Loading presentation...

Present Remotely

Send the link below via email or IM

Copy

Present to your audience

Start remote presentation

  • Invited audience members will follow you as you navigate and present
  • People invited to a presentation do not need a Prezi account
  • This link expires 10 minutes after you close the presentation
  • A maximum of 30 users can follow your presentation
  • Learn more about this feature in our knowledge base article

Do you really want to delete this prezi?

Neither you, nor the coeditors you shared it with will be able to recover it again.

DeleteCancel

World at Risk: Climate Change Evidence (L17)

No description
by

Terry Dhillon

on 2 November 2016

Comments (0)

Please log in to add your comment.

Report abuse

Transcript of World at Risk: Climate Change Evidence (L17)

Climate Change Evidence
What is the title?
What is the title?
How accurate and reliable are ice cores as sources of data?
What do they tell us?
Using Information
Enquiry Question 4
How and why has climate changed in the past and how significant is recent global warming?
Discuss the meaning of this image
Tree Rings (Dendrochronology)
How accurate and reliable are these as data sources?
Good reliability – However, tree records only give
localised
records!

But climate change is NOT a new thing!
LONG TERM EVIDENCE - POLLEN ANALYSIS
Where do we get the evidence from?
Learning Objective: To explore a range of evidence that identifies climate change as a short and long term phenomenon.
The world´s climate has been changing over the last 18 000 years, sometimes getting
hotter
and sometimes
colder
as you can see from the graph above.

Clue: use the labels along the axises to create a title.
Extension: how do these graphs provide evidence that global warming and climate change are increasing due to human activity?
LONG TERM EVIDENCE - 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.

From looking at the graph below you can see clearly the periods of
low concentrations
of CO2 occur during
glacial periods.
High concentrations
of CO2 link with
warmer periods
of time- like the Holocene interglacial we are going through now!

From the ice cores we can also detect oxygen isotopes. Combined with the CO2 concentration the two link in well to explain sea level changes.
When there was low levels of CO2 recorded sea levels were lower (why?)

The sequences of sea level change links very closely with oxygen and CO2 isotope levels suggesting that this is a very reliable source!

Source: NASA (link to climate change website on Google classrooms)
Pollen is produced by all plants and was extracted from sediment cores in peat bogs and lake beds.
Pollen grains are preserved in waterlogged sediments.
By analysing pollen we can see how ecosystems have changed in response to climate change.
HOWEVER, not as reliable - as accurate pollen reconstructions rely on good preservation of pollen. Long pollen sequences are rare, and vegetation change may lag behind “climate change”.

MEDIUM TERM EVIDENCE - TREE RINGS (DENDROCHRONOLOGY)
Many trees are sensitive to changes in temp, sunlight and precipitation
In warm years trees have wide rings & vice versa
Record can go back 10,000years+

Give 2 examples of research methods that show long term historical climate change?
How reliable are these?
Give 2 ways of measuring medium term climate change?
How reliable are these?
What about short term?

MEDIUM TERM EVIDENCE - HISTORICAL ACCOUNTS
Painting of the River Thames frozen
Dickensian winters
Unreliable – These sources did not set out to record climate, and must be used with care. They are usually local, and difficult to generalise.

MEDIUM TERM EVIDENCE - GLACIAL RETREAT
Reliable – Good records stretch back to around 1880, before this the record is patchy.

Glaciers change in response to climate change.
We can look at old photos/maps/paintings to measure direct differences in glacial positions

SHORT TERM EVIDENCE - "SINCE RECORDS BEGAN!"
The last 128yrs of data suggest the Earth is 0.7 – 0.8 oC warmer
11 of the world’s hottest 12 years occurred in the decade 1995-2006

Full transcript