Big Cycles

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Big Cycles Ecosystems PDO NAO
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The problem
Humans
years
century
decades
centuries
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Top normal Bottom El Niño condition
Normal
El Nino
Open University, 1998
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Large changes have long been recognized by
humanity

• It comes up to the shore here from the great fish
  pond which is the Icelandic Sea, towards the
  winter when the great part of other fish have
  left the land. And the herring does not seek the
  shore along the whole, but at special points
  which God in his Good Grace has found fitting,
  and here in my days there have been two large and
  wonderful herring fisheries at different places
  in Norway. The first was between Stavanger and
  Bergen and much further north, and this fishery
  did begin to diminish and fall away in the year
  1560. And I do not believe there is any man to
  know how far the herring travelled. For the
  Norwegian Books of Law show that the herring
  fishery in most of the northern part of Norway
  has continued for many hundreds of years,
  although it may well be that in punishment for
  the unthankfulness of men it has moved from place
  to place, or has been taken away for a long
  period.
• Clergyman Peder Claussøn Friis
• (1545-1614)

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Northward extension of cod stock from 1920 to
late 1930s. Published in 1939
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Herring migration - traditional
from Vilhjalmsson 1997
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Herring migration 1965 - 66
from Vilhjalmsson 1997
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Herring migration 1995
from Vilhjalmsson 1997
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Jean-Claude Quero Ital.J.Zool.,65 Suppl.493-499
(1998)
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Climate change or fishing?

• Both climate and fishing affect populations
• The level of fishing is excessive on most stocks
• Populations increase when climate (and other
  conditions) are favourable
• (distribution and abundance are linked)

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Ratio of catch of warm/cold species
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Ratio of catch of warm/cold species
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Characteristic PDO sea surface temperature
anomaly pattern. Solid blue contours depict
cooler than average temperatures, while dashed
red contours reflect warmer than average
temperatures. Contour interval is 0.1 degree C.
PDO indices based upon projections of observed
North Pacific sst and slp patterns onto those
shown. PDOgt0 is referred to as warm phase (see
NE Pacific SST)
Characteristic PDO (atmospheric) sea level
pressure anomaly pattern. Solid blue contours
depict lower than average pressures, while dashed
red contours reflect warmer than average
pressures. Contour interval is 0.2 millibars.
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PDO warm Phase 1871-1890 1927-1947 1977-1999(?) P
DO Cold phase 1890-1927 1947-1976
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Climate shifts perturb fisheries and have
socio-economic impacts.
Late 1960s
Late 1970s
1980s
Bottom trawl surveys, Pavlov Bay, AK (from
Botsford et al. 1997)
(from Anderson and Piatt, 1999)
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Climate regime shift in mid 1970s Appears to
coincide with changes in the NE Pacific ecosystem
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SST Anomalies
El Niño, PDO Pattern
La Niña, -PDO Pattern
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1994-1997
1998-2001
shift in North Atlantic atmospheric forcing
shift in North Pacific atmospheric forcing
Climate acts globally, but is modulated locally
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Geographic pattern of effect of NAO on sea
surface temperature
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Digression on regional differences

• The effects of climate regime shifts on fish
  stocks are well known for the Pacific
• The science has moved on from description to
  modelling and improving detection
• The North Atlantic lags some way behind, partly
  because climate effects are less obvious.

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Cold water zooplankton
Warmer water zooplankton
Otterson et al. 2001
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North Sea plankton

• For nerds
• Monthly values of the first PC (33.78 of the
  total variability).
• Main variables by order of importance
• mean abundance of C. finmarchicus
• mean abundance of euphausiids
• mean size of calanoid copepod
• mean abundance of C. helgolandicus
• calanoid copepod biomass
• mean abundance of Pseudocalanus spp.

Gadoid outburst
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3
11
10
2
9
1
8
7
0
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Months
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-1
4
-2
3
2
-3
1
60
65
70
75
80
85
90
95
Years (1958-1999)
1.0
North Sea cod recruitment
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This does not mean that changes in plankton are
the only cause of decline in cod
0.5
1 y old 10
0.0
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60
65
70
75
80
85
90
95
0
0
Year
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Red symbols indicate strength and sign of effect
of NAO on cod recruitment
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Poleward range shifts in terrestrial species

• Global meta-analysis of gt1700 species showed
  average poleward shift of 6.1 km per decade.
• The analysis generates very high confidence
  that climate change is already affecting living
  systems.

Parmesan and Yohe Nature 42137-42 (2003)
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Evidence that climate effects are stronger when
fish stocks are at low levels

• NAO (North Atlantic Oscillation) has a regular
  geographic pattern of effects on SST (and wind,
  cloud cover, precipitation) and on ecosystems
• NAO affects cod recruitment on the same pattern
  European cod stocks show a common response
• Recruitment is higher when NAO is low
• Meta-analysis shows that the effect is strongest
  when spawning stock levels are low

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Interaction between climate and fish stock
indicators

• Recruitment is affected by environment
• Effect of NAO on cod is consistent with its
  geography
• European cod stocks are sensitive when spawning
  stock biomass (SSB) is low
• We need to develop recruitment models which test
  for environmental effects related to SSB

Recovery of cod stocks depends a lot on
favourable environmental conditions
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Otterson et al. 2001
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• LONGER CYCLES

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North Pole.
Last glacial maximum.
Present day.
Source Climap project.
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The Oceans are changing
ARCTIC IS ALSO CHANGING!!
2090
Our grand children
Polar Amplification of Global Warming
2005
1979
2060
Our children
2030
Us
1980
2000
YEAR
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The Role of the Oceans in the Earths Climate

• The Mid-Atlantic Bight
• Experiences Some of the
• Largest Temperature
• Differences in the World
• Summer to Winter
• Top to Bottom
• Migratory Fish Species
• Have Evolved
• Most Urbanized
• U.S. Coast
• Is getting
• Fresher
• Warmer with
• Global Change

Needs Understanding Monitoring
Forecasting
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HUMANS NOW CAPABLE OF CHANGING THE EARTH
EUTROPHICATION
ATMOSPHERE
HUMAN CHEMICALS DOWN TO 1000 m DEEP IN OCEAN
IPC TAR
OVERFISHING
Sabine et al. 2002
Myers and Worm 2003
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Global trends
Myers et al. Science 2003