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Climate Change Climate Change In the last 90 years the Earth’s mean temp rose 0.6 o C, a rate not seen in 10K yrs The scientific facts are clear and the vast majority of climatic scientists have determined that the major cause is anthropogenically produced greenhouses

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Climate Change

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climate change2
Climate Change
  • In the last 90 years the Earth’s mean temp rose 0.6oC, a rate not seen in 10K yrs
  • The scientific facts are clear and the vast majority of climatic scientists have determined that the major cause is anthropogenically produced greenhouses

(but don’t call global warming)

climate change3
Climate Change
  • However, the most influential discussions are in the policy and public arenas
  • What does anthropogenic climate change signify for the future?
  • Is climate change reversible?
  • How quickly will weather patterns change?
  • What can be done to mitigate the detrimental effect of altered climates?
  • How will new climatic patterns influence species’ distributions and biodiversity?
the nature of climate change
The Nature of Climate Change
  • Generally, climate shifts have been caused by changes in retention and distribution of solar energy across the planet
  • Solar radiation passes through the atmosphere as short wavelength ultraviolet (UV) wavs
the nature of climate change7
The Nature of Climate Change
  • The most important gases in the energy balance are CO2, CH4, and H2O as these cannot be penetrated by radiation in the infrared spectrum (long-wave)
  • These ‘greenhouse’ gases keep the earth approximately 60oC warmer than would be expected without them
climate change through time
Climate Change through Time
  • Since the industrial revolution, burning fossil fuels has increased greenhouse gases by about 30%
  • However, we know there is always variation in systems
  • Historically, we have been cooling since the Tertiary period (50-60MYA)..10oC
climate change through time9
Climate Change through Time
  • Average global temperature over last 65MY. Gray indicate hotter than current, black cooler. Note from 2MYA to 12KYA strong cycles
climate change through time10
Climate Change through Time
  • Looking at a finer time scale we can see fluctuations throughout the Pleistocene (1.8MYA to 12KYA)
  • The Milankovitch cycles match the Earth’s orbit and tilt relative to the sun and drives the temperature cycle through a series of positive and negative feedbacks
climate change through time11
Climate Change through Time
  • Small bubbles trapped in ice of Antarctica yield info on atmospheric composition
  • Furthermore, ration of 18O2 to 16O2 can accurately record temperature
  • This approach has yielded a relatively accurate temperature history going back 740KYA
climate change through time12
Climate Change through Time
  • Relationship between temperature and CO2 over past 160K yrs.
  • Note the current elevated CO2 levels
climate change through time13
Climate Change through Time
  • It is important to remember the impact of relatively small changes
  • E.g. peak glacial periods were only about 5oC cooler than current temperatures
  • Our current warming trend will push it to one warmer than was ever experienced during the Pleistocene period
human enhancement of greenhouse effect
Human Enhancement of Greenhouse Effect
  • The insulating properties of CO2 were discovered in the mid-1800’s
  • CO2 has rose 36% since 1910, which is well outside historical ranges
current and future climate and change
Current and Future Climate and Change
  • Scientists have developed a series of global climate models (GCMs) based upon the processes by which atmospheric greenhouse gases affect global climate
  • The models vary based upon different rates of gas emission (what affects rate?)
  • All models suggest warming should be greatest at the poles, least in the tropics
current and future climate and change16
Current and Future Climate and Change
  • E.g. in some parts of AL, Canada and Siberia mean annual has risen 2-4oC since 1900
  • Another pattern is the lack of nights below freezing in the mid-latitudes (fig 10.6)
  • Another pattern is the change is precipitation (especially in intensity), but again, not consistent everywhere
current and future climate and change17
Current and Future Climate and Change
  • Black indicates warming and gray indicates cooling
  • Size indicates magnitude of change
current and future climate and change18
Current and Future Climate and Change
  • Black is wetter and gray is drier
  • Size indicates magnitude of change
current and future climate and change19
Current and Future Climate and Change
  • Ironically, the GCMs all suggest continued increase in precipitation, but with warmer climate, evapotranspiration is increased
  • Furthermore, the variance in precipitation events gets larger
  • What is the impact of larger variances but not means?
oceans sea level and circulation
Oceans: Sea Level and Circulation
  • Is beach front property consistent?
