"Global Warming Beer" Taps Melted Arctic Ice (UPDATE) The brewery filed for bankruptcy in Aug 2008 The Greenland Brewhouse is the world's first Inuit microbrewery. The water, the brewers say, is the beer's key ingredient, having been locked away for more than 2,000 years in Greenland's vast ice sheet. AP August 3, 2006
Basis of Understanding 1. Earth s Paleoclimate History 2. On-Going Global Changes 3. Climate Models (note: modeling #3, but aids other two) Hansen, AGU 2008
Climate Change Depends on (global, averaged over chaos) 1. Equilibrium Climate Sensitivity 2. Forcings: Human & Natural 3. Response Time (Ocean Inertia) Hansen, AGU 2008
Tools for Studying Global Climate Change Wanted: geologic and other materials which provide information on changing environments and climate AND which can be dated or that yield a means to determine how much time they represent
The Long View- Paleoclimate Proxy data records (archives) used to interpret changing environments and infer paleoclimate Biological: tree rings; plant, animal and insect fossils Cryological: glacial Ice cores Geological: marine sediments; glacial deposits; wind-blown sand (dunes) and silt (loess); lake and swamp deposits Historical: written weather records- 100 s of years
The Long View- Paleoclimate Dating Techniques Depositional (annual layers) Radiometric Luminescence
The Long View- Paleoclimate Computer Models Used to help interpretations of proxy data Well known paleoclimate records are used as a test of global climate models used to estimate future climate change
Climate has changed in the past http://en.wikipedia.org/wiki/file:all_palaeotemps.png
Climate has changed in the past http://en.wikipedia.org/wiki/file:all_palaeotemps.png
The Long View from Archer, 2009
The Long View- Atmospheric CO2 from Archer, 2009
Climate has changed in the past http://en.wikipedia.org/wiki/file:all_palaeotemps.png
Why Does Climate Change? Milankovitch Cycles they produce most of the major climatic changes observed over past two million years Variation in Earth s orbit - 100,000 years = major glacial and interglacial periods Wobbles in Earth s tilt - 40,000 and 20,000 years These changing orbital cycles get help from additional processes such as greenhouse effect and changes in the ocean conveyor belt system
Milankovitch Cycles Milutin Milankovitch Serbian mathematician and astrophysicist 1920s
Eccentricity of 0.5 Earth's orbit varies from nearly 0.0034 to almost 0.058 NASA
Obliquity (axial tilt) Less tilt causes polar regions to receive less seasonally contrasting solar radiation, producing conditions more favorable to glaciation. NASA and http://en.wikipedia.org/wiki/file:axialtiltobliquity.png
NASA Precession a gravitationallyinduced slow but continuous change in an astronomical body's rotational axis or orbital path.
The Long View- Milankovich cycles and insolation From Archer, 2009
The Long View- Milankovich cycles and CO2 from Archer, 2009
The Long View- Antarctic Ice cores Source: Vimeux, and others, 2002 CO 2, CH 4 and temperature records from Antarctic ice core data
Maximum Extent of Glaciation 18,000 years ago http://home.earthlink.net/~icedneuron/iceagemap.jpg
Note that only the easternmost part of Nebraska has been glaciated Glaciation of middle North America started about 2.5 to 3 million years ago.
Maximum Extent of Glaciation 18,000 years ago www.geography.wisc.edu/classes/geog527/glacial_record.pdf
The Long View- Antarctic Ice cores YD Temperature change for the past 150,000 years at the VOSTOK site in Antarctica. www.ncdc.noaa.gov/paleo/globalwarming/paleobefore.html
2000
The Long View- Greenland Ice cores
The Long View- Greenland Ice cores YD Temperature from ice isotopic values. When has Greenland s temperature been most stable? Alley (Fig. 12.2) 2000
The Long View- Greenland Ice cores and the Younger Dryas There is strong evidence that during the YD, the North Pacific cooled, many mountain glaciers advanced and lakes in the Sahara shrank. Much of the Earth was cold, dry and windy for almost 1.300 years. The YD cold event in Greenland - snow accumulation ends in one to three years! With an increase in T of 12 deg C! Alley (Fig. 12.1) 2000
The Long View- Mid-Latitude Glacial Ice Cores Lonnie Thompson Over his career Lonnie Thompson and his crew have worked on the ice fields and glaciers of the mid-latitudes throughout the world. Lonnie and his wife and colleague, Ellen Mosley- Thompson
Thin Ice (2005)
Holocene glacial retreat Fig. 1. The locations of ice cores and evidence for glacial retreat Thompson and others, 2006, PNAS, v. 103 p. 10536-10543
Bolivia- Sajama mountain- Lonnie Thompson and team ice coring at 21,500 ft
Sajama ice core- Bolivia 21,500 ft
Bruce Kosci Lonnie Thompson
Huscaran Peru Garganta Col (19,800 ft) Huscaran at 22,205 ft, the highest tropical mountain in the world L. Thompson On the climb to the Garganta Col 23 people took 5 tons of equipment up Huscaran for 53 days of coring. B. Koci
Holocene tropical climate variability The present warming and associated glacier retreat are unprecedented in some areas for at least the last 5,200 yr. The ongoing global-scale, rapid retreat of mountain glaciers is not only contributing to global sea level rise but also threatening freshwater supplies in many of the world s most populous regions. Bruce Koci and Lonnie Thompson
Climate has changed in the past http://en.wikipedia.org/wiki/file:all_palaeotemps.png
The Long View- The Last 20,000 yrs on the Great Plains Distribution of mostly stabilized sand dunes in the Great Plains of the USA. http://esp.cr.usgs.gov/info/eolian/task1.html
Stokes and Swinehart, 1997
Wind Deposition Loess Houghton Mifflin 1998
Muhs, 2006
5 cm Mark Burbach Geoprobe and cores 15 m depth
Aa Central Great Plains paleoclimate recorded in dunes and loess Miao et al, 2007
Longitudinal dunes active during the Medieval Warm Period (700-1100 yrs ago) Nebraska Sand Hills Sridhar et al., Science, 2006
Northern Hemisphere Temperatures From Low and High Resolution Data MWP Medieval Warm Period MWP 2000 1000 0 Years before present Moberg and others, 2005
Aa Central Great Plains paleoclimate recorded in dunes and loess Miao et al, 2007
For the last 700 years vegetation has won the day. but how long before the rains decline and the sand breaks free? Will a rise of one degree C be enough?
The Long View- Paleoclimate The Take Home Messages The bottom line for our forecast for the future is that the earth has the ability to look after its own climate, but only if we are willing to wait a few hundred thousand years. It takes that long for the imbalance between CO2 release and uptake back into the Earth to affect the CO2 concentration of the atmosphere and ocean. Archer, 2009
The Long View- Paleoclimate The Take Home Messages 1. Climate in the past has been wildly variable, with larger and faster changes than anything industrial or agricultural humans have ever faced. 2. Climate can be rather stable if nothing is causing it to change, but when the climate is pushed or forced to change, it often jumps suddenly to very different conditions. Alley, 2000
The Long View- Paleoclimate The Take Home Messages 3. The pushes that have caused climate changes in the past probably have included drifting continents, wiggles in the Earth s orbit, sudden reversals in ocean circulation, and others. 4. Small pushes have caused large changes because many processes in the Earth system amplify the pushes. Greenhouse gases have probably been the most important amplifiers. 5. Humans can foul our own nest and we can clean it up. Alley, 2000