Why can we talk about climate 100 years from now when we can not even forecast the weather more

than a week?

Is stratospheric ozone depletion the same thing as global warming?

NO!

Stratosphericozoneabsorbsultravioletwavelengths.Alwayshas;Alwayswould- ifwedon’tdestroyit...

OZONEHASNOTHINGTODOWITHCLIMATE!(oratleastverylittlecomparedtothemainGHGs)

USEPA

WhatcausestheozoneholeoverAntarctica?

Fig.2-12,p.42

Hasn’t climate changed before humans even were important?

LGMSeaLevel&IceExtent21,000yearsago

ClimaticForcingsandTimeScale

orbital

(orbital)solar/ocean

solar/volcanic

greenhousegases/naturalvariability

YD

LIA

CausesofClimateChange

• TheSun(solaroutput– e.g.sunspots)

• OrbitalpositionofEarth(glacials)

• Volcanoes

• Tectonicprocesses:continentalpositionandtopography

• Greenhousegases(H2O,CO2,CH4,N2O,O3,CFCs)

• Aerosols(sulfates)

• Ocean’s“globalconveyerbelt”circulation

Have humans really changed the composition of the atmosphere?

Human-DrivenGlobalChange

Nov. 2016: 402 ppm

GreenhouseGasandAerosolTrends(AR4)

How much have we really actually warmed?

Figure19:NorthernHemispherereconstructedtemperaturechangesince200AD

Global temperature has not changed by more than 0.5oC/century

Hockey Stick and Medieval Climate Anomaly

Role of Interannual Variability (ENSO)

(Trenberth, K. and Faullo, J. T., 2013)

What are some effects of the warming?

https://www.youtube.com/watch?v=Vj1G9gqhkYA

Arctic Sea Ice Melt Video

https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4419http://www.climate-lab-book.ac.uk/files/2016/05/spiral_optimized.gif

Temperature Warming Video

https://www.carbonbrief.org/new-nasa-videos-show-stark-ice-loss-from-earths-ice-sheets

Ice Sheet Melt Video

Climate Extremes

(Climate Change Impacts in the United States, 2014)

Isn’t the warming just due to the sun?

ModelwithNatural/

AnthropogenicVariability

IPCC, AR4

CauseandEffect(AR4)

TroposphericWarming,StratosphericCooling

ClimateForcings (AR5)

from Realclimate

From skepticalscience

What might the future look like?

EmissionsScenarios(AR5)

ALookattheFuture:GlobalTemperature(AR5)

FutureSeaLevelRise(AR5)

Future Increasing Extremes

THC

GreenlandandAntarctica(AR5)

GlobalWarmingFeedbacks

• Clouds:Domorecloudsmeanmorewarming(+feedback)orlesswarming(- feedback)?:highvs.low,nightvs.day

• WaterVaporFeedback(+):tropics

• SeaIceAlbedoFeedback(+):highlatitudes

• LandSurfaceFeedbacks

Weathernotebookexercise

• Collect6hourlyanddailylocalweatherdatafromweb(weatherunderground– localweather– history)

(http://www.wunderground.com)• Useexceltoplotdataforweekormonth• TrackstormswithdailyU.S.weathermapsfromNOAANCEP

(http://www.wpc.ncep.noaa.gov/dailywxmap/)