Arctic Climate Change

1
Arctic Climate Change

• Summary of GCM Predictions
• John Falkingham
• IICWG, November 2001

2
The Arctic Ice-Scape Is Changing General
agreement on 3 per decade reduction in extent
and thickness
Source Rothrock, U. of Washington
Source Parkinson SMMR/SSM I Analysis
3
IPCCObserved Changes in Sea-Ice Extent

• Northern Hemisphere sea-ice amounts are
  decreasing, but no significant trends in
  Antarctic sea-ice extent are apparent.
• Arctic spring and summer decrease of 10 to 15
  since the 1950s
• little indication of reduced Arctic sea-ice
  extent during winter when temperatures have
  increased in the surrounding region
• likely a 40 decline in Arctic sea-ice thickness
  in late summer to early autumn between the period
  of 1958 to 1976 and the mid-1990s, and a
  substantially smaller decline in winter
• The relatively short record length and incomplete
  sampling limit the interpretation of these data.
  Interannual variability and inter-decadal
  variability could be influencing these changes.

4
But Will It Continue To Change?
No Summer Ice Cover
5
Modeling Global Mean Temperature
IPCC Third Assessment Report
6
GCM Predictions of Global Mean Temperature
IPCC Third Assessment Report
7
Annual Mean NH Ice Extent 1900 to 2100
Obs. (Walsh)
Canadian Centre for Climate Modelling and Analysis
8
CGCM1 Ice Concentration in September 1985
Canadian Centre for Climate Modelling and Analysis
9
CGCM1 Ice Thickness in September 1985
Canadian Centre for Climate Modelling and Analysis
10
Minimum Ice Extent 1950 to 2050
Institute for Ocean Sciences, DFO
11
CGCM2 Winter and Summer Projected Ice Cover
Change1971-90 vs 2041-2060
March
September
Canadian Centre for Climate Modelling and Analysis
12
Change in Annual Mean Sea Ice Thickness1971-90
vs2041-60
Canadian Centre for Climate Modelling and Analysis
13
Conclusions

• Almost all GCMs predict less sea ice in future
  than at present
• although there is wide disagreement about the
  timing and magnitude
• Key areas to watch for signs of change
• Sea of Okhotsk
• East Siberian Sea
• Laptev Sea
• East Greenland Sea
• Baltic Sea
• Hudson Bay
• Baffin Bay

14
Sequel The Other Story

• Long term observers have found many different
  climate and sea ice cycles, including
• 3-4 year
• 7-10 year
• 11 22 year
• multi-decadel, most notably 60-80 years
• There is a learned opinion that several of these
  cycles have combined to produce the marked
  decrease in sea ice in the past 20 years
• Further, this opinion holds that we will see an
  increasing trend in sea ice by 2005

15
Stay Tuned .

• Extreme inter-annual variability will continue to
  obscure the signal with noise

Canadian Ice Service