Robert Howarth Cornell University Ithaca, NY USA Ocean Hypoxia and its Impacts on Ecosystems

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Robert Howarth Cornell University Ithaca, NY USA Ocean Hypoxia and its Impacts on Ecosystems UNDP Side Event at GESAMP #39 New York City, USA 18 April 2012 Nutrient Pollution of Coastal Waters: Trends, Drivers, and Potential Solutions

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Nutrient Pollution of Coastal Waters: Trends, Drivers, and Potential Solutions. Robert Howarth Cornell University Ithaca, NY USA Ocean Hypoxia and its Impacts on Ecosystems UNDP Side Event at GESAMP #39 New York City, USA 18 April 2012. - PowerPoint PPT Presentation

Transcript of Robert Howarth Cornell University Ithaca, NY USA Ocean Hypoxia and its Impacts on Ecosystems

Page 1: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Robert Howarth Cornell UniversityIthaca, NY USA

Ocean Hypoxia and its Impacts on Ecosystems UNDP Side Event at GESAMP #39

New York City, USA

18 April 2012

Nutrient Pollution of Coastal Waters: Trends, Drivers, and Potential Solutions

Page 2: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

(Rockstrom et al. 2009)

Global status of earth’s 10 life-sustaining biophysical systems

nitrogen

Page 3: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Nitrogen (and not phosphorus) is the primary culprit for coastal eutrophication and hypoxia

(although controlling both is best policy)

Page 4: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

+ nitrogen

+ phosphorus

+ nitrogen & phosphorus

No nutrients added

Oviatt et al. 1996

Page 5: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Seine and Scheldt Basins and Belgian coast of North Sea

North Sea

English Channel

Page 6: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

0

200

400

600

800

1970 1980 1990 2000 2010

ann

ual

mea

n d

isch

arg

e, m

3/s

0

500

1000

1500

2000

2500

3000

1970 1980 1990 2000 2010

TN

flu

x, k

gN

/km

²/yr

0

50

100

150

200

250

300

1975 1980 1985 1990 1995 2000 2005 2010

TP fl

ux, k

gP/k

m²/y

r

Seine River basinFreshwater discharge

TN load TP load

Page 7: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

0

10

20

30

1970 1980 1990 2000 2010

ma

x C

hla

, mg

/m3 Chlorophyll in

North Sea on Belgian coast

0

500

1000

1500

2000

2500

3000

1970 1980 1990 2000 2010

TN

flu

x, k

gN

/km

²/yr

Seine River N load

0

1000

2000

3000

4000

1970 1980 1990 2000 2010

TN

flu

x, k

gN

/km

²/yr

Scheldt River N load

Page 8: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

0

50

100

150

200

1900 1920 1940 1960 1980 2000

Ter

agra

ms

of

nit

rog

en

Natural N fixation on the continents

Total humaninputs

Fertilizer

N fixation in agro-ecosystems

Fossil fuel burning

Global trends in nitrogen use per year

(modified from Howarth et al. 2005)

Page 9: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Regional scale perspective important for nutrients.

Changes are driven by global energy and agricultural policies.

But with exception of N2O, nutrient cycles are altered at local to regional scales, not global scales, and effects are manifested at these local to regional scales.

Page 10: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

New York Times (4/30/08)

Townsend & Howarth 2010

Page 11: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

0 500 1000 1500 2000

1

2

3

4

5

6

7

8

9

Series1

Republic of Korea

North Sea watersheds

Northeastern U.S.

Yellow River basin

Mississippi River basin

Baltic Sea watersheds

St. Lawrence River basin

Southwestern Europe

Labrador and Hudson’s Bay

Natural background flux

Flux of nitrogen from the landscape to coastal oceans in rivers for contrasting regions of the world in the temperate zone (kg per km2 of watershed

area per year; from Howarth et al. 2005).

Page 12: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Kg N km-2 year-1

NorthAtlanticOcean

International SCOPE N Project(Howarth et al. 1996)

NANI(net anthropogenic N inputs)

Page 13: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

(Howarth et al. 2012)

~ 150 watersheds on two continents

~ 25% of NANI exported to coastal oceans on average from 150 watersheds in Europe and the US

Page 14: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Swaney et al. 2012

Chinese watersheds

Page 15: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

(Hong et al. 2011)

Page 16: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

NOy deposition Fertilizer Ag N fixation Net food & feed

NANI

Hong et al., 2012

Page 17: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Region

Nutrient fertilizer

consumption (kg N/capita,

2009)

