geos 110 fall 2011
DESCRIPTION
GEOS 110 FALL 2011. SEA ICE. Polynyas – openings in the ice. Persistent, forming year after year 2 types: Sensible & Katabatic. Polynyas – openings in the ice Katabatic – Dense Drainage Winds. - PowerPoint PPT PresentationTRANSCRIPT
GEOS 110 FALL 2011
SEA ICE
Polynyas – openings in the ice
• Persistent, forming year after year
• 2 types: Sensible & Katabatic
Polynyas – openings in the iceKatabatic – Dense Drainage Winds
Understanding and Projecting the Changes in the Oceanic Conveyor Belt is a Critical Question for
Science
The North Atlantic Current provides about 60% of the inflow to the Arctic Ocean bringing warmer water from the Atlantic Ocean. Some water also moves into the Arctic Ocean from the Bering Sea and the Pacific Ocean, by way of the Bering Strait.
Water flows from the Arctic Ocean into the Pacific and Atlantic Oceans, as well as into a number of surrounding seas. By far, the greatest volume of water leaves the Arctic Ocean through the passage between Greenland and Spitsbergen.
Arctic inflow Arctic outflow
Minimum arctic sea-ice extent from 1979 to 2007
observations vs. models
observed sea ice decline is 50 years ahead of expectation frommodels forced by GHG’s (and other human and natural radiativeforcings discussed earlier) suggesting models do not capture allrelevant interactions
IPCC FARmodelensemble
mean ofall models
“A linear increase in heat in the Arctic willlead to a non-linear, and accelerating,loss of ice”
impacts of an summer-ice free Arctic ?
• sharply warmer Arctic Autumn andWinter from increased O-A heat fluxes(polar amplification of warming)
• local ecological and human impacts
• altered weather patterns outside theArctic (due to altered patterns of heatingand pressure)
• altered salinity and ocean circulation
no evidence of summer-ice free Arctic inlast million years