The Arctic Water The Arctic Water CycleCycle

Emma Emma

Rebecca HaleRebecca Hale

1 March 20051 March 2005

Photograph © Michael Hambrey

The Arctic Water The Arctic Water CycleCycle Emma Sage Emma Sage

Rebecca HaleRebecca Hale

BiogeochemistryBiogeochemistry

2 March 20052 March 2005

The Game PlanThe Game Plan

• Global and Arctic Water CyclesGlobal and Arctic Water Cycles• Ice SheetsIce Sheets• Primary controls on the water cycle – global Primary controls on the water cycle – global

and Arctic and Arctic • Field Methods and Modeling: how we figure Field Methods and Modeling: how we figure

it all outit all out• ““In nature there are neither rewards nor In nature there are neither rewards nor

punishments, there are consequences.” – punishments, there are consequences.” – Robert Green IngersollRobert Green Ingersoll

• DiscussionDiscussion

The Global Water CycleThe Global Water Cycle

The Global Water CycleThe Global Water Cycle

• Global and Arctic Global and Arctic Water CyclesWater Cycles

The Arctic Water The Arctic Water CycleCycle

Arctic Ice SheetsArctic Ice Sheets

Arctic Rivers and WatershedsArctic Rivers and Watersheds

Arctic Ice SheetsArctic Ice Sheets

What Drives the Water What Drives the Water Cycle?Cycle?

• Precipitation Precipitation solar radiation, Hadley solar radiation, Hadley cells, wind patterns, all those good things cells, wind patterns, all those good things we talked about with Laura and Julie.we talked about with Laura and Julie.

• Ice Ice wind! air temperature, ocean wind! air temperature, ocean temperature, ocean currents, pressure temperature, ocean currents, pressure oscillationsoscillations

• Ocean currents Ocean currents salinity, river salinity, river discharge, temperaturedischarge, temperature

• River discharge River discharge temperature, arctic temperature, arctic ice/glaciers, human modificationsice/glaciers, human modifications

Some Really Cool Big Some Really Cool Big PatternsPatterns

• Arctic OscillationArctic Oscillation – atmospheric pressure – atmospheric pressure see-saw between upper and middle northern see-saw between upper and middle northern (~45N) latitudes(~45N) latitudes

• North Atlantic OscillationNorth Atlantic Oscillation – related to the – related to the AO, similar seesaw of pressure between AO, similar seesaw of pressure between Iceland and subtropical AtlanticIceland and subtropical Atlantic

• Debate whether these are part of the same Debate whether these are part of the same mode or whether they are different. mode or whether they are different.

• Time scales of these are debatable –Time scales of these are debatable –paleoclimate studies show that neither seem paleoclimate studies show that neither seem to have had set schedules in the past, but to have had set schedules in the past, but they change about every 10 to 40 yearsthey change about every 10 to 40 years• Right now both are in positive phasesRight now both are in positive phases

Arctic Ice SheetsArctic Ice Sheets

Arctic OscillationArctic Oscillation- some effects -- some effects -

Positive AO•Low pressure

over arctic

Negative AO•High pressure

over arctic

• Pacific Decadal OscillationPacific Decadal Oscillation – major source – major source of variability in sea surface temperature of variability in sea surface temperature lasting 20-30 years. lasting 20-30 years. • Since 1990s has begun to go back into cool phase.Since 1990s has begun to go back into cool phase.

Warm phaseWarm phase Cool phaseCool phase

These Pressure and These Pressure and Temperature Oscillations…Temperature Oscillations…

• Control currents of air Control currents of air positive AO positive AO creates strong wind current circling the creates strong wind current circling the ArcticArctic• Effects on iceEffects on ice

• affect the heating and cooling of the ocean affect the heating and cooling of the ocean and therefore…and therefore…

• Thermohaline Circulation!Thermohaline Circulation!• Circulation of ocean water based on temperature Circulation of ocean water based on temperature

(thermo) and salinity (haline)(thermo) and salinity (haline)• Temperature and salinity determine density of Temperature and salinity determine density of

sea water and cause sinking and upwellingsea water and cause sinking and upwelling

Arctic Ice SheetsArctic Ice Sheets

Arctic Ice SheetsArctic Ice SheetsAtlantic Thermohaline Circulation

Changes in the Arctic CycleChanges in the Arctic Cycle

• AO and NAO have been in AO and NAO have been in long positive cycleslong positive cycles• caused by increases in caused by increases in

GHG?GHG?

• Surface air temperatures Surface air temperatures are increasing are increasing accelerate water cycleaccelerate water cycle

• Increase in freshwater Increase in freshwater discharge to Arcticdischarge to Arctic

• Increase in cloud coverIncrease in cloud cover• Ice thinningIce thinning• Changes in precipitationChanges in precipitation

Spring Cloud Fraction of Arctic Seas (from www.arctic.noaa.gov)

Research QuestionsResearch Questions• Atlantic hydrologic sensitivity parameter (HSP)Atlantic hydrologic sensitivity parameter (HSP)

• Determines how thermohaline circulation will Determines how thermohaline circulation will change as freshwater discharge increaseschange as freshwater discharge increases

• Freshwater discharge (Eurasian) expected to Freshwater discharge (Eurasian) expected to increase 18-70% in response to 1.4-5.8°C SAT increase 18-70% in response to 1.4-5.8°C SAT increaseincrease

• Arctic ice – what’s causing changes in Arctic ice – what’s causing changes in thickness and extent?thickness and extent?

• How are the AO/NAO and greenhouse gases How are the AO/NAO and greenhouse gases related?related?

• How will ocean currents change? Three modes How will ocean currents change? Three modes of ocean currents discussed by Taylor (1999)of ocean currents discussed by Taylor (1999)

Experimental Methods and Experimental Methods and ModelingModeling

Our Questions for You!Our Questions for You!

• We want you to speculate some effects of We want you to speculate some effects of the following scenarios. Be creative: the following scenarios. Be creative: effects on ocean/wind currents, migration effects on ocean/wind currents, migration patterns, Arctic ice, economics, human patterns, Arctic ice, economics, human society, etc.society, etc.• Global warming causes almost total melting Global warming causes almost total melting

of the Arctic ice sheetof the Arctic ice sheet• Greenhouse gases push AO into permanent Greenhouse gases push AO into permanent

positive phasepositive phase• Global temperatures increase and cause two-Global temperatures increase and cause two-

fold increase in freshwater discharge to fold increase in freshwater discharge to Arctic Ocean Arctic Ocean