Transcript Slide 1

|Met Éireann’s role in supporting the National
Climate Change Strategy (2007-2012)
Ray McGrath
Met Éireann
Climate Change Conference/Workshop for Directors of Services and Senior Local Authority Staff:
Kilkenny, 4 April 2008.
Overview
• Summary of recent climate research in Met Éireann.
• Knowledge gaps.
• Future work.
It’s not easy to forecast the future… there
may be surprises ahead!
“If you can look into the
seeds of time and say
which grain will grow
and which will not,
speak then to me…”
Banquo to witches in
Shakespeare's Macbeth
The climate system is complex…
Source: IPCC, 2007
1990-2007
typical for
short-term
climate
simulations;
century long
~1 step
behind.
Single-layer
slab ocean+10
atm -> 30/30
Source: IPCC, 2007
Atmosphere-Ocean General Circulation
Models (AOGCMs) very expensive to
run – limits resolution
C4I: Regional Climate Modelling
Generating local detail from the coarse picture Atmosphere-Ocean
General Circulation Models (AOGCMs)
AOGCM
RCM
Regional model built out of
operational HIRLAM model
used in Met Éireann
1900-2100 Irish Air Temperature Difference from 1961-1990 Normal Values
9-year running mean
5
Observed
HC high sens A1B large
HC high sens A1B small
HC low sens A1B small
ECHAM5 A2 large
ECHAM5 A2 small
ECHAM5 A1B small
ECHAM5 B1 small
ECHAM4 B2 small
Ensemble mean
3
2
1
0
1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090
-1
Year
Difference from 1961 - 1991 Normal Temperatures_
4
Seasonal and Regional changes in temperature
DJF
MAM
2021-2060 relative to 1961-2000
Warming, particularly in the
summer and autumn (1.2-1.4°C).
The warming is most pronounced
in the south and east.
Similar pattern towards end of
century - increase up to 3.4°C.
JJA
SAN
SeasonalRegional
and Regional
changes
changes
in rainfall
(%) in rainfall
DJF
MAM
2021-2060 relative to 1961-2000
Wetter in autumn and winter:
5-10% increase in mid century,
increasing 15-25% towards the
end of the century.
Summers are drier:
5-10% decrease for 2021-2060;
10-18% decrease towards the end
of the century.
Regional details are unreliable
JJA
SAN
Changes in monthly rainfall for mid century
Generally drier summers and wetter winters but details depend on the model –
large uncertainty!
Yearly Precipitation (mm) – Ireland/UK
Seasonal and Regional changes in surface winds
DJF
MAM
2021-2060 relative to 1961-2000
Changes are small:
slight increases in winter (1-2%)
and decreases in summer (2-3%).
Towards the end of the century
there is an overall decline in
speeds, particularly in summer (46%).
JJA
SAN
Atlantic Sea Temperatures
Sea temperatures are
rising slowly - since the
1980s 0.3-0.4˚C per
decade, particularly in the
Irish Sea.
Trend will continue and
possibly accelerate impacts on marine
ecology.
Trends in sea surface temperatures 19822006 (˚C per year)
Inland river temperatures
also rising – impacts on
cold water fish
(trout/salmon).
Rising sea levels around Ireland
Coastal Region
Northern
Northwestern
Southwestern
Southern
Irish Sea
All
Net trend
(mm/year)
2.7-3.3
4.3-4.7
3.9-4.0
3.1-3.5
2.3-2.7
3.3-3.6
Projections for the future
are for rises in the range
23-47 cm by the end of the
century.
Estimates are probably
conservative.
Trends in sea surface height based on satellite
measurements over the period 1993-2006. Trends allow
for isostatic rebound of the earth’s crust
Sea level rise – large regional variations expected
Source: IPCC, 2007
“During spring high tides, the visible land mass of
Okinotorishima (Japan) is only slightly larger than a
generous king-size futon bed and about the same height.
If sea levels rise by just a few centimetres, the contentious
pimple of coral will vanish beneath the waves for ever, a
moment that scientists say may not be far off.” The Times,
Jan 12, 2008
Changes in weather extremes
Increase in the
frequency of very
intense cyclones
affecting Ireland
(storm
damage/flooding).
Changing patterns in tropical and extratropical
cyclones due to a 2˚C rise in sea temperatures.
Extreme rainfall
events may increase
in frequency in
autumn and winter but considerable
uncertainty in these
projections.
Storm Surges
Galway Bay
Increase in storm
surge events around
Irish coastal areas,
except along the
south coast.
Significant increase
in the height of
extreme surges (in
excess of 1 m)
along the west and
east coasts.
Histogram of Surge Heights (cm)
Future wave/swell conditions
Some evidence of a
significant increase in
future autumn/winter
values.
Extreme wave height
show an increase (up to
10% in some coastal
areas).
Relative change (%) of 10-year return value of
annual maximum significant wave height (20312060 compared with 1961-1990)
Impacts on river flow
Amplification of seasonal
cycle:
Increased winter rainfall
=> increased winter flow
Increased summer
temperature and reduced
rainfall => reduced
summer flow
But, uncertainty in the
details…
% change in monthly mean daily flow (2021-2060
compared with period 1961-2000) for 9 catchments.
Impacts on Agriculture
18000
Climate change has
significant effect on some
crops (e.g. silage maize).
16000
Top weight (kg ha -1)
14000
12000
10000
8000
6000
Control
+ 20% temperature
+ 40% temperature
4000
2000
0
0
50
100
150
200
Days after planting (day)
14000
-1
Top weight (kg ha )
12000
Enhanced temperatures and
CO2 levels may increase
yields but increased winter
precipitation may reduce
yields.
10000
8000
6000
Control
4000
+ 20% precipitation
2000
+ 40% precipitation
0
0
50
100
150
200
Time for crop maturity may
shorten (e.g. two weeks early
in the TCD study for silage
maize).
days after planting (day)
Silage maize yields:
sensitivity to climate change
(Mohamed Abdalah / Mick
Jones TCD/TEAGASC)
Changes in energy demand (thermal heating)
2021-2060
2061-2100
Thermal heating accounts for
~34% of primary energy in
Ireland (2006).
Closely linked with ‘outside
weather’ temperature.
% change in degree heating days over
winter months due to a warming
climate (relative to 1961-2000)
‘Heating degree days’ a rough
measure of heat requirement.
Climate change => ~10%
decrease for 2021-2060 and
~22% decrease for 2061-2100
relative to 1961-2000.
Key issues for forecasting impacts of climate change
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Climate models are only models – they do not provide a perfect
simulation of reality.
Extent of climate change will depend on future greenhouse gas
emissions (less of an issue up to mid century).
Some weather elements are inherently ‘noisy’ (e.g. rainfall) – difficult
to predict extent of change.

