Ch. 27 Climate Change

7/21/2019 Ch. 27 Climate Change

http://slidepdf.com/reader/full/ch-27-climate-change 1/21

12/3/2015

Ch. 27 Climate Change

The Ecology of Climate ChangeEarth’s rotation affects the amount of sunlightstriking the different parts of the globe and causesthe seasons

Tilt of Earth’s axis varies from 22.5 to 24 over acycle of 41,000 yearsThis is responsible for the ice ages- glacial expansion

© 2015 PearsonEducation, Inc. © 2015 PearsonEducation, Inc.

The Ecology of Climate Change

Variations in climate have been affecting life onEarth and its evolution over geologic timeClimate influences the function of naturalecosystemsThe current widely accepted belief is that humanshave the ability to alter Earth’s climate and they aredoing so1896 : Arrhenius published the first calculation ofglobal warming from human emissions of CO2




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http://www.paulchefurka.ca/Population.html

The Ecology of Climate Change

Since the Industrial Revolution began, the burningof fossil fuels has led to an exponential increase inthe concentration of carbon dioxide and othergreenhouse gases in the atmosphere

This has led to a general pattern of warming overthe past century

© 2015 PearsonEducation, Inc.


1300 - 1850.



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Earth’s Climate Has Warmed over the PastCentury

Earth’s climate has warmed by an estimated 0.74 Cover the past century

The rate of warming during the second half of thecentury has been about double that of the first half


1970s 0.00

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0.18 1980s

1990s

3.2 1.5 1 .6 .3 .1 .1 .3 .6 1 1.5 2 1.5 1 .6 .3 . 1 .1 .3 .6 1 1.5 2.2

0.31 0.51 2000s

Polar regions have warmed themost (Artic)The winter months show thegreatest warmingMinimum temperatures haverisen twice as fast as maximum10% decrease in snow cover/iceextent since the late 1960s


All things are not equal -The Temperature is changing unevenly

Ocean Temperature Change

Average global ocean temperature has increased toa depth of at least 3000 feet

The ocean has absorbed > 80% of the added heat


Figure 27.2a


30

35

40

45

1900 1920 1940 1960 1980 2000

Year

N o r t h e r n

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i s p h e r e s p r i n g

s n o w c o v e r ( m

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Figure 27.2b


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Warming of ocean surface is largest overthe Arctic Ocean


0

10

20

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1900 1920 1940 1960 1980 2000 Year

C h a n g e i n g l o b a l a v e r a g e u p p e r

o c e a n h e a t c o n t e n t ( 1 0 2 2 J )

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Rising sea levelsWarming causes seawater to expand, raising thesea level


Figure 27.2d


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1900 1920 1940 1960 1980 2000 Year

G l o b a l a v e r a g e

s e a l e v e l c h a n g e ( m m

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Precipitation from 1950 - 2010. Precipitation trend is inmm/day over the period of observation. Stippling indicates theobserved trend is statistically significant (From Dai 2011).

75

60

45

30 15

0

15

30

45

60 180 120 60 60 0 120 180

Longitude

Precipitation trend (mm/day/50yr), 1950-2010

L a t i t u d e

4.0 2.0 1.0 0.4 0.2 0 0.1 0.2 0.4 1.0 2.0 4.0

Changes in precipitation have not beenspatially or temporally uniform

Climate Change Has a Direct Influence on thePhysiology and Development of Organisms

How does temperature affect organisms?Is there a difference in the effect on endotherms

versus ectotherms?How could the global patterns of warming seen overthe last century impact organisms?

Are some groups more vulnerable to the effects ofwarming than others?


CC influence on Physiology andDevelopment of Organisms

Endotherms have a constant body temperatureEnvironmental temperatures affect metabolism,determining heat exchange with the environment

The larger the body size, the less surface area forheat dissipationGeographic trend for average body size to increasewith decreasing mean annual temperature

In both birds and mammals, a smaller body size is

more energetically efficient in a warm climate


Ectotherm metabolic activity increasesexponentially with temperature, rather thenlinearly

If a species is at the upper thermal tolerance limit, thenthe species might be in troubleDillion from Univ. of Wyoming showed that ectothermswere more vulnerable to temperature rises in tropicalregions

Metabolic rates increased more quickly in thetropics than in the temperate or artic regions!WHY?


