This Class: Short-term climate change

1. This Class: Short-term climate change • Climate – 30 year “average” weather conditions • Short-term – over the last 1000 to 12,000 years • Climate records • Causes of climatic variation • Past climate change

2. Records of climate

3. Records of climate • Historical (human) records • instrumental • written observations • maritime records • paintings • 12,000 paintings • 1400-1967

4. Records of climate, cont. • Phenological observations • agricultural records • price of rye in Germany • bird migrations

5. Dendrochronology • dating of past events through study of tree ring growth • thickness of the tree ring indicates growing season conditions • precipitation

6. building a chronology • overlapping rings from different trees • Bristlecone pine chronology is 9000 years long • long lives - 4,767 years old

7. Lake and ocean sediments • Sediments record environmental conditions present when they were deposited

8. Clues in the sediments • pollen - vegetation type • skeletons of small organisms - water chemistry, temperature • type of organisms - windiness • chemistry of sediments or organisms – temperature, precipitation

9. Elk Lake, Minnesota • http://geology.cr.usgs.gov/pub/fact-sheets/fs-0059-99/

10. Signals in Elk Lake sediments • diatoms - heavy, need wind to keep afloat = windy • quartz - blown into the lake = windy • sodium – retained in soils, not washed away = dry • pollen - vegetation type • 8,500 to 4000 years ago it was drier, prairie vegetation

11. Coral reefs • growth bands • chemistry records sea temperature (oxygen isotopes)

12. Coral core and X-ray with growth bands slide/ coral core and x-ray

13. Calibration curve slide/ calibration curve of 18O and SST in coral oxygen isotope temperature (oC)

14. -5.3 -4.9 -4.5 -4.1 -3.7 1840 1860 1880 1900 1920 1940 1960 1980 2000 two prolonged La Niña events Oxygen isotope index Period of instrumental data

15. Ice cores • volcanic eruptions - ashes • atmospheric gasses - small air bubbles • temperature - oxygen isotopes • windiness - dust

16. Greenhouse gasses in ice cores • http://www.pages.unibe.ch/products/overheads2/icecores.html

17. Some causes of climatic variation • Ocean circulation • Sunspots • Volcanic eruptions • Atmospheric conditions • El Nino Southern Oscillation

18. Currents and climate • Miller 2.167

19. Sunspots • Dark spots (cool areas) that move across the surface of the sun* • Every 11 years there is a period called a “solar maximum” with lots of sunspots and solar flares • Today’s sunspot number http://www.sunspotcycle.com/ *But these dark areas are surrounded by hotter rings that more than make up for the difference in radiation

20. Fewer sunspots seem to be associated with: • lower temperatures • more severe winters • glacial advances

21. Volcanoes • blast gasses (sulfur dioxide) and ash into the lower stratosphere. • strong winds in stratosphere blow material around the world. • sulfur dioxide combines with water to for sulfuric acid aerosols (fine droplets) How does this affect climate?

22. Volcanic eruption

23. Volcanoes, cont. • scatters incoming radiation back to space • reduces heating of earth’s surface • last up to four years

24. Mt Pinatubo, Philippines

25. Pinatubo sulfur dioxide cloud June 17, 1991 June 19, 1991

26. Pinatubo sulfur dioxide cloud

27. Pinatubo stratospheric aerosols 40 days before 40 days after 20 months after

28. Average temperatures dropped by 0.2 to 0.5 oC for 1 to 3 years

29. El Niño – Southern Oscillation (ENSO) • Oscillation of southern high and low pressure zones • Weakening of Peruvian high pressure zone • Weakening of Indonesian low pressure zone • Weakening of southeast trade winds • Affects local climate

30. Sea surface temperatures off South America

31. Upwelling off South America • 9.12a 2.209

32. El Niño sea temperature

33. El Niño year • 9.12b 2.207

34. ENSO teleconnections – affects on global climate Segar, 1998

35. Past periods of climate change • Medieval Warm Period • Little Ice Age Insert temperature recoreds

36. The Medieval Warm Period • 1000 to 1300 AD • regional warming (not necessarily global) • Longer and warmer growing season • grapes in England • Higher treelines • Warmer sea surface temperatures in North Atlantic • approx. 1o C warmer than present

37. Viking settlement on Iceland and Greenland from 800 to 1200

39. The Little Ice Age • Very cold climate between 1560 and 1890 • Greater frequency of storms • Glacial advances 1560-1610,1816-1890

40. Wheat prices higher in Europe • Paintings darker, cloudier

41. Iceland Iceland population • Population declines in Iceland indicated by tax records • shift from grains to barley (short growing season) to no grains • fishing failed as fish migrated southward due to water temperatures. • Height declines • from 5’8” in 900s to 5’6” in 1700s in Iceland barley no grain

42. Greenland • 1300 highest population (3000) • Poor harvests, fewer livestock • Increase in sea ice decreased trade • Settlements abandoned • Height decrease from 5’7” to < 5’ by 1400

43. Intro to activity: The Palmer Drought Severity Index

44. Based on temperature, precipitation, and tree ring records • http://www.ngdc.noaa.gov/paleo/drought/drght_pdsi.html • http://www.ngdc.noaa.gov/paleo/pdsiyear.html Locations of tree rings • http://www.ngdc.noaa.gov/paleo/pdsiyear.html

46. Pinatubo sulfur dioxide cloud 3 months after eruption

47. Little ice age • glacial advances

48. http://www.ucar.edu/learn/1_2_1.htm • for pollen, tree ring w/ fire scar

49. slide/ drilling coral Drilling a massive coral

50. http://www2.sunysuffolk.edu/mandias/lia/little_ice_age.html Many pictures of paintings, wheat prices, etc.