date: Mon, 11 Feb 2002 15:20:17 +0000
from: Juliette Shackleton <j.shackleton@nmsi.ac.uk>
subject: Tree rings Mark 2
to: k.briffa@uea.ac.uk

Keith
Just in case you've not had a look at the piece I sent through late last
week, here's a second version (after it has been improved by our editor).
I've attached it and also pasted it in below - in case you've got any
problems opening the attachment.

Many thanks
Juliette S



Chapter 3: Before records began: Tree rings

Page 1
What can chunks of old wood tell scientists about historical climate change? 

If you've ever seen a tree stump you'll have noticed the growth rings - new
wood added around the trunk each year in the growing season. 

Each tree's rings provide a year-by-year climate record, because their
thickness is affected by the weather. Dendrochronolosit Keith Briffa tells
antenna more.

Page 2
'Rather than cutting down trees, we work by drilling a small core through
the tree. It doesn't harm the tree and we get the record.' 

But translating what the rings tell scientists about the climate isn't easy
- because climate isn't the only thing that can affect how thick the annual
rings grow.

'It isn't just about sunshine and rainfall. It's also things like how
fertile the soil is, how old the tree is, and whether there has been any
insect attack. We have to separate all these things out to see what the
climate signal is.'
 
Page 3
To work out which years the rings in any one core belong to, Dr Briffa has
to compare and align rings from one tree to those of another tree of
similar age from the forest, looking for certain rings that he knows
represent years of fast growth.

By doing this, scientist build libraries of tree records based on average
growth widths for each area. In some cases, they can even match trees up
from overlapping historical periods to get a very long record.

Page 4
'We have used fossilised trees from peat bogs to get a timeline that goes
back thousands of years, even though individual trees that make up the
record only lived for a few hundred years. ' 

'Using tree rings, we can take a serious look at natural changes in the
climate, before man had much influence. They are the only detailed records
we have before records began. '

Page 5  
'The tree rings really back up the climate change message - that what we're
seeing this century is really unusual warming. We've seen nothing like it
in the past thousand years and more.' Keith Briffa, Climatic Research Unit,
UEA

Other natural indicators including corals, stalactites and ice cores also
show year-by-year changes in climate - put together, they point at today's
climate changes being quicker than ever before. 


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Attachment Converted: "c:\eudora\attach\Keith Briffa Mark2.doc"





Dr Juliette Shackleton
Wellcome Wing Project

National Museum of Science and Industry
Science Museum
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Tel:  0207942 4819
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http://www.sciencemuseum.org.uk/wellcome-wing/

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