. Oxygen 16 ( 16 O) & 18 ( 18 O)  18 O heavier than 16 O  harder to evaporate  Ice Cores  High ratio of 18 O/ 16 O for warm globe  Deep Sea Sediments  High ratio of 18 O/ 16 O for cool globe Number of neutrons in nuclei varies  eg. Oxygen 16 ( 16 O) & 18 ( 18 O)  18 O heavier than 16 O  harder to evaporate  Ice Cores  High ratio of 18 O/ 16 O for warm globe  Deep Sea Sediments  High ratio of 18 O/ 16 O for cool globe 18 O 16 O 8 protons 8 neutrons 8 protons 10 neutrons 1 18 O in 1000 16 O

11. Ice Core Data Isotopes indicate glaciations

12. Ice Core Data Annual Layers  Dating & N-S correlation Isotopes  Correlate with temperature  Ice rich in heavy isotope indicates a warmer ocean Trapped air  Atmospheric composition Annual Layers  Dating & N-S correlation Isotopes  Correlate with temperature  Ice rich in heavy isotope indicates a warmer ocean Trapped air  Atmospheric composition 18 O/ 16 O 2 H/ 1 H Greenland ice core: arrows indicate summers. GISP2 = Greenland Vostok = Antarctica

13. Ice Core Data Isotopes & Temperature  Difference from current gives temperatures in past Isotopes & Temperature  Difference from current gives temperatures in past 18 O/ 16 O 2 H/ 1 H GISP2 = Greenland Vostok = Antarctica

14. Ice Core Data Composition  Correlation of temperature (isotopes) with CO 2 and CH 4 content  Difference from 1996 over 150,000 yr Composition  Correlation of temperature (isotopes) with CO 2 and CH 4 content  Difference from 1996 over 150,000 yr Mostly much cooler: Ice Ages!

15. Global CO 2 CO 2 from Ice Cores & Mauna Loa

16. Carbon Dioxide Long-term sources: Volcanoes Long-term sinks: Chemical Weathering  H 2 O + CO 2  H 2 CO 3  H + + HCO 3  CaCO 3 + H +  Ca + HCO 3 Variable storage: Biosphere  plants absorb  decay releases Long-term sources: Volcanoes Long-term sinks: Chemical Weathering  H 2 O + CO 2  H 2 CO 3  H + + HCO 3  CaCO 3 + H +  Ca + HCO 3 Variable storage: Biosphere  plants absorb  decay releases Relative Temperature CO 2 Concentration Carbonic Acid Bicarbonate can combine with many compounds eg. NaHCO 3, Ca(HCO 3 ) 2

17. Climate History Crowley “Remembrance of Things Past” Last 1000 Years Crowley “Remembrance of Things Past” Last 1000 Years Seems to be Northern Hemisphere only. Temperature Changes from 1900 level.

18. Climate History Last 18ky Younger Dryas: Gulf Stream shutdown due to glacial meltwater flood down St. Lawrence River. Wisconsonian Glaciation

19. Climate History Last 150ky  mostly ice core data Last 150ky  mostly ice core data

20. Climate History Last 140 ky

21. Climate History Last 800ky  Deep sea cores, 16 O/ 18 O Last 800ky  Deep sea cores, 16 O/ 18 O Humans Repeating ice ages much cooler than today!

22. Climate History Last 100My  Marine & Terrestrial data Last 100My  Marine & Terrestrial data Much warmer in Mesozoic! ice ages Dinosaurs Chicxulub Impact

23. Impact Craters on Earth Slowly erased by erosion Fractured rock, gravitational variations indicate ancient craters Slowly erased by erosion Fractured rock, gravitational variations indicate ancient craters World Impact Craters

24. Chicxulub Impact Demise of the dinosaurs? http://www.lpl.arizona.edu/SIC/impact_cratering/Chicxulub/Chicx_title.html Mapped by gravitational anomalies On Edge of Yucatan Peninsula Earth c. 65 million BCE

25. Impacts Cause of mass extinctions? Cause of climate change Cause of mass extinctions? Cause of climate change

26. Variations in the Atmosphere Atmospheric Oscillations  El Niño Southern Oscillation (ENSO)  Trade winds slacken, warm water sloshes east  Rain in Peru, Drought in Oceania, Varies elsewhere  Pacific Decadal Oscillation (PCO)  Latitude of warm pool varies  Deflects positions of Jet Streams (storm tracks) Atmospheric Oscillations  El Niño Southern Oscillation (ENSO)  Trade winds slacken, warm water sloshes east  Rain in Peru, Drought in Oceania, Varies elsewhere  Pacific Decadal Oscillation (PCO)  Latitude of warm pool varies  Deflects positions of Jet Streams (storm tracks)

