k branderapplying ipcc-class models of global warming to fisheries prediction - princeton june 2009...

K Brander Applying IPCC-class models of global warming to fisheries prediction - Princeton June 2009

Past and future impacts of climate changePast and future impacts of climate changeon North Atlantic codon North Atlantic cod

Keith BranderICES/GLOBEC Coordinator

Artist: Glynn Gorick

http://www.dtu.dk/

http://www.aqua.dtu.dk/


Assumptions on nutrient and biotic

fluxes

Futurescenari

oGCMlow

resolution

Regional Modelhigh

resolution

hydrodynamics

Lower trophic

level dynamics

IPCC provides Climate Change scenarios from GCMs

Downscale GCMs output for regional models of hydrodynamics (and biota)

Aim of WKCFCC - 20-50 year projections of fisheries productivity

Global climate change and regional impactsSchrum


Conclusions from WKCFCC

• IPCC 2007 model results differ from observations for the current climate, especially at regional level

• GCMs do not reproduce the two major modes of N Atlantic variability over the last century (AMO, NAO)

• global and regional climate models are not yet adequate for impact studies on the marine ecosystem

• models that assimilate recent climate data (and include the decadal modes) show useful forecasting skill, at least over periods of a few years


What do ecosystem models require from climate models (resolution,

error margins)?

• skilful in the region of interest - validity and skill tested with a present day reference simulation

• validation exercise needs to be performed regionally for the following variables:

– winds and air pressure (i.e. the correct location of the mean large-scale pressure systems is the single most important requirement)

– short wave radiation (clouds) and air temperature

– humidity

– precipitation and runoff

– temperature and salinity in the ocean.


• skilful not only for the average climate signal but also for the seasonal signal, the inter-annual variability and the diurnal variability, since variability on all of these different timescales can be an important drivers of biological processes

• regional bias and model errors in dynamically active (nonlinear processes) variables (temperature gradients, wind fields) need to be clearly smaller than the climate change signal, while error margins need to be given with reference to the present day climate simulations. Larger error margins have to be corrected and specific corrections have to be developed.


• Variables needed to force the regional ocean physical-biological models are:– wind fields (10 m)– sea level pressure– sea surface– air temperature– dew point temperature (humidity)– short wave radiation– cloud cover– atmospheric long-wave radiation– runoff– sea ice


• It might also be necessary to correct for resolution bias in the global models

• Oceanic data requirements are:

– initial and boundary conditions in the temperature, salinity and sea level

– temporal resolution needed is 3h-6h for the atmosphere and daily to weekly for the oceanic parameters.


Back to biology and history


Where did cod survive during the last ice age?Estimated time (thousand yrs) since population sub-division

50-85 pre LGM

20-30 post LGM?

10-50 post LGM?

75-150 pre LGM

80-200 pre LGM

Bigg, G.R., Cunningham, C. W., Ottersen, G. Pogson, G.H., Bigg, G.R., Cunningham, C. W., Ottersen, G. Pogson, G.H., Wadley, M.R., and Williamson, P. 2008. Ice-age survival of Wadley, M.R., and Williamson, P. 2008. Ice-age survival of Atlantic cod: agreement between palaeoecology models and Atlantic cod: agreement between palaeoecology models and genetics genetics Proc Roy Soc BProc Roy Soc B (2008) 275, 163-72 (2008) 275, 163-72


Cod survived the last ice-age on both sides of Cod survived the last ice-age on both sides of the Atlantic, but were probably limited to the Atlantic, but were probably limited to European waters in the penultimate ice age, European waters in the penultimate ice age, around 150k yr agoaround 150k yr ago

Cod populations seem able to survive even Cod populations seem able to survive even large changes in climatelarge changes in climate

(However they also respond very rapidly to (However they also respond very rapidly to change in climate)change in climate)


• Temperature was 2 to 3 oC higher• Salinity was up to 4 psu higher• Water level was much higher (see map)• Atlantic cod were common, together with southern

species

1 -

Ven

dsys

sel

2 -

Lim

fjord

3 -

E. J

utla

nd

4 -

NW

Fun

en

5 -

NE

Sjæ

lland

6 -

Bor

nhol

m

Per

cent

age

0

20

40

60

80

100

% gadids % flatfish

Map: K. Rosenlund

Vendsyssel

Limfjord E. Jutland

NW Funen

NE Sjælland

Bornholm


Climate is one of many pressures


From http://www.ipcc.ch/pdf/presentations/wg1-report-2007-02.pdf


Climate was a big issue in the 1930s.

