ENVIRONMENTAL CHANGE RESEARCH CENTRE
Birkbeck, March 13th, 2009
Rick Battarbee
Environmental Change Research CentreUCL
Does climate change pose a threat to our freshwater ecosystems:
ENVIRONMENTAL CHANGE RESEARCH CENTRE
• Climate change revision• Evidence for unprecedented climate change• Evidence for change in remote freshwater lakes• The relative importance of climate change at the present time• Evidence from contemporary long term data-sets• Looking to the future – different approaches and examples• Implications of climate change for restoration policies and practice• Adaptive management• Conclusions
Outline
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What are the current IPCC projections for climate change?
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IPCC 2007
Current GCM projections for global mean temperature
ENVIRONMENTAL CHANGE RESEARCH CENTRE
IPCC 2007
Shift in global mean annual temperature patterns, comparing 2020s and 2090s and different scenarios
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Shift in global precipitation patterns for the 2090s, comparing winter and summer
White areas show poor model agreement, stippled areas show strong model agreement
Wetter in high latitudes (especially in winter)Drier in low latitudes (especially in summer)
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Is unprecedented climate change already occurring?
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From Phil Jones
Global air temperature increase seems unprecedentedfrom the instrumental record!
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From Wikipedia
On a 1000 year time-scale the picture is not so clear
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But models only match measurements over the last 100 years ifgreenhouse gases are included
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250
275
300
325
350
375
1000 1200 1400 1600 1800 2000
Mauna Loa atmosphericLaw Dome (Etheridge et al., 1996)Siple (Friedli et al., 1986)EPICA DML (Siegenthaler et al., 2005)S. Pole (Siegenthaler et al., 2005)
Age (Year AD)
CO
2 / pp
mv
And carbon dioxide concentrations are certainly unprecedented
380
275
ENVIRONMENTAL CHANGE RESEARCH CENTRE
But, what evidence is there that this has caused unprecedented changes in our freshwater ecosystems
so far?
Difficult to identify because:
(i) observational records are short and cannot be used to distinguish between greenhouse gas impacts and
natural variability
(ii) almost all surface waters in populated regions suffer from human impacts that mask the climate signals
ENVIRONMENTAL CHANGE RESEARCH CENTRE
River Thur, Switzerland(From Peter, EAWAG News 2006)
Hydromorphological modification
Ladybower, Stephen Walker
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Soil erosion andland-use change
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Eutrophication
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Water abstraction andsalinisation
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Because of these masking stresses we need to go toremote regions where human impact can be assumed
to be minimal
Research in the last 15 years has focussed on lakesediment records from arctic and alpine regions
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Elison Lake,Herschel Is.
(Douglas & Smol, Science, 1994,
Diatom evidence for unprecedented (?) change in high arctic lakes
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(Catalan et al.JOPL, 2002)
Diatom evidence for unprecedented (?) change in alpine lakes
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So we can argue that there have already been changes in climate due to increases in greenhouse gases and that there is evidence that this is reflected by changes in the ecology of
remote lakes over and above that expected as a result of natural variability.
Can we therefore find evidence for the impact of climate change on freshwater ecosystems in populated regions, despite the
dominance of other stresses?
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Euro-limpacs
Integrated Project to Evaluate the Impacts of Global Change on European Freshwater Ecosystems
http://www.eurolimpacs.ucl.ac.uk
Euro-limpacs is a large (36 partners, 18 countries) EU projectco-ordinated by ECRC-UCL
2004-2009
See the Euro-limpacs Position Paper (Deliverable 301)
ENVIRONMENTAL CHANGE RESEARCH CENTRELong-term changes in river and stream temperatures in Switzerland
4
5
6
7
8
9
10
11
12
13
BA, 541 RH, 645 LU, 455 BR, 654 ME, 738 BG, 437 RE, 628 CH, 1701 HA, 1011 BE, 803 TN, 571 BI, 762 TR, 778 BY, 717 WE, 608 KE, 1050 TI, 1649 EM, 1069 AR, 1834 VB, 1732 MO, 1730 PO, 2099 SI, 2295 UR, 2012 BW, 2140
1990 200019801970
T [°C]River &altitude[m a.s.l.]