  • 20KYA, sea levels were as much as 120m lower than current levels
  • Annual changes are relatively small (e.g. 0.1-0.2mm) over past 3K yrs
  • However, past 200 yrs there has been rapid rising of ocean levels due to two factors: precip, ice caps (.2-.4mm) and thermal expansion (1mm annually)
oceans sea level and circulation21
Oceans: Sea Level and Circulation
  • Sea levels rise over 3K yrs in 3 Euro cities
oceans sea level and circulation22
Oceans: Sea Level and Circulation
  • Major ocean circulation systems are already showing signs of being affected by the rise in atmospheric temperatures
  • El Niño (and La Niña) events have increased in frequently and intensity (warming of mid-Pacific, pushing into cold waters)
  • Some models predict by 2050 “normal” years will resemble current El Niño yrs
oceans sea level and circulation23
Oceans: Sea Level and Circulation
  • Warm H2O surges in cold water areas
oceans sea level and circulation24
Oceans: Sea Level and Circulation
  • Snow, Ice, and Hydrological changes
  • Widespread retreat of glaciers in N & S Am, NZ, Af, Europe and Asia
  • (e.g. GNP, 70% glaciers lost…gone 2020)
  • (e.g. Mt Kilimanjaro 60%)
  • Approximately 30% of projected sea change will come from glacial melt
oceans sea level and circulation25
Oceans: Sea Level and Circulation
  • Another problem is flood events rather than water soaking into the soil
  • In many areas, H2O comes in the form of snowfall with gradual melting feeding streams/rivers throughout summer
  • Spring melts are occurring earlier
oceans sea level and circulation26
Oceans: Sea Level and Circulation
  • Glacial retreat (1973 and 2000)
predicted biological impacts
Predicted Biological Impacts
  • So many biological processes are tied to climatic events, the idea that these will change may have profound impacts
  • One approach to better understand the potential impact is to identify species’ distributions and their ‘climate envelope” from manipulative studies
  • For an in-depth look, Case Study 10.1
predicted biological impacts28
Predicted Biological Impacts
  • A simplistic view of biotic responses is that species may simply alter their distribution quickly (e.g. birds) or gradually (e.g. seed dispersal)
  • Paleoecologists have found many communities found together no longer co-occur
  • Why?
predicted biological impacts extreme weather
Predicted Biological Impactsextreme weather
  • Many systems are strongly influenced by climate and weather extremes
  • E.g. frost boundaries and plants
  • E.g. precipitation limits animals & plants
    • Drought in NM in 1950’s, pine and p-j, 2km
    • 9-banded armadillo, 39cm and <24 freezes
  • Single events can have long-term affects
    • Drought and Darwin’s finches
    • Warm water events, bleach coral reefs
predicted biological impacts30
Predicted Biological Impacts
  • Prolonged climate swings can impact
    • Map turtles; 28oC<M and >30oC F
  • Many insect populations boom/bust with climatic events
  • Host-parasite and infectious diseases are strongly influenced by climate
  • Even if extremes don’t increase, their frequency may increase
predicted biological impacts31
Predicted Biological Impacts
  • Increases in mean temperature, leading to more record temperatures
observed biological impacts
Observed Biological Impacts
  • An increase in both mean and variance temperatures
observed biological impacts33
Observed Biological Impacts
  • Detection and Attribution
  • It is extremely important to determine the relative impact of climate change
  • Won’t review the evidence on CC
  • Studies examining the impact of CC on wildlife are by nature, correlative rather than experimental (FACE-free air CO2 Exchange)
  • Attribution now a priority for many
observed biological impacts34
Observed Biological Impacts
  • Evolutionary & Morphological Changes
  • Because of the rapid nature of CC, little discussion of evolutionary adaptations
    • Drosophila subobscura from N Euro had longer wings than S, 20 yrs adjusted to the climate envelop (more similar to S Euro)
    • E.g. Desert rodents have gotten 16% smaller body size… why?