Published in1939


1937

1931

1929

1927

1922

1919

1917

1908-

191271ºN

69ºN

73ºN

63ºN

67ºN

65ºN

65ºW

61ºN

59ºN61ºW

Maniitsoq

Qeqertarsuaq

Upernavik

49ºW57ºW 53ºW

Kangaatsiaq

Sisimiut

Ilulissat

Uummannaq

Paamiut

Nanortalik

Ivittuut

Nuuk

Fiskenæsset

45ºW 41ºW 37ºW

Qaqortoq

Tasiilaq

(Jensen, 1939)

Cod ”invasion”


(modified after Wieland and Storr-Paulsen 2005)

Potential spawning areas, larval drift and migration

58°

60°

62°

64°

66°

68°

70°N

200 m

500 m

1000 m

55° 45° 40° 35° 25°60° 20° W30°50°

1950s

1960s

Spawning area

Eggs and larvae

Juveniles

Adults (> 4-6 yrs)

1990s: No spawning off SE and SW Greenland

(Logeman et al. 2004)


0

100

200

300

400

500

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Lan

din

gs i

n t

ho

usan

d t

on

nes

0.5

1

1.5

2

2.5

Tem

peratu

re

Atlantic cod catch at Greenland


Changes in distribution and abundance of fish species off West Greenland during the period of warming from 1920 onwards.Prepared by Brander (2003) based on Saemundsson (1937) and Jensen (1939).

Changes in distribution and abundance Fish species

Species previously absent, but which appeared from 1920 onwards

Haddock (Melanogrammus aeglefinus),Tusk (Brosme brosme), Ling (Molva molva)

Rare species which became more common and extended their ranges

Saithe (Pollachius virens; new records of spawning fish), Atlantic salmon (Salmo salar), Spurdog (Squalus acanthias)

Species which became abundant and extended their ranges poleward

Atlantic cod, Atlantic herring (new records of spawning fish)

Arctic species which no longer occurred in southern areas, and extended their northern limits

Capelin, Greenland cod, Greenland halibut (became much less common)


Changes in distribution and abundance of fish species off Iceland during the period of warming from 1920 onwards.Prepared by Brander (2003) based on Saemundsson (1937) and Jensen (1939).

Changes in distribution and abundance Fish species

Species previously absent, but which appeared from 1920 onwards

Bluntnose sixgill shark (Notidanus griseus), Swordfish (Xiphias gladius), Horse mackerel (Trachurus trachurus)

Rare species which became more common and extended their ranges

Witch (Glyptocephalus cynoglossus), Turbot (Psetta maxima), Basking shark (Cetorhinus maximus), Northern bluefin tuna (Thunnus thynnus), Mackerel (Scomber scombrus), Atlantic saury (Scomberesox saurus), Ocean sunfish (Mola mola)

Species which became abundant and extended their ranges poleward

Atlantic cod, Atlantic herring (both extended their spawning distribution)

Arctic species which no longer occurred in southern areas, and extended their northern limits

Capelin


Sundby and Nakken (2008)

Another multidecadal effect

Changes in spawning areas of Arcto-Norwegian cod in

response to multidecadal climate oscillations


Conclusion:

• Fish (and other marine species) can expand and contract their ranges and populations very rapidly

• The past may provide an analogue for the future. As Greenland warms cod is expected to extend its range and become more abundant


1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 20002 .5

3

3 .5

4

4 .5

5

Tem

pe

ratu

re [

C]

o

Kilde: PINRO, Murmansk

NAO ~10 år

AMO ~60 år

Annual, decadal and multidecadal variability

Relations between spatial and temporal scales Sundby

0,0001

0,001

0,01

0,1

1

10

100

1000

10000

1 10 100 1000 10000 100000

Length scale (km)

Tim

e s

ca

le (

ye

ar)

Length scale (km)

Per

iod

(ye

ars)

~1 år


Red symbols indicate strength and sign of effect of NAO on cod recruitment

The NAO governs windfields (and hence temperature, cloud, inflows). It affects plankton, fish recruitment and many other marine and terrestrial systems.


