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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 Change


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 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

  • 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


Climate Change

  • Fig 10.1


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

  • 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 Time

  • Average global temperature over last 65MY. Gray indicate hotter than current, black cooler. Note from 2MYA to 12KYA strong cycles


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 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 Time

  • Relationship between temperature and CO2 over past 160K yrs.

  • Note the current elevated CO2 levels


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

  • 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

  • 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 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 Change

  • Black indicates warming and gray indicates cooling

  • Size indicates magnitude of change


Current and Future Climate and Change

  • Black is wetter and gray is drier

  • Size indicates magnitude of change


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

  • 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 Circulation

  • Sea levels rise over 3K yrs in 3 Euro cities


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 Circulation

  • Warm H2O surges in cold water areas


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 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 Circulation

  • Glacial retreat (1973 and 2000)


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 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 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 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 Impacts

  • Increases in mean temperature, leading to more record temperatures


Observed Biological Impacts

  • An increase in both mean and variance temperatures


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 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 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

  • 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 Reassembly

  • Mean annual ocean temperatures at Scripps


Abundance Change and Community Reassembly

  • Southern species have increased in abundance while Northern species have decreased in S CA


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

  • Species ranges are dynamic, changing both spatially and temporally


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 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 Shifts

  • Overwintering range of the sachem skipper butterfly, which is limited by repeated to exposures to -4oC


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 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 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 CCExtinctions

  • Range shift model of a S Af plant


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

  • 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 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

  • 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…


Climate Change


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