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Geography Lecture #7 - November 21 - 2013.docx

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Geography 1400F/G
Anthony Weis

-IPCC assessments and projections of 2007 were far off from the models and projections – one far off predication was the artic sea ice melt -IPCC predicted no sea ice by end of century of Artic…this could happen within the next decade -max sea ice melt is getting smaller and smaller every year -this year had more ice than last year -2012 smashed record of 2007 of max sea ice melt (2007 also smashed previous record of melt) -smaller ice surfaces mean more dark surfaces exposed to absorption -artic ice is quarter of it was 30 years ago -expansions and contraction of ice is artic is important in ocean’s surface currents and volume -climate change is happening very fast in the artic and indigenous/Inuit’s people have been seeing changes for decades. Their culture is refined to knowledge of water and ice -reported changes are very high -average world surface temperature is 0.8C from warmer pre-industrial temperatures and it is double in the artic -Middle of this century – it will be 4-5 degrees warmer than what it was in 2007. Projected warming is greater -Albedo (reflection) – white bright surface (ice) reflect a lot of solar radiation. Less ice means more solar radiation absorption in land and water -NASA major player in understanding climate change – satellite images and imagery of the Artic -Carbon and methane bomb – how much carbon and methane is in the permafrost. Some estimates say there are 1.5 trillion tons of hydrocarbons (carbon or methane) in the permafrost. This could massively accelerate predictions being modelled -Ice story – important on ocean circulation -Climate change is like miners canary – prior to technology they would send canaries into mines, if they survived they knew the air was safe. Canary was an early warning system, and this artic was identified as one in the 1980-90s. it hints at changes and positive feedbacks (methane, carbons, heat) -methane bomb (acceleration of ocean and surface temperatures) is happening in Siberia – fear that warming will be beyond repair -extreme ice survey looks an documents changes in ice -climate change is turning into tourism – in Greenland there is the massive thawing of ice sheets -basic controls of climate is the tilt – insolation received at poles (way less than at equator). Pole high is like subtropical high – it is very dry and very cold (a lot of cold descending air). Hadley cells lose moisture as they move northward and southward. Subtropical highs lose a lot of moisture, and its deposited in ITCZ. Ferrell cells, move dry air from subtropical. Polar Cells (Polar high pressure zones – cold and dry air) -at poles there is low angle sunlight and less solar radiation energy per sq. /m. The tilt of earth means that there are points in the orbit that there is little to no sunlight (during the winter). In the course of human history atmospheric concentrations of CO2 has been between 180-310PPM (we are now past 400PPM). Ice is shiny so it reflects and cools (positive feedback for cooling and warming). The earths poles are cryosphere (portion of hydrosphere which is frozen). Most of the cryosphere is in the poles and contains a lot of fresh water (which relates to ocean circulation…what fresh water will do to the chemistry of oceans water). Almost 4/5 of world’s fresh water is frozen (but it’s frozen). Most of this fresh water is in ice sheets (Greenland and Antarctica) -what is under ice – in the arctic circle there is a low lying ocean shelf (ocean circulation can be affected). Greenland is main landmass in arctic region. -Antarctica is continent. Ice sheet covers land mass, and a shelf is ice that hangs over top of landmass and over water (permanently). Greenland and Antarctica has huge ice sheets and shelves (shelves disappear first). South pole there is a huge land mass, meaning it is warming at a much lower rate than Arctic -arctic ecosystem is very dependent on sea ice. Phytoplankton move with expansion and contraction of sea ice. It goes into Hudson Bay, Newfoundland and Siberia -expanding sea ice means moving species (phytoplankton is near edge of sea ice) -glacier ice is long-term sheet ice – glacier is constantly growing ice that it melts (glacier shape based on accumulation and precipitation). Accumulation zone is at the top and loss of volume is at the bottom -20,000 years ago ice sheets were massive and sea level was low and glacial mass was huge NEXT DAY -glaciers are dynamic, constantly moving even if balance is relatively the same (mass of glacier is almost constant, and moving). There is a shift, mass of ice is moving (shaped by landscapes and the flow in the glacier) -glacier flows over long periods of time have advanced and retreated (soak up a lot of moisture or release a lot of water). Glacial advances are positive feedback in earths long term period (Malankovich theory) is helpful for the overall climate and atmospheric chemistry. Amplification of cooling from them (due to changing insulation) -glacial retreat is has more of a negative effect. Mt. Kilimanjaro, Himalayas, Greenland (cryosphere needs high latitude and elevation). Most of the cryosphere is around the poles. -lower latitudes need higher elevation to have snow – like the Swiss Alps and Canadian Rockies there
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