Impacts on ocean biology I: physiological underpinnings, projections and uncertainties

CLIMATE CHANGE

Hans-O. Pörtner: AR5 CLA WGII CH. 6, Ocean Systems, Ocean products in TS and SPM, CC-Boxes, SYR, SEDAR6 Co-chair WGII

UNFCCC Art. 2: ......prevent dangerous anthropogenic interference.... ............allow ecosystems to adapt naturally... ............ensure that food production is not threatened... ............enable economic development to proceed in a

sustainable manner

A role for natural systems to define the long-term global (climate) goals (LTGG, relative to preindustrial)?:

Projection of impacts:Define the key risks

Identify avoided impacts

Article 2 UNFCCC

Historical change in SST

RCP 2.6

RCP 8.5

projected

... warmingAccording to emission scenarios oceans are:

CMIP5 model runs

Gattuso et al., 2015

WGI Figure 6.30

... losing oxygen

Historical projected

committedclimate change

Historical Projections...acidifying

committed

Climate change in the oceans: warming, acidification, expanding hypoxia

occur on top of regional and natural variability: Organism and ecosystem functional changes may depend on climate zone

warmingon top of

means and variability

Pörtner et al. 2014

Pelejero et al. 2010

Natural variabilityin pH

Ocean surface layer

Deep ocean

Natural variability: vertical distribution of PCO2, pH

RCP2.6pH change = −0.13“What we hope for”

RCP8.5pH change = −0.42“Where we’re headed”

Average pH of the ocean surface

pH

Year

The ocean is acidifying rapidly

Figure courtesy of Jim Orr

We are here

WGI 3-18

Observations in surface waters

Historical Projections

Oceans are acidifying

+0.8°C to >>2 °C

How to explain ocean acidification?The earth has seen much higher atmospheric CO2 levels… but actual rates of CO2 accumulation are exceptionally high.

TodayGlacial-Interglacial

Currently, atmospheric CO2 levels change 100-fold faster than in glacial- interglacial intervals.

Calculated from Petit et al (1999) Calculated from Keeling and Whorf (2005)

Courtesy: Ken Caldeira

The uptake of excess CO2 from Ocean and atmosphere by weathering occurs in > 10,000 years.

Volcanic CO2 release =

CO2 removal by weathering

≈ 0.1 PgC / yr

CO2 emissions by human activities ≈ 7 PgC / yr

Pg = Petagram (1015 grams)

Human activities exceed by far the capacity of natural processes (sediment weathering) for buffering

www.globalchange.umich.edu

Natural volcanicCO2 emissions

More than 50 timesnatural CO2 emissions

Natural CO2 cycleCO2 from coal,

oil and gas

Bill

ions

of t

ons

carb

on p

er

year

CO2fromcoal,oil,andgas

Weathering: CO2 neutralisation occurs onTime scales >10 000 years

Caldeira and Wickett, 2003, 2005

Pre-industrial

Today

∆pH = - 0.12

32 % more acidification

2100

∆pH = - 0.45

2.8 fold more ….

2300

∆pH = - 0.77

5.9 fold more …

Specific effect of CO2: Reduction of carbonate levels in the oceans

Verons 2009

WAragonite =Ca 2+[ ] CO3

2-[ ]Ksp,Aragonite

*

Calcifiers need over-saturation and prosper at W > 3.3 (coral reefs)

Feely et al (in press) with modeled saturation levels from Orr et al (2005)

Calcium carbonate (aragonite) saturation levels 1765 - 2100

Observations: Oxygen depletionAreas with low oxygen expand:

deadzones at the coastOxygen minimum level reached in the water column

Habitat-“comprimation” und –loss for pelagic fish

Gruber (2012)

.....Extension, shoaling of hypoxic / anoxic dead zones.....

.....associated with enhanced CO2 accumulation

L. Stramma et al., Science 320, 655 -658 (2008)

(A) Eastern tropical North Atlantic

(10° to 14°N, 20° to 30°W)

dissolved oxygen

(µmol kg-1)

depth(m)

(D) Eastern equatorial Pacific Ocean

(5°S to 5°N, 105° to 115°W)

Climate change in the oceans: warming, acidification, expanding hypoxia

occur on top of regional and natural variability: Organism and ecosystem functional changes may depend on climate zone

light, nutrients, food

warmingon top of

means and variability

Pörtner et al. 2014

true also for:

progressive acidification

(Pelejero et al., 2010)

expanding oxygen minimum zones

(Stramma et al., 2008)

Ecosystem effects of ocean warming, acidification, hypoxia?

Are there unifying principles involved?

Bent

hic A

lgae

Bent

hic C

nidar

ians

Bent

hic M

ollus

ks

Bent

hic C

rusta

cean

Bent

hic In

vert

(Oth

er)

Phytop

lankton

Zoop

lankton

Larv

al Bo

ny Fi

shes

Non-B

ony F

ishes

Bony

Fish

es

All Tax

a

DIS

TRIB

UTI

ON

CH

AN

GE

(Km

per

Dec

ade)

-20

0

20

400

Standard Error

Mean

Standard Error

(359)100

World-wide marine species displacements due to climate change

OBSERVATIONS

WGII, SPM.2

+0.8°CGMT

Cod

Anglerfish

Snake blenny

Perry A.L. et al., 2005

Snake blenny (Lumpenus lampretaeformis)

Anglerfish(Lophius piscatorius)

Cod(Gadus morhua)

Data : 1977 - 2001

East Atlantic species are moving North …..to various degrees (!)