Ectotherms



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1970s 0.00

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0.18 1980s

1990s

3.2 1.5 1 .6 .3 .1 .1 .3 .6 1 1.5 2 1.5 1 .6 .3 . 1 .1 .3 .6 1 1.5 2.2

0.31 0.51 2000s

(Data from Dillon et al. 2010.)

0.5

0

0.5

1.0

1.5

2.0

10

0

1980 1990 2000 2010

10

20

30

40

50

Tropical North temperate

South temperate

Arctic

C h a n g e i n t e m p e r a

t u r e ( ° C )

C h a n g e i n m e t a b o l i c r a t e

Year 1980 1990 2000 2010

Year

.70 /3#$<" 5$ *"-#72(58 ,#-"6 5$?5==","$- ,"<52$6

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Several species ofporcelain crabs live in theintertidal of the easternPacificThe upper thermaltolerance limits – LT 50

temperature at which 50%mortality occurs

Thermal Tolerance

25 15 20 30 35 40 45 26

28

30

32

34

36

38

40

42

10

California Chile

N. Gulf of California Panama

Maximal habitat temperature ( °C)

L T 5 0

( ° C )

Species above theline are okbecause the maxlethal temperatureis above what themax habitattemperature is inthe environment.

Thermal ToleranceTropical species generally have a currentmaximum habitat temperature (MHT) closer to

their LT 50

Relatively small ability to increase LT 50 throughacclimationOther tropical invertebrates living in intertidalzones are have shown similar vulnerabilitiesHypothesis = tropical ectotherms are morethreatened by CC than species from mid-latitudes because tropical species livecloser to their temp limit


Thermal Tolerance



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400

600

800

1200

1000

18 20 22 24 26 28 30 32 34 36 38 40 Body temperature ( °C)

Body temperature

.5

1

0 Tolerance range

“Optimal” temperature

(T opt )

Upper criticaltemperature

(T max )

Lower criticaltemperature

(T min )

R e l a t i v e p e r f o r m a n c e

S p r i n t s p e e d

( m m p e r s e c )

Impacts on terrestrial plant species are morecomplicated

Response of plants to changes in climate involve

Temperature

Precipitation

Sometimes CO 2 as a fertilizer

Regional changes affect soil and microhabitatconditions


Terrestrial Species’ Response to CC

Tree Growth

In the past century analysis of tree rings shows:

The temperate forest of Eastern North America

correlated to an increase in the length of thegrowing season

In Western North America, increasing droughtsassociated with increase in mortality


Figure 27.6

Pacific Northwest California Interior

FirPineHemlockOther

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Year

M o r t a l i t y r a t e

( % / y r )

M o r t a l i t y r a t e

( % / y r )

1960 1980 2000

2.0

1.5

1.0

0.5

0.0 1960 1980 2000

Mixed results from studies of the response oftree growthSome studies have shown localized increasesthe past 50 years of warmingMost showed declines in growth rates andincreases in mortality related to water stressSites from the entire boreal forest region ofCanada were studied from 1963-2008 (96sample plots)

Tree mortality rates increased, greater in thewest than the east


ArcticFigure 27.7


4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

Western region

2000 2010 1990 1960 1970 1980

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Trembling aspen Jack pine Black spruce White spruce

2000 2010 1990 1960 1970 1980 Year

T r e e

m o r t a l i t y

( p e r c e n t p e r y e a r )

T r e e m o r t a l i t y


T r e e m o r t a l i t y


Eastern region



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http://www.nasa.gov/topics/earth/features/shrub-spread.html

Shrub Expansion in Northern Quebec

Global vegetation models predict rapid polewardmigration of tundra and boreal forest vegetation inresponse to climate warming

