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Climate Change

Climate Change

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Climate Change

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  1. Climate Change

  2. 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)

  3. 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?

  4. 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

  5. Climate Change • Fig 10.1

  6. 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

  7. 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

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

  9. 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

  10. 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

  11. Climate Change through Time • Relationship between temperature and CO2 over past 160K yrs. • Note the current elevated CO2 levels

  12. 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

  13. 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

  14. 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

  15. 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

  16. Current and Future Climate and Change • Black indicates warming and gray indicates cooling • Size indicates magnitude of change

  17. Current and Future Climate and Change • Black is wetter and gray is drier • Size indicates magnitude of change

  18. 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?

  19. 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)

  20. Oceans: Sea Level and Circulation • Sea levels rise over 3K yrs in 3 Euro cities

  21. 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

  22. Oceans: Sea Level and Circulation • Warm H2O surges in cold water areas

  23. 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

  24. 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

  25. Oceans: Sea Level and Circulation • Glacial retreat (1973 and 2000)

  26. 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

  27. 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?

  28. 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

  29. 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

  30. Predicted Biological Impacts • Increases in mean temperature, leading to more record temperatures

  31. Observed Biological Impacts • An increase in both mean and variance temperatures

  32. 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

  33. 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?

  34. 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

  35. 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

  36. Abundance Change and Community Reassembly • Mean annual ocean temperatures at Scripps

  37. Abundance Change and Community Reassembly • Southern species have increased in abundance while Northern species have decreased in S CA

  38. 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

  39. Range Shifts • Species ranges are dynamic, changing both spatially and temporally

  40. 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

  41. 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

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

  43. 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

  44. 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

  45. 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

  46. Conservation Implications of CCExtinctions • Range shift model of a S Af plant

  47. 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?

  48. 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

  49. 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