MAAT, Permafrost Characterization and Climate Warming Jim Cassie, P.Eng. BGC Engineering Inc.

MAAT, Permafrost Characterization and Climate Warming

Jim Cassie, P.Eng.BGC Engineering Inc.

PRESENTATION OUTLINE1. 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

Contwoyto Lake (65.48oN)

280 km S 1959-1981 -11.9oC

Lupin (65.76oN) 200 km S 1982-recent(25 years)

-11.0oC

PLUS 3 MINES

MAAT vs. LATITUDE

60

62

64

66

68

70

-16-14-12-10-8-6-4-2

MAAT (oC)

La

titu

de

(oN

)

Yellowknife A

Cambridge Bay

Snap Lake

Ekati

Kugluktuk

Lupin

Notes1. 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).

High Lake '04-'05

Ulu '04-'05

Fu

rth

er

No

rth

Getting Colder

-9.3oC

RWDI

-11.8oC

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.






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.







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

500

550

600

650

700

750

800

850

900

950

1000

-8 -7 -6 -5 -4 -3 -2 -1 0 1 2

Temperature (°C)

Ele

vati

on

(m

)

0m 10m

20m 30m

50m 75m

100m 150m

Distance from lake:

LARGE LAKE HAS PROFOUND THERMAL IMPACT ON NEARBY TEMPERATURES

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.







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






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 / KUGLUKTUKCombined Coppermine Kugluktuk Weather Record

y = 0.0245x - 59.29

R2 = 0.1604

-16.0

-14.0

-12.0

-10.0

-8.0

-6.0

-4.0

1928 1938 1948 1958 1968 1978 1988 1998 2008

YEAR

MA

AT

(oC

)

MAAT Value

Linear (MAAT Value)

Coppermine Kugluktukn 44 29Mean 11.5oC 10.5oCStd. Deviation 1.10oC 1.37oC

63 YEARS

2.5oC/ 100 YEARS

CONTWOYTO / LUPINCombined Contwoyto Lupin Weather Record

y = 0.0561x - 122.65

R2 = 0.3152

-14.0

-13.0

-12.0

-11.0

-10.0

-9.0

-8.0

-7.0

-6.0

-5.0

-4.0

1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008

YEAR

MA

AT

(oC

)

MAAT Value

Linear (MAAT Value)

Contwoyto Lupinn 23 25Mean 11.9oC 10.9oCStd. Deviation 1.16oC 1.39oC

48 YEARS

5.6oC/ 100 YEARS

ALL DATA POST 1960

-18.0

-16.0

-14.0

-12.0

-10.0

-8.0

-6.0

-4.0

-2.0

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010

YEAR

Mea

n A

nn

ual

Air

Tem

per

atu

re (

oC

)

Coppermine MAAT (oC)

Kugluktuk MAAT (oC)

Contwoyto MAAT (oC)

Lupin MAAT (oC)

Best Fit Line

46 YEARS

~6oC/ 100 YEARS

INAC REVIEWER’S APPROACH

WHY?

SUMMARY OF ESTIMATESG

CM

(4

scen

ario

s)

Plu

mm

er e

t al.

(Upp

er V

alue

)

Plu

mm

er e

t al.

(Low

er V

alue

)

Env

ironm

ent C

anad

a (U

pper

Val

ue)

Env

ironm

ent C

anad

a (L

ower

Val

ue)

Com

bine

d C

onto

ytal

/ Lu

pin

Com

bine

d C

oppe

r M

ine

/ Kug

lukt

uk

Bes

t Fit

BG

C U

pper

Val

ue

BG

C L

ower

Val

ue

INA

C C

onto

ytal

/ Lu

pin

INA

C C

oppe

r M

ine

/ Kug

lukt

uk

0

2

4

6

8

10

12

14

War

min

g V

alu

e (o

C /

100

yrs

) Government / Researcher GCM Estimates

Factual Warming Trends

BGC Proposed Allowances

INAC Proposal

WARMING ALLOWANCES ON OTHER PROJECTSProject Mean

Annual Air Temperature

Global Warming Allowances

Project Status

Polaris Mine Closure, NU

-16.5oC 3.0oC/100 years 5.1oC/100 years

Permits received Closure work completed Active monitoring

Nanisivik Mine Closure, NU

-15.1oC 2.8oC/100 years 5.0oC/100 years

Permits received Closure work almost completed

Doris North Mine, NU (2 year mine life)

-12.0oC worst case of 5.3oC over next century. Used simplying assumption of 6.5oC over next century

NIRB approval provided in September 2006.

Ekati Mine -8.5oC ~9.5oC/200 years Closure plannig

Meadowbank Mine, NU (8 year mine life)

-11.3oC 5.5oC/100 years NIRB approval provided in August 2006.







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.

MAAT, Permafrost Characterization and Climate Warming Jim Cassie, P.Eng. BGC Engineering Inc.

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Transcript of MAAT, Permafrost Characterization and Climate Warming Jim Cassie, P.Eng. BGC Engineering Inc.