The Arctic Water Cycle Emma Rebecca Hale 1 March 2005 Photograph © Michael Hambrey The Arctic Water Cycle Emma Sage Rebecca Hale Biogeochemistry 2 March 2005

The Game Plan Global and Arctic Water Cycles Global and Arctic Water Cycles Ice Sheets Ice Sheets Primary controls on the water cycle – global and Arctic Primary controls on the water cycle – global and Arctic Field Methods and Modeling: how we figure it all out Field Methods and Modeling: how we figure it all out In nature there are neither rewards nor punishments, there are consequences. – Robert Green Ingersoll In nature there are neither rewards nor punishments, there are consequences. – Robert Green Ingersoll Discussion Discussion

The Global Water Cycle

Global and Arctic Water Cycles Global and Arctic Water Cycles The Arctic Water Cycle

Arctic Ice Sheets Arctic Ice Sheets Arctic Rivers and Watersheds

Arctic Ice Sheets Arctic Ice Sheets

What Drives the Water Cycle? What Drives the Water Cycle? Precipitation solar radiation, Hadley cells, wind patterns, all those good things we talked about with Laura and Julie. Precipitation solar radiation, Hadley cells, wind patterns, all those good things we talked about with Laura and Julie. Ice wind! air temperature, ocean temperature, ocean currents, pressure oscillations Ice wind! air temperature, ocean temperature, ocean currents, pressure oscillations Ocean currents salinity, river discharge, temperature Ocean currents salinity, river discharge, temperature River discharge temperature, arctic ice/glaciers, human modifications River discharge temperature, arctic ice/glaciers, human modifications

Some Really Cool Big Patterns Arctic Oscillation – atmospheric pressure see-saw between upper and middle northern (~45N) latitudes Arctic Oscillation – atmospheric pressure see-saw between upper and middle northern (~45N) latitudes North Atlantic Oscillation – related to the AO, similar seesaw of pressure between Iceland and subtropical Atlantic North Atlantic Oscillation – related to the AO, similar seesaw of pressure between Iceland and subtropical Atlantic Debate whether these are part of the same mode or whether they are different. Debate whether these are part of the same mode or whether they are different. Time scales of these are debatable –paleoclimate studies show that neither seem to have had set schedules in the past, but they change about every 10 to 40 years Time scales of these are debatable –paleoclimate studies show that neither seem to have had set schedules in the past, but they change about every 10 to 40 years Right now both are in positive phases Right now both are in positive phases

Arctic Ice Sheets Arctic Ice Sheets Arctic Oscillation - some effects - Positive AO Low pressure over arctic Negative AO High pressure over arctic

Pacific Decadal Oscillation – major source of variability in sea surface temperature lasting years. Pacific Decadal Oscillation – major source of variability in sea surface temperature lasting years. Since 1990s has begun to go back into cool phase. Since 1990s has begun to go back into cool phase. Warm phase Cool phase

These Pressure and Temperature Oscillations… Control currents of air positive AO creates strong wind current circling the Arctic Control currents of air positive AO creates strong wind current circling the Arctic Effects on ice Effects on ice affect the heating and cooling of the ocean and therefore… affect the heating and cooling of the ocean and therefore… Thermohaline Circulation! Thermohaline Circulation! Circulation of ocean water based on temperature (thermo) and salinity (haline) Circulation of ocean water based on temperature (thermo) and salinity (haline) Temperature and salinity determine density of sea water and cause sinking and upwelling Temperature and salinity determine density of sea water and cause sinking and upwelling

Arctic Ice Sheets Arctic Ice Sheets

Atlantic Thermohaline Circulation

Changes in the Arctic Cycle AO and NAO have been in long positive cycles AO and NAO have been in long positive cycles caused by increases in GHG? caused by increases in GHG? Surface air temperatures are increasing accelerate water cycle Surface air temperatures are increasing accelerate water cycle Increase in freshwater discharge to Arctic Increase in freshwater discharge to Arctic Increase in cloud cover Increase in cloud cover Ice thinning Ice thinning Changes in precipitation Changes in precipitation Spring Cloud Fraction of Arctic Seas ( from

Research Questions Research Questions Atlantic hydrologic sensitivity parameter (HSP) Atlantic hydrologic sensitivity parameter (HSP) Determines how thermohaline circulation will change as freshwater discharge increases Determines how thermohaline circulation will change as freshwater discharge increases Freshwater discharge (Eurasian) expected to increase 18-70% in response to °C SAT increase Freshwater discharge (Eurasian) expected to increase 18-70% in response to °C SAT increase Arctic ice – whats causing changes in thickness and extent? Arctic ice – whats causing changes in thickness and extent? How are the AO/NAO and greenhouse gases related? How are the AO/NAO and greenhouse gases related? How will ocean currents change? Three modes of ocean currents discussed by Taylor (1999) How will ocean currents change? Three modes of ocean currents discussed by Taylor (1999)

Experimental Methods and Modeling

Our Questions for You! We want you to speculate some effects of the following scenarios. Be creative: effects on ocean/wind currents, migration patterns, Arctic ice, economics, human society, etc. We want you to speculate some effects of the following scenarios. Be creative: effects on ocean/wind currents, migration patterns, Arctic ice, economics, human society, etc. Global warming causes almost total melting of the Arctic ice sheet Global warming causes almost total melting of the Arctic ice sheet Greenhouse gases push AO into permanent positive phase Greenhouse gases push AO into permanent positive phase Global temperatures increase and cause two-fold increase in freshwater discharge to Arctic Ocean Global temperatures increase and cause two-fold increase in freshwater discharge to Arctic Ocean