Arctic albedo loss and feedbacksPresentation Transcript
Arctic ‘albedo’ reflective coolingand its +ve feedbacks
One feedback, the ‘albedo flip’ property ofice/water, provides a powerful trigger mechanism.A climate forcing that ‘flips’ the albedo of asufficient portion of an ice sheet can spark acataclysm.Climate change and trace gases JAMES HANSEN et al 2007
Three large sources of Arctic albedo cooling> Far North snow cover > Summer sea ice extent > Greenland ice sheet surface Snow Sea Open ice ocean Exposed land 2012 record Arctic summer sea ice loss
Arctic summer albedo is the ‘air conditioner ‘ for the entire Northern hemisphere
Loss of Arctic cooling is the first of a series of strong Arctic +ve (bad) feedbacksArctic climate positive (bad) feedbacks are caused bythe very rapid warming of the Arctic region due toglobal warming, which is now 3 to 4 times the rate ofglobal warming.The effect of the multiple Arctic feedbacks is to amplifythe Arctic warming, Northern hemisphere warmingand to some extent global warming.The Arctic +ve feedbacks us1. Snow albedo spring summer cooling loss of (aboutthe same warming as sea ice loss).2. Sea ice albedo summer cooling loss of the sea iceLoss of, would be about one third of the warming byCO2. The extent is about the same as the permafrost.3. Peat rich wetlands warming increases emissionsof methane (70 times CO2 warming over 20 years).4. Permafrost methane emissions from thawing(permafrost has double all atmospheric carbon).5. Permafrost nitrous oxide emissions from thawingcryoturbation.6. Methane hydrate - Emissions of methane fromdestabilized ‘melting’ sea floor frozen solid Arcticmethane gas hydrates (1 to 2 times atmosphericcarbon).
All Arctic sources of feedback methane emissions are releasing moremethane, in relatively small amounts today- but this will be greatlyincreased with continued rapid loss of Arctic snow and ice albedocooling.
Loss of Arctic cooling is the first of a series of strong Arctic +ve (bad) feedbacksThe loss ofArctic snow and Warmingsummer sea ice peat richalbedo, by wetlandsincreasing Arcticwarming, willincrease therate of Arctic Thawingmethane (and permafrostCO2) feedbackemissions,and the rate of Melting seaGreenland ice floorsheet melting methane hydrate
The loss of Arcticalbedo is a+ve feedbackSnow and icereflect almostall incomingsolar energyback out tospace .Snow is thevery bestreflectorthere is.
Arctic summer sea ice albedo coolingLess sea ice extentMore thin iceMore dark openwater Open Sea ocean ice 2012 record Arctic summer sea ice loss
Thin firstyear ormelting icehas lessalbedo thanthick multiyear ice.Thereforethinning ofthe ice as wellas decreasingice extentreducesalbedo. Thin ice less albedo
Feed Dark open ocean water is the best absorber of heat energy there is. back It absorbs almost all the incoming solar energy as heat.Dark oceanwater opens This warms the Arctic surface sea water andup as sea ice the air above it.melts awaywhichabsorbsHeat. . Dark open water
Feed backMelting icerequires atremendousamount of energyto force thephysical phasechange of solidice to liquid Latent heatwater. of ice This is using up alot of the solarenergy during theArctic summer ,that will becomeavailable to causemore surfacewarming as moreice is melted.
FeedbackThe layer of intact seaice insulates the oceanwater from warmer airabove in the Arcticsummer. Insulating layer of seaAs sea ice melts this ice and snowinsulation is lost.
Loss of Arctic snow and summer sea ice albedo positive feedbacks Dark open water Thin ice less albedo