Slides in this set
1. Climate change and its causes
Climate change is on a variety of scales:
1. Short-term change
Climate over the last few decades
- hundred years e.g.El Nino, La
Nina (very short)
2. Medium-term change
Global climate over billions of years
3. Long-term change
Climates from thousands / millions of years ago…read more
Evidence for past climatic change
Climate varies on all time scales from the short term (the recent retreat of
glaciers) to the long-term (deposition of desert sediments to form sandstone) in
response to random and periodic forcing factors.
Some of these could be due
to short-term changes e.g.
random variations (noise) in
the climatic systems.
Present day ice limit
Extent of glacier
retreat in little over
Ice limit in 1946…read more
What was the climate like 740,000 years ago?
· Scientists extracted an Antarctic ice core
· This represents 740,000 years of snow, with
each year preserved like an annual growth
ring in a tree.
· By analysing the gases in each year's
deposit we can tell how much CO2 there was
in the atmosphere in that year
· Isotopes trapped in the ice can be used to
calculate the atmospheric temperature for
each year…read more