Transcript BACC - hvonstorch.de

BACC - Assessment
of past and expected future
regional climate change in the
Baltic Sea Region
Szczecin, 25. May 2009
Speaker:
Hans von Storch
GKSS Research Centre, Germany
The Baltic Sea Basin = The BALTEX Region
• Basin: 2.2 Mill. km2
• Baltic Sea: 380 000 km2
• 85 million in 14 countries
• Variable climate and
topography
• Considerable seasonal, interannual, decadal and longterm variations
• Environmental issues of
concern (HELCOM)
from SeaWiFS on 1 April 2004
The Baltic Sea Catchment Assessment: BACC
An effort to establish which
scientifically legitimized knowledge
about anthropogenic climate change
is available for the Baltic Sea
catchment.
Approximately 80 scientist from 10
countries have documented and
assessed the published knowledge.
The assessment has been
accepted by the intergovernmental HELCOM
commission as a basis
for its future deliberations.
In 2012 a second assessment report
(BACC II) will be published.
The purpose
of BACC is to provide the scientific community and
the public with an assessment of ongoing and future
climate change in the Baltic Sea Basin. This is done
by reviewing and assessing published scientific
knowledge on climate change in the Basin.
An important element is the comparison with the
historical past (until about 1800) to provide a
framework for the severity and unusualness of the
change.
The unique feature of BACC is the combination of
evidence on climate change and related impacts on
marine, freshwater and terrestrial ecosystems in
the Baltic Sea Basin.
It is the first systematic scientific effort for
assessing climate change in the Baltic Sea Basin.
No additional or external funding was needed.
The results have not been influenced by either
political or special interests.
www.baltex-research.eu/BACC
Past and current climate
change
 Air temperature increased by about 1.2 C since
1871 until 2004.
 Most pronounced warming in spring.
 Related observed changes in winter runoff, ice
duration and snow.
 More precipitation in the 2nd half of the 20th
century with major regional variations.
 No systematic change in windiness found.
 No clear long-term trends in Baltic Sea salinity.
Past and current climate change: Air temperature
Temperature anomaly ( C)
4
Baltic Sea basin land
surface spring air
temperature
1871-2004
3
2
1
0
-1
-2
-3
-4
-5
1870
1900
1930
North Spring
Filter
1960
1990
South Spring
Filter
Winter
Spring
Summer
Fall
Year
North
1,17
1,95
0,78
1,04
1,3
South
1,30
1,43
0,40
0.80
1,01
Linear temperature trends 1871 – 2004 for the northern (latitude > 60
°N) and southern (latitude < 60 °N) Baltic Sea basin.
Anomaly time series of annual precipitation over
Sweden, 1860-2004 (reference period 1961-90).
Precipitation
Past and current climate change: Wind
No changes in wind and storminess
Number of low pressure systems (p< 980 hPa) in Stockholm and
Lund
Past and current climate change: Precip and ice
Volkhov-Volkhovo
Tornionjoki
9.6. 200
Ice cover
duration,days
30.5. 150
20.5.
10.5.
30.4.
100
50
0
19
46
19
50
19
54
19
58
19
62
19
66
19
70
19
74
19
78
19
82
19
86
19
90
Break-up (date)
19.6.
20.4.
1693
Years
1743
1793
1843
1893
1943
1993
Year
Variation
of
annual
precipitation
amount
overFinland.
Ice
break
up
in Tornionjoki
River,
Changes
in river
ice
cover
duration
(Volkhov
river,
Russia).
Denmark, 1874-2004 (Cappelen and Christensen
2005).
salinity
Ongoing changes
in regional ecosystems
 Associated changes in terrestrial ecosystems
include
- earlier spring phenological phase,
- northward species shift, and
- increased growth and vigour of vegetation.
 Robust assessments of changes in marine
ecosystems related to climate change are
hardly possible at this time. Further research
is needed to discriminate between climate
change and other anthropogenic drivers such
as over-fishing, euthrophication, air pollution
and land use changes.
Past and current climate change: Terrestrial ecosystems
Mean rate of change (days/year) of date of
leaf unfolding in birch, 1958-2000
Marine Ecosystems:
Regime Shift in about 1988?
Caveats
 Link to raising greenhouse gas concentrations is plausible,
but no robust regional attribution has been established.
(On the global scale this link has been established)
 Many conclusions relate to different time periods
studied, changes occur at different time scales:
Variability versus trend problem.
 Only few observational records span the entire recent
150 to 200 years.
 Changing observational techniques influence data
homogeneity.
 “Detection and attribution” studies at the regional scale
are urgently needed to determine the influence of
anthropogenic factors in changing the regional climate.
Past and current climate change: Baltic Sea Temperature
Assessment of Baltic
Sea water temperature
1900-2000:
Data inhomogeneities
prevail
Fonselius and Vaderrama (2003)
Scenarios of future climate …
 … constructed by feeding assumed emissions
of greenhouse gases and aerosols into quasirealistic models of the climate system.
 Future emissions can not be predicted; only
plausible and consistent visions of the future
(i.e., scenarios) are possible.
 Scenarios provide a frame for decision
makers to explore the range of policy options
to deal with the reality of anthropogenic
climate change.
