Transcript 071201-06MN082-Zinifex MAAT Presentation-167

MAAT,
Permafrost
Characterization
and Climate
Warming
Jim Cassie, P.Eng.
BGC Engineering Inc.
PRESENTATION OUTLINE
1.
Validation of proposed mean annual air
temperature (MAAT) value for the site
2.
Overview of permafrost assessment work
3.
Relationship of ground temperatures to air
temperatures
4.
Introduction to climate change and global
warming
5.
Global warming model estimates
6.
Conclusions
1. MAAT VALUE FOR SITE
• Few definitions to review
• Nearby long term climate stations
• Review MAAT values from those
stations
• Add mine site weather stations
(slightly shorter term)
• Rationalize MAAT versus latitude
CLIMATE - DEFINITION
•
•
•
•
•
Climate, in a narrow sense, is usually
defined as the “average weather”.
“Climate is what you expect, weather is
what you get.”
More rigorously, as the statistical
description in terms of the mean and
variability of relevant quantities, over an
appropriate period of time.
The classical time period is 30 years, as
defined by the World Meteorological
Organization (WMO).
Long period to account for climate cycles.
MAAT - DEFINITION
•
•
•
•
Mean annual air temperature value is for
either one specific year (e.g. 2007) or for
period of record (e.g. 1971 to 2000).
One single temperature parameter used
to define the climate of an area.
Used to define the mean and the ranges
of the expected temperature.
Used in climate, geography and
permafrost work as opposed to annual
ground temperatures.
REASONABLE - DEFINITION
1. Capable of reasoning; rational: a
reasonable person.
2. Governed by or being in accordance
with reason or sound thinking: a
reasonable solution to the problem.
3. Being within the bounds of common
sense: arrive home at a reasonable
hour.
4. Not excessive or extreme; fair:
reasonable prices.
CLIMATE
STATIONS
PROXIMAL MAAT VALUES
Station Name
Distance and
Direction from
High Lake
Period of
Record
MAAT
Cambridge Bay
300 km NE
1929-recent
-14.7oC
Coppermine
200 km WNW
1933-1977
-11.4oC
Kugluktuk
200 km WNW
1978-recent
(29 years)
-10.4oC
280 km S
1959-1981
-11.9oC
200 km S
1982-recent
(25 years)
-11.0oC
Contwoyto
(65.48oN)
Lupin (65.76oN)
Lake
PLUS 3
MINES
MAAT vs. LATITUDE
RWDI
-11.8oC
o
MAAT ( C)
-4
-2
-6
-8
o
-9.3 C
-14
-12
-10
-16
70
Cambridge Bay
Kugluktuk
68
High Lake '04-'05
66
o
Lupin
Latitude ( N)
Further North
Ulu '04-'05
Ekati
Snap Lake
Yellowknife A
Notes
1. Most MAAT values based on 1971 to 2000 Canadian Climate
Normals, except for individual mine sites.
2. Kugluktuk and Cambridge Bap stations are located proximal to
major water bodies (Coronation and Queen Maud Gulfs).
64
62
Getting Colder
60
MAAT CONCLUSION
•
•
Based on interpolation/extrapolation of
nearby long-term climate station, a
MAAT value of -11.8oC for the High Lake
site appears reasonable.
Any warmer value is not scientifically
defensible and does not appear
reasonable from data trends.
PRESENTATION OUTLINE
1.
Validation of proposed mean annual air
temperature (MAAT) value for the site
2.
Overview of permafrost assessment
work
3.
Relationship of ground temperatures to air
temperatures
4.
Introduction to climate change and global
warming
5.
Global warming estimates
6.
Conclusions
2. PERMAFROST WORK
• Two definitions to start
• Thermistor locations
• Results – both deep and shallow
DEFINITIONS
•
•
•
Permafrost is ground
that remains below
0oC for at least two
years.
Definition is purely
thermal – no
commentary on
“frozen” nature or on
ground ice content.
Permafrost types –
sporadic,
discontinuous and
continuous.
DEFINITIONS
• Talik – unfrozen zone within
continuous permafrost. Usually
caused by water bodies (heat
source).
• Closed, open and through types.
THERMISTORS AT SITE
2 DEEP CABLES
16 SHALLOW CABLES
THERMAL REGIME
• Permafrost zone defined by its
thermal regime – trumpet curve
RESULTS
•
•
•
•
Permafrost is 440 m deep (measured at
the West Zone).