Low shrub and grass-like vegetation in tundracontributed preferentially to the greening trend,while forested areas were less likely to showsignificant trends in Normalized DifferenceVegetation Index (NDVI)

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120010311.pdf

Phenology- timing of seasonal activity

Many processes related to activity

Migration

Reproduction

Hibernation

Many studies show that activities that take place inspring have occurred earlier and earlier since the1960s



My trip to Alaska January 2014England - 47 year studyof common woodlandbirds (1961-2007)

Mean egg-laying datehas become earlier byabout 14 days,beginning in the mid-1970s

Anne Chamantier, Oxford University



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10

20

30

40

1960 1970 1980 1990 2000 Year

Mean laying date declinedover the study period - theyare laying their eggs earlier

Mean laying date1= April 1

Migratory birdsStudy of 20 migratory bird species that breed inEngland and winter in sub-Saharan Africa

For 17 of the 20 species, the arrival date inEngland has been earlier in response toincreases in temperature trends in Africa

The departure date has also advanced, so thelength of time in England is the same, but startsabout 8 days earlier (data span 30 years)


Figure 27.9


1971 1976 1981 1986 1991 1996 2001

M e a n a r r i v a l d a t e

M e a n

d e p a r t u r e d a t e

Year

150

140

130

120

110

100

90

80

70

60

340

330

320

310

300

290

280

270

260

250

Meta Analysis-Impact of CC on plants and animals in Europe

203 plant and animal species

Overall, shifts are larger at higher latitudes

Amphibians had a greater shift toward earlybreeding times than other taxonomic groups

2x as fast as trees, birds, butterflies

Butterfly emergence or migratory arrival advanced

3x as fast as first herbaceous plant flowering

Parmesan 2007


10

5

10

0

5

15

20

25

30

35

C h a n g e i n s p r i n g

t i m i n g

( d a y s / d e c a d e )

Amphibian Bird Shrub

Tree

Fish Fly Mammal Butterfly

Herbs and grass

Individual species

Most species are experiencing advanceof spring activity in Alberta regions



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http://onlinelibrary.wiley.com/doi/10.1111/gcb.12382/abstract

• Study of 92 tree species in the easternUnited States from 1999-2009

• No consistent evidence that shifts in thesepopulations are greatest in areas whereclimate has changed the most

• Results suggest that for 77% and 83% of thetree species, juveniles have higher optimaltemperature and optimal precipitation,respectively, than adults

• Tree species might respond to climatechange by having faster turnover as dynamicsaccelerate with longer growing seasons andhigher temperatures , before there is evidenceof poleward migration at biogeographicscales

Study (1942 to 2002) shows that the cover of alder,willow and dwarf birch has been increasing

most obvious on hill slopes and valley bottoms

Studies in Canada, Scandinavia, and parts ofRussia have reported similar findings


Arctic northern expansion of shrub species

Plant surveys in 1977 vs. 2007 in So. Cal. overan elevation gradient30-year period

0.4 C increase in mean tempprecipitation variability increaseddecreased snow cover

Average elevation of the dominant plantspecies increased by 65 m;

All species except one showed a distributionshift up the mountain range

Range ShiftsFigure 27.15

100

50

0

50

100

150

200

C h a n g e i n e l e v a t i o n

( m )

CC & Geographic Distribution of Species

Direct influence on species-specific temperaturetolerancesHigher elevation distribution are constrained byminimum temperaturesMinimum temperature are rising

CC Impact on Species Interactions

Often reproduction is timed to correspond to

resource availabilityFor herbivores, this is the plant growing season




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Study conducted over six summers in westernGreenland

Monitored caribou calving season and plantphenology (timing and progression of emergence)

Successful caribou reproduction depends onsynchrony of calving with resource abundance

In the far north, plant nutrient content and digestibilitypeak soon after emergence and then decline rapidly



Onset of plant growing season (based on plantspecies emergence) advanced by 14.8 days

Onset of calving advanced by 1.28 daysThis results in a rapidly developing mismatchbetween caribou reproduction and food supply