Reliability of results is scale dependent i.e. worse at a regional level.

Applications introduce their own errors – ‘cascade of uncertainty’.
Tackling uncertainty -1
EU ENSEMBLES Project – European Climate
Quantify uncertainty by:
Running several global models.
Then running several regional climate
models on a 25km grid covering Europe.
Met Éireann a partner.
contributed 2 climate simulations
100/150 years (1951-2100).
These simulations (15-20 in total) are
now becoming available.
Basis for future applications to reduce
uncertainty.
Average number of days per month with ground frost (1961-1990)
Tackling Uncertainty -2
EC-EARTH Project
International project to develop a state-of-the-art global Earth
System Model:
atmosphere, ocean, sea-ice, land, atmospheric chemistry – unified
within a single package.
Irish partners: Met Éireann, UCD and ICHEC.
Work will focus initially on near term (~10-20 years ahead).
Work in progress or to commence this year
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Examine influence of Atlantic circulation on Irish climate (goal:
determine sensitivity to changing sea ice, changes in the Gulf Stream;
provide estimates of sea level rise).
Catchment flooding: initial study to be expanded using an ensemble of
climate simulations (goal: more reliable estimates of impacts,
particularly on extremes).
Storm surges: use ensemble simulations to extend initial study (goal:
as for catchment flooding).

Impacts on crop growth /forestry using ensemble simulations.

Impacts on fish stocks.
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
Variability of the future climate: impacts on renewables (e.g. wind
energy).
Impacts of climate change on air quality.
Influence of the Oceans
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Ocean heat capacity ~1000 times that of the atmosphere; net heat
uptake by the oceans since 1960 is ~20 times that of the atmosphere.
Transport of heat/water via Meridional Overturning Circulation
(“Thermohaline Circulation”) has a large influence on global climate.
Local influences very large.
Ireland and NW Europe have mild winters compared with
Labrador/Newfoundland at same latitude (up to 20˚C locally) – due to
Gulf Stream (but also the influence of the Rockies on the prevailing
winds).
Modelling the influence of the Atlantic Ocean
 Develop and validate a coupled
atmosphere/ocean limited area model.
 Use the model to test the sensitivity of
the climate system to changes in:
Changes in Arctic sea-ice cover
The MOC
Sea surface temperatures
River discharge
 Provide initial estimate of sea level rise
around Irish waters
Where does our air originate from?
If the flow patterns are changing what are the implications for
air quality in Ireland?
5-day 3D atmospheric back-trajectories (start points),
1985-1999, arriving at Dublin (at 10m level). Shading
indicates numbers in each 2° x 2° box (right legend).
Further details
http://www.c4i.ie
“The Government is committed to sustaining and
developing a climate-modelling framework within
Met Éireann, building on the C4I project, with links
to national and international research in this area, to
ensure that Ireland has an advanced capability for
prediction of future climate conditions.” National
Climate Change Strategy 2007-2012.
End