Download BACC - Hans von Storch

Studying climate change in the
Baltic Sea Region
Hans von Storch
Institut für Küstenforschung
Helmholtz Zentrum Geesthacht
with material from
Sirje Keevalik (Tallinn), Anders Omstedt (Göteborg),
Markus Meier (Norrköping)
and Marcus Reckermann (Baltic Earth Secretariat)
Deutsch-Polnische Wissenschaftliche Begegnung , in Warszawa, 12. Juni 2014
BALTEX, BACC, Baltic Earth
The Baltic Sea region,
• The catchment of the Baltic Sea
• Temperate to subarctic climate
• Different cultures
• Joint history
Until 1991 divided into two different, partly
hostile parts of the world.
Atmospheric scientists began building a joint
platform for bridging the divide – BALTEX
Beginning in 2003, another effort for uniting
scientific communities – the BACC effort
In 2013, in recognition of the Earth System
science character, BALTEX is renewed as “Baltic
Earth”
Sirje Keevalik, Tallinn
1991 Overcoming the
big divide
Sirje Keevalik, Tallinn
Sirje Keevalik, Tallinn
The beginning …
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3-8 August 1992, Tallinn
International Radiation Symposium
Bringing scientist from East and West together
Making the Baltic Sea region another site for
the international GEWEX program with its
emphasis on the regional energy and water
cycle – named BALTEX
• Bringing together meteorologists, hydrologists
and oceanographers
Basis of knowledge:
Temperature,
precipitation,
river runoff,
salinity, and ice
The first BALTEX phase
Sirje Keevalik, Tallinn
Sirje Keevalik, Tallinn
Additional:
Connecting climate and
environmental changes:
Carbon and nutrient cycles
The second BALTEX phase
Achievements of 20 years of BALTEX
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overcoming the division between East and West
Synergistically combining forces from West and East
consolidating data bases
novel observational databases
coupled atmosphere-ice-ocean models
novel reanalysis products
outreach and communication activities like the homepage,
study conferences and summer schools
• organized and coordinated by the International BALTEX
Secretariat
• several working groups, e.g. BALTEX Assessment of
Climate Change for the Baltic Sea Basin (BACC)
BACC as „regional IPCC“
BALTEX Assessment of Climate Change for the
Baltic Sea basin - BACC
An effort to establish which scientifically
legitimized knowledge about climate change
and its impacts is available for the Baltic Sea
catchment.
The assessment has been
accepted by the intergovernmental HELCOM
commission as a basis
for its judgment and
recommendations.
Östersjöfondens
pris 2014
BACC- Principles
→ The assessment is a synthesis of material drawn comprehensively
from the available scientifically legitimate literature (e.g. peer
reviewed literature, conference proceedings,
reports of scientific institutes).
→ Influence or funding from groups with a political,
economical or ideological agenda is not allowed;
however, questions from such groups are welcome.
→ If a consensus view cannot be found in the above
defined literature, this is clearly stated and the
differing views are documented. The assessment thus
encompasses the knowledge about what scientists agree on but
also identify cases of disagreement or knowledge gaps.
→ The assessment is evaluated by independent scientific reviewers.
2013: A new science and outreach program for
the Baltic Sea region: Baltic Earth
• interdisciplinary and international
collaboration (study conferences,
workshops, etc.)
• holistic view on the Earth System of
the Baltic Sea region, encompassing
processes in the atmosphere on
land and in the sea and also in the
anthroposphere
• 'service to society'‘= thematic
assessments of knowledge gaps
• education (Summer schools)
Societal challenges in the Baltic Sea Region
for which scientific knowledge is needed
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Climate change
Eutrophication
Pollution
Habitat degradation
Invasive species
Overfishing
Suggested Grand Challenges
1. Salinity dynamics in the Baltic Sea.
2. Land-Sea biogeochemical feedbacks in the Baltic Sea region.
3. Natural hazards and extreme events as the key factor in
understanding and predicting natural disasters in the Baltic
Sea region.
4. Understanding sea Ievel dynamics using new technologies
(remote sensing).
5. Anthropogenic changes and how the Earth system of the
Baltic Sea region is affected.
6. Understanding regional/local variability of
water and energy exchanges
The BACC effort:
How does climate change affect the
Baltic Sea Region?
2003-2014
IPCC: Global temperature development during
“instrumental times”
Consensus among climate scientists
Bray, 2010
Climate scientists agree more and more that
a) the world is warming („manifestation“)
b) and that this warming can not be explained without referring to
increased GHG levels („attribution“)
Thus, on the global scale, the knowledge
about climate, climate change and
climate impact is well documented, but
what about the regional scale?
This should be an effort of regional
scientific communities – thus a task for
BALTEX and, now, Baltic Earth
BALTEX Assessment of Climate Change
for the Baltic Sea basin - BACC
An effort to establish which scientifically
legitimized knowledge about climate
change and its impacts is available for the
Baltic Sea catchment.
Approximately 80 scientists from 12
countries have documented and assessed
the published knowledge in 2008 in BACC 1;
in 2014 BACC-2 comes out, with about 130
contributing authors.
A truly Baltic Sea Region effort …
BACC (2008) results – in short
→ Presently a warming is going on in the Baltic Sea region,
and will continue throughout the 21st century.
→ BACC considers it plausible that this warming is at least
partly related to anthropogenic factors.
→ So far, and in the next few decades, the signal
is limited to temperature and directly related variables,
such as ice conditions.
→ Later, changes in the water cycle are expected to become
obvious.
→ This regional warming will have a variety of effects on
terrestrial and marine ecosystems – some predictable such
as the changes in the phenology others so far hardly
predictable.
