Climate ChangeClimate Change

Bullshit or Not?Bullshit or Not?

How is such change reliable detected?

How can the agents of change be identified in a scientifically rigorous manner?

Limiting FactorsLimiting Factors

Climate Data is very noisy – hard to Climate Data is very noisy – hard to discern “natural” timescalesdiscern “natural” timescales

Past climate data has low time resolutionPast climate data has low time resolution Climate models do not know all the input Climate models do not know all the input

physicsphysics Grid models have too coarse of resolution Grid models have too coarse of resolution

to adequately account for the presence of to adequately account for the presence of clouds in the grid cell.clouds in the grid cell.

System Lag time!System Lag time!

Assumptions about our AtmosphereAssumptions about our Atmosphere

Its thinIts thin Its in hydrostatic equilibriumIts in hydrostatic equilibrium Its isothermal (where most of its mass is)Its isothermal (where most of its mass is) Equation of state is that of an ideal gasEquation of state is that of an ideal gas

These assumptions allow us to treat These assumptions allow us to treat the atmosphere as a thin, uniform the atmosphere as a thin, uniform slab of material at constant density slab of material at constant density and temperature. and temperature.

Equilibrium TemperatureEquilibrium Temperature

Planet radiates as a blackbody in TE with Planet radiates as a blackbody in TE with incoming solar radiation:incoming solar radiation:

A = Albedo; L = 1370 watts per sq meter

T = 278(1-A)4

T = 255K for A=0.32

This is not the right answer compared to observations

The Role of the AtmosphereThe Role of the Atmosphere

Fo = incident flux Ts = transmission percentage of short wavelength incoming radiation

Tt = transmission percentage of outgoing long wavelength radiation Fg = Flux from ground Fa = Flux from the atmosphere.

Fo = Fa + TtFg ; Fg = Fa + TsFo Let Fa = Fo –TtFg

Ultimately get that Fg = Fo

The transmission factors are set by atmospheric chemical composition which human activities are modifying

Our AtmosphereOur Atmosphere

TTSS = 0.9 = 0.9 (Highly transparent)(Highly transparent)

TTtt = = 0.20.2 (fairly opaque) (fairly opaque)

FFgg = 1.58F = 1.58Foo T Tgg = 255*(1.58) = 255*(1.58)1/41/4 = = 287K (limiting case T287K (limiting case Ttt =0; T=300K ) =0; T=300K )

Fa = 0.68Fo

Ta = 255*(0.68)1/4 = 245K

Net Effect: Surface is warmed above equilibrium temperature due to flux radiated by our atmosphere. Atmosphere is therefore below the equilibrium temperature.

Why is TWhy is Tt t Relatively Low?Relatively Low?

Methane: Broad absorption Methane: Broad absorption from 1.5 to 2.5 and 8-10 from 1.5 to 2.5 and 8-10

MicronsMicrons

Climate Forcing TermsClimate Forcing Terms

Changes in atmospheric composition Changes in atmospheric composition or properties that are equivalent to or properties that are equivalent to flux changes (in Watts/mflux changes (in Watts/m22))

Changes in Greenhouse gas mixtureChanges in Greenhouse gas mixture Changes in scattering propertiesChanges in scattering properties Changes in cloud cover, thickness, Changes in cloud cover, thickness,

and altitude.and altitude.

Estimates of Climate ForcingEstimates of Climate Forcing

Aerosols are Important but a Aerosols are Important but a very difficult mixed scattering very difficult mixed scattering

problemproblem

Pick a Model: 2100 COPick a Model: 2100 CO22 DoublingDoubling

Source of UncertaintiesSource of Uncertainties

Roles of clouds and aerosols in radiative Roles of clouds and aerosols in radiative transfer models? (e.g. scattering!)transfer models? (e.g. scattering!)

Role of tropical convection and the water Role of tropical convection and the water vapor feedback loop?vapor feedback loop?

How well do observations constrain the How well do observations constrain the input climate parameters?input climate parameters?

How to weight the inputs for best fit How to weight the inputs for best fit statistical model?statistical model?

Water Vapor Feedback

Understanding large scale convection in the tropics may be crucial this determines high cumulonimbus clouds

Effects could be significantEffects could be significant

Complete Feedback Models too Complete Feedback Models too Difficult to reliably constructDifficult to reliably construct

GEOPHYSICAL RESEARCH LETTERS, VOL. 32, L19809, 2005

Anthropogenic greenhouse forcing and strong water vapor feedback increase

temperature in EuropeRolf Philipona

Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Davos Dorf, Switzerland

Bruno DürrMeteoSwiss, Zürich, Switzerland

Atsumu OhmuraInstitute for Atmospheric and Climate Science,

Swiss Federal Institute of Technology (ETH), Zürich, Switzerland

Christian RuckstuhlInstitute for Atmospheric and Climate Science,

Swiss Federal Institute of Technolog

Those Pesky Swiss

Is Water Vapor Increasing?

