Saturday, May 19, 2012


date: Mon Mar 11 17:51:39 2002
from: Mike Hulme <>
subject: unresolved issue
to: wilkins_diana,jenkins_geoff

Diana and Geoff,
There is one issue remaining unresolved re. the Briefing Report. This concerns the Box on
p.13 about levels of confidence.
- DEFRA/UKCIP want the box, ideally to also include statements with M and L status also.
- Hadley don't think it really works unless DIRECTION is included
Tyndall therefore suggest the version below (there is just not space to include M and L
statements and remember, we spent a lot more time on this than in the UKCIP98 version
(p.57) which was highly arbitrary. If we cannot get agreement the demands of space would
suggest we drop it!
We have negotiated an extra 24 hours with the designers so please let me have your views

Levels of confidence

In the scientific report for the UKCIP02 scenarios we adopt a scale of relative confidence
High, Medium and Low when presenting summary statements about future changes in UK
climate. These are expert judgements made by the authors based on our understanding of the
physical reasoning involved, consistency between models and statistical significance of the
results. It should be emphasised that these are relative rather than absolute
judgements. We summarise here the statements regarding the direction of change in which we
have High Confidence (annual results unless stated):
Average temperature increases
Summer temperature increases more in the southeast than the northwest
High temperature extremes increase in frequency
Low temperature extremes decrease in frequency
Sea-surface temperature warms
Thermal growing season lengthens
Heating degree days reduce
Cooling degree days increase
Winter precipitation increases
Winter precipitation intensity increases
Snowfall decreases
Summer soil moisture decreases
Specific humidity increases
Sea-level rises

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