27. Variations in the Atmosphere Atmospheric Oscillations  Northern Atlantic Oscillation  Strength of westerlies between 40°N and 60°N  Driven by Azores/Iceland pressure difference  Positive  larger difference  Recent positive phase unprecedented in last 500 years  Negative  smaller difference Atmospheric Oscillations  Northern Atlantic Oscillation  Strength of westerlies between 40°N and 60°N  Driven by Azores/Iceland pressure difference  Positive  larger difference  Recent positive phase unprecedented in last 500 years  Negative  smaller difference Positive Negative

28. Variations in the Atmosphere NAO  Known since 19 th Century  Positive  strong Gulf Stream  warm winter & spring in Scandinavia & E. US  cool along east coast of Canada & west Greenland  Negative – dry in E. N.Am, wet in S. Europe NAO  Known since 19 th Century  Positive  strong Gulf Stream  warm winter & spring in Scandinavia & E. US  cool along east coast of Canada & west Greenland  Negative – dry in E. N.Am, wet in S. Europe Positive: Strong westerlies Negative: Weak westerlies Cool Warm

29. Variations in the Atmosphere Atlantic Oscillation  Relation to NAO?  Varies over days  Mostly in positive mode recently Atlantic Oscillation  Relation to NAO?  Varies over days  Mostly in positive mode recently Positive: Strong circumarctic winds trap cold air near pole Negative: Weak winds allow polar air to move south

30. Variations in the Atmosphere Atmosphere/Ocean Connections  Atlantic Multidecadal Oscillation  Greenland icecores show oscillations  80 & 180 year variations in N. Atlantic temperature  Driven by NAO?  Positive NAO  strong westerlies across Labrador sea cool ocean  strengthens Gulf Stream & Thermohaline Circulation (THC)  Negative NAO  weak westerlies across Labrador sea keep ocean warmer  weakens Gulf Stream & THC Atmosphere/Ocean Connections  Atlantic Multidecadal Oscillation  Greenland icecores show oscillations  80 & 180 year variations in N. Atlantic temperature  Driven by NAO?  Positive NAO  strong westerlies across Labrador sea cool ocean  strengthens Gulf Stream & Thermohaline Circulation (THC)  Negative NAO  weak westerlies across Labrador sea keep ocean warmer  weakens Gulf Stream & THC

31. THC: Thermohaline Circulation Great Conveyor Belt moving HEAT  circuit ~ 2000 years Great Conveyor Belt moving HEAT  circuit ~ 2000 years

32. Variations in the Atmosphere Insolation Variations  Solar brightness variations  sunspots & other stellar variations  Earth orbital variations  other planets’ gravity vary Earth’s orbit  Solar system environmental variation  moves through galactic environment Insolation Variations  Solar brightness variations  sunspots & other stellar variations  Earth orbital variations  other planets’ gravity vary Earth’s orbit  Solar system environmental variation  moves through galactic environment

33. Spaceship Earth Galactic Environment  Solar system passes through nebulae Galactic Environment  Solar system passes through nebulae

34. Spaceship Earth Sun is a variable star  Solar constant ≈ 1370 W/m 2 … varies  stars evolve, luminosity varies  early sun ~ 25% -30% dimmer than today  Sunspot Cycle  11 year number cycle  22 year polarity cycle  Earth gets more energy from sun when sunspot numbers are high. Sun is a variable star  Solar constant ≈ 1370 W/m 2 … varies  stars evolve, luminosity varies  early sun ~ 25% -30% dimmer than today  Sunspot Cycle  11 year number cycle  22 year polarity cycle  Earth gets more energy from sun when sunspot numbers are high.

35. The Sun

36. Sunspots Magnetic Hernias  Sun’s equator rotates faster than poles  Magnetic Field wraps up, bulges up Magnetic Hernias  Sun’s equator rotates faster than poles  Magnetic Field wraps up, bulges up

37. Sunspots Observed since 1611 (Johann Fabricius)  Discovered by Johann Fabricius  Observed by Galileo Observed since 1611 (Johann Fabricius)  Discovered by Johann Fabricius  Observed by Galileo Sol 04/09/04

38. Sunspots Number observed since 1611 Regular 11-year cycle Maunder Minimum

39. Associated with Little Ice Age  Began due to solar cooling  Continued due to ice albedo effect Associated with Little Ice Age  Began due to solar cooling  Continued due to ice albedo effect Maunder Minimum

40. Spaceship Earth Current Orbit moderates seasons  Northern Summer at Aphelion  mostly land, less solar flux reduces heat  Southern Summer at Perihelion  mostly water, more solar flux absorbed by oceans Current Orbit moderates seasons  Northern Summer at Aphelion  mostly land, less solar flux reduces heat  Southern Summer at Perihelion  mostly water, more solar flux absorbed by oceans Aphelion: 7/5/5 r = 152.1 Gm Perihelion: 1/2/5 r = 147.1 Gm

