Thursday, May 05, 2011

Shad O'Neel, Can We Predict Global Sea Level Change?

Shad O'Neel, USGS Research Glaciologist.  [This guy gave a great talk.  I have more video I'll try to put more up later.  He really knows his stuff and is animated about it.  Well worth a look.  And if you are particularly interested in the relationship between glaciers and sea-level, definitely watch!]  [NOTE:  I'm putting this up quick - translation:  no editing until later maybe.]


Not all glaciers change because of climate change, but some based on geometry of the basin they live in.

Who cares?
Glaciers out of equilibrium, so we're in for a change whether we like it or not, and if climate continues to change, it will be greater. 
Large tourism base, visiting to see our glaciers.  Cruise ships, recreational, aviation to see glaciers.  So big that state parks have built visitor centers, but now they can't see the glaciers from them any more.

What may be more important is culture's ability to adapt to sea level rise.  If there is a 2 foot sea level rise in Florida, we're screwed.  But we can deal with it.  But what about the sea level islands in Asia - a lot more people?

Water from our glaciers.  Snow that lands on glaciers has different chemistry because not on dirt and when it goes into the water it's totally different from other water going into the sea.  So the eco systems near the glaciers are very different and changes the currents that go up to the Arctic - fisheries, flooding, coastal erosion, hydro electric.  Sea level rise.  Glacials modulate the sea level budget - if we want to understand sea level rise, we have to understand glaciers.

1-3% loss of total land loss by 2080.  $100 billion problem by 2080.  The longer we wait to deal with it, the bigger the problems.

Implications of sealevel rise.
1.  Adding or subtracting new water  -
2.  Steric

Chart of different contributions from small glaciers, ice sheets, terrestrial storage, and ???.

Bottom panel shows problem because we can't measure and compare perfectly with space born - capture the same trend, but not exactly the same.

What does global sea level rise mean?  How to measure it?  Each component tricky.  We're doing pretty good job.  Sea level budget.

Glaciare Surface Mass Balance - slide is showing time lapse of and Icelandic glacier changing from winter and summer - if it melts more than it snows it gets smaller.  This is what we thought was glacier health and what controlled sea level budget.  If positive it grows, negative should shrink, if 0 stays the same.
There's more than just snow and melt.  How do you measure?  Especially mountain glaciers.  Ice sheets easier.  Like a bucket of water.  But if I threw the water over the carpet - more like mountain glaciers.  Traditionally measured with poles - raid electric supply stores and they think we're crazy.  Bury pole in the winter.  Meters of snow every winter and meters of melt in the summer.
Now, we need to understand what these measures mean for glaciers as proxy of climate.  Two benchmark glaciers in Alaska.  Gulkana and Wolverine - small and simple.  Chosen because easy logistics.  Alaska glaciers go back to late 60s.  Do they mean anything.  Can we use them as proxy for regional and then global context?
Yeah, ok job, but asking those questions.
Record from the glaciers.
Washington state glacier has greatest loss.  But both continental has dwindling trend.  Coastal glacier - Wolverine - has been up and down.  More influenced by winter snow than summer climate.  No more recovery periods.
World Glacier Monitoring service tries to integrate global records.

Global record shows decreasing glaciers.  Old measures.  Now we have satellite pictures.  Long time series data is supercritical, but motivation has changed from 50's when no one was thinking of climate change and were just curious.

Do we have the right signal?  Whats the response time.  Changes that happened when?  Do the space measurements compare well with these traditional measurements?  Or is there a difference that warrants caution?  Can we model the measurement?

World Glacial Inventory
Looking at all the mountain glaciers 19 different regions.  Gray - complete inventories.  Clear, incomplete.  You're probably surprised we don't know how many glaciers there are.  In US, we're lacking behind China and Russia.  We don't know as much as we know.  Shocking to me that this is the state of the science now.

What about our measurement skills?  Getting better at measuring over broad spatial area.  Airplanes fly over glacier and measure surface and then return years later.  A lot more sophisticated the sticking poles in, but doesn't give us density.  Now laser from space.  Discovered there were lakes under Antarctica that rise and drain with lasers.

Mountain Glacier Changes
Alaska ones are long interval change.
1.  Not every region represented
2.  Alaska dominates - we have a lot of ice
3.  Similar shapes as Wolverine and Gulkana - decreasing curve
West Antarctica similar curve
East Antarctica actually gaining ice.

Only since space born measurements can we have confidence to say losing mass at increasing rates.

Graph - can't even see clear white bar for glaciers, but sea level % is huge.  Massive loss of glaciers compared to ice sheets.

Forecasting - what people want from glaciologists.  We have handle of measuring sea level change, but can't predict?  Just temperature?  Some regions changing temperature faster than others?  Some traction but not enough.  The gorilla in the corner is ice dynamics, well illustrated by Chugach.  Big bullesye over Columbia.  One part gaining another part losing.  Columbia accounts for have the mass loss in this mountain range.  Why is this so important and why we ignored it.  Scale of this is hundred meters tall, instantaneous transfer of mass from land ice to sea.  Not just stagnant disintegration of glaciers.  Like Manhattan going out into the ocean.  Imagine trying to study this.  Just can't.

All these couplings and feedbacks that are non-linear.  This process at Columbia is happening fast - ocean, atmosphere involved - we don't have a handle yet, so we can't predict sea-level rise.  Major speed up.

Why the uncertainty?  Ice dynamic thing.  Can't predict it.

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