Albedo. This means low reflectants of short-wave radiation hence the earth converts that to
infrared and starts to heat it up.
You have these two slides but in different order. It is a composite picture by NASA. It does a
good job at showing how much snow there is in the Northern Hemisphere. Whatever shortens
the period of snow affects the amount of infrared. Many of these things are interconnected.
Snow cover effectively cools the earth and the more of it the cooler the earth.
The other thing that snow does is it acts as an insulator. Have you ever dug into the Arctic at all?
You will find permafrost if you dig and with snow cover it insulates this. In 1986/87 I was
studying Lemmings which are animals that jump off cliffs and kill themselves. They don’t
usually do that. They are between a rock and a hard place and when they have babies everything
wants to kill them. They are very small. I wanted to capture females and their young but usually
you can’t see them. I put radios around their necks and used antennas to pinpoint where they
were. You use a wand to see where they are. When she has babies she sits on them and 1 inch
from where she is the rock is solid. I would dig down really fast and catch the mom and babies
to do my research. I had to go down about 30 cm before I could catch them. While I was there a
guy from UBC was there and he was a famous permafrost researcher. They could bore down
into the permafrost and the found that it is warming and you can see the signature. If you get a
change in the insulation of snow cover in winter then many things will change. If you go to
Inuvik the houses are all on permafrost and they have big columns sunk into the ground which
they cool with Freon or whatever they use now because once it melts these guys are in the water.
The Cryosphere stores about 75% of the world’s fresh water. The critical role that fresh water
plays is for irrigation, feeding rivers, etc. A slight change in temperature will change the snow to
water and if it comes out as water it is flowing. That will change the runoff immediately and
how much runoff comes in the spring and summer and this has major implications.
The last big of data is new and it came through in September. It shows the extent of Arctic ice
depreciation. We lost approximately 1 million sq km in the summer. Remember that sea water
is 35/million parts salt so that has to be compensated as well. So now we only have 3 million sq
km up there in the summer so who knows the problems we are facing.
Glacier mass balance:
This is where we left off. Remember the slides in the Gore movie? That was dramatic but you
can look on the internet and find similar slides. This shows the cumulative change in glaciers
worldwide by area. They have been measured since the 1960’s. You can see some of the other
places are showing major losses of ice and it appears to be accelerating. Mass loss in ice is
estimated in water equivalence in a 40 year period is about ½ mm/year. You can see on the
BGYC58H3F.October,2, 2007 LECTURE 4 2