2001 120

130

140

150

160

2002 2003 2004 2005 2006 Year

D a t e s o f 5 % e m e r g e n c e

o r b i r t h s

Caribou

Forage species

There is a difference in the environmental cues thattrigger each event

Caribou are cued by changes in day length

same from year to year

The growing season of the plants is correlated withmean spring temperature

increased by 4.6 C during the study



0

0.2

0.4

0.6

E a r l y c a l f m o r t a l i t y

Calf mortality increased as the degree of mismatch increased

0 0.5 1.0 0

0.2

0.4

0.6

Index of trophic mismatch

C a l f p r o d u c t i o n

Calf production decreased as the degree of mismatch increased



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Lake Systems and CC

Changes in phenology of phytoplankton andzooplankton populations in Lake Washingtonbetween 1962 - 2002

Spring (Mar - June) water temperatures showedsignificant warming trendsThe upper 10m water layer increased in temperaturean average of 1.4 C over 40 years

In response to this warming, the springphytoplankton bloom advanced by 27 days overthose 40 years


1970 1960 1980 1990 2000 March

April

May

June

6

8 10 12

14

16

18

W a t e r

t e m p e r a t u r e

( ° C )

Increasing trend in temperatureover in the top 10-m water in Lake Washington

1970 1960 1980 1990 2000

)5*5$< 2= -3" ?5#-2* 7(22*

80

100

120

140

D a y o f y e a r

100

120

140

160

180

D a y o f y e a r

1970 1960 1980 1990 2000

Relation of Daphnia densities in May to the mismatch(in days) between the timing of diatom bloom andDaphnia peak for the period of 1977 – 2002

Mountain pine beetle (native to western North America) attacks most trees in the genus Pinus

can erupt into epidemics

Over the past ten years, these epidemics have beenlarger than previously recorded




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Region has experiencedincreased temperaturesincreased frequency of drought

This has decreased tree health and increasedsusceptibility to beetlesRegional warming has led to range expansion ofthe beetle, especially at higher elevationsWarming has also affected the beetle’s life history

The beetle flight season (flying to attack new trees)starts one month earlier and lasts twice as long


Forest Systems and CC

Historical life history patternof single generation per year

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Recent life history patternof two generations per year

As a result, some beetle populations havetwo generations in a year instead of one

Forest Systems and CC

Arctic Fox vs Red Fox

Red fox – its northern range limit is determined bytemperature limitation

Arctic fox – its southern limit is determined byinterspecific competition with the red fox

Arctic warming for the past 40 years has allowedred fox populations to expand north, leading to adecline in Arctic fox populations

Shifts in species composition and diversity

Examination of the impact of climate warming onplant communities in the Santa Catalina Mountains

– comparison with data from 1963 resampled 2011

During that time

the mean annual rainfall has decreased

the mean annual temperature has increased by0.25 C per decade between 1949 and 2011


Plant Communities and CC

Resampled the original elevation transectFocused on the 27 most abundant species

75 % of the species now grow in a more narrow range

some shifting as much as 1000ft up the slope

Figure 27.19a


M e a n a n n u a l t e m p e r a t u r e

( C )

22

21

20

19

181950 1960 1970 1980 1990 2000 2010

Year

M e a n a n n u a l r a i n f a l

l ( m m

)600

450

300

150

0

.#0



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Figure 27.19b

Juniperus deppeana var. deppeana

Pseudotsuga menzesi i var. glauca

Quercus emoryi

Quercus hypoleucoidesRobina neomexicana

WOODYSHRUBS

Ceanothus fendleri

Mimosa aculeaticarpa

Brickellia californica

Pteridium aquilinum

Thalictrum fendleri

SMALLSHRUBSAND HERBS

Agave schottiiDasylirion wheeleri

Yucca madrensisSUCCULENTS

Aristida ternipes var. ternipes

Muhlenbergia emersleyi

Urochloa arizonicaGRASSES

2500 3000 4000 5000 6000 7000 8000 9000Elevation (feet)

Muhlenbergia porteri

Bouteloua curtipendula

Nolina microcarpa

Packera neomexicana

Lotus greenei

Arceuthobium vaginatum

Garrya wrightii

Arctostaphylos pungens

Quercus gambelii

Quercus arizonica

Pinus strobiformis

TREES

White bars are 1963 elevational range data black bars represent 2011 elevationdata from the current study.