NOx Emission

(kg N/capita,

2000)

N fixation and net flux of N in food

and feeds

Sum of Reactive Nitrogen

(kg N per

capita)

Consumption relative to

safe operating boundary

Africa 2.5 0.9 ? 3.4 0.7

South America 12.2 1.2 ? 13.4 2.6

Southeast Asia 12.7 0.7 ? 13.4 2.6

India 13.0 0.5 ? 13.5 2.6

North America 35.9 9.6 ? 45.5 8.9

Europe 18.4 3.1 ? 21.5 4.2

East Asia 24.3 1.2 ? 25.4 5.0

Australia 30.8 7.9 ? 38.8 7.6

Other 10.5 0.6 ? 11.0 2.2

Global 15.4 1.5 4.6 21.5 4.2

Per capita NANI by region (partial analysis)

UNEP Sustainable Resource Use Panel (2011 draft)

Page 18: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Technical solutions for nitrogen pollution:

• Agricultural fields: reduce fertilizer amount and timing; change cropping systems; plant winter cover crops; control drainage seasonally

• CAFOs: treat wastes as society does for human waste

• Vehicle exhaust: tighten emission standards; encourage hybrid vehicles and electric vehicles

• Power plants: tighten emission standards; encourage renewable electricity (solar, wind)

• Sewage treatment: require denitrification treatment

Howarth et al. (2005) Millennium Ecosystem Assessment

Page 19: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

But also think about policy solutions, particularly regarding diet and biofuels….

Page 20: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

FieldLevel

Leached to water

Harvested in crops

3.6

10.5

0.2 (4.2)(1.2)

1.3

5.9

(3.1)

AnimalConsumption

Leached to water?Denitrified?

NH3

1.9

Denitrified?Building up in soil?NH3

Landfilled?Leached? Landfilled?

Denitrified?

(0.8)

1.4

Wastewater&

Denitrified

Human Consumption

0.9

Exported from U.S.

2.1

18.5

(Howarth et al. 2002)

Farm nitrogen balance for US (~1995; Tg per year for entire US)

Page 21: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

If everyone in the US ate this:

Instead of this:

The country would use only 1/3rd as much fertilizer, and would have much less nitrogen pollution!

0.02.04.06.08.0

10.012.014.016.018.020.0

1960

1970

1980

1990

2000

2010

2020

2030

fert

iliz

er u

se, T

gN y

r -1

increasing grain exports,standard US dietconstant grain exports,standard US dietconstant grain exports,Swedish dietconstant grain exports,Mediterranean diet

(Howarth et al. 2002)

Page 22: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Howarth et al. 2009

Global Production of Liquid Biofuels:

0

200

400

600

800

1000

1200

1975 1979 1983 1987 1991 1995 1999 2003 2007

Year

Pe

ta J

ou

les

Ethanol

Biodiesel Equiv.

15 billion liters

Biofuels

Page 23: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

2009: National goal to reduce nitrogen pollution down Mississippi River by 45% to limit size of dead zone.

Several models indicate national ethanol policy will make this difficult or impossible, and instead nitrogen pollution likely to increase…. 30% to 40% or more (Donner and Kucarik 2008; Simpson et al. 2008, 2009; EPA 2009; Costello et al. 2010)

Page 24: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

2.0

1.0

0

Predicted Nitrogen Load from Mississippi River basin to meet US Ethanol TargetsM

illio

n to

ns n

itrog

en p

er y

ear

No biofuels

EtOh fro

m corn

plus cellu

losic

(corn st

over)

EtOh fr

om corn

plus cellu

losic

(switc

hgrass

)

Cellulosic

EtO

h only

(switc

hgrass)

2015 targets

2022 targets

(Costello et al. 2010)

National target to reduce area of Dead Zone

Page 25: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

CONCLUSIONS:

Nitrogen is the primary culprit.

Nitrogen pollution is growing globally, with agriculture as the primary driver.

Technical solutions exist, and can help, often at little cost.

But policy considerations of diet (meat!) and energy (liquid biofuels!) are critical.

Page 26: Robert Howarth  Cornell University Ithaca, NY   USA Ocean Hypoxia and its Impacts on Ecosystems

Thanks for invitation to participate!

Coastal Hypoxia Research Program

Agriculture, Energy & Environment Program at

Cornell University

Thanks for many collaborators, especially:

• Dennis Swaney• Bongghi Hong• Roxanne Marino• Christine Costello• Gilles Billen• Josette Garnier• Christoph Humborg• Alan Townsend