observed biological impacts35
Observed Biological Impacts
  • Phenological Shifts (e.g. amount of daylight, seasonal weather) in organisms (e.g. arrival of migratory birds)
  • Many biological events are temp driven (e.g. leaf emergence, turtle hatching)
    • E.g. in AZ, MEJA hatch 10 days (’71 to ’98)
    • Many other examples (ice out, spring bloom)
    • European amphibian breeding advanced
  • There can be desynchronization…BTBW
abundance change and community reassembly
Abundance Change and Community Reassembly
  • Climate can have a direct impact on populations and communities
    • E.g. BTBW and El Niño (S) and La Niña (W)
  • Community structure has been changed
    • In CA waters, warming waters have favored a different plant community
abundance change and community reassembly37
Abundance Change and Community Reassembly
  • Mean annual ocean temperatures at Scripps
abundance change and community reassembly38
Abundance Change and Community Reassembly
  • Southern species have increased in abundance while Northern species have decreased in S CA
abundance change and community reassembly39
Abundance Change and Community Reassembly
  • In terrestrial communities, there has been woody incursion into grasslands
  • In experimental communities, increases in temp, H2O, and CO2, all result in increases in woody species
range shifts
Range Shifts
  • Species ranges are dynamic, changing both spatially and temporally
range shifts41
Range Shifts
  • There are many examples of range shifts in apparent direct response to CC
  • In N Am and Europe, 2/3 of butterflies (n=58) studied have shifted N by 100km per decade
  • Montane studies have shown plants and animals are being found at higher elevations
range shifts42
Range Shifts
  • Patterns of population extinction of Edith’s checkerspot butterfly Eupydryas editha from 1860 to 1996
  • Note significantly higher extinction in N
  • Black present, gray extinct
range shifts43
Range Shifts
  • Overwintering range of the sachem skipper butterfly, which is limited by repeated to exposures to -4oC
synthesis of impacts
Synthesis of Impacts
  • Is there a bias in our conclusions about the impact of CC? “positive publishing”
  • A meta-study (1700 sp), about ½ the sp were stable
  • However, 50% exhibited significant responses to regional warming (e.g. phenology or distributional shifts)
  • Table 10.1
conservation implications of cc extinctions
Conservation Implications of CCExtinctions
  • There has been a spike in extinctions in recent centuries
  • There have only been 2 extinctions directly attributable to CC (2 trop frog)
  • Abundance of zooplankton off CA has declined by 80%...and sp relying on this food base are in trouble
conservation implications of cc extinctions46
Conservation Implications of CCExtinctions
  • The ability to track changes is important for species’ survival
  • Unfortunately, many endangered sp tend to have such traits (e.g. limited dispersal, small ranges, strong local adaptation)
  • Constructing a ‘climate envelope’ of threshold values (of precip and temp) can help predict impacts of species
conservation implications of cc extinctions47
Conservation Implications of CCExtinctions
  • Range shift model of a S Af plant
conservation implications of cc extinctions48
Conservation Implications of CCExtinctions
  • A synthesis study of extinction risk estimates suggests a rough estimate of extinctions by 2050
  • With perfect dispersal and minimal reduction in climate envelope, ranges from about 9-13% of sp would go extinct (1.2oC) to 21-32% (2oC)
  • Note: these estimates are strictly climate-based. Other problems?
responses to cc by managers
Responses to CC by Managers
  • Most managers and conservation planners focus on local-scale projects
  • Climate shifts cause problems for locals because they don’t account for climate
  • Consequently, they need climate models that are not only accurate, but at a spatial scale relevant to locals
responses to cc by managers50
Responses to CC by Managers
  • There are adaptive approaches managers could use
    • Susceptibility analysis of impact of CC
    • Design/adjust reserve to allow movement
    • Promote corridors
    • Create dynamic habitat conservation plans
    • Alleviate nonclimate stressors
    • Generalization of climate prediction models
cc and conservation policy
CC and Conservation Policy
  • The widescale potential impact of CC makes is potentially more important than any other conservation issue
  • Marketing 101: Global CC is a local issue
  • Policy issues are difficult to achieve due to the potential costs and ‘fairness’
  • There are many, many issues here…