Lec10_Climate

Lec10_Climate - Climate Change • Disease and transmission...

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Unformatted text preview: Climate Change • Disease and transmission • Climate Change – Climate Drivers • Glaciation and latitudinal shifts • Solar activity and northern forests • CO2 and plant productivity – Modeling climate change Class Business • Midterm Thursday 10/27 – One 8.5x11 sheet with notes (front and back) allowed. Typed OK – OK to study together, but sheets must be your own work – Sheets will be collected after midterm – No calculators – Multiple choice (scantron) and short answer – Through lecture material today Transmission and Virulence: Vectors • Parasites transmit disease between hosts • Vector: – low virulence from disease – Need healthy vector for transmission • Host – high virulence Transmission and Virulence: Vectors • Malaria (Plasmodium falciparum) – human host can be completely immobile and still transmit disease – human mortality (untreated) 10-20% Parasites transmitted by vectors are more virulent Ewald 1994 Transmission and Virulence: Trophic Transmission • Disease is transmitted from prey to predator – may have 2-3 trophic levels in cycle • Prey – used as energy resource – high virulence • Top predator – needed for transmission – low virulence Trophic Transmission • Euhaplorchis californiensis – trematode Marsh killifish Fundulus parvipinnus Brain infected behavior change increases predation Marsh horn snail Cerithidea californica Castrated by parasite Vertebrate host releases eggs in feces Transmission & Virulence: Sit and Wait • Sit-and-wait pathogens tend to be virulent – Can survive period between hosts • Smallpox (Variola major): 30% mortality – Survives on bedding and clothes – Also person to person transmission • Anthrax: 90% mortality (inhaled) – spores can survive >10 years outside host Climate Change • Climate Change Over Earth History – Drivers of climate – Interactions between organisms and climate • Paleoecology – What it can tell us – Issues • Modern Climate Change – Global Warming – Predicting the Effects of Climate Change Geologically Recent Climate • Past 10,000 yrs fairly stable climate • 2000-100 years ago most temperature changes due to solar activity, volcanoes, ocean currents • Last 100 years changes from human activity Temperatures Over Past 1000 yrs • Global Mean Temperatures have increased over last 150 years Recent Global Temperature Changes • Global Mean Temperatures have increased over last 150 years Global Temperatures Are Increasing Changes are most pronounced at higher latitudes, especially northern latitudes Drivers of Global Climate • Milankovitch Cycle • Albedo • “greenhouse” gasses – CO2 – Volcanoes – Anthropogenic (human) • Ocean Currents • El Niño and La Niña • Solar Activity Drivers of Climate • Milankovitch Cycle- – Cycles in eccentricity, tilt, and precession of earth – Affect the amount of sunlight and density of photons striking earths surface – Phases of cycle can combine to cause major ice ages every 41-100K years, and minor ice age every 19-23K – Fits ocean temperature data well – Currently coming out of cooling phase Precession 19-23K yrs Orbital Eccentricity 100K years Axial Tilt 41K years Drivers of Climate: Ice Albedo • Albedo=reflectivity of sunlight off of surface • Ice at poles reflects sunlight back into space • Prevents warming of surface • Feedback – Warming leads to ice melting – Melting lowers albedo – Lower albedo leads to more warming at surface – Also works in reverse Ice Albedo Warming Phase Melting Ice Warmer Surface Lower Albedo Cooling Phase Freezing Ice Higher Albedo Colder Surface • Other drivers (such as Milankovitch Cycle) cause overall warming or cooling • Albedo feedback accelerates warming or cooling effect Milankovitch & Albedo: Glaciation • Milankovitch and Albedo contribute to glaciation (may be other factors) • Last Glaciation peak ~10 Kya • Earth has warmed gradually (~8C) since • Pollen record – Forms layers in sediment – Can track species ranges • Species may alter distributions – Latitudinally – Altitudinally Glaciation: Species Ranges Oak distribution % pollen in cores Glaciation: Species Ranges Elevational Changes in Nevada Dots= During glaciation Bars= Present Climate Drivers: Solar Activity • Low sunspot activity=lower solar input=lower temperature • Little ice age- 1650s • 10-12 year cycles in sunspot activity • Currently at a sunspot minima Solar Activity: Klvana et al. 2004 • Porcupines chew on bark • Form “scars” on tree • Rings can’t form at scar, but will form in rest of trunk • Can date time of scar formation up to 133 years ago Solar Activity: Klvana et al. 2004 • Quantified historical porcupine feeding from scars • Correspondence between feeding, rainfall temperature and 10-12 yr solar cycle • Also correspondence between hare cycles and solar cycle • Currently coming out of solar activity minimum Solar Activity: Mabille et al. • Tagged & tracked porcupines over 6 years • Adult porcupines more vulnerable to predators in snowy winters • Both adults and juveniles more likely to starve in snow • Solar cycles linked to snow cover CO2 and the Greenhouse Effect Climate Drivers: Volcanic Eruptions • Immediate Effect-Cooling – Emit ash and sulfur dioxide – Temporarily block sunlight and cool atmosphere • Longer Effect (potential) – Emit CO2 – Greenhouse gas • Volcanoes: Cooling followed by warming from CO2 CO2 Levels Records from Hawaii Atmospheric Cycling CO2 •Human inputs much less than natural •But they are a net increase CO2 sources, sinks, and sequestration • Sources – Emit CO2 into atmosphere – Organismal respiration, decay, burning of fossil fuels, etc • Sinks – Absorbs CO2 from atmosphere – Plant and plankton growth • Sequestration – After Sink absorbs CO2, sequestered CO2 remains out of circulation – Ocean sediments, rocks, standing biomass, etc Climate Drivers: Greenhouse Gases • Natural and Anthropogenic – – – – – Water vapor- largest greenhouse gas Carbon dioxide Methane Nitrous oxide Ozone • Anthropogenic only – Chlorofluorocarbons (CFCs) – Other fluorinated compounds CO2 Effects: Shaw et al. 2002 • Grasslands in San Mateo, CA • Manipulated water, nitrogen, and CO2 • Measured net primary productivity (NPP) CO2 Effects: Shaw et al. 2002 • CO2 addition decreased NPP across all treatments • CO2 only stimulating when natural NPP is low • C=CO2 treatment • T=temperature • N=Nitrogen • P=precipitation Climate Drivers: Ocean Currents • Ocean Currents help redistribute heat around globe • Factors – Land mass arrangement – Sea level – Glaciation • Example: Gulf stream brings warm water to Europe, heating continent El Niño and La Niña • El Niño- adds heat to atmosphere • La Niña- cools atmosphere Modeling Climate Change • Must account for all factors • Volcanoes, solar forcing, greenhouse gases, sulfate • Of all greenhouse gases, CO2 is major driver – Produced by human activity – Accumulating in atmosphere in large quantities Climate models • Current models fit data fairly well, incorporating heating and cooling effects from natural and anthropogenic sources • Models will evolve as data is collected as research continues Climate Models: Volcanoes • 1991: Mt Pinatubo erupts – 17 MT of SO2 sent into atmosphere – 5 km3 of volcanic material – Gas and ash plume 22 miles high • 1992: Hansen predicts, based on models – Global cooling of 0.5C for 15 months – Warm to pre-eruption temperatures by 1995 • Predictions were accurate Climate Modeling ...
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