Study of calanoid copepods (crustaceans – zooplankton) in the eastern North Atlantic andEuropean shelf seasCompared distribution 1958 - 1999 and seasurface temp change

177,000 samples collectedhas monitored 1946

Ocean Systems and CC

Increases in regional sea surface temperatureshave led to a major reorganization ofzooplankton species composition andbiodiversity in the entire North Atlantic Basin

All associations show consistent, long-term changesWarmer-water species moved north by 10 latitudeColder-water species retreated to the north

This is more pronounced than any movement seenfor terrestrial organisms

Why should we care?© 2015 PearsonEducation, Inc.



These types of geographical shifts may haveserious consequences for North Sea fisheriesIf they continue, could lead to changes in fishabundanceStocks of northern species, such as cod, coulddecline or even collapse



Net primary productivity and decomposition aretwo key ecosystem processes

These control energy and nutrients in theecosystem

Climate has a direct influence on both processesSite-based studies of local ecosystems can bedifficult to interpret because there are multiplefactors influencing these ecosystems

soils, topography, CO 2 concentrationCurrent studies used data from satellites





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Net Primary Productivity

Net primary productivity (NPP) is defined asthe net flux of carbon from the atmosphere intogreen plants per unit time

Energy potential available for the next trophic level


CC impact on NPP

Net primarily productivity estimated from satellite-based measures of absorbed

can examine temporal and spatial changes

Study from 1982 - 1999

Global changes in climate have eased climaticconstraints on plant growth and NPP increased 6%over the 18-year study

largest increase in tropical ecosystems


Figure 27.22a


Change in mean NPP (1982 –1999) (percentage per year)1.5 1.5

.#0

0

A more recent analysis used the same methodsbut extended the analysis to cover 2002-2009

The decade between 2000 and 2009 is thewarmest recorded since instrumentalmeasurements started

Results suggest a reduction in NPP of 0.55petagrams of carbon as a result of regional dryingthat would constrain plant growth


CC impact on NPP

Figure 27.23a


21 14 7 0 7 14 21NPP trend (2000 –2009) (gC/m 2 /yr)

.#0

Spatial patterns of NPP over the past decade havenot been globally consistentNPP has increased over large areas in the NorthernHemisphere

65% of vegetated land area had an increaseNPP has generally decreased in the SouthernHemisphere

70% of vegetated land area had a decreaseHigher temperatures lead to increased evaporationand reduced water availability

CC impact on NPP



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Are humans to blame for CC?

The preindustrial level of atmospheric carbondioxide was 280 parts per million (ppm)

The level will double sometime this century

In October 2015 it was 398 ppmCarbon dioxide is not the only greenhouse gas,other significant components include:

methane (CH 4)chlorofluorocarbons (CFCs)hydrogenated chlorofluorocarbons (HCFCs)nitrous oxide (N 2O)


Greenhouse gases in the atmosphere warm Earth’ssurface

What effect will doubling the concentration of carbondioxide in the atmosphere have on global climatesystems?

General circulation models (GCMs ) are complexcomputer models of Earth’s climate system Give insight into the influence of increasing CO 2 concentration on large-scale patterns of globalclimate



There are some consistent patterns in thepredictions from these GCMs

an increase in average global temperatureIntergovernmental Panel on Climate Change report(2013) suggests a global average surface temperatureincrease of 1.1 to 6.4 C by 2100Last glacial maximum had decrease 5

!

