September 25, 2007
1. Recap -> will bring you up to speed.
2.Evidence -> there is major changes in terms of climate.
What’s Happening, and What Can We Expect
You have seen this slide before. Both sections of the lesson are on-line but after 2 weeks I will remove
them. I will try to give you a series of quotes and often they state ‘truisms’ and they are short. They
are obviously what you think is true. The first is by Aldous Huxley, 1927 – Brave New World. If you
haven’t read it you should read it. That and 1984, read them next summer. “Facts do not cease to exist
because they are ignored.” I was talking to a guy the other day who if you look at his hands they look
like he works hard every day. I told him what I did and I talked about cows. He told me about his herd
and he has 35 cows. Twice a day he has to milk them. He asked about what I did and I told him.
Farmer and professor are worlds apart. He told me about his neighbour and he wondered if global
change even exists. They are skeptical. Is it a hoax? What are the facts? I told him I would send him
the stuff to make a choice for himself. I don’t know if he will take me up on my offer. He provides our
milk and consumes a large amount of fossil fuel with his tractors etc.
Donald Rumsfeld, Feb. 2002 – who is he? He was the equivalent of the Minister of Defense in the US
government, basically Bush’s side-kick. He implemented the police in Iraq. There is a profound of this
gobbly-gook and he isn’t a stupid man, actually he is a smart man but it does apply to global change
(reads quote). What does “unknown unknowns” mean? We are entering a period where we can’t
really predict. There are areas that we can’t predict in the short run. This statement (originally I
thought he was an idiot and I still do) with respect to global change I think there are ‘truisms’ in this
mind-twisting quote that is probably right.
Components of the Climate Change Process
Up to this point we talk about human activities and this shows where we are going and where we have
been. I will show you this from time to time. We are looking to some extent at the direct and indirect
changes in climate change drivers. A good deal of focus is on the gases (aerosols, greenhouse). We
will talk about natural influences at the end of the lecture and finish it off the next day. We will talk
about the solar processes, earth orbit, and volcanoes. It is these processes that cause long-term changes
no matter what we do. We are going then to radiative forcing. How do these factors interact to change
the amount of sunlight that is retained in the earth?
If you are going to keep a balance what goes in has to come out. Remember the numbers 340 or 342
Wm-2. You will see how much our contribution is to the trace gasses.
Here again this is the greenhouse effect and it happens in the troposphere. Here is the colour cartoon
(already showed you) and you see the major players in this system. There are other players in this
BGYC58H3F.September ,25, 2007 LECTURE 3 1
system as well. Water vapour is important. You have all this from last time. This shows the
greenhouse gasses and how they didn’t really change until 1750.
Industrial revolution and the atmosphere. It started in the holoscene and that is really what we are in
right now. Again you have the 3 gasses:
1. Carbon dioxide
3. Nitrous oxide
It is constant all through this time and these are basically the average levels. Nothing happens and then
things change rapidly.
This is a graph and you have seen it before. I had 1998 before and I updated the 2 gasses to 2005. This
is a critical graph about how long we can expect the effects to last. These are long term effects and
scientists have modeled that if we stop today how long will they last?
The Carbon Cycle
You have seen this. The big one is the deep water in the ocean. This is a good graph of CO2.
This one is new. This is the carbon dioxide annual change (ppm). There is a problem in the balance
sheet in terms of how much CO2 goes into the atmosphere and how much stays there. Scientists don’t
know where it is all going. The problem comes out in this particular graph. Fossil fuel emissions of
CO2 are growing like this from about 1960 to the present time. If you look at actual growth in the
atmosphere it is significantly less (red bars). You can see the difference between the line and the bars
and that represents what is missing. Where is it going? We can’t balance the ‘global carbon budget’
but this is what we know. Oceanographers believe that carbon dioxide goes into the ocean each year.
Particularly at higher latitudes. The biggest pool is deep but this occurs at the surface of the oceans.
The exchange that occurs between surface and deep water occurs slowly. When talking about the
exchange rate here you look at a time span of about 350 years. The change is about 30% (1/3) of total
CO2 levels that goes into the oceans. It is kind of like a ‘sink’ and that accounts for a bit of this. So
the oceans are one of the sinks.
The second major sink is terrestrial vegetation. If you think of this, a tree outside here or in the Boreal
Forests it can be a sink and source of CO2. As a sink it is when trees, plants, grassland, suck CO2 out
through photosynthesis and make it into organic matter. It is also a source of CO2. The obvious way is
by forest fires. IN places like the tropics you had shifting agriculture in the rain forests. Poor farmers
would knock down a hector or so and then once the nutrients disappeared they would move on but that
has changed. Large sections are being converted to grazing and things like that now.
It is estimated in 1990 that tropical areas were a source of 1.6 gigatons of CO2 because of
deforestation. In the temperate areas the reverse has occurred in some areas and that is that
reforestation sucks up CO2. Example: the Eastern Deciduous Zone all the land was cut down but it
was a poor land for farming and once the US pushed off the Natives from the Prairies they abandoned
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the places. The trees grew up and that is a major area of regrowth. Remember that plant growth is
dependent on nutrients. Canadian government and other governments hope that plants will be a major
way of sequestering CO2 (taking it up). What are the assumptions? If CO2 levels increase does
photosynthesis increase? Yes but quickly that is not limiting nutrient for plant growth then it doesn’t
matter how much CO2 you have. The next limiting factor kicks in. Water is the first one and nitrogen
is the second. Phosphorous is the third.
Here is the ‘balance sheet’ and it is in gigatons. This is not CO2 but it is a carbon transfer (reads
statistics). There was an accumulation in the atmosphere which you expect. The oceans are also
playing a role, they are sucking it in. There should be an equivalent but instead there is an imbalance
so there is some ‘sink’ out there that we don’t know about. You can see it going up again in the 1990’s.
The accumulation in the atmosphere is about the same and oceans are going down slightly. Take these
levels with a grain of salt because they are not ‘spot on’. The imbalance is worse here.
Focus on the last 5 years but this is from the 4th assessment report of the international program on
climate change (UN). You can see the amount of fossil fuel is going up each decade. There is a flux
going into the oceans and this flux is a retrospective estimate and it is in the same ballpark as the last
chart. There is a sucking out of the land-to-atmosphere and they think that the land is sequestering
CO2 but we don’t know the unknowns. It will take about 5 years to the next report but you get the
idea. It has to be balanced or you are in trouble. Scientists are still trying to find out where the
imbalance is occurring.
In Canada we have huge costs because Canada is huge. In addition the Fort McMurray Oil Sands
produces a lot of our CO2. If we look at the Canadian situation and how much fossil fuels we produce
and where it goes about 1/3 of all fossil fuels we consume is used for our homes and for export. It is
used to keep you warm and to export it to the U.S.A.
About ½ of that 1/3 comes from the combustion of fossil fuels to produce electricity and the production
of those fossil fuels from oil, coal, and natural gas. 21% is involved in transportation (goods and
people). Remember the entire state of California has a population equivalent to all of Canada. 17% is
involved in construction and agriculture is about 9%. There is non-electrical use in the residential,
commercial, and industrial segment.
Basically the fossil fuel and CO2 level of production is increasing over a 20 year span (almost 2
gigatons). Since the 1980’s the natural processes of CO2 uptake by the oceans in the terrestrial
biosphere have accounted for 50% of the emissions. So remember that these removal processes are in
fact influenced directly by how much is already there. How much there is in the atmosphere and
changes in climate (warmer or cooler) will also affect the uptake processes. The uptake by the
terrestrial biosphere is more variable and it is thought to be higher in the 1990’s than in the 1980’s.
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