Transcript 1.5 MB - arcus

RAPID SHIFTS IN THE
ARCTIC SYSTEM :
Implications for vulnerability and resilience
John E. Walsh
ARCUS Arctic Forum 2003
“If you take the last 100,000 years from the
Greenland ice core, the only few thousand
years that have not had abrupt changes are
the few thousand we are living in.”
- Richard Alley/Earth and Sky
GRIP ice core temperature reconstruction
from Dansgaard et al. (1993)
Objectives :
 Assess recent Arctic changes in context of abrupt changes
of the past
 Highlight issues of resilience and vulnerability to abrupt
changes
 Examine some projections of changes in the Arctic
Abrupt climate change
from CLIVAR/PAGES
The Younger-Dryas changes of ~12K BP were abrupt.
 Smaller changes have had large impacts on people
e.g., Viking settlements in Greenland
 Although climate has been relatively quiescent during the
past few thousand years, greenhouse gas emissions
may alter the likelihood of abrupt climate changes
Surface temperature trend - recent 1000 years
from Michael Mann
Abrupt climate change
from CLIVAR/PAGES
Surface air temperature : January
(1977-1986) – (1966-1975)
Arctic surface air temperature anomalies
from Polyakov et al. (2002)
Spawning stock biomass of herring
in the Nordic Seas
from Torensen and Ostvedt (2000)
Vulnerability = Impacts - Adaptive Capacity
Vulnerability decreases as adaptive capacity increases
-- increasing size and interconnectedness of system
provide more possibilities for compensation within
the system
Net economic value
from National Academy of Sciences (2002)
Variability of total U.S. farm output :
1929-2000
from National Academy of Sciences (2002)
Relative variability of U.S. farm output as share of
total domestic product : 1929-2000
from National Academy of Sciences (2002)
Longer-term vulnerability decreases with
1) Longer warning time
2) Decreased lifetime
(infrastructure, capital investment)
(Both enhance adaptability)
Vulnerability of capital stocks
from National Academy of Sciences (2002)
How might 21st-century climate change
test the vulnerability and adaptability
of the Arctic system?
growing season length
open water season length
sea level
coastal storms, erosion
permafrost degradation
fire frequency
CCC growing season - Tmin greater than 0 °C
(2071-2090) - (1976-1995)
Projected sea level rise
from IPCC (2001)
Projected continuous permafrost area : 5 GCMs
Projected total permafrost area : 5 GCMs
Sfc. air temperature : (high-low) fire severity composite
March-July 1951-2002
Key uncertainties in vulnerability ( = impacts-adaptability)
Uncertainties in impacts:
• climate change scenarios from coarse models are highly
uncertain
-- large scatter among models
-- common errors
• local effects are not captured by climate model projections
• changes in variability will likely be at least as important as
changes in the mean
Uncertainties in adaptive capacity:
• Non-climatic factors (societal, cultural, economic,
technological) are at least as difficult to anticipate
as climate change