41. Variations in Earth’s Orbit Orbits characterized by  eccentricity (ovalness)  inclination (axial tilt)  precession (axial wobble) All change due to gravitational influence of sun, moon & other planets  Precession – 140 BCE by Hipparchus  Eccentricity & Tilt  Back 100,000 years – 1843 by Leverrier  Back 1 million years – 1904 by Pilgrim Orbits characterized by  eccentricity (ovalness)  inclination (axial tilt)  precession (axial wobble) All change due to gravitational influence of sun, moon & other planets  Precession – 140 BCE by Hipparchus  Eccentricity & Tilt  Back 100,000 years – 1843 by Leverrier  Back 1 million years – 1904 by Pilgrim

42. Milankovitch Cycles Insolation changes with orbital variations  Axial Tilt: 41,000 year cycle  Makes seasons more or less severe  Precession: 26,000 year cycle  Changes season of perihelion  Now: perihelion in early January  Southern summer when Earth closes to sun  Eccentricity: 100,000 year cycle  Changes severity of seasons  distance to sun varies more through the year Do Ice Ages correlate with orbit? Insolation changes with orbital variations  Axial Tilt: 41,000 year cycle  Makes seasons more or less severe  Precession: 26,000 year cycle  Changes season of perihelion  Now: perihelion in early January  Southern summer when Earth closes to sun  Eccentricity: 100,000 year cycle  Changes severity of seasons  distance to sun varies more through the year Do Ice Ages correlate with orbit?

43. Milankovitch Cycles Variation in Earth’s orbit due to gravitational attractions of other planets

44. Eccentricity 100,000 years  Currently 3% difference in distance  7% difference in insolation  At Maximum, 9% difference in distance  20% difference in insolation 100,000 years  Currently 3% difference in distance  7% difference in insolation  At Maximum, 9% difference in distance  20% difference in insolation

45. Precession 23,000 years  Changes season of perihelion  Northern seasons much more severe  more insolation on land masses in summer  less insolation on land masses in winter 23,000 years  Changes season of perihelion  Northern seasons much more severe  more insolation on land masses in summer  less insolation on land masses in winter

46. Obliquity 41,000 years  Axis Tilt  Now: 23.5º  Minimum: 22.5º  Tropics closer to equator, Circles closer to poles  Poles get less summer insolation (glaciation?)  Equator gets more insolation (shallow angles at solstices)  Maximum 24.5º  Tropics farther from equator, Circles farther from poles  Poles get more summer insolation (melting?)  Equator gets less insolation (steeper angles at solstices) 41,000 years  Axis Tilt  Now: 23.5º  Minimum: 22.5º  Tropics closer to equator, Circles closer to poles  Poles get less summer insolation (glaciation?)  Equator gets more insolation (shallow angles at solstices)  Maximum 24.5º  Tropics farther from equator, Circles farther from poles  Poles get more summer insolation (melting?)  Equator gets less insolation (steeper angles at solstices)

47. Insolation Varies with Milankovitch Cycles  Calculation for 65 N ( Berger (1991) ) Varies with Milankovitch Cycles  Calculation for 65 N ( Berger (1991) ) 9,000 years ago, ice age ended! Some argue this is the cause of all climate change … so we can ignore our CO 2

48. Predicting the Future Climate Systems  Atmosphere – changes over hours  Oceans – surface changes over weeks – depths change over millennia  Biosphere – changes annually to centuries  Cryosphere – ice, glaciers permafrost, snow – various change scales  Geosphere – volcanos, continental drif – long time scales, large changes Climate Systems  Atmosphere – changes over hours  Oceans – surface changes over weeks – depths change over millennia  Biosphere – changes annually to centuries  Cryosphere – ice, glaciers permafrost, snow – various change scales  Geosphere – volcanos, continental drif – long time scales, large changes

49. Modeling the Climate Systems & Feedbacks Among  Radiation  insolation (incoming sunlight varies)  reflection, absorption, re-radiation by surface, air  Water cycle  evaportion, precipitation, runoff  Land surface  soil moisture, vegitation, topography, snow & ice  Ocean  surface currents, deep currents, chemistry (salinity)  Sea Ice  strongly affected by feedbacks Systems & Feedbacks Among  Radiation  insolation (incoming sunlight varies)  reflection, absorption, re-radiation by surface, air  Water cycle  evaportion, precipitation, runoff  Land surface  soil moisture, vegitation, topography, snow & ice  Ocean  surface currents, deep currents, chemistry (salinity)  Sea Ice  strongly affected by feedbacks

