T'tlI CO2 GREENHOUSE UPDATE 1985

o Lamont-Doherty Research

. CRSL Research+ Contribution to DOE State of the Art Report* Oceanic effects on transient climate change

o Budget Status, Proposal

o DOE and other reports

o Recent research developments

October 4, 1985New York CityB. P. Flannery

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LAMONT-DOHERTY PROGRAM 1985 PROGRESS REPORT

SEASONAL STUDY OF THE CO2 AND TRACER DISTRIBUTIONS INTHE HIGH LATITUDE ATLANTIC, W. Broecker and T. Takahashi

. Goal: gain better understanding of the air-sea exchangeof CO2 in high latitude surface waters

. First systematic study of seasonal CO2 chemistry in North Atlantic

o Field studies complete March 1985

. Related studies+ North Pacific (DOE support)+ South Pacific (EXXON, DOE)

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SAMPLING POSITIONS IN THE NORTH ATLANTIC

. Transport Freight Limited ships, Greenland stations

EXXON/IFL N()BIH RILRNIIC PNOJECI

LARGE SEASONAL VARTATTON rN P(CO2)

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. Previously only summer data available, low valuesassumed to persist all year

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PRINCIPAL FINDINGS, CONCLUSIONS

. Large, unexpected seasonal variation in P(CO2) in high latitudesurface waters

. Standard thermodynamic models for CO2 variationcannot explain observations

+ Biology and mixing required

. lmplication for CO2 uptake by ocean two sided+ Lower exchange from air to surface ocean+ Higher exchange from surface to deep water

. Results need to be assessed in quantitative models ofoceanic carbon cycle

AVATLABLE COMPTLATTON OF OCEANTC p(CO2)

. GEOSECS data (Atlantic 72, Pacific 73, lndian 78)

. No information on seasonal variation

. Much additional data acquired, but not compiled

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" LAMONT PROPOSAL 1986: SEASONAL AND GEOGRAPHICALMAP OF P(CO2) tN SURFACE WATERS

o Compilation of seasonal P(CO2)map+ All available data+ 10 x 10 degree grid* February, August

. Objectives+ Differentiate regional behavior, important effects+ Develop a seasonal modelto explain variation+ Re-examine oceanic carbon cycle

DOE STATE-OF-THE-ART REPORTMODEL PROJECTIONS OF TIME DEPENDENT RESPONSE

TO INCREASING CARBON DIOXIDEMJ. HOFFRERT (NYU) and B.P. FLANNERY

. Observational data for modern climate (1850-1980)

. Elements of transient climate models

. Disagreement among results for steady state models

. Hindcasting for model verification

e Forecasting of future change, first effects

r Conclusions and Recommendations

HISTORICAL DATA FOR TRANSIENT MODEL VERIFICATIONVARIATION OF GLOBAL MEAN TEMPERATURE 1880.1980

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1880 r89s r0t0 t025 r0a0 rg55 r0ro r0E5-{r3

YEAR

. Temperature change +0.5 C (1980-1880)

. Factors besides CO2 must operate* volcanoes, solar variability, oceanic upwelling

o Other archived data exist, Sea lce, Regional Temperature, ...+ Less reliably predicted by models+ Display more variability, as measured

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Ch.nges ot Oc.an aas'nShap.. Saln'lt. alc

ELEMENTS OF STEADY STATE AND TRANSIENT MODELS

Steady State response CO2 addition* lR decreases, temperature rises+ Additionalfeedbacks

- Atmospheric water vapor- Snow/ice cover- Cloudiness amounts, types

r Transient evolution, timescales+Land, 1 week+Atmosphere, 1 month+Ocean mixed layer, 8 yrs+Deep ocean,(1 -.10) thousand yrs

GENERAL CIRCULATION MODELS DISAGREE ONSTEADY STATE RESPONSE 2xCO2

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. Basic results+ Global mean temperature rise 1.5-4.S C* Warming greater at poles

. Major disagreement between models

. Sources of disagreement+ Treatment of oceanic transport* Treatment of cloudiness feedback

. Recent models show 4-5 C Global warming+ lnclude other trace gasses

DOUBLED CO2

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YEAR

r Models claim to detect CO2 effect, but requiredother types of forcing* volcanoes, solar variation, (oceanic upwelling)

o Spurious agreement in conclusions+ Treatment of forcing differs* Observational data differs

o Consensus view CO2 warming not yet confirmed by observation

FORECASTING RESULTS/ PREDICTION AND FIRST EFFECTS

. Requires forecast of future CO2 emissions

. Ocean delays CO2 warming+ As yet unrealized warming could be substantial

o Results from General Circulation Model still unavailable+ lnclusion oceanic transport challenging task