C

an increase in global precipitationThese changes would not be evenly distributed

greatest warming during winter months and innorthern latitudes



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0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5

( C)

0.8 0.6 0.4 0.2 0 0.2 0.4 0.6 0.8

(mm day 1)

0 0.5 1 1.5 2 2.5 3.5 4 4.5 5.5 6 6.5 7 7.53 5

( C) (mm day 1)

0.8 0.6 0.4 0.2 0 0.2 0.4 0.6 0.8

1980-1999

2080-2099

What are the models saying?Increasing climate variation is predicted

more stormsgreater snowfallincreased variability in rainfall

The predictions that rising concentrations ofgreenhouse gases will significantly affect globalclimate in the future are consistent



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QuestionsWhat are the sources of uncertainty in predicting theresponse of ecological systems to future climatechange?

What type of investigations are being undertaken toexamine possible impacts of future climate change?

What are some models used to investigate theresponse of biosystem to climate change?


Uncertainty in Predicting EcologicalResponse to CC

Uncertainty in predicting ecological systemsresponse to future climate change

the limitations in our understanding of processes thatcontrol the current distribution and abundance ofspeciesthe uncertainly associated with the specificpredictions of how the climate in a given region willchange in response to GHGs


Research is being conducted at all levels oforganization, from individual to global scaleThe studies fall into two categories:

examining the response of ecological systems toexperimental warming and the associatedenvironmental factorsusing models of ecological systems to evaluate theresponse to future climate scenarios



A number of experimental studies in variousenvironments (tropical to polar) show thatcommunities and ecosystems respond strongly towarming

Most studies have been done at a single location fora short period of time

Comparison among studies is difficultdiverse techniques used to produce warming

experimentally



International Tundra Experiment (ITEX) is acoordinated international effort using standardizedmethods

Network of Arctic and alpine research sitesthroughout the worldExperimental and observational studies usestandardized protocols to measure responses oftundra plants and plant communities to increases intemperatureInvestigators from 13 countries working at 11 sites


Figure 27.25


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4

32

1

5

6

7

8

9

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11NorthPole



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Passive warming treatmentsIncreased plant-level air temperature by 1 – 3 C

This is in the range of observed and predicted tundraregion warming

Responses were rapid, detected in whole plantcommunities after two growing seasons

increased height and cover of deciduous shrubs andgrassesdecreased cover of mosses and lichensdecreased species diversity


Network of Ecosystem Warming Studies

Experiments focus on the response of soilrespiration, net nitrogen mineralization, andaboveground NPPThere are 32 research sites in four broadly definedbiomes

high (latitude or altitude) tundra, low tundra,grassland, forest


MinnesotaPeatlands

HowlandForest

Ny Alesund Flakaliden

CLIMEX

Buxton

WythamWoods

HarvardForest

Rio MayoHuntingtonForest

Oak Ridge

RockyMountain

NiwotRidge

ShortgrassSteppe

TERA

ToolikLake

Abisko

Results show considerable variation in response towarming

Across all sites, experimental warming (0.3 to 6.0 C)for 2 to 9 years durationIncreases were seen in

soil respiration rates, by 20%larger in forested ecosystems

Net nitrogen mineralization Organic N -> N2 rates inc.by 46%NPP, by 19%

larger in low tundra ecosystems


The Future

Most research focuses on developing mathematicalmodels that can provide information on futureclimate change impactsThe bioclimatic envelope model is one of the mostwidely applied modeling approaches to investigatethe response of speciesQualitative relationship between climate and speciesgeographic distribution




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Figure 27.27

The quantitative relationship betweenspecies distribution and current climatecan then be used to predict the potentialdistribution of the species under changedclimate conditions.

The current distribution of the species (reddots represent local populations) is relatedquantitatively to features of the climate,such as mean annual temperature (shownas temperature isopleths).