Overall Summary of BACC-2 (2013)
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New assessment finds results of BACC I valid
Significant detail and additional material has been found and assessed.
Some contested issues have been reconciled (e.g. sea surface temperature
trends)
Ability to run multi-model ensembles seems a major addition; first signs of
detection studies, but attribution still weak
Regional climate models still suffer from partly severe biases; the effect of
certain drivers (aerosols, land use change) on regional climate statistics
cannot be described by these models.
Data homogeneity is still a problem and sometimes not taken seriously
enough
The issue of multiple drivers on ecosystems and socio-economy is
recognized, but more efforts to deal with are needed
In many cases, the relative importance of different drivers, not only
climate change, needs to be evaluated.
Overall Summary of BACC-2 (2013)
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Estimates of future deposition and fluxes of substances like sulphur and nitrogen
oxides, ammonium, ozone, carbondioxide depend on future emissions and climate
conditions. Atmospheric factors are relatively less important than emission changes.
In the narrow coastal zone, where climate change and land uplift act together plant
and animal communities had to adapt to changing environment conditions.
Climate change is a compounding factor to major drivers of freshwater
biogeochemistry, but evidence is still often based on small scale. The effect of climate
change cannot be quantified yet on a Baltic Basin wide-scale.
Scenario simulations suggest that most probably the Baltic Sea will become more acid
in the future.
Increased oxygen deficiency, increased temperature, changed salinity and increased
acidification will impact the marine ecosystem in several ways and may erode the
resilience of the ecosystem.
Increasing need for adaptive management strategies (forestry, agriculture, urban
complexes) in the Baltic Sea Basin that deal with both climate change but also
emissions of nutrients, aerosols, carbondioxide and other substances.
Past change: air
temperature
The warming of the low level atmosphere
is larger in the Baltic Sea regions than the
global mean for the corresponding period.
Warming
• continued for the last decade but not
in winter
• largest in spring
• largest for northern areas
Data sets
Year
Winter
Spring
Summer
Autumn
Northern area
0.11
0.10
0.15
0.08
0.10
Southern area
0.08
0.10
0.10
0.04
0.07
1 Linear surface air temperature trends (K per decade) for the period 1871-2011 for the Baltic Sea
Basin. Northern area is latitude > 60°N. Bold numbers are significant at the 0.05 level.
Data updated for BACCII from the CRUTEM3v dataset (Brohan et al. 2006)
Same for
1871-2004
(BACC I):
Annual and seasonal mean surface air temperature
anomalies for the Baltic Sea Basin 1871-2011, Blue colour
comprises the Baltic Sea basin to the north of 60°N, and red
colour to the south of that latitude.
Range of projected change of: Temperature – at the end of the century
Range of projected change of: precipitation amount – at the end of the century
Range of projected change of: maximum wind speed at the end of the century
Marine ecosysteme
Higher Temperature are expected to go along with
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Stronger growth
Earlier plankton blooms
Modification of species composition
Possibly advantages for blue algae
Invading of foreign species
Threatening of ringed seals (loss of ice cover)
and lower salinity
 Changing species composition; immigration of new species
 Reduced oxygen supply in deeper waters, which may be associated with problems for fisheries
(cod)
 Changed distribution and composition of zooplankton (food for small fish and fish larvae) and
bottom-dwelling organisms.
Detection and Attribution
→ Detection of non-natural influence on regional warming. Can be explained
only by increased greenhouse gas concentrations. Present trend consistent
with model scenarios.
→ Detection of non-natural component in trends of precipitation amounts;
present trends much larger than what is anticipated by models; thus no
consistent explanation for the time being.
→ Lack of studies on detection of changes in other variables
(e.g. snow cover, runoff, sea ice)
→ Lack of studies of the effect of other drivers (reduction of industrial aerosols,
land use change)
Regional attribution
Observed CRU, EOBS (1982-2011)
Projected GS signal, A1B scenario
10 simulations (ENSEMBLES)
Observed and projected
temperature
trends (1982-2011)
The observed (grey)
trends are mostly
consistent with what the
regional climate models
(green) suggest as
response to elevated GHG
levels.
However, the observed
warming was in all
seasons larger than what
the models suggested.
Regional attribution
Observed 1972-2011 (CRU, EOBS)
Observed (grey) and
projected (green)
precipitation trends (19722011)
Projected GS signal (ENSEMBLES)
The observed changes are in
all seasons, except for fall
(SON), larger than those
suggested by the regional
climate models.
The observed changes in
winter (DJF) , summer (JJA)
und fall (SON) are inconsistent
with the models’ suggestion.
In fall (SON) observation and
projection even contradict
each other.
Climate science has provided sufficient knowledge for
societies to decide about limiting climate change
• Yes, Climate is changing,
We can not explain this change in terms of temperature
without referring to elevated greenhouse gases
When looking at change in general, global climate change
is one factor; others may be at work as well, sometimes
dominantly so.
Climate change represents a challenge for human
societies and ecosystems
Climate change can be limited by limiting the
accumulation of greenhouse gases in the atmosphere.
• Whether societies agree on joining to actually limit climate
change is legitimately a matter of policymaking, of values, of
societal choices.
Independently of mitigation, a need for adaptation
remains – this is a regional and local issue
• We have not done our homework
- to study ongoing and possible future change.
- to separate the different causes for observed change.
• Climate science needs to deal more with options of
adaptation to prepare for societal decisions.
• The more successful the climate change limitation policy is,
the less adaptation is needed – but adaptation is needed, and is
useful in any case, if vulnerability is reduced.
• The regional scientific community is asked to generate the
needed knowledge. The eventual decisions needed are again a
matter of policymaking, of values, of societal choices.