Outflow of cold Arctic water

Inflow of warm Atlantic water

Sundby and Drinkwater (2007)

2

3

4

5

1950 1960 1970 1980 1990 2000

Tem

per

atu

re /

In

v. I

ce I

nd

ex

Davis Strait

Kola Section

Inverse winter temperature fluctuations between Greenland and Denmark were already known in the 18th century


Effects of reduced Atlantic inflow:

“.. in the Norwegian Sea the Polar Front, which separates

Atlantic and Arctic waters, typically lies a few hundred

km north of the Faroe Islands and reduced inflow would

be likely to move the front closer to or even onto the

Faroe Shelf. If such a shift takes place a cooling of the

order of 5oC would possibly occur in the areas affected.”From ACIA report 2005


Inflows are not just about heat transport Average PP in spring north of Iceland

(borrowed from Olafur Astthorsson)

0

5

10

15

20

25

61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93

Year

Pro

du

ctiv

ity

(mg

C m

-3 h

-1) Salinity > 34.5

Salinity < 34.5


Need to know:

How will the THC (MOC) change? What are the consequences of change in the THC for the position and strength of ocean fronts, ocean current patterns and vertical stratification?

This has consequences for inflows, position of the polar front, plankton production, fish distribution (which are only partly to do with temperature)From ACIA report 2005


Back to processes and fish


What does climate do to fish?

Define ”bioclimate envelopes” based on temperature and other factors.


Cod growth experiments - satiated feeding

0

1

2

3

4

0 5 10 15 20Temperature oC

gro

wth

ra

te

to 32

to 320

to 1000

to 3200

Weight group in g

Small cod (>32g) grow quickly and have a high optimal temp

The curve (for fish >32g) is domed and pretty flat over most of the range

Effects of temperature variability are greatest on small fish and at low (<5oC) temperature.

Food limitation alters things, but only seems to happen sometimes

Wild growth is lower because of higher activity levels, sex and sometimes food limitation etc.

Growth performance of cod

Data from Bjornsson and Steinarsson (2002)


Sensitivity of cod growth rate to temperature changes with size

(results from experiments with satiation feeding)


Reproductive performance of cod

0

20

40

60

80

100

0 2 4 6 8 10 12Surface temperature (weeks 14 - 26)

1 yr

old

fish

per

ha

GreenlandNE ArcticIcelandNorth SeaIrish Sea

Less sensitive rangeSensitive range


Image: Glynn Gorick for ‘Cod and Climate’ (ICES)

>99.99% mortality in first few weeks of life

Many millions of eggs produced per female

Dynamics of early life is critical and Dynamics of early life is critical and sensitivesensitive


Water depth <500m

ICES empirical data for 23 cod stocks (Brander 1994, 2005)


Key parameters for spawningKey parameters for spawning


Water depth <500m

Time of spawning Feb -June





Water depth <500m

Time of spawning Feb -June

Temperature


Egg survival data from Pepin (1997)

0 - 9°C (3 - 7 °C)




2 5 10 20 50 100 200

Gro

wth

rate

(m

m d

-1)

0,0

0,2

0,4

0,6

0,8

Total zooplankton biomass mgC m-3

4°C 8°C 12°C 16°C 20°C

Growth (and survival) of larvae depends on temperature and foodHigh temperature high metabolism high food requirement

4 8 12 16 200

5

10

15

20

25

Cri

t. z

oopla

nkto

n b

iom

ass

mgC

m

-3

Temperature (°C)

Higher turbulence levels Higher zooplankton biomass requirements

Trade off:

fast growth reduces predation risk, but increases risk of starvation


Regional examples:Baltic

North SeaCanadian cod stocsk


In the Baltic low O2 and salinity limits cod reproduction

(Plikshs et al. 1993; Wieland et al. 1994)


Variability in Cod Reproductive Volume

Plikshs et al. 1993MacKenzie et al. 2000

Reproduction requiresS > 11 psuO2 > 2 ml/l


Reproductive Volume depends on hydrographicand climatic processes

Such as inflows from the North Sea


Distribution of cod contracts when salinity is low

High salinity (frequent inflows)

Aro & Sjöblom 1983; MacKenzie et al. 2000; Köster et al. 2005

Low salinity (few inflows)


Complexity of intra- and inter-species interactions:cod and clupeids in the Baltic

predation on sprat & cod eggs

food competition

cannibalism on juveniles

predation onjuvenile herring

predationon sprat

continuous process,modulated by habitat

overlap (S, T, O2)

cannibalismon eggs

food competition


• Will there be adaptation? (how did they survive 7000 years ago)

• Period in life which is sensitive to low salinity is very short

• Depends on fisheries management (in short to medium term)

What will happen to cod as the Baltic gets warmer and fresher?


