Transcript lesson-2-evidence

Climate Change:
Evidence
Climate Change is not a new thing
The worlds climate has been changing over the last
18,000 years, sometimes getting hotter and
sometimes colder as you can see from the graph
below.
The period of time since the last
glaciation, about 10,000 years ago. We
are still in the Holocene (the time since
the end of the last major "ice age) today.
Little Ice Age is a
time of cooler
climate in most
parts of the world.
Is the name for a cold climatic event lasting
about 1500 years which interrupted the
warming of the Earth after the last ice age.
Where do we get evidence for climate
change from?
Ice Cores
• Best evidence for climate
change comes from
Greenland and Antarctic ice
cores.
• Ice cores are a frozen record
of past climates (like a time
capsule).
• Within these layers the ice
contains air bubbles which
contain carbon dioxide and
oxygen isotopes.
Location of the
Greenland ice
cores
Ice Cores- How accurate and reliable
are these sources of data?
• The sequences of sea level change
links very closely with oxygen and CO2
isotope levels suggesting that this is a
very reliable source.
Evidence from recent weather
observations
• One effect of climate change is that extreme
weather events are likely to get more common
in the future.
• So do recent weather records show any
evidence that the weather is getting more
extreme?
Evidence of climate change in
Iceland?
• Mean temperatures is 3.5°c in Stykkisholmur, a small
fishing port on the west coast of Iceland.
• The mean July and August temperatures here are below
10°c.
• However, in July 2008, Iceland experienced its hottest
summer on record – between 24-27°c (higher than
Portugal temperatures)
• Evidence of climate change?
Study the graph. Describe the trend in annual temperatures
in Stykkisholmur between 1800 and 2000. (5)
• The trend of the graph shows the annual
temperature increases.
• It does not rise at a steady rate
• As the average temp starts to drop around
1850 and then rise again and then drops again
in 1950.
• The temp increases on average from 2.5 to
over 4.0
• It was at its highest in 2003 at 5.4