 Scenarios are no predictions.
Scenarios of future climate change
Global climate models (GCMs) project warming over the
Baltic Sea basin.
Regional scenarios are constructed from regional
climate modelling, which provides more geographical
detail and is broadly consistent with GCM projections.
Results from regional climate modelling do not fully
reflect model and scenario uncertainties.
Within these limits, these results give an indication of
plausible future changes by the end of the 21st century.
Projections of
future regional climate change
 Increasing temperatures very likely during
the entire 21st century, but size of the trend
depends considerably on model.
 Projected mean precipitation increases,
largest increase in winter throughout the
basin and decrease in summer in the southern
basin.
 No clear projection for wind speed and
storms.
BACC projections: Winter precipitation
1
Regional climate model simulated precipitation changes in % for winter (DJF) between the
periods 1961-1990 and 2071-2100 using the SRES-A2 emissions scenario. The upper plots
show results from the HIRHAM Model and the lower plots are from the RCAO Model. Plots
on the left used GCM boundary conditions from HadAM3H; plots on the right used
ECHAM4/OPYC3.
BACC projections: Summer precipitation
1
Regional climate model simulated precipitation changes in % for summer (JJA) between the
periods 1961-1990 and 2071-2100 using the SRES-A2 emissions scenario. The upper plots
show results from the HIRHAM Model and the lower plots are from the RCAO Model. Plots
on the left used GCM boundary conditions from HadAM3H; plots on the right used
ECHAM4/OPYC3.
BACC projections: River runoff
Change of river flow to
Baltic Sea basins 2071-2100
BACC projections: Sea ice
Mean number of ice
days in a present day
simulation (right) and
two scenarios for
2070-2100 (bottom)
Projections of future climate
impacts on terrestrial ecosystems
The expected future
warming is associated to
a possibly accelerated
continuation of the
present trends in
- earlier spring
phenological phases,
- northward species
shifts and
- increased growth and
vigour of vegetation
changes in the relative cover of different
vegetation types in Northern Europe
Projections of future climate
impacts on marine ecosystems
 No detailed, comprehensive analysis available –
projections are more ad-hoc and uncertain.
 Effect of other changing influences hardly
predictable.
 Possible Baltic Sea salinity decrease would have major
effect on marine fauna.
 Expected changes in precipitation and river runoff
may have additional detrimental effects on the
problem of eutrophication.
Marine ecosystems
– expected consequences of ...
… increase of temperature
 Higher metabolic rates
 Impact on acclimation capacity
 Reduce the general fitness
 Reduce enzyme activities
 Shift in species composition (phytoplankton)
 Enhanced cyanobacteria blooms
Marine ecosystems
– expected consequences of ...
… reduction in sea ice
 Ringed seal survival
… decrease of salinity
Osmotic stress
Shift in species composition (phyto– & zooplankton)
Egg survival
Food quality for fish (growth rate)
Distribution of benthos
Reduction of fitness
Invading species
Major findings (1)
-a marked increase of mean surface air temperature of more than 0.7 C in the
region during the recent century;
- consistent changes in other variables such as extreme temperatures, increase
of winter runoff, shorter ice seasons and reduced ice thickness on rivers and
lakes in many areas;
- a spatially non-uniform pattern of upward and downward trends in
precipitation, which is difficult to be related to anthropogenic climate change;
- evidence on increasing Baltic Sea SST only significant for the 3 recent
decades, the century-long data records may have severe inhomogeneities;
- assessment of indications that at least part of the recent warming in the
Baltic Sea basin is related to the steadily increasing atmospheric concentrations
of greenhouse gases;
Major findings (2)
- for the future, projections indicate that increased winter precipitation
may emerge later in this century over the entire area, while summers may
become drier in the southern part – but this expectation is uncertain for the
time being;
-for the Baltic Sea, a tendency towards lower salinity and less ice coverage
could be expected;
-no clear signals, whether for the past or for future scenarios, are available
with regard to wind conditions;
- observed changes in past temperature have been associated with
consistent changes in terrestrial ecosystems, such as earlier spring
phenological phases, northward species shifts and increased growth and
vigour of vegetation, these changes are expected to continue and become
more pronounced in the future;
- an assessment for the marine ecosystem of the Baltic Sea is particularly
difficult because of the presence of strong non-climatic stressors such as
eutrophication, fishing, release of pollutants, related to human activities.
BACC @ Springer
Publication in January 2008:
More than 30 contributing institutions
More than 80 contributing authors from
13 countries
More than 475 pages
More than 2000 references (~150 nonEnglish)
Ch1: Introduction and summary
Ch2: Past and current climate change
Ch3: Projections of future climate change
Ch4: Climate-related change in terrestrial and
freshwater ecosystems
Ch5: Climate-related change in marine ecosystems
Ch6: Annexes
www.baltex-research.eu/BACC
BACC and HELCOM
HELCOM Thematic Assessment
published May 2007
The report is based on the BACC
material but condensed to 59 pages with
a focus of the marine environment of the
Baltic Sea. It has been approved by the
HELCOM contracting governments of 9
countries and the European Commission.
An unprecedented cooperation of a
climate-related research program
and an intergovernmental body