Thursday, June 7, 2012

4928.txt

date: Tue Oct 25 15:46:44 2005
from: Keith Briffa <k.briffaatXYZxyz.ac.uk>
subject: Review of Proposal - NE/D001463/1- CONFIDENTIAL
to: paneldatXYZxyzc.ac.uk

Sarah
here is my assessment of the Huntley proposal . These are good people but I can not in
conscience rate this as a high proposal in terms of blue skies research or strategic
outcomes for future modelling of climate changes. Some of the work is worthy , but none is
particularly novel and it can not be considered good value for money. I have to ask that
this review be kept anonymous. Thank you.
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Your Ref NE/D001463/1
Principal Investigator Professor B Huntley
1 No entry
2 Medium
3 Whole application
4
(a) alpha 3
What are the proposal's strengths
The main attribute of the project is the expertise of the proposers in the fields of lake
sourced Palaeoenvironmental data. Assembling the evidence of the past as a way of testing
forest dynamics in a vegetation model is good in concept and the selection of the region
and the types of proxies are as good as could be achieved in most regions. These strengths
are undermined by limitations in the relevance of the likely outcomes to the proposers
over-achieving goal.
What are the proposal's weaknesses
The over-arching goal of the proposal is stated as to improve knowledge and understanding
of the rate and character of the response of Boreal and sub-Arctic ecotones to climate
change, in order to improve parameterisation of seasonal albedo feedbacks in climate change
models. The extent to which this is achievable depends on the relevance of the results for
the chosen location to Arctic scale earth system models being used to predict climate
change.
The emphasis in the proposal is on one model LandClim which will operate at a spatial
resolution far beyond the achievable resolution of all climate models being used to project
climate change in fifty to one hundred years time. Typically these have a resolution of 2.5
degrees of latitude or about 250km. Even with an embedded high resolution regional model,
(not routinely run in model projections), this would still likely be 50km or at very best
25kms. This virtually encompasses the entire range of the proposed study.

The proposal does not make a convincing case for how the results of this localised
vegetation modelling would impact on the design of current large modelling of future
climate or vegetation schemes used by general circulation models. Besides mean climate,
issues to do with the realistic simulation of extreme short lived or small scale events
like frost day probability terrain influenced exposure and snow cover, or localised
palludification must all influence germination and mortality of seedlings and must be
parameterised in some way.

The comparison of different estimates of local climate change produced by a range of
different lake proxy data is of scientific value and comparing this evidence with
indications of changing tree cover through time will also produce results that are of
scientific use. Neither idea can be considered original. For an example see Heinrichs et
al. in Boreas (2005) pages 192-206 or Lotter et al. in Palaeoclimatology (1997) pages
395-420, or Heiri et al. (2003) in Palaeo� pages 35-53, or Seppa and Birks (2002) in
Quaternary Research pages 191-199. A review of these and other work shows significant
variability in even the major subdivisions of inferred Holocene climate or characteristic
vegetation biomes in the north of Scandinavia. Apparent contradictions in the character and
timing of transitions are probably the result of different sampling approaches and limited
sensitivities in the available proxies, coupled with real dating uncertainties.

Complex ecological changes in lake structure and the chemical and biological evolution of
internal lake conditions can confound the simple interpretation of different biological
proxies as monitors of external climate conditions. Climate estimates based on modern day
training sets for specific proxies typically produce large uncertainty and past climate
estimates might have uncertainty of an order equal to the magnitude of temperature change
in this area during most of the Holocene.

There is also likely to be additional significant uncertainty in the age-depth models for
different lakes. Even if some tephras are reliably identified they will be likely
associated with uncertainty of decades to centuries when the stratigraphic uncertainty in a
particularly lake core sample is taken into account. See Pilcher et al in Boreas (2005)
pages 136-156. All of the above will limit the accuracy and precision with which climate
changes can be deduced or can be associated with tree cover changes but it will especially
limit the degree to which inferences about the phasing and rapidity of tree distribution
responses to rapid warming.


The work is scientifically interesting but the reward can be considered medium as far as
relevance for future climate modelling. The part of the work proposed that deals with
simulation of present tree distribution using modern climate in the selected region, and
comparison with satellite and detailed terrain mapping of trees on to GIS seems a useful
preliminary exercise. This could act as a test of the model sensitivity to climate changes
in temperature and precipitation that are well enough known over hundreds of years.
Looking more widely at how well this model performs at different locations and climate
across the northern tree line ecotone also seems more valuable preliminary exercise and one
that should come before this paleo attempt at testing the model.

In summary the considerable resources requested to develop very localised reconstructions
of tree cover and basic climate for thousands of years is hard to justify when the likely
impact of the results on future modelling studies is not likely to be great. Instead
further sensitivity studies using a range of assumptions about localised albedo changes
could be proposed using general circulation models or linking them to different vegetation
models.
(b) Fit to NERC priorities C
(c) Risk Reward Medium for both Risk and Reward
(d) Cost Effectiveness 3
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Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.

Phone: +44-1603-593909
Fax: +44-1603-507784

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