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Abrupt Change – Past, Present and Future
The Hard Reality, and the Silver Lining, in a Sustainable Future
Jim White, Director, INSTAARUniversity of Colorado Boulder
2014 Stefansson Memorial Lecture
Vilhjálmur Stefansson
Context
• We are in the midst of climate change, but HOW climate changes will be critical to adaptation.
• In adapting to change, “speed kills.”
• So understanding, and preparing for abrupt change is critical.
Defining abrupt climate change
• No universally accepted definition.
• In general, one needs:
– A fast change (much less than a human lifetime)
– A big change (in average or in variability)
– A change that seems out of proportion (too big) relative to the suspected cause
Moon Lake, ND, (Laird et al, 1996)
Abrupt Impacts of Climate Change:
Anticipating Surprises
New study from the US National Academy of Sciences:
Follow on from 2002 NRC report
This report also considers abrupt climate impacts:
Steady changes in climate and/or environment that trigger abrupt shifts in related human and natural systems
Abrupt Climate Impacts
Abrupt Change: abrupt climate change and abrupt impacts
• Scale in time and magnitude are relative to, and faster and larger than expectations and ability to adapt, including economic ability
– Air conditioning example
– New York City subway example?
Change won’t always be obvious: Timing and tipping points
• Abrupt changes, tipping points… a point of no return is crossed resulting in large, inevitable change.
• The“canoe on the Niagara River” type events: strong positive feedbacks
On the edge already
• The earth is more vulnerable to abrupt change today
– We have altered the earth’s energy balance and changed climate
– We cause 10 times more erosion than all natural processes
– We make more nitrogen fertilizer than all bacteria on land
– We make more sulfate than all ocean phytoplankton
Reason #2: Use per capita, the multiplier
Low income is 3.5
times below middle
income, and 7 times
less than high income
The Nasty Dilemma:
we want others to live
well, but if they do, the
energy and resource
needs will be
staggering
Abrupt change: the past
• Abrupt change is a common and natural feature of the Earth’s climate system
• Up until the 1990’s we thought of climate change as mostly “gradual”, forced primarily by sun-earth changes
• Greenland ice cores and ocean sediment cores changed that view…
Abrupt events: the ice core view
Green is Greenland temperatureBlue is sea level
Dansgaard-Oeschger events
Last ice age
Abrupt change: the early storyYounger Dryas Termination
Willi Dansgaard
SigfusJohnsen
Dansgaard, White and Johnsen, Nature, 1989
Abrupt climate
changes: the story evolves
•>10˚C increase in Greenland temperature in 50 years•Double snow in 1 to 3 years•Sea ice retreat in 1 to 2 years•CH4 up 50% in 50 years•N2O up 10% in 50 years
Copenhagen to Gibraltar is 10˚CAtlanta to Minneapolis is 9˚C
d-excess comparison among three cores across 350 years:
NGRIP and GISP2 and NEEM
NEEM - NGRIP synchronizing match points (S.O. Rasmussen)
0
2
4
6
8
10
12
14
16
14500 14550 14600 14650 14700 14750 14800 14850
Bølling WarmingD
eute
riu
m e
xce
ss
GICC05 age (b2k)
Shift in 1 to 2 years
Multiple cores: signal versus noise
Recent breakthroughs in analytical systems allow us to look at sub-annual variations in multiple cores rapidly and more accurately
How abrupt is abrupt?
-380
-360
-340
-320
-300
-280
-260
-240
11500 11600 11700 11800 11900 12000
Younger Dryas Termination
D
GICC05 age (b2k)
NGRIPGISP2
~1˚C per year for 5 years in each step… 100 times faster than current warming
Stunningly abrupt: Bølling warming in northern Greenland
NGRIP and NEEM
NEEM - NGRIP synchronizing match points (S.O. Rasmussen)
-380
-360
-340
-320
-300
-280
-260
-240
14500 14600 14700 14800 14900 15000
Bølling warming
D
GICC05 age (b2k)
Isotope change in 1 to 2 years in 2 cores…Rate of inferred warming at northern sites 5-10 C per year!!!
Up to 1,000 times faster than current warming
Abrupt change: the present
• We are experiencing abrupt change today
– Arctic sea ice
– Groundwater loss
– Species extinction
– Ocean acidification
Abrupt Climate Changes and Impacts Now Underway
• Disappearance of summer time Arctic sea ice
– Faster than anticipated
• Impacts on Arctic ecosystems, changes to shipping, coastal erosion
Ice melt in water is highly non-linear
Lake Erie ice melts…in 2 weeks… that’s ~27,000 sqkm (Massachusetts, or 6.8 Rhode Islands)
Lake Erie example from 1973
Abrupt change: the future
• Many thresholds of interest…– Sea level rise rate
– Species loss, marine and terrestrial
– Droughts and floods (water extremes)
– Oceanic oxygen minima zones
• Others concerning, but not abrupt– Permafrost carbon
Pika
corals
The surprising reality of sea level change
Credit: PBS: ExtremeIce
The dynamic range of sea level change is difficult for people to grasp.
Over 500 feet of ocean is traded for land ice and vice versa
Major glaciations (20,000 years ago) = 400 feet lowering
Melt Greenland and Antarctica = 170 feet higher
Sea level rise (SLR) rate
• The rate of SLR is currently such that we expect about 1m of SLR by 2100.– Rates of 3 to 5 times faster are
common in the past record.
– Abrupt change: 1m in 100 years is fundamentally different than 1m in 30 years, or 20 years.
• The 3 “hows”: – How fast?
– How far?
– How inevitable?
Sea level is rising: 1 meter by the end of this century is current estimate… and it won’t stop there…
The reality of sea level rise
Miami Beach Mayor Philip Levine said the city is too valuable to lose, with real estate worth more than $23 billion and tourism revenue over $9 billion. Washington Post, 23/4/14
The long, slow, losing battle
Abrupt points:• Federal flood insurance• Property values• Key infrastructure• Fresh water
How inevitable?
“Deep time” sea level and temperature: Ultimate SLR
David Archer
Last time Earth had 400 ppm CO2
How far?
“Deep time” sea level and temperature: Ultimate SLR
Foster and Rohling, PNAS
~14 m is the sea water stored in West Antarctica and Greenland
How far?
Need For Action
• It is time to take concrete steps; an early warning system is needed
– Useful vehicle towards action
– Builds on existing systems
– Helps arguments for continued monitoring
– No need to argue attribution
A water world
Ours is a water planet and it takes time to heat up the water:
– The impacts (warmer) come after the causes (increased GHGs) by 50 years or more
– Leads to intergenerational inequity
The good news
Ethics and sustainability
My 3 simple rules of sustainability:
1. Everything must cycle2. Population must be
controlled (equality of the sexes), and vary inversely with resource use per capita
3. Equity must be considered and acted upon
Committee Members
• James White (Chair)– University of Colorado at Boulder
• Richard Alley– Pennsylvania State University
• David Archer– The University of Chicago
• Anthony Barnosky– University of California, Berkeley
• Jonathan Foley– University of Minnesota
• Rong Fu– The University of Texas at Austin
• Marika Holland– National Center for Atmospheric
Research
• Susan Lozier– Duke University
• Johanna Schmitt– University of California, Davis
• Laurence Smith– University of California, Los
Angeles
• George Sugihara– University of California, San Diego
• David Thompson– Colorado State University
• Andrew Weaver– University of Victoria, British
Columbia
• Steven Wofsy– Harvard University