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coNcLUS roNS/RECOMMENDATTONS

o Modern climate is forced by factors other than CO2

. Oceanic response delays warming by at least 10 years

. Consensus prediction 1 C warming (1860-200 O), 2-5 C (2100)

o To date models do not provide unique forecasts. Model development:

+ GCM results display substantial discrepancies* Research requires a hierarchy of climate models+ Reliable GCM results are at least 10 years away

o Must develop improved understanding of oceanic transporto Must develop observationally based strategies for model verification

CR RESEARCH 1984-85

. Continuing role in the environmental impact assessmentof the Natuna Gas Project

. Preparation of the "Transient Climate Models" chapterof the DOE State of the Art Report on CO2 Research

. Role of oceanic effects on climate change+ Collaborative development of a sophisticated Energy

Balance Climate model (Livermore, NYU)+ Studies of thermal lag from oceanic effects

EMERGING DILEMMA FOR CLIMATE MODELS:WHY HASN'T WARMING BEEN OBSERVED?

. Recent GCM models predict greater sensitivitywarming 2xCO2 (1 850-1 980)

2-3 C 0.8 C marginally detectable4-5 C 1.6 C readily detectable

. Proposed solution, delay from oceanic thermal bufferingmuch greater than found in previous studies

. Requires strong thermal coupling between surfaceand deep ocean

MODELS INCLUDING ENERGY TRANSFER TO DEEP OCEANPREDICT LONG DELAYS FOR ATMOSPHERIC WARMING

. Purely Diffusive (PD) Model (Hansen 1984)5

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o Pattern of global response* Average lag time 125 years90

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THE UPWELLING DIFFUSION MODEL FOR HEAT TRANSFERINTO THE MIXED LAYER AND DEEP OCEAN

. Schematic of model (Hoffert, Callegari, Hseih 1gg0)

. Timescales+ Mixed layer heat exchange, 10 years (heat capacity)+ Diffussion time 5000 years+ Upwelling time 1000 years

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uPWzulNG DlFFusloN (uD) nxo punEr-v orrrusrvE (pD) M.DELS

o Orrent climate, average surface temperature 15 C

e lvlodels with 3 C strface warming

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COMPARISON OF STEADY STATE SOLUTIONSUPWzuING DIFFUSION (UD) AND PUREr-V Orr_rUSrVE(PD) MODELS

o Curent climate, average surface temperature 15 C

o Temperature change vs+ PD models requiredepth for 3 C surface warrningmaximum heating

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TRANSIENT EVOLUTION, COMPARISON WITH HANSEN

o Addition of upwelling decreases response time

. Recalibrate Diffusion coefficient using UD model

. Lag time decades

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HISTORICAL AND FORECAST CO2 INCREASE 1850-2100

o CO2 record and forecastsfrom Weubbles (SOA Report)

o Corresponding change in equilibrium temperature+AT=AT(2xCO2)xln(CO2 ppm/540 ppm)

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TEMPERATURE CHANGE WITH UD MODEL

. Surface temperature variation+ Lag time 30 years in 1983

but increases with time(poorly defined concept)

. Profile of ocean warming (year 2100)

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Depth (meters)

TEMPERATURE CHANGE FOR VARIOUS CO2 FORECASTS

. Surface temperature variation+ (1850-1985) 0.52 C+ 1 C warming (2007, 2018,2033)

. Lag time decades, not hundreds of years

W=4K= 3000AT(2xCO.)= 2.5

CONCLUSIONS FROM 1D OCEAN MODEL

. Purely diffusive models overestimate response time* lmproper steady state solution+ Overestimate diffusion coefficient

. Lag time poorly defined concept to expressdelay in warming caused by oceans

. Response delayed by decades, 30 years, not centuries

. Simple models can contribute to understanding of oceanic effects

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CO2 GREENHOI.JSE BUDGET, PROPOSAL

CR EFFOFf,

Professional timeConsultants/R.rchased ResearchTravelOther

TotalCR

Lamont-Doherty

Total

Projected1985K$

1321474

Proposed1986K$

'14035105

190

60

250

157

93

250