In the associated talik modeling, mean
annual ground temperature of -7oC
matched permafrost depth and
measured geothermal gradient at depth.
Estimated mean annual ground
temperatures of -6oC found for the site.
Ground temperatures (10 to 25 m depth)
of -4o to -5oC under three dams. Also
found -3.5o to -4oC under two dams
directly beside water.
PRESENTATION OUTLINE
1.
Validation of proposed mean annual air
temperature (MAAT) value for the site
2.
Overview of permafrost assessment work
3.
Relationship of ground temperatures to
air temperatures
4.
Introduction to climate change and global
warming
5.
Global warming estimates
6.
Conclusions
3. GROUND TO AIR TEMPS
• Offset from air to ground temperatures
• Impact of nearby water bodies
• Validation of site ground temperatures
AIR TO GROUND
GROUND IS 3o TO 6oC
WARMER THAN THE AIR
(AVERAGE +/- 4.5oC)
IMPACT OF WATER BODIES
1000
950
900
850
LARGE LAKE HAS
PROFOUND THERMAL
IMPACT ON NEARBY
TEMPERATURES
Elevation (m)
800
750
700
650
Distance from lake:
0m
10m
20m
30m
50m
75m
100m
150m
600
550
500
-8
-7
-6
-5
-4
-3
Temperature (°C)
-2
-1
0
1
2
RESULTS
•
•
•
•
•
MAAT of -11.8oC.
Warming in the ground (3o to 6oC with
4.5oC average) = -8.8o to -5.8oC (-7.3oC)
which correlates to -6oC found in the
area
Within 20 to 30 m of major water body,
2o to 3oC warming can be felt
Ground temperatures of -4o to -5oC
under three dams. Also found -3.5o to
-4oC under two dams directly beside
water.
Measured ground temperatures are
reasonable with MAAT of -11.8oC.
PRESENTATION OUTLINE
1.
Validation of proposed mean annual air
temperature (MAAT) value for the site
2.
Overview of permafrost assessment work
3.
Relationship of ground temperatures to air
temperatures
4.
Introduction to climate change and
global warming
5.
Global warming estimates
6.
Conclusions
4. CLIMATE CHANGE
• Few definitions
• Observations
• Causes
CLIMATE CHANGE DEFINITION
•
•
Changes in the variability or average
state of the atmosphere over appropriate
time scales relative to a given reference
period.
These changes can be caused by
processes internal to the Earth, external
forces (e.g. variations in sunlight
intensity) and, more recently, human
activities.
CLIMATE CHANGE OBSERVATIONS
•
•
•
•
•
•
•
•
Early decline of the spring snow
cover
Arctic melt seasons are longer
Rivers and lakes are melting earlier
Permafrost is warming or
disappearing
Arctic lakes are disappearing
Shorter winter road seasons
Less sea ice
Thunder and lightning in the north
CLIMATE CHANGE - CAUSES
•
These changes can be caused by
processes internal to the Earth,
external forces (e.g. variations in
sunlight intensity) and, more
recently, human activities.
1. Natural
•
Solar variability, volcanic dust levels,
ocean variability, geological change
2. Human related (anthropogenic)
•
Greenhouse gases, aerosols, ozone
depletion
PRESENTATION OUTLINE
1.
Validation of proposed mean annual air
temperature (MAAT) value for the site
2.
Overview of permafrost assessment work
3.
Relationship of ground temperatures to air
temperatures
4.
Introduction to climate change and global
warming
5.
Global warming model estimates
6.
Conclusions
5. GLOBAL WARMING MODELS
•
•
•
To simulate the effects of human
warming, scientists formulate very large
and very complex mathematical models
in computers.
General Circulation Models (GCMs) are
a class of computer-driven models for
understanding climate and projecting
climate change.
Models require input assumptions
regarding greenhouse gases (scenarios)
in terms on amount and trend.
MODEL LIMITATIONS
•
•
•
Mathematical model
simulating the interaction
of the earth, atmosphere,
oceans and ice cover
(WOW!).
Models have numerous
noted errors.
Generally, the mean of the •
results has relatively good
agreement for
temperature but not so
good agreement for
precipitation.
•
Models also
have large
nodes and
hence are NOT
site specific.