Increasing river temperature in Switzerland
(from Hari et al. (2006): Global Change Biol. 12: 10-26).
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New EA database on river temperatures of over 30,000sites in England and Wales
From des Clers, Hughes & Simpson, UCL
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River temperature change in the UK from 1990-2006
(degrees C/decade) Most sites show increases of between 0.3 and 0.6 degrees
per decade
River Dee @ LlandderfelSH982366 (146 m a.s.l.)
1974-2007 712 recordsLinear trend
+0.52 °C/decade (1985-2006)
From des Clers, Hughes & Simpson, UCL
ENVIRONMENTAL CHANGE RESEARCH CENTRE
A. mixta A. imperator
O. cancellatum*
S. sanguineum
S. sanguineum
Is this responsible for some southern species of dragon-fly showing northern range expansion?
(1995-2006)
From Steve Brooks, NHM
ENVIRONMENTAL CHANGE RESEARCH CENTRE
The long-term change in the summer biomass of phytoplankton in the Queen Elizabeth Reservoir in the UK.
Years
Chl
orop
hyll
(ug
L-1)
0
20
40
60
80
100
120
140
1980 1985 1990 1995 2000
From George et al (2005)
The key climatic driver has been an increase in the stability of the reservoir and the increased frequency of calm, sunny days
Is climate change leading to increased algal growth in lakes?
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Is climate change responsible for increased algal growth and
invasive roach populations in Windermere?
Average [PO4-P] in first 4-weeks of year
0
5
10
15
20
25
30
1945 1955 1965 1975 1985 1995 2005Year
[PO
4-P]
/ mg
m-3
Windermere North BasinWindermere South Basin
y = 0.09x - 167.10R2 = 0.32
y = 0.16x - 315.84R2 = 0.18
y = 0.10x - 197.59R2 = 0.62
y = 0.20x - 389.20R2 = 0.47
0
2
4
6
8
10
12
1960 1970 1980 1990 2000 2010Year
Annu
al m
ean
Chl
a (m
g m
-3)
South Basin
North Basin
From Stephen Maberly, CEH
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Long-term changes in Windermere: improvement following P-stripping but subsequent deterioration
Max Chla [JJA] (mg m-3)
0
5
10
15
20
25
30
1950 1960 1970 1980 1990 2000 2010Year
North Basin
South Basin
Mean zooplankton [JJA] (No. dm-3)
0
5
10
15
20
25
30
1950 1960 1970 1980 1990 2000 2010Year
North Basin
South Basin
Summer phytoplankton have increased in the last decade despite an initial marked reduction following tertiary P-removal in 1992
The increased phytoplankton has coincided with a marked decrease in the apparent grazing pressure from summer zooplankton
From Stephen Maberly, CEH
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Hypothesis: roachinvasion followingclimate warming
Maitland 1972
Davies et al. 2004Pre 1990 1995
20000
10
20
30
40
1995 2000 2005
Cat
ch p
er u
nit e
ffort
(roac
h 10
0 m
-2 n
et d
-1)
NorthBasinSouthBasin
From Stephen Maberly, CEH
ENVIRONMENTAL CHANGE RESEARCH CENTRE
So water temperatures are increasing, probably as a result of global warming rather than natural variability and there is evidence that climate change is beginning to influence species distributions and the structure and functioning of
freshwater ecosystems in the UK, in expected and unexpectedways
What about the future?
How can projections be made?