Climate

Fish

ing

Effects of fishing and climate interact

Risk that cod will disappear from the

Baltic


North Sea cod distribution has changedThere are (at least) five hypotheses to explain

this

1. Warming ‘drives’ cod further north (tagging does not support this)

2. Temperature reduces recruitment and/or survival in the south

3. Fishing pressure is higher in the south

4. Winds alter larval drift and adults then remain in north

5. Different substocks respond differently to local climate and fishing pressure variability

Engelhard, South, Pinnegar


The data

1913-1980: cpue steam and motor otter trawlers

1982-present: cpue motor otter trawlers


-4 -2 0 2 4 6 8

5152

5354

5556

5758

5960

6162

c(-4, 9)

c(51

, 62)

Otter1920s

-4 -2 0 2 4 6 8

5152

5354

5556

5758

5960

6162

c(-4, 9)

c(51

, 62)

Otter1930s

-4 -2 0 2 4 6 8

5152

5354

5556

5758

5960

6162

c(-4, 9)

c(51

, 62)

Otter1940s

-4 -2 0 2 4 6 851

5253

5455

5657

5859

6061

62

c(-4, 9)

c(51

, 62)

Otter1950s

-4 -2 0 2 4 6 8

5152

5354

5556

5758

5960

6162

c(-4, 9)

c(51

, 62)

Otter1960s

-4 -2 0 2 4 6 8

5152

5354

5556

5758

5960

6162

c(-4, 9)

c(51

, 62)

Otter1970s

-4 -2 0 2 4 6 8

5152

5354

5556

5758

5960

6162

c(51

, 62)

Otter1980s

-4 -2 0 2 4 6 8

5152

5354

5556

5758

5960

6162

c(51

, 62)

Otter1990s

-4 -2 0 2 4 6 8

5152

5354

5556

5758

5960

6162

c(51

, 62)

Otter2000s

Decades 1920s–2000s: distribution cod cpue(normalised by year)

20s

30s

40s

50s

60s

70s

80s

90s

00s


1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

56.5

57.0

57.5

58.0

58.5

Year

Latit

ude

(°N

)

(a)

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Year

Long

itude

(°E)

(b)

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

-2-1

01

2

Year

T an

omal

y (°

C)

(c)

Changed centre of gravity of cod distribution

• Latitude• Longitude• SST anomaly

• Major cod distribution shifts, but not obviously linked to temperature, changes fishing, winds etc.

• Mean population depth increases as annual mean temperature increases, but individual fish do not show clear temperature response


It is very difficult to explain past distribution changes in the North Sea, so how can we be confident

of our predictions of future changes?


Canadian cod stocks collapsed in the late 1980s due to cooling and heavy fishing

Period of very low temperature

Productivity and sustainable F very low


Can we be confident about predictions?

How do we increase confidence?

How urgent is it to address climate impacts?

Can we give advice already?

What should priorities be?


How confidently can we predict future impacts?

• Depends on how confident climatologists are about changes over next 20 - 50 years?

• Temperature, salinity, oxygen, pH, wind, stratification, nutrients

• extreme events as well as changes in means

• Even with good climate predictions we can only predict a few biological responses with confidence


How do we increase our confidence?

• Use the past as an analogue for the future• 1920-45 warm period; Historic reconstructions

• Do experiments• like crop experiments;

• Understand processes and represent them in predictions and models

• salinity and cod ; nutrient supply (vertical mixing, aeolian)


How urgent is it to tackle climate impacts on fisheries?

• Depends on how quickly climate changes over next 20 to 50 years (and on sensitivity of biota to change)

• Depends on where you are in the world (some areas and countries are more vulnerable)

• Tackling excess fishing is much more urgent•pressures of fishing and climate interact so the issues are interrelated

• [Mitigation actions are very urgent]


Reduce fishing pressureA triple-win, no regret strategy

More resilient populations and ecosystems (enhances adaptation)

Lower use of fuel (mitigation of GHG emission)

Higher yields (most stocks overfished)


What should our priorities be?

• Model primary production and aggregate fish production (by size, guild, life history type)

• Do experiments (like crop experiments)

• Pool data and carry out meta-analyses

k branderapplying ipcc-class models of global warming to fisheries prediction - princeton june 2009...

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