Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
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.