ENVIRONMENTAL CHANGE RESEARCH CENTRE
• palaeolimnology– learning from the past beyond the range of the observational record
• space for time substitution– to explore the structure and function of ecosystems in potentially analogous
climatic conditions
• experiments (field manipulations, mesocosms)– to examine responses to projected climate under controlled conditions
• modelling (statistical and process based)– to understand processes and assess time-scale of response for differentscenarios based on climate projections
First, we need to establish, if possible, robust relationships between changes in climate variables and hydro-ecological responses
From the Euro-limpacs project
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IPCC 2007
And then apply a climate change scenario for the future
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Temperature
Spec
ies
abun
danc
e species 1species 2
Climate scenario: T
current future
Grenouillet et al. Euro-limpacs, Blanes 2008
Assessing the effect of temperature increase – fish in France
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Cha
nge
in p
roba
bilit
yof
occ
urre
nce
Bam Am
mG
og
Chn
Rha
Gaa
Cog
Les
Lec
Ana Bar
Cht
Alb
Leg
Sas Lel
Rur
Sce
Cyc
Tht
Blb Tit
Sal Cac
Ala
Esl
Bab
Lol
Abb
Gyc
Pup
Php
Pef
Lap
Sat
-0.5
0
0.5
+
Comparison between the current and projected probabilities of occurrence under
HadCM3 A1Fi scenario using SpeciesDistribution Models (SDMs)
Contrasted responses to climate change between species
Species
Grenouillet et al. Euro-limpacs, Blanes 2008
Potential impact of temperature change on fish species occurrence in France
ENVIRONMENTAL CHANGE RESEARCH CENTRE
±0 0.5 1 1.5 20.25
Kilometers
Embankment
DitchHigh : 14
Low : 0
Assessing the effect of changing hydrology: the Elmley Marshes, North Kent
Ramsar site, SSSI, NNR
redshank
lapwingFrom Julian Thompson, UCL
ENVIRONMENTAL CHANGE RESEARCH CENTRE
From the TIMES newspaper 2005Concern following the previous dry winter
What about 2050?
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Projections of water table depth based on hydrological modelling(MIKE SHE) forced by UKCIP02 climate scenarios for the 2050s
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.325/06/97 25/10/97 25/02/98 25/06/98 25/10/98 25/02/99 25/06/99 25/10/99 25/02/00
Gro
undw
ater
dep
th (m
) CalibratedL-trwsML-trwsMH-trwsH-trws
b
Water table depth (PETtrws)
From Julian Thompson
From Mike Acreman
Salt marsh rush (Juncus gerardi),Sea arrow grass (Triglochin maritima),Divided sedge (Carex divisa)
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Restoring shallow lakes from a turbid algal-dominated state to a clear-water plant-dominated state
Tai Hu, China
(Steffen et al. 2004) Photo Li Shijie 2005
Interactions between climate change and eutrophication –will CC make restoration of shallow lakes even more difficult?
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Approaches – eutrophication experiments using mesocosms
• aquatic macrophyte response to nutrients and temperature in 24 temperature controlledtanks including sediments and mixed plankton (Erik Jeppesen, Denmark)
• phytoplankton response to nutrients and temperature in 48 temperature controlled tanks withand without fish (Brian Moss, UK)
submerged plant (Denmark) phytoplankton (UK)
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Six lakes per country
From Moss et al. ECOFRAME
Eutrophication – space-time substitution and experiments
Space-time and mesocosm experiments with algae, zooplankton and fish across a N – S gradient
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Eutrophication – resultsfor shallow lakes
• Higher fish fecundity• More intense fish predation• Shorter food chain• Increased algal biomass and
turbidity• Decreased oxygen
concentrations• Accelerated nutrient re-cycling
Solutions to eutrophication problemsare likely to require much morestringent nutrient control than in
cooler lakes
Fish:zooplankton
Zoopl:phytopl
Cold Cool WarmFrom Moss et al. 2003
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Model calculated S deposition over Europe: 1980 – 2000 (mg S m-2)
1980 1995 2000
Interactions between climate change and acidification –will CC affect attempts to restore acidified lakes and streams?
From The UNECE website
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Round Loch of Glenhead: diatom-inferred pHmeasured pH and MAGIC-modelled pH, 1800 - 2030
From Battarbee et al. 2005
Diatom evidence for acidification and slight recovery
2005 pH
20 ANC?
core traps
1800 1990 2004AD
ENVIRONMENTAL CHANGE RESEARCH CENTRE
seasalt deposition (storminess)
dust (desertification)
runoff (precipitation and more evapotranspiration)
weathering rate (temperature)
concentrations of organic acids (precip + temp)
pCO2 in soil air and water
forest growth (precip + temp + CO2)
organic matter decomposition (temp)
temperature
precipitation
wind
CO2
Modelling climate – acidification interactions
(from Wright et al. unpub.)
