Physical Environment of the Boreal-Arctic Region
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t/f northern areas vary vastly in elevation
true northern conditions are exacerbated at higher elevations
The ___ ridge divides the Arctic ocean into 2 major basins, and influences - ____ circulation - marine ___ - ___ movement
Lomonosov ridge water circulation marine life ice movement
Why does the geology of the north matter? Give 2 reasons
• we need to know how the rocks/ soils work in order to know how the plants and animals work • also, territorial claims (diamond extraction is changing the north)
The ___ Expedition in 1845 was trying to find the northwest passage and never returned
Franklin
t/f Canada is the largest producer of diamonds in the world, and it’s harming our northern ecosystems
false 2nd largest after Russia but it IS harming our north!
what’s a main problem with pipelines in the north?
They have to be above ground because the ground is frozen This disturbs the habitat even more (natural gas & oil)
How old are 75% of the rocks in the north?
Precambrian- Archean and Proterozoic 543 million yrs to 4.5 billion years old
The Canadian Shield is about __% of Canada’s land, and is very old rock
50%
What are the 3 basic classes of rock? (with a brief explanation of each)
• Igneous: formed by cooling & solidification of molten earth material (mostly silicate minerals) • Sedimentary: formed at or near earth’s surface- accumulation and lithification of sediment or precipitation from solution • Metamorphic: formed by altering preexisting rocks (by changing conditions like temp/ pressure)
t/f millions of years ago there were forests in the arctic with huge biomasses
true we know because preservation is so good in these conditions: mummification of stumps & litter etc
Where is Axel heiberg island? What used to be there?
an uninhabited island in nunavut ~45million years ago there were forests there (similar to temperate old-growth forests): represented max productivity achievable near the poles • also Champsosaurs (like a crocodile) lived there with fish and turtles ~86 million years ago = climate in the north was much warmer than it is today
Why is the arctic warming so much faster than other areas? Give 5 explanations
• As snow and ice melt, darker land & ocean surfaces absorb more solar energy • more of the extra trapped energy goes directly into warming rather than into evaporation • the arctic atmosphere layer that’s warming is thinner that at lower latitudes (atmosphere thicker at equator and thinner at poles) • with sea ice retreat, solar heat absorbed is easily transferred to the atmosphere • alterations in atmospheric and oceanic circulation
current atmospheric CO2 concentration is ___ ppm
419
List 5 of the most influential greenhouse gases
• CO2 (very abundant but doesn’t persist long) • Methane • Nitrous oxide N2O • SF6 Sulfur hexafluoride • Water vapour
How does the production of CH4 create positive feedback?
CH4 in atmosphere causes warming because it’s a GHG warmer= more decomposition occurs more decomp= more CH4 released
What are the 3 components of the Milankovitch cycles? What do they do?
• Eccentricity= shape of earth’s orbit around the sun • Axial tilt (23.5 degrees today) • Precession= wobble of earth on its axis these drive our seasonal variation
What would less axial tilt result in?
= solar radiation more evenly distributed between summer and winter (cooler summers, warmer winters) less axial tilt would promote glaciation!
What’s the periodicity of each of the Milankovich cycles?
Eccentricity: 100,000 yrs Axial Tilt: 41,000 yrs Precession: 23,000 yrs
How do Milankovich cycles start/ end ice ages?
The amount of summer sunshine on northern continents is crucial - if it drops below a critial value, snow from the past winter doesn’t melt in the summer –> an ice sheet starts to grow as more snow accumulates • more ice = more ice positive feedback b/c of higher albedo
t/f Milanovich cycles have a significant effect on the decade- century timescale
false good for explaining long-term changes in climate
Clouds and Earth’s surface reflect some ___ solar radiation back out to ___. Some is absorbed by the ___ and the rest is absorbed by earth’s ___
incoming space atmosphere surface
What happens to the solar energy absorbed by Earth’s surface?
it’s emitted as weaker radiation with longer wavelength (infrared) • some of this passes through atmosphere unimpeded, but most is absorbed by GHGs and reemitted in all directions, including back to earth’s surface