Major Feedbacks originatingfrom Northern Eurasia that

are of global change concern

Guy P. BrasseurNational Center for Atmospheric Research

Boulder, CO

Regions of Strong Influences on theGlobal Earth System

Schellnhuber

Vulnerability of the Carbon Cycle in the 21st Century

Permafrost

HL PeatlandsTr PeatlandsVeg.-Fire/LUC CH4 Hydrates

Biological PumpSolubility Pump

Hot Spots of the Carbon-Climate-Human System

Oceans

Land

GCP 2005

Recent Historical Climate Change

Global Temperature Trends: 2005 Summation

Understanding and Attributing ClimateChange

Anthropogenicwarming is

likely significantaveraged over

each of theinhabited

continentsObserved

Expected for allforcings

Natural forcingonly

Smoothed annual anomalies for precipitation (%) over land from1900 to 2005; other regions are dominated by variability.

Land precipitation is changing significantly over broad areas

Increases

Decreases

An ice free Arctic?

City Lights from Space

1979 2003

Changes inspring snow

cover

Widespreaddelays in lakeand river freezedates, whilebreakup isearlier, i.e., winteris shorter[Magnuson,Science, 2000]

Glaciers and frozen ground are receding

Area of seasonally frozenground in NH has decreasedby 7% from 1901 to 2002Increased Glacier retreat

since the early 1990s

Models of Future Climate Change

Change in Temperature

Frontier Research Center, Japan

A1B is a typical “business as usual” (2090-2099)scenario: Global mean warming 2.8oC;

Much of land area warms by ~3.5oCArctic warms by ~7oC; would be less for less emission

Future Global Warming

Figure TS-30

Updated:27 March 2007

IPCC Scenario with ECHAM5/MPI-OM

OCEAN / ICE

Abrupt Transitions in the Summer Sea Ice (NCAR Model)

ObservationsSimulated5-year running mean

• Gradual forcing results inabrupt Sept ice decrease

• Extent decreases from 80 to20% coverage in 10 years.

• Relevant factors:• Ice thinning• Arctic heat transport• Albedo feedback

• Winter maximum showssmaller, gradual decreases

“Abrupt”transition

Better Representation of the Ice Sheet

From Climate Models to EarthSystem Models

The Conceptual Framework

The Conceptual Framework

Climatechange

Air pollution

Climatechange

Air pollution

Earth System Framework

General Circulation Models

Regional Atmospheric Models

Chemical Transport Models

Ocean General Circulation Models

Ocean Biogeochemical Models

Dynamic Global Vegetation Models

Biophysical and Biogeochemical Models

Terrestrial Hydrology Models

Socio-economic Models

Climatechange

Air pollution

Climatechange

Air pollution

Introducing Life into Earth System Models

• To develop a modelling system for the biosphere,in its broadest terms, which can represent infunctional form how it is influenced by, and itselfinfluences, human activities and the climatesystem

• To establish a modelling framework that allowssuch a modelling system to be fully coupled withthe physical system.

Challenges for the Future

CLIMATE

(Gas-phase)CHEMISTRY ECOSYSTEMS

AEROSOLS GREENHOUSE GASES

Greenhouse Effect

CO2

Direct and Indirect Effects / Feedbacks on natural sources

CH4, O3,N2O, CFC

HumanEmissions

HumanEmissions

HumanEmissions

Land-useChange, Fires

Oxidants:OH, H2O2

HO2,O3

Fires: sootMineral dust

Biogenic Emissions:CH4,DMS,VOC’sDry deposition: stomatal conductance

N deposition03, UV radiation

The future: a full treatment of climate-chemistry-ecosystem-land surface feedbacks

LAND WATER / CITIES

Damming /Irrigation /Emission of heat

Heat island effect

Based on P. Cox, 2004

Feedbacks between the Euroasiancontinent and the global Earth system

• The water cycle, precipitation, run-off• Surface moisture, energy and vegetation• Snow cover/melt• The cryosphere• Permafrost and methane release• Vegetation and the carbon cycle• Dust and other aerosols• Fires• Biogenic emissions and air quality• Etc.