Possible climate effects on acidified lakes and streams
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Climate – acidification interactions:evidence from palaeolimnology
in the Austrian Tyrol
Decadal-scale swings in pH (inferred from the diatom record)
follow similar swings in temperature from the instrumental record
(Psenner & Schmidt 1992)
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Climate – acidification interactions: evidence from
palaeolimnology in the Scottish Cairngorms
Lochan Uaine
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Climate – acidification interactions: increased discharge especially from winter storms may depress pH and offset
recovery in upland streams
4
4 .5
5
5 .5
6
6 .5
7
0 10 0 0 20 0 0 30 0 0 40 0 0D isc h ar g e (l/s )
pH
1 97 9 -1 9 841 98 5 -1 9 891 99 0 -1 9 941 99 5 -2 0 01
(from Hutchins et al. unpub.)
Afon Gwy, Wales
ENVIRONMENTAL CHANGE RESEARCH CENTRE
?
Can the reference state be used to define the target?
Implications for policy and management: the goal-posts are continually shifting
Battarbee et al. 2005
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Trends of macroinvertebrate biodiversity in boreal lakes
Time
Res
pons
e
Acidified
Expected
Reference
Res
pons
e
Time
Observed
Acidified
Reference
habitat-dependent response
(from Stendera & Johnson unpub.)
Lake acidification in Sweden – how stable are thereference sites?
Positive trends in littoral and negative trends in sub-littoral and profundal habitats:related to temperature increase (increasing deep water anoxia?)
ENVIRONMENTAL CHANGE RESEARCH CENTRE
1800
1990
2004
or are there other explanations?- random?- hysteresis?- nitrate?
1800
Lake acidification in the UK: is climate change causing “recovery” towards a new reference?
Battarbee et al. unpub.
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Eutrophication of Windermere: will climate change prevent restoration to “good” status?
y = 0.09x - 167.10R2 = 0.32
y = 0.16x - 315.84R2 = 0.18
y = 0.10x - 197.59R2 = 0.62
y = 0.20x - 389.20R2 = 0.47
0
2
4
6
8
10
12
1960 1970 1980 1990 2000 2010Year
Ann
ual m
ean
Chl
a (m
g m
-3)
South Basin
North Basin
From Stephen Maberly
?
ENVIRONMENTAL CHANGE RESEARCH CENTRE
To what extent can foreseen problems be avoided by adaptive management?
Do we have sufficient understanding to take effective action now?
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Adaptive management: INCA-N scenarios to prevent nitrate increase in lowland rivers: what are the options?
0
2
4
6
8
10
12
1960 1980 2000 2020 2040 2060 2080 2100
mgN
/l
Baseline Fertiliser Deposition
Meadows Combined
Wade & Whitehead (unpublished)R. Lambourn
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Adaptive management: excavating scrapes to preserve wetland habitat
±0 0.5 1 1.5 20.25
Kilometers
Embankment
Ditch
High : 14
Low : 0
Scrape
Scrapes 0.30 m deep, 0.55 km2
From Julian Thompson, UCL
ENVIRONMENTAL CHANGE RESEARCH CENTRE
Conclusions
• greenhouse gas-forced climate change is almost certainly taking place
• despite substantial natural variability there is growing evidence from lake sedimentrecords that unprecedented change is occurring in arctic and alpine lakes
• however, in populated regions, other stresses from human activity are still thedominant drivers of change
• evidence for the impact of global warming on UK surface waters can be inferred from increases in surface water temperatures, range expansion of dragon-flies,and increased algal growth in reservoirs and lakes
• examples of research that aims to predict the response of freshwater ecosystemsto future warming include range change in stenothermic taxa, hydrological stressin wetlands, intensification of eutrophication symptoms in shallow lakes, and increased acid episodes in upland streams
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Conclusions (cont.)
• climate change undermines some of the basic concepts in current EU directives, especially the Water Framework Directive, with respect especially to the role ofthe reference state in defining targets
• in our research we need to continue attempting to understand the underlyingprocesses that control the response of freshwater ecosystems to climate change, but also need to evaluate alternative adaptive management strategies that might minimise damage in the future.