Global Ocean Challenges

Transcription

1 Stephen Macko Professor Department of Environmental Sciences University of Virginia Global Ocean Challenges Charleston Flooded BATIK by Mary Edna Fraser, Charleston, SC, USA

2 Some challenges have direct relationship to human activity Plastic waste; islands of waste in central gyres. Unknown effects of entering foodchains, endocrine disruption by manufacturing chemicals (BPA) Petroleum hydrocarbon leakage or spills Loss of diversity and modification of trophic structure (food webs) or environment, habitat (overfishing, stock management)

3 Some challenges likely have some direct relationship to human activity: some effects are identified, others less so Warming of the ocean (thermal expansion, melting of sea ice, glaciers) The other carbon dioxide problem: lowering of the ph though carbonic acid acidification

4 Some challenges have effects or collateral impacts are not so obvious and desperately need more data Release of methane from either gas hydrates on the seabed, or stored in the coastal permafrost peats (coastal modification, GHG amplification) Rising sea levels, modification of currents, changes in storm intensities

5 Graphics courtesy Michael Mann/ IPCC

6 How much and how fast?

7 Graphics courtesy Michael Mann, IPCC Projected Future Warming

8 Photo: Stephen Macko This is a time of unprecedented change in the Arctic. Conditions are changing faster than at any time in the past 10,000 years. The Arctic is warming twice as fast as the rest of the planet; ph is declining more.

9 Higher sea level Warmer water Graphic courtesy Introduction to Oceanography, Sverdrup et al. Prentice Hall

10 Graphics courtesy Robert A. Rohde / Global Warming Art

11 Hundreds of millions of people will be affected by rising sea level; Challenge: how much and how fast? Graphics courtesy Robert A. Rohde / Global Warming Art

12 The usual suspects Methane has ~20 times the effect of carbon dioxide, but does not reside in the atmosphere as long Most of the emissions come from the developed world, and chiefly a few countries. This will change with higher and warmer seas.

13 Modification of coasts (loss of peats and permafrost, release of methane, also in the subsurface seabed- 1,000s of Gt) Challenge: How much and how fast? Lena River delta, Siberia North slope, Alaska Photo credit Department of Energy

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15 How much and how fast will the loss be?

16 SUMMER 2012 LOWEST EVER

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18 Long/Lat.: W, N 2007 ( ) Photo credit: Larry Mayer, UNH

19 Long/Lat.: W, N 2012 ( ) Photo credit: Larry Mayer, UNH

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21 How much and how fast? Chasing Ice

22 More Icebergs

23 Currents carry about 50-60% of excess at the equator Deficit Surplus Transfer by air (winds) and water (currents) Winds dominate in high latitudes Graphic courtesy Introduction to Oceanography, Sverdrup et al. Prentice Hall

24 The conveyer belt Graphic courtesy Introduction to Oceanography, Sverdrup et al. Prentice Hall

25 How much and how fast?

26 Implications: High pressure/ low pressure systems Zones of water land interactions/onshore and the offshore

27 Challenge: a growing population

28 Challenge: feeding that population Fish are the only important food source that is primarily gathered from wild stock Represents 16% of human protein nutrition

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30 Loss of sharks in the Gulf of Mexico 300 fold decline no one noticed 1950 s 1990 s Oceanic Whitetip captures per 10,000 hooks Baum and Myers, Ecology Letters

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38 Open Ocean Fishery: Ram Myers: Science Tuna, billfishes, sharks In the northern hemisphere intensive fisheries were being conducted before quantitative records were kept Japan harvested ~1,000,000 tons of tuna and marlin in the 5 years before WWII. In 1950 the US harvested ~170,000 tons. The 1950 harvest of albacore by Spain was greater than the recent total recent harvest in the North Atlantic.

39 Decline in cod fishery

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42 Challenge: Do we understand the Arctic fishery sufficiently to begin commercial fisheries?

43 Primary production may increase in the warmer, ice free water column but are there enough nutrients in ice meltwaters? A bloom of coccolithophore plankton recorded near Newfoundland in 1999 and by NASA s SeaWiFs satellite SEAWIFS Image courtesy NASA

44 Primary production or ice algae under coastal ice diminishes or falls off too early with ice loss Life at the edge: Melosira arctica Massive production supports the community of the benthic environment. Diminished sea ice suggests significant loss of this production to coastal food webs Perhaps 25% of Arctic primary production is associated with ice (Gradinger, 2009)

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46 Can we manage wild populations sustainably? Large land animals almost lost Coastal waters overfished The open ocean and the Antarctic and High Arctic: the last frontiers?

47 U.S. Bans Commercial Fishing in Warming Arctic : 2009

48 Overfished, closed and still has not recovered

49 Not aimed at conservation but on management

50 The ocean is now > 0.1 ph units lower than pre-industrial times and contains about 400 billion tons of fossil fuel CO 2.

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52 Declining ph of the Ocean: increasing acidity, declining carbonate Year ? CO 2 ppm (1.36x) 750 (2.73x) ph of the Ocean (1.29x H + ) 7.87 (2.35x H + ) Lowest ph in millions of years Effect is highly predictable

53 Coccolithophores and Ocean Acidification A bloom of coccolithophore plankton recorded near Newfoundland in 1999 by NASA s SeaWiFs satellite Acidification of the ocean waters means difficulty in calcification by phytoplankton

54 Recognize change cascades with trophic level Graphic courtesy Introduction to Oceanography, Sverdrup et al. Prentice Hall

55 Zooplankton also. Foraminifera: composed of calcium carbonate

56 Lower ph negatively affects larval stages of planktonic stages: increased mortality, affects hardening of chitin with calcite formation Blue king crab zoea Juvenile blue king crab

57 Potential economic impact of ocean acidification on US fisheries (Cooley and Doney, 2009)

58 Spill date: 20 April 15 July 2010 Well officially sealed: 19 September 2010 Challenge: Technology has outpaced our ability to respond.

59 2006, Prudhoe Bay, 1 million liters As exploration increases in newly available locations in the ice free Arctic and Antarctic, the likelihood of a spill will increase and we are essentially unprepared for even moderate amounts of introduction in remote locations

60 5 MT/year; 50,000 piece/ sq mi

61 Dead Zones in the Gulf of Mexico

62 Figure 17_02 Graphic courtesy Introduction to Oceanography, Sverdrup et al. Prentice Hall

63 The number of challenges is great, some with severe consequences if unaddressed. Figure 17_07 While the path forward looks complex and risky. Photo credit: Stephen Macko

64 There are paths

65 Photo Stephen Macko and an unprecedented opportunity for international cooperation

66 Thank you.