Water vapour from oceans

Some rain water“recycled”

Drainage to rivers

Evaporation &transpiration

affect sensibleand latentheat fluxes

Extraction ofsoil water by

roots

Rain

Effects of vegetation on climate via surface moisture budget

More reflection ofsolar radiation by

open land

More absorption ofsolar radiation

by forest

Effect of land cover change on climate

Transpiration

Surface runoff

Subsurface runoffInfiltration

Surfaceevaporation

Precipitation

CO2 rise, climate change and the hydrologicalcycle

Affected byclimate change

Also affecteddirectly bychanging CO2

concentration(“PhysiologicalForcing”)

Gas/oil production Agriculture

Organic aerosolprocesses

Photo-oxidantprocesses

Cloud processes

CarbonCycle

NitrogenCycle

Water & EnergyCycles

Ozone and Ndeposition

NO/NH3emission

CO2H2O NOy

NH3

Precipitation andsolar radiation

Latent andsensible heat

Biologicalparticles andVOCemissions

Insect outbreaksDisturbances:

Net Primary Productivity

Carbon ClimateInteractions

Pre-industrial carbon fluxes(positive upward)

[gC/day m2]

uptake release

January July

Feedback

Atmospheric CO2

Atmospheric CO2 Difference

C4MIP (IGBP/AIMES)

positive feedback negative feedback

Difference in carbon uptake between experiments(with minus without carbon cycle - climate feedback)

[kgC / m2]

2100

Summary

Carbon-climate feedback is positive: + 83 ppm in 2100IPSL (Friedlingstein et al., 2001): + 75 ppmHadley Centre (Cox et al., 2000): + 250 ppm

This is caused, predominantly, by reduced NPP at low latitudes(GPP is unchanged but autotrophic respiration is enhanced)

At middle and high latitudes the carbon uptake is larger in the climatechange experiment, because the increase in NPP is larger than thedecrease in soil carbon uptake (heterotrophic respiration is enhanced inthe warmer climate)

The carbon uptake by the ocean is almost identical in both experiments(exception: reduced uptake in the North Atlantic due to a weakening ofthe THC in the warmer climate)

Challenges for the Future

• Better quantify the different processes affecting theglobal carbon cycle.

• Study biogeochemistry of the land-atmosphereinterface, and couple it to the hydrological cycle,human perturbations, and climate changes

• Couple the carbon cycle with other biogeochemicalcycles (e.g., nitrogen).

• Consider a potential positive methane climatefeedback

From 1860 to Present

Grain Production

Meat Production

EnergyProduction

Changes in nutrient loading

Humans have already doubled the flow ofreactive nitrogen on the continents, and someprojections suggest that this may increase byroughly a further two thirds by 2050

Estimated Total ReactiveNitrogen Deposition from the

Atmosphere

66 77

88

0.30.3

66 99

1111 881515

2727

NONOyyNN22 NHNHxx

55 66

NONOyyNN22 NHNHxx

2121 2525

1616

2525

55

3333 2323 2626

66

3939

5454

1818

100100

N2 + 3H2

2NH3

The Global Nitrogen Budget in 1860 and mid-1990s, TgN/yr18

60m

id-1

990s

110110

120120

Galloway et al., 2002b

Dynamic Global Nitrogen Scheme

Plant N Pool

Litter N Pool

NH3

NH4+ NO3

- NO2-

Soil Organic N Pool

Soil Inorganic N Pool

NH3

LitterFall

Uptake N2O

NO

NON2ON2

AssimilationMineralization

Mineralization

Mineralization

Nitrification

Denitrification

NaturalN fix

NDeposition

Volatilizaiton

Leaching

XuRi et al., MPI, 2005

CH4 from space in August through Nov. 2003.

