MAINSTREAMING CLIMATE CHANGE ADAPTATION IN AGRICULTURAL EXTENSION
SLIDE 7 - What is happening to the amount of greenhouse gasses in the
world‟s atmosphere?
Show people the graphs – there are three graphs for three different GHGs
These show the amount of them in the atmosphere (on the y axis ie the line going
up) AND how these have changed over many years (on the x axis ie the line going
from left to right).
Look at the overall pattern – This shows that the amount of each of the GHGs has
gone up hugely SINCE MAN STARTED BURNING FUELS IN LARGE AMOUNTS
(the industrial revolution)
(if people want to know, ppb stands for parts per billion, ppm stands for parts per
million)
SLIDE 8 – What can influence the greenhouse effect
- The Sun
- Solar cycles
- How reflective the Earth is (its albedo)
i.e. how much energy gets absorbed in the first place
- The composition of the atmosphere
- We can measure these independently, so we can make a computer model of
them and see if they agree with observations
Solar cycles – the sun goes through periods of giving out more or less heat
How reflective the earth is – eg much of the far north and south are covered in
snow and ice. Snow and ice reflect back the light and heat. As these melt and
become sea water or land, less light and heat is reflected back and so the earth
heats up more.
The composition of the atmosphere
As we have already explained - Greenhouse gases warm the
atmosphere by stopping some of the heat escaping back to space.
We can measure these independently, so we can make a computer model of
them and see if they agree with observations. In other words we can see how
much effect each of these different causes is having on temperature.
A Training Manual on Use of Climate Information and Vulnerability and Capacity Assessment for
Agricultural Extension Staff in Zimbabwe
Page 13