50. Feedbacks Positive  Any change leads to further change  eg. Ball on a hill Negative  System always returns to equilibrium  eg. Ball in a bowl Neutral  System stays in new state  eg. Ball on a plain Positive  Any change leads to further change  eg. Ball on a hill Negative  System always returns to equilibrium  eg. Ball in a bowl Neutral  System stays in new state  eg. Ball on a plain

51. Feedbacks Greenhouse Effect: Warming  Good … makes Earth inhabitable!!  Ground absorbs sunlight Ground heats (parking lots in summer) Ground radiates heat (Infrared, IR) Atmosphere absorbs (some) IR Atmosphere heats  Feedback Mechanism: Evaporation  Clouds shade surface, cool it, warming stops?  H 2 O vapor absorbs more IR warming increases?  Runaway Greenhouse … Venus! Greenhouse Effect: Warming  Good … makes Earth inhabitable!!  Ground absorbs sunlight Ground heats (parking lots in summer) Ground radiates heat (Infrared, IR) Atmosphere absorbs (some) IR Atmosphere heats  Feedback Mechanism: Evaporation  Clouds shade surface, cool it, warming stops?  H 2 O vapor absorbs more IR warming increases?  Runaway Greenhouse … Venus!

52. Feedbacks Greenhouse Effect: Warming  Feedback Mechanism: Plant Growth  More CO 2 increases plant growth Plants absorb CO 2 (Keeling curve annual cycles) CO 2 is Reduced BUT … why isn’t it working yet?  More CO 2 increases plant growth More plant growth is good!! (Greening Earth Society of Western Fuels Assn.) Greenhouse Effect: Warming  Feedback Mechanism: Plant Growth  More CO 2 increases plant growth Plants absorb CO 2 (Keeling curve annual cycles) CO 2 is Reduced BUT … why isn’t it working yet?  More CO 2 increases plant growth More plant growth is good!! (Greening Earth Society of Western Fuels Assn.)

53. Feedbacks Ice-Albedo Effect: Warming  Warming melts glaciers, sea ice  Ground warms more than snow/ice Ground warms, radiates more IR Atmosphere warms More ice melts  Feedback Mechanism: Evaporation  More water available  More clouds & cooling, snow comes back  H 2 O vapor absorbs more IR, more warming  “Hot House Earth” Ice-Albedo Effect: Warming  Warming melts glaciers, sea ice  Ground warms more than snow/ice Ground warms, radiates more IR Atmosphere warms More ice melts  Feedback Mechanism: Evaporation  More water available  More clouds & cooling, snow comes back  H 2 O vapor absorbs more IR, more warming  “Hot House Earth”

54. Feedbacks Ice-Albedo Effect: Cooling  Cooling causes more snow  Snow reflects sunlight Ground cools, radiates little IR Atmosphere cools Snow doesn’t melt More precipitation falls as snow  Feedback Mechanism: Ocean absorbs CO 2  CO 2 builds up over icy world, warming starts  “Ice House Earth” Ice-Albedo Effect: Cooling  Cooling causes more snow  Snow reflects sunlight Ground cools, radiates little IR Atmosphere cools Snow doesn’t melt More precipitation falls as snow  Feedback Mechanism: Ocean absorbs CO 2  CO 2 builds up over icy world, warming starts  “Ice House Earth”

55. IPCC Intergovenmental Panel on Climate Change  View of the bulk of the scientific community  Computer models estimate feedbacks  Reports every 5 years  2005 report in draft form (www.ipcc.ch)www.ipcc.ch  “Hockey Stick” plot of temperature Intergovenmental Panel on Climate Change  View of the bulk of the scientific community  Computer models estimate feedbacks  Reports every 5 years  2005 report in draft form (www.ipcc.ch)www.ipcc.ch  “Hockey Stick” plot of temperature

56. Third Assessment Report 2001

57. The Skeptics Important voices!  Skeptics keep science honest Agreements  CO 2 in atmosphere is increasing  CO 2 levels correlate with temperature Arguments  Climate is driven exclusively by insolation  Milankovitch Cycles  Sunspot Cycles  Too expensive to reduce CO 2 : Adapt  Global warming is good! Important voices!  Skeptics keep science honest Agreements  CO 2 in atmosphere is increasing  CO 2 levels correlate with temperature Arguments  Climate is driven exclusively by insolation  Milankovitch Cycles  Sunspot Cycles  Too expensive to reduce CO 2 : Adapt  Global warming is good!

58. What to Do? Complex system hard to model Experts don’t agree Could be global disaster Complex system hard to model Experts don’t agree Could be global disaster Ignore it? Mitigate it? Kyoto + ? Adapt?