EESA06H3 Lecture Notes - Lecture 12: Dense Non-Aqueous Phase Liquid, Brimley Road, Sydney Tar Ponds
Introduction to Planet Earth
March 28th, 2016
Lecture 12: A wide Ranging Review of Environmental Challenges (Part 2)
3-hour final multiple choice exam based on chapters 16, 20 & Lectures 10, 11 and 12
*have a quick look at chapter 15 also
Permafrost
- If you dig a hole, you’ll find sediments but you’ll also find large pieces of ice and
crystals.
- Permafrost table is what is melting due to the warming climate
- What happens when this melts?
o The ground surface actually subsides (maybe by several feet)
o Imagine a building or pipeline that has been built on permafrost has been faced
with a problem of subsidence
Permafrost in Canada
- Talik: it’s an area of unfrozen ground in permafrost. If you drill down, you will hit water.
- Discontinuous: the discontinuation of it
- Thermokarst
o Refers to the melting of permafrosting in response to warming
Thaw Ponds: Formed During Hypsithermal Warm Period (c. 5000 years ago)
- Thaw Ponds
o If you drop a heavy tube down in these ponds, you can recover sediments and you
can age/date them
o That was a very warm episode
- Hypsithermal (important term)
o It means elevated
o A time of elevated warmth
- All these are a product of Thermokarst
- The whole place is subsiding
o It’s only held above sea level because of the frozen ground underneath
o The thaw ponds are getting bigger
Impact of Climate Warming on Transportation
- What’s the trend of the duration of these ice roads?
o It’s getting shorter
Mackenzie gas pipeline
find more resources at oneclass.com
find more resources at oneclass.com
- A proposed 1220 kilometer natural gas pipeline system along the Mackenzie Valley
- Will cross large areas of permafrost
Trans-Alaska Pipeline
- Has been sitting there for over 25 years
- The heat there can’t be transmitted down to the ground
o There are tubes filled with anti-freeze
Watersheds Under Pressure
- How much of the flow of water is used in agriculture?
o Orographic precipitation: rainfall that has been triggered because it has to cross
mountains
o Canada is actually running out of water
Dendrochronology
- We need to know about events in the recent past to try to predict what might happen in
the near future
- So he looks at tree roots and each ring is produced every year. The width of the ring tells
us how well they are doing. It is a beautiful way to record climate.
Californian Megadroughts
- The official definition of a drought is if we don’t have precipitation for over 14 days
- Evidence of tree rings show that drought was historically much more widespread in the
American West than now, while 20th century was wetter than normal
- The West experienced two abnormally dry periods lasting close to 200 years during the
Middle Ages
- Our modern society is not really resilient to these droughts
- What is the ultimate solution?
o Exporting water
o At the moment, it’s a no-no
Dams or Trains: Build Water Storage now
- You’ll see a lot of these signs if you travel through California
- Why is that sign incorrect?
o What’s the point in building a dam?
▪ It’s to pond water but there isn’t water for the use of it.
▪ California is physically running out of water
find more resources at oneclass.com
find more resources at oneclass.com
