Outline 24: The Holocene Record

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1 Outline 24: The Holocene Record Climate Change in the Late Cenozoic New York Harbor in an ice-free world (= Eocene sea level) Kenneth Miller, Rutgers University An Ice-Free World: eastern U.S. shoreline assuming 73 m higher sea level Blue = flooded Kenneth Miller, Rutgers University 1

2 Glaciers retreating on Greenland capture stunning glacierretreat/#fqadt6kmxaqtkm07.01 What Do We Know? Ancient Sea Level Records, including the Holocene Historical Temperatures past 150 yrs Ancient Temperature Records based on proxies: Annual ice layer thickness records Oxygen isotope data from both fossils and ice Tree ring data provide growth rates that reflect climate change CO 2 record in detail for past 400,000 yrs What Do We Know? Sea Level rose about 100 m since the peak of the last glaciation about 20 ka. Peak sea level was m higher in an ice free world. Global temperatures have risen overall about 1.0 o C since records started in the 1870s. Climate change has been common, and sometimes rapid, during the past 20,000 years. 2

3 Barbados Sea Level Curve based on fossil corals that lived near the surface Sea Level rose about 100 m since the peak of the last glaciation about 20 ka. Eastern Beringia during the last glacial maximum with eustatic sea level lowering of 120 m. The region was largely unglaciated with the exception of local uplands that supported alpine glaciers. (GSA Today, August 2009) 3

4 Western Europe at the end of the last glacial stage as sea level was rising towards present day levels. National Geographic, Dec Long term Sea Level Present = 0 m Peak sea level m Fell ~100 m from 50 0 Ma Long term 18 O variations (red) covary with sea level (blue) Ocean crust production controlled greenhouse gases, causing global temperature changes long term Kenneth Miller, Rutgers University Source: IPCC, Intergovernmental Panel on Climate Change,

5 Carbon dioxide concentration at Mauna Loa Observatory. / Scripps Institution of Oceanography Atmospheric CO 2 Levels 2010: 390 ppm Animation of CO2 changes over time What Do We Know? Global temperature and CO 2 patterns are correlated over the past 400,000 years. CO 2 curve lags temperature curve by about 800 years. The ocean holds 50X more CO 2 than the atmosphere. As atmospheric temperatures warm, so does the ocean, which releases CO 2 into the atmosphere. When the ocean cools it absorbs more CO 2. CO 2 is more soluable in cold water than warm water. So temperature changes may drive CO 2 changes rather than the other way around. At least before the Industrial Revolution started in the 1800s. 5

6 Antarctica Vostok Station, Antarctica: Ice Core for last 400,000 yrs Russian Drill Penetrates 14-Million-Year-Old Antarctic Lake 6

7 CO 2 lags temperature by ~800 yrs The Antarctic Ice Sheet will not be destroyed any time soon. But major glaciers will slide into the ocean over the next few hundred years raising sea level more than 10 ft. glaciers slow collapseunstoppable scientists say/ thwaites glaciermelting collapse west antarctica ice warming/ Antarctic Ice Sheet over last 100 m.y. Antarctic Ice Sheet ~15 Ma = modern, = 63 m of ocean water ~33 Ma Oligo., m ~70 Ma Cret., 40 m ~92 Ma Cret., 25 m ~93 Ma Cret. 15 m Miller, Rutgers U. Maps from models of Deconto and Pollard (2002) 7

8 Antarctic Ice Sheet over last 100 m.y. Antarctic Ice Sheet ~15 Ma = modern, = 63 m of ocean water ~33 Ma Oligo., m ~70 Ma Cret., 40 m ~92 Ma Cret., 25 m ~93 Ma Cret. 15 m Miller, Rutgers U. Maps from models of Deconto and Pollard (2002) But, the Arctic Sea Ice is melting rapidly, which reduces Earth s albedo, speeding up warming September 16, 2012: Arctic Ocean ice levels 18 percent smaller than previous record 8

9 Area of Arctic Sea Ice at end of Summer Greenland Is Melting Away nland-is-melting-away.html?emc=eta1&_r=0 What does the Future Hold? Rising global temperatures in the next century? Yes, but how much? Models depend a great deal on estimates of atmospheric water vapor levels. Rising sea level in the next century? Yes, but how much? More and stronger hurricanes? Probably. 9

10 2012 already brings record breaking heat in U.S _ /2012 already brings record breaking heat in u.s/?tag=cbscontent;c bscarousel Maximum temperature anomalies in the U.S. for the month ending March 31, (Credit: National Weather Service) Estimates of Future Global Temperatures based on Computer Models IPCC Worse case? hot! IPCC Best case? much warmer IPCC Facts about Sea Level Rise From , sea level has risen 9 inches (0.23 m). IPCC forecasts a rise over the next 100 years of 14 inches (0.36 m), but some estimates double or even quadruple that. 10

11 U.S. EPA Estimates of Future Sea Level Rise based on Computer Models 39 in. 29 in. 16 in. 8 in. Sink or Swim? clips/w6itwj/the colbert report theword sink or swim 11

12 Response by Humanity? Find alternatives to burning fossil fuels CO 2 from fossil fuels is adding to global warming, even if we are not sure of the magnitude of this effect. Fossil fuels will be greatly depleted within a century, civilization needs other energy sources. Response by Humanity? Adapt to changing climate and rising sea level Changes in climate and sea level are part of natural cyclical processes. Find political solutions to conflicts over water, fuel, and food resources. Otherwise regional wars will be common. Be realistic about development along coasts. Can t fight long term rising sea levels. Move back! As Arctic ice cap melts, a new Cold War is developing over oil and gas in the Arctic Russian flag planted on the ocean floor at the North Pole 12

13 Shorelines are Moving Shorelines composed of sediments are geologically unstable. They shift position from various geologic variables including: Sea level change Subsidence Erosion Deposition Shoreline shift is a reality humans must face. Hurricane Irene hits Outer Banks of North Carolina August 27, comparisons/ 13

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16 Superstorm Sandy hits the east coast, October 29, Jersey Shore Jersey Shore 16

17 New York City Subway in Lower Manhattan Jersey Shore That s All Folks Have a great summer! 17