From J. Burrows, Univ. of Bremen

Frankenberg et al., Science, 2005 (Science Express 17th March)

Methane allocation andtransport

anaerobic horizon

micro-aerobic horizon

aerobic horizon water table level

decomposition of dead organic matterdecomposition of dead organic matter

rootrootexudationexudation

entrappedgas bubbles

dissolved CHdissolved CH44

acetate, COacetate, CO22, H, H22

vasc

ula

r tr

ansp

ort

vasc

ula

r tr

ansp

ort

dif

fusi

on

dif

fusi

on

ebu

llit

ion

ebu

llit

iono x i d a t i o no x i d a t i o n

gaseous CHgaseous CH44

m e t h a n o -m e t h a n o -g e n e s i sg e n e s i s

↑ E M I S S I O N ↑

rootrootoxidationoxidation

OO22

Aerosols and Climate

Springtime aerosols over Eastern Asia, 2007

March 30

March 31

March 31 marked openingceremonies for the first“Green China Day”established to increaseawareness of the need forenvironmental protection.

However, the ceremony inBeijing saw an unwelcomeguest: Gobi Desert dust.Roughly 2,000 kilometerssouth of the capital city, airquality also suffered, in thiscase from fires in SoutheastAsia.

Global Aerosol Distribution

From: Ph. Stier; Animation: M. Boettinger, DKRZ

Climate Responseto Potential

Improvement in AirQuality

• In blue: GHG unchangedafter year 2000(commitment experiment).

• In Red: GHG unchangedand anthropogenic sulfateaerosols removed after year2000 (sensitivityexperiment).

(K)

(%)

Changes in the Short-wave radiative energy(Wm-2) in response to

sulfate removal(30 year average)

•Removal of aerosols leads toanomalous radiative heating inindustrialized regions.

•Cloud radiative forcing is positivein a warmer and cleaner tropicalatmosphere where clouds are lessabundant.

•Cloud reflection at high latitudes isincreased due to enhanced cloudformation in areas where sea ice ismelting.

Response inTemperature and

Precipitation(30 year average)

• Temperature increase largerthan 1K over the continents,larger than 4K in the Arctic.

• Temperature and precipitationchanges bear someresemblance with greenhousewarming experiments

• A significant increase inprecipitation is found in EasternPacific, suggesting an El-Ninolike change in the mean climatestate.

Challenges for the Future

• Address fundamental uncertainties in ourunderstanding of aerosol microphysics, chemicalcomposition of aerosols, aerosol-cloud interactions,indirect climate effects, etc.

• Assess in particular the role of organic aerosols.• Develop appropriate field campaigns, laboratory

experiments, and physical models to provide thebasic knowledge required to study the aerosolclimate interactions.

• Investigate the role of aerosols in the earth system:impact on the biosphere, on the ocean, the carboncycle, etc.

Research Challengesfor Tomorrow

Atmospheric Composition

AtmosphericChemistry

OceanCarbonCycle

Human Activities

EnergySystem

OtherHuman

Systems

Agriculture,Livestock

and Forestry

CoastalSystem

TerrestrialCarbonCycle

UnmanagedEcosystem

Crops andForestry

Hydrology

Ecosystems

Climate and Sea Level

Climate

Ocean- temperature

- sea level

Global Change Interactions

Demand

Natural &ManagedEcoystems

IndustrialMetabolism

Demand

Emissions Radiative Forcing

Emissions

AtmosphericComposition

Impacts

Impacts Impacts

RisksRisks

ClimateDynamics

Perceptions

Human Behaviour& Well-Being

Costs &Benefits

Costs &Benefits

Geoengineering

Conservation

DisasterManagement

Compensation

Adaptation

Investment

Education

MitigationAdaptation

Mitigation

StrategicDecisionMaking

From: H.-J. Schellnhuber

Hot Topics for Future Research

• Interfaces between components of the Earth System.• Global water and biogeochemical cycles• Hot spots and teleconnections in the Earth System• Integrated interdisciplinary regional studies (inc.

social systems)• Integration of scales: from nano-processes to global

evolution.• Research towards operational systems for monitoring,

and predicting the evolution of the Earth System ondifferent timescales (data assimilation).

Thank You