RGM’s
GOVERNMENT /
RESEARCHERS
•
•
•
GCM’s extracted from the Canadian
Institute for Climate Studies (CICS) at
U of Vic (average of 4 different
scenarios and 7 different models) =
7.6oC/100 years
Canadian RCM for eastern Arctic =
5.1o to 6.1oC/100 years
Environment Canada (2007) = 3.8o
and 6.8°C of warming until the period
2070 to 2099.
COPPERMINE / KUGLUKTUK
Combined Coppermine Kugluktuk Weather Record
-4.0
n
Mean
Std. Deviation
-6.0
Coppermine
44
11.5oC
1.10oC
Kugluktuk
29
10.5oC
1.37oC
MAAT Value
Linear (MAAT Value)
MAAT (oC)
-8.0
-10.0
y = 0.0245x - 59.29
R2 = 0.1604
-12.0
63 YEARS
-14.0
2.5oC/ 100 YEARS
-16.0
1928
1938
1948
1958
1968
YEAR
1978
1988
1998
2008
CONTWOYTO / LUPIN
Combined Contwoyto Lupin Weather Record
-4.0
-5.0
-6.0
n
Mean
Std. Deviation
MAAT Value
Linear (MAAT Value)
Contwoyto
23
11.9oC
1.16oC
Lupin
25
10.9oC
1.39oC
-7.0
48 YEARS
MAAT (oC)
-8.0
5.6oC/ 100 YEARS
-9.0
-10.0
-11.0
y = 0.0561x - 122.65
R2 = 0.3152
-12.0
-13.0
-14.0
1958
1963
1968
1973
1978
1983
YEAR
1988
1993
1998
2003
2008
ALL DATA POST 1960
-2.0
Coppermine MAAT (oC)
-4.0
46 YEARS
Kugluktuk MAAT (oC)
Contwoyto MAAT (oC)
~6oC/ 100 YEARS
Lupin MAAT (oC)
Mean Annual Air Temperature (oC)
-6.0
-8.0
Best Fit Line
-10.0
-12.0
-14.0
-16.0
-18.0
1960
1965
1970
1975
1980
1985
YEAR
1990
1995
2000
2005
2010
INAC REVIEWER’S APPROACH
WHY?
4
2
0
INAC Copper Mine / Kugluktuk
INAC Contoytal / Lupin
8
BGC Lower Value
Government /
Researcher GCM
Estimates
BGC Upper Value
Best Fit
Combined Copper Mine / Kugluktuk
Combined Contoytal / Lupin
Environment Canada (Lower Value)
Environment Canada (Upper Value)
Plummer et al. (Lower Value)
Plummer et al. (Upper Value)
10
GCM (4 scenarios)
o
Warming Value ( C / 100 yrs)
SUMMARY OF ESTIMATES
14
INAC Proposal
12
BGC Proposed
Allowances
Factual Warming
Trends
6
WARMING ALLOWANCES ON
OTHER PROJECTS
Project
Polaris Mine Closure,
NU
Mean
Annual Air
Temperature
o
-16.5 C
Global Warming
Allowances
Project Status
o
3.0 C/100 years
o
5.1 C/100 years
o
o
2.8 C/100 years
o
5.0 C/100 years
o
worst case of 5.3 C over
next century.
Used simplying
o
assumption of 6.5 C over
next century
o
~9.5 C/200 years
o
5.5 C/100 years
Nanisivik Mine
Closure, NU
-15.1 C
Doris North Mine, NU
(2 year mine life)
-12.0 C
Ekati Mine
Meadowbank Mine,
NU (8 year mine life)
-8.5 C
o
-11.3 C
o
o
Permits received
Closure work
completed
Active monitoring
Permits received
Closure work
almost completed
NIRB approval
provided in
September 2006.
Closure plannig
NIRB approval
provided in
August 2006.
PRESENTATION OUTLINE
1.
Validation of proposed mean annual air
temperature (MAAT) value for the site
2.
Overview of permafrost assessment work
3.
Relationship of ground temperatures to air
temperatures
4.
Introduction to climate change and global
warming
5.
Global warming estimates
6.
Conclusions
6. CONCLUSIONS
•
•
•
•
High Lake MAAT Value = -11.8oC is
reasonable.
Air temperatures correlate with deep
permafrost and shallow ground
temperatures, allowing for heating due to
large water bodies.
Warming estimates of 5o to 6.5oC / 100
years are reasonable in light of
government/researcher estimates and
actual warming over climate period in the
north.
These estimates still have an additional
Factor of Safety when applied to dam
design.