Shifting biogeographies~ Different thermal

sensitivities→ Changes in community

composition

Knowing the physiological underpinnings:

How to identify cause and effect and explain these observations?

Why?Such knowlege enhances confidence in projections of the

impacts of different climate futures!

PROJECTING VARIOUS FUTURES (PRESENT CHOICES)Poleward Shifts in ocean phytoplankton and

primary production...and a small overall decrease

IPCC AR5 WGII Figure 6.13

4°C~1.5°C

+1.5 to>>2 °C ... warming:

Considering ocean currents and stratification

CHANGE IN MAXIMUM CATCH POTENTIAL (2051-2060 COMPARED TO 2001-2010, SRES A1B, 2°C warming of global surface T0.7°C warmer Sea Surface T)

<50% -21 – 50%

-6 – 20% -1 – 5% No data 0 – 4% 5 – 19% 20 – 49% 50 – 100% >100%

WGII, 6-14, SPM.6, SYR 2.6

2051-60: shifted productivity, fish and invertebrate biodiversity

... Warming, a simplified view into the future: +2°C

HIGH RISK FOR FISHERIES AT LOW LATITUDES:small human adaptation capacity over time

CHANGE IN MAXIMUM CATCH POTENTIAL (2051-2060 COMPARED TO 2001-2010, SRES A1B, 2°C warming of global surface T0.7°C warmer Sea Surface T)

<50% -21 – 50%

-6 – 20% -1 – 5% No data 0 – 4% 5 – 19% 20 – 49% 50 – 100% >100%

WGII, 6-14, SPM.6, SYR 2.6

2051-60: displaced and reduced fish and invertebrate biodiversity... warming: Food security constrained, ....Fisheries

..... 2°C:Combined human pressures

affecting presently overexploited stocks.

BACKGROUND: OVERFISHING caused

predatory fish biomass to decline

(by ≈ 70%!)

Christensen et al.MEPS 512: 155–166, 2014

+2°C

Latitude of Field Population (°N or S)0 10 20 30 40 50 60 70 80 90

Wat

er Te

mpe

ratu

re (°

C)

-5

0

5

10

15

20

25

30

35

40

45

50

(3 spp)

(3 spp)

Pörtner and Peck 2010.

Metaanalysis: Across latitudes lethal limits and preferred temperatures reflect thermal specialization on climate and the limits of

the thermal niche

large juveniles and adults of various fish species

Thermal windows (niches): Large scale patterns with respect to temperature

Peck to al. 2009,

updated for Pörtner et al.

2010

Upper temperature limits and rate of change in Antarctic ectotherms

Rate of change

Upper temperature limit (°C)

0

2

4

6

8

10

12

14

16

18

20

day-1 week-1 1 month 3 month

Functional meaning?

(in experiments)

0Exposure time at T > Tp

Lethal temperature

upper Tp

0

Tem

pera

ture

(°C

)

Tp

Heat excess tolerated over time ((T–Tp) * h)

Pörtner, 2010

A heat tolerance budget delaying mortality: underlying mechanisms?

-2,0

-1,0

0,0

1,0

2,0

3,0

-3,0

-2,0

-1,0

0,0

1,0

2,0

3,0

-3,0 -2,0 -1,0 0,0 1,0 2,0 3,0

Barents Sea

North Sea

Temperature anomaly

Cod

recr

uitm

ent a

nom

aly

-2,0

-1,0

0,0

1,0

2,0

3,0

-3,0

-2,0

-1,0

0,0

1,0

2,0

3,0

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995

Barents SeaSpring water temperatureCod recruitment

North SeaWinter water temperatureCod recruitment

Ano

mal

y

Colosimo et al. 2003, Pörtner at al. 2008

Temperature dependent recruitment success in cod

La Sapienza

Unicellular Eukaryotes(Fungi, Protozoans)

Prokaryotes

Metazoa

Organisms (groups)

Organisationalcomplexity

Functional units

Adding higherlevels of

function andcoordination

Plants

Status

productive

productive

productive

productive

productive

Maximum heattolerance (˚C)

> 90

55-60

ca. 42

ca. 42

ca. 41

Pörtner (2002)

...when explaining thermal limits & windows: where to look across organisms?

Unicellular Algae

Highest complexitylevels

Compartmental coordination

Membrane functionsMolecular functionsMetabolic complexes

multiple organelles

The

evol

utio

nary

bac

kgro

und

Meta-analysis of the literature on thermal specialization:

Maximum heat limits (sublethal, loss of productivity)

across marine organism domains

related to habitat

D. Storch et al. Global Change Biology 2014

The

evol

utio

nary

bac

kgro

und

Meta-analysis: Thermal window widths (sublethal) across marine organism domains

D. Storch et al. Global Change Biology 2014

D. Storch et al. Global Change Biology 2014

Meta-analysis: Thermal limits found at the highest level of organismal complexity

The evolutionary background / brickwall

Higher (complex) organisms will become extinct in the warmest ocean areas.

Such projections relate to observed distribution patterns during warming periods in earth history.

Organisms respond to shifts in nutrients (ocean currents) as well as changes in temperature (causing stratification), CO2 accumulation, hypoxia.

Physiological underpinnings?:

How to explain observations across organism domains?

....as a basis and support for projections

End of Part I

Thank you!