Temperature ( C)

A b u n d a n c e

20 21 22 23

Current ClimateConditions

18 C19 C

20 C

21 C

22 C

23 C

23 C

20 C

21 C

22 C

19 C

24 C

Longitude

L a t i t u d e

Longitude

L a t i t u d e

Projected FutureClimate

ConditionsThis relationship can be used to map the possiblegeographic range of the species under differentclimate change scenarios

Investigation of the effect of climate change on 134tree species in the eastern United States with 36environmental variables

Climate change could have large impacts onsuitable habitat for these tree species


The Future

FIA-Current RF-Current

GCM3 Avg Hi GCM3 Avg Lo

< 1 1 –3 4 –6 7 –10 11 –20 21 –30 31 –50 > 50E'<#, *#+(" . &8", 6#883#,'* 0

FIA-Current RF-Current

GCM3 Avg Hi GCM3 Avg Lo

.70 E(#63 +5$" . I5$'6 "((52--55 0< 1 1 –3 4 –6 7 –10 11 –20 21 –30 31 –50 > 50

FIA - Current RF - Current

GCM3Avg Lo GCM3Avg Hi

White/Red/JackSpruce/FirLnglg/SlshLobolly/Shrtif

Oak/PineOak/HickoryOak/Gum/CyprElm/Ash/Ctnw

Maple/Beech/BirchAspen/BirchNoDat/NoFor

By combiningindividual speciesinto groups basedon forest types,potential changesin the geographicdistribution offorest communitiescould be examined

Projected changes in climate and tree species richness for NorthAmerica under future climate change scenario of CGCM2 (2071-2100)

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3 to 22 to 11 to 0

0 –11 –22 –2

< 6060 to 3030 to 2020 to 0

0 –1010 –2020 –3030 –60

119 to 8584 to 6160 to 3938 to 2120 to 65 to 10

11 –2627 –4546 –84

Degrees C % of current values Tree richness



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Predicting Future Climate Change Requires anUnderstanding of the Interactions between the Biosphere

and the Other Components of Earth’s System

• The global carbon cycle links the atmosphere,hydrosphere, biosphere, and geosphere on aglobal scale

• 50% of the carbon released through humanactivities remains in the atmosphere

• Of the remaining 50%,• 26% is taken up by terrestrial ecosystems• 24% is taken up by the oceans

• forms carbonic acid, which increases surface acidity


• Diffusion is the primary factor controlling theexchange of carbon between the atmosphereand surface waters

• On land, the major factors are• the net uptake of carbon by terrestrial

ecosystems as NPP - carbon storage

• the loss of carbon from terrestrial ecosystems indecomposition

• The difference in the rate between these twoprocesses is net ecosystem productivity (NEP)

Net Ecosystem Productivity

Net Ecosystem Production, NEP amount of carbonaccumulated by the ecosystem

NEP = GPP - (R plant + R heterotrophs + Rdecomposers)

A measure of Net Ecosystem Production is of greatinterest when determining the CO 2 balancebetween various ecosystems, or the entire earth,and the atmosphereModels try to simulate the basic processes of NPPand decomposition


Net Ecosystem Productivity • In order to predict the fate of future CO 2 emissions

• NPP increases and there is a net removal ofcarbon dioxide – negative feedback

• NPP decreases (or decompositionincreases) and there is a net addition ofcarbon dioxide – positive feedback

Terrestrial biosphere model developed at thePotsdam Institute for Climate ImpactResearch

• Terrestrial plants groups attributes• C3 or C4• Deciduous vs Evergreen• Woody or Herbaceous

• P/S & Respiration modeled• atmospheric and soil condition

• Rates of decomposition organic matter


• Terrestrial biosphere model used futureclimate change scenarios based on five

general circulation models• Results show great uncertainty in thepredicted patterns of carbon exchange

• This is mainly the result of large differencesin climate projections for each model




12/3/2015

4

2

0

2

41900 1940 1980 2020 2060 2100

C-SOURCE

C-SINK

P g C

/ y r

In 3 out of the 5 climate projection the terrestrialbiosphere was a source of carbon to the atmosphere bythe year 2100. With would imply that we have a positivefeed back loop.

Can we do anythingabout climate change

and should we?


Earth and Environmental System PodcastDr. Christain Shorey


http://inside.mines.edu/~cshorey/pages/sygn.html

Documents

Ch. 27 Climate Change