Very difficult to accurately measure even with satellites calibration issues and strong seasonal variations plus El Nino fluctuations

But Tropics are everything:

The Potential Role of Methane

Global Warming Potential

TH = Time Horizon (20 or 100 years) Ax = increased forcing from X (Watts m^2 kg) x(t) = decay following some hypothetical

instantaneous release of X Denominator is relevant quantities for CO2

Methane GWP

A Methane molecule has an atmospheric lifetime of 12 +/- 3 years before its broken down through chemical reactions involving OH- (Leaving some CO2 as a by product)

On 100 year timescale GWP = 23 But, on 20 year timescale GWP = 62 Note that CO2 has atmospheric lifetime of 50-

200 years depending on SST.

Sources of Methane Emission

Rice

Cows

Sewage

Oil and Gas Production

Methane Tracks Population

A PUZZLE

So There is a Scientifically Plausible Case to be made for Potential Global Warming Based on Changing Atmospheric Composition

Can extant Data support this is actually happening now?

Poorest Evidence for Poorest Evidence for WarmingWarming

Problems with Mean Annual Problems with Mean Annual Temperature as and IndicatorTemperature as and Indicator

►How is it defined or measured?How is it defined or measured?►Role of Urbanization?Role of Urbanization?►Are measurements equally reliable Are measurements equally reliable

in time?in time?►Does this just reveal small natural Does this just reveal small natural

cycles that would be lost in more cycles that would be lost in more distant climate record?distant climate record?

Its not as simple as this

This is not the best chi^2 fit to noisy data

Those Crazy Swiss Again

Better Evidence for Climate Change

Latest Data

It May Even be Getting WetterIt May Even be Getting Wetter

Local Measurements May be the real smoking guns

Statistics of ExtremesStatistics of Extremes

Other IndicatorsOther Indicators

• Rapid Loss of Arctic Ice; Larson Ice Shelf

• Rapid retreat/loss of glaciers

• Increase vector borne diseases (insects)

• Worldwide coral bleaching

• Marine life migrations• Heat Waves• Earlier

Spring/Snowmelt• Increase

droughts/wildfires• Well documented rise

of sea level (from thermal expansion)

Ice Core DataNote: Time Resolution is Not Sufficient to reveal if CO2 Increases Cause Warming or Follow Warming

Using the Past as a Guide

Do Tipping Points Exist in Climate? Does the system have critical phenomena?

Or do the various and somewhat unknown feedback mechanisms serve to counter this?

Possible Tipping PointsPossible Tipping Points Permafrost Melt In Western Siberia and the Permafrost Melt In Western Siberia and the

release of vast amounts of stored methanerelease of vast amounts of stored methane As the southern summer limit of Arctic sea As the southern summer limit of Arctic sea

ice cover diminishes, the reflectivity of the ice cover diminishes, the reflectivity of the earth decreases and more heat is absorbedearth decreases and more heat is absorbed

The strength of the current in the Atlantic The strength of the current in the Atlantic Ocean between Africa and the east coast of Ocean between Africa and the east coast of America has slowed by 30 percent from America has slowed by 30 percent from 1993-2005 due to the sinking of cold, salty, 1993-2005 due to the sinking of cold, salty, dense waters in the North Atlantic Ocean.dense waters in the North Atlantic Ocean.

Reverse the Reverse the Thermohaline?Thermohaline?

Methane BurpsMethane Burps

Source of Bermuda Triangle Source of Bermuda Triangle DisappearancesDisappearances

Norwegian Coast landslide 8150 Norwegian Coast landslide 8150 years agoyears ago

More tippingMore tipping

COCO22 reaches 400 ppm (in 10 years) reaches 400 ppm (in 10 years) important to remember that COimportant to remember that CO2 2 mixes mixes out very slowlyout very slowly

COCO22 equivalency = 480 ppm (in 10 equivalency = 480 ppm (in 10 years) years) nominal 2 deg C response nominal 2 deg C response

Does this put us in an irrecoverable (on Does this put us in an irrecoverable (on the 50 – 200 year timescale) position?the 50 – 200 year timescale) position?

Methane is most serious potential Methane is most serious potential feedbackfeedback

The China ProblemThe China Problem

What About HurricanesWhat About Hurricanes

FrequencyFrequency IntensityIntensity Wind RadiusWind Radius TracksTracks

No connectionNo connection Length of time Length of time

over 83+ degree over 83+ degree waterwater

Some measure of Some measure of total power but no total power but no adequate temporal adequate temporal baselinebaseline

Currently under Currently under analysisanalysis