What role does the Ocean What role does the Ocean play in Global Climate play in Global Climate

Change?Change?

The Global GreenhouseThe Global Greenhouse

Balancing the Earth’s Heat BudgetBalancing the Earth’s Heat Budget

Heat Budget© The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

How the Greenhouse Effect WorksHow the Greenhouse Effect Works

Emission Spectra of Sun and Earth and Emission Spectra of Sun and Earth and Absorption Spectra of AtmosphereAbsorption Spectra of Atmosphere

Interplanetary Comparisons:Interplanetary Comparisons:

Venus:Venus: Higher concentrations: 400 Higher concentrations: 400o o CC

Mars:Mars: Lower concentrations: -50 Lower concentrations: -50o o CC

Intergovernmental Panel on Climate Change Intergovernmental Panel on Climate Change (IPCC)(IPCC)

• Established by the UN and World Meteorological Organization in Established by the UN and World Meteorological Organization in 19881988

• Mission of the IPCC: to assess the scientific, technical, and socio-Mission of the IPCC: to assess the scientific, technical, and socio-economic information relevant for the understanding of the economic information relevant for the understanding of the

risks of human-induced climate changerisks of human-induced climate change

• 2,500 of the world’s leading climate scientists and technical 2,500 of the world’s leading climate scientists and technical experts contribute to reportsexperts contribute to reports

• Provides comprehensive and balanced assessments of climate Provides comprehensive and balanced assessments of climate change science, impacts, and adaptation and mitigation change science, impacts, and adaptation and mitigation optionsoptions

• Extensive peer-review and governmental review ensures scientific Extensive peer-review and governmental review ensures scientific credibility and policy relevancecredibility and policy relevance

Observed Changes in Greenhouse Gas Observed Changes in Greenhouse Gas ConcentrationsConcentrations

Predicted Increases in COPredicted Increases in CO22 Emissions and Emissions and

Concentrations (from IPCC SAR 1995)Concentrations (from IPCC SAR 1995)

Global Temperature and Atmospheric Global Temperature and Atmospheric COCO22 over Geological Time over Geological Time

• Current level of COCurrent level of CO22 is outside is outside

bounds of natural bounds of natural variabilityvariability

• Rate of change of CORate of change of CO22 is also is also

unprecedentedunprecedented

• Clear correlation between Clear correlation between atmospheric COatmospheric CO22 and and

temperature over last temperature over last 160,000 160,000 yearsyears

Observed Changes in Global Mean Temperature Observed Changes in Global Mean Temperature (measured and proxy data)(measured and proxy data)

*relative to 1961-1990 average*relative to 1961-1990 average

IPCC Global Mean IPCC Global Mean Temperature Predictions:Temperature Predictions:

• Global average temperature is Global average temperature is projected to increase by projected to increase by 1.5 to 5.5° C (2.5 to 10.4° F) 1.5 to 5.5° C (2.5 to 10.4° F) from 1990 to 2100from 1990 to 2100

• Projected temperature increases in Projected temperature increases in TAR are greater than those TAR are greater than those in SAR.in SAR.

• Projected rate of warming is Projected rate of warming is unprecedented for last unprecedented for last 10,000 years10,000 years

• 1861 to 2000:1861 to 2000:

Instrumental dataInstrumental data

• 1000 to 1861:1000 to 1861:

Proxy data Proxy data

• 2000 to 2100:2000 to 2100:

Model projectionsModel projections

Predicted Temperature Change Predicted Temperature Change in the Context of Last 1000 Yearsin the Context of Last 1000 Years

Observed Changes in Spatial Patterns of Land Observed Changes in Spatial Patterns of Land and Sea Surface Temperatureand Sea Surface Temperature

Surface temperature change between 20 year mean 1955-1974 and 20 year mean 1975-1994

Predicted Changes in Spatial Patterns of Land Predicted Changes in Spatial Patterns of Land and Sea Surface Temperatureand Sea Surface Temperature

Model-predicted surface temperature change by 2050

Atmospheric COAtmospheric CO22 and Sea Level Rise and Sea Level Rise

• Global average sea level is Global average sea level is projected to rise by 10 to projected to rise by 10 to 80 cm (4 to 35 inches) 80 cm (4 to 35 inches) between 1990 and 2100between 1990 and 2100

• Projected rise is slightly lower Projected rise is slightly lower than the range than the range

presented presented in the SAR.in the SAR.

• Sea level will continue to rise Sea level will continue to rise for hundreds of years for hundreds of years

after stabilization of after stabilization of greenhouse gas greenhouse gas concentrationsconcentrations

IPCC Global Sea Level Rise Predictions:IPCC Global Sea Level Rise Predictions:

Components of Sea Level RiseComponents of Sea Level Rise

• Thermal expansion and land ice melt after an initial 1% increase in COThermal expansion and land ice melt after an initial 1% increase in CO22

for 70 yearsfor 70 years• Eventually. most of sea-level rise will be due to thermal expansion of ocean, Eventually. most of sea-level rise will be due to thermal expansion of ocean,

not melting of icenot melting of ice

Predicted Changes in Annual Precipitation by 2050Predicted Changes in Annual Precipitation by 2050

The projected change is compared to the present day with a ~1% increase per year in equivalent COThe projected change is compared to the present day with a ~1% increase per year in equivalent CO 22

Increase in Extreme Precipitation Increase in Extreme Precipitation Events in the U.S.Events in the U.S.

0

1

2

3

4

5

6

7

Events

80 82 84 86 88 90 92 94 96 98

Year

Number of Billion Dollar Weather DisastersNumber of Billion Dollar Weather Disasters

Change in Phenomenon Confidence in projected change*

Increase in tropical cyclone peak wind and precipitation intensities Likely, over some areas

Increased summer continental drying & associated risk of drought

More intense precipitation events

Increase of heat index

Higher minimum temperatures, fewer cold days and frost days

Higher maximum temperatures, more hot days

Likely, over most mid-latitude continental interiors

Very likely, over most areas

Very likely, over many areas

Very likely

Very likely

Extreme Weather EventsExtreme Weather Events

*Judgmental estimates of confidence by IPCC: *Judgmental estimates of confidence by IPCC: very likelyvery likely - 90-99% chance, - 90-99% chance,likelylikely - 66-90% chance. - 66-90% chance.

• Economic losses from catastrophic weather events Economic losses from catastrophic weather events have increased 10-fold in recent decadeshave increased 10-fold in recent decades

• Increasing losses are due in part to socioeconomic Increasing losses are due in part to socioeconomic factors and in part to climatic factorsfactors and in part to climatic factors

• Because of expensive coastal development and Because of expensive coastal development and projection of more extreme events - insurance projection of more extreme events - insurance damages, claims, and costs are likely to increasedamages, claims, and costs are likely to increase

• Significant challenges in the future if high impact Significant challenges in the future if high impact events occur or if catastrophes are closely-events occur or if catastrophes are closely- spacedspaced

Impacts of Climate Change Impacts of Climate Change on Insuranceon Insurance

IPCC Policy-Makers Summary:IPCC Policy-Makers Summary:ObservationsObservations

• Human activities are changing the atmospheric concentrations Human activities are changing the atmospheric concentrations of greenhouse gases.of greenhouse gases.

• Extensive and wide-spread evidence that the earth has warmed Extensive and wide-spread evidence that the earth has warmed 0.3 - 0.6° C over the last century; however, this warming 0.3 - 0.6° C over the last century; however, this warming has not been uniform. has not been uniform.

• Global sea level has risen 10 – 20 cm over the last century.Global sea level has risen 10 – 20 cm over the last century.

ForecastsForecasts

• Global average temperature is projected to increase by 1.5 Global average temperature is projected to increase by 1.5 to to 5.5° C (2.5 to 10.4° F) from 1990 to 21005.5° C (2.5 to 10.4° F) from 1990 to 2100

• Global average sea level is projected to rise by 10 to 80 cm Global average sea level is projected to rise by 10 to 80 cm (4 to 35 inches) between 1990 and 2100(4 to 35 inches) between 1990 and 2100

• Likely to be an increase in extreme weather eventsLikely to be an increase in extreme weather events

IPCC History: Evolution of IPCC History: Evolution of Our KnowledgeOur Knowledge

• FAR (1990): “FAR (1990): “The size of the warming is broadly The size of the warming is broadly consistent with predictions of climate models, . . . but consistent with predictions of climate models, . . . but the unequivocal detection of the enhanced greenhouse the unequivocal detection of the enhanced greenhouse effect from observations is not likely for a decade or effect from observations is not likely for a decade or more.”more.”

• SAR (1996):SAR (1996): “The balance of evidence suggests a “The balance of evidence suggests a discernible human influence on climate.”discernible human influence on climate.”

• TAR (2001):TAR (2001): “There is new and stronger evidence “There is new and stronger evidence that most of the warming observed over the last 50 that most of the warming observed over the last 50 years is attributable to human activities.”years is attributable to human activities.”

Unpredictability: What if our Unpredictability: What if our models are not complete?models are not complete?

Greater warming, lesser Greater warming, lesser warming, but what about warming, but what about

cooling?cooling?

Example:Example: Shutdown of NADW Formation Shutdown of NADW Formation and Collapse of Ocean Thermohaline and Collapse of Ocean Thermohaline

Circulation?Circulation?