Unit 9: Global Change

Notes

Unit 9: Global Change

9.1 + 9.2 - reducing stratospheric ozone depletion

objective :

• explain the importance of stratospheric ozone to life on earth

• describe chemicals used to substitute for chlorofluorocarbons (cfcs)

why :

• ozone in stratosphere absorbs uv-c + ub-b radiation

• without ozone layer, life on land would not be possible bc uv damages skin + mutates dna

• human health benefits = prevention of skin cancer + cataracts

• tropospheric = bad bc respiratory irritant

how :

• forms from uv-c radiation splits and oxygen into two atoms then forms with oxygen molecule to make ozone

• continued formation + break down of ozone in stratosphere absorbs all uv-c + most of uv-b radiation protecting earth

anthropogenic :

• cfcs (chlorofluorocarbons) are a primary anthropogenic (human) cause of ozone breakdown

• used as refrigeration chemicals (e.g. hair spray, febreeze)

• uv radiation causes free chlorine atom to separate

• basically releases chlorine atoms which break down ozone

natural ozone depletion :

• antarctica spring melt forms polar stratospheric clouds (psc)

• clouds made of water that can only form in low temperature

• chlorine nitrate + hydrochloric acid give off chlorine which again breaks ozone

fix :

• phase out cfc + replace w/ hcfcs which are less ozone depleting but still ghg

• cfcs (high ozone + high ghgs) -> hcfcs (low ozone -> high ghgs) -> hfcs (zero ozone + high ghgs) -> hfos (zero ozone + low ghgs)

• now we are at hfcs bc no ozone depletion

9.3 - greenhouse effect

objective :

• identify the greenhouse gases

• identify the source and potency of the greenhouse gases

solar radiation :

• not all solar radiation reaches earth

• 25% is reflected back into space by clouds + atmosphere

• 20% is absorbed into atmosphere

• rest reaches earth’s surface

• can be absorbed (infrared radiation) or reflected

• darker, lower albedo surfaces absorb sunlight + release warmth

• lighter, higher albedo surface reflects it back

greenhouse effect :

• without it no life on earth

• gases in earth’s atmosphere trap heat from the sun + radiate it back to earth

• works by solar radiation striking earth’s surface + heating it

• earth’s surface releases the infrared radiation

• ghgs absorb infrared radiation both out into space + toward earth

• portion coming back = greenhouse effect

sources :

• co2 = ff combustion, decomposition, deforestation

• methane = natural gas extraction + combustion, animal agriculture, anaerobic decomposition (permafrost thaw)

• nitrous oxide = agricultural soils (adding nitrate (fertilizer) into the soils)

• cfcs/hcfcs/hfcs = refrigerants, aerosol

• water vapor = evaporation + transpiration from plants

global warming potential (gwp) :

• how much a gas can contribute to warming of the atmosphere

• co2 = 1 

• two factors, residence time (how long it stays in the atmosphere) + infrared absorption

• methane = 23x worse

• nitrous oxide = 300x worse

• cfcs = 1,600-13,000x worse

• basically co2 -> methane -> nitrous oxide -> cfcs

9.4 - increases in greenhouse gases

objective :

• identify the threats to human health + the environment posed by an increase in greenhouse gases

thermal expansion :

• water molecules move further apart when they are heated

• meaning that more water so basically sea levels rise

melting polar + glacial ice :

• more ghgs lead to warmer climate so melting of ice sheets 

• water goes into ocean and sea level rise

environmental impacts of sea level rise :

• flooding of coastal ecosystems (e.g. estuaries, mangroves, salt marshes)

• loss of species that need arctic + tundra ecosystems (e.g. polar bears, penguins, reindeer)

• loss of thaw-freeze cycle that glaciers go through so less water

human impacts :

• relocation of coastal human populations 

• e.g. new orleans = below sea level

• more flood -> higher insurance

• saltwater intrusion (salt water pushing into groundwater + contaminating wells)

• refugees forced to move inland

disease vectors :

• living vectors that can transmit diseases

• basically warmer temp = expanded range

9.5 - global climate change

objective :

• explain how changes in climate, both short-term and long-term, impact ecosystems

historic climate change :

• earth’s climate has varied over geologic time bc of variations in earth’s orbit around the sun

• varies in eccentricity (around every 100,000 years)

• more eccentric = further from sun

• varies in obliquity (around every 40,000 years)

• exposing northern latitudes to higher insolation

• leads to predictable variations in climate called milankovitch cycles

measured :

• foraminifera = ocean sediments and different species have different temperature tolerance

• air bubbles in ice cores that contain ancient atmospheric gas (co2 levels)

• can see oxygen isotopes (heavier oxygen = warmer)

• why ice ages are predictable

• co2 levels are strongly correlated w/ temperature but causality is not understood

effects of climate change :

• global warming = habitat/species loss, drought, soil dessication, heat waves, more rain in some regions

• rising sea level = glacial + polar ice melt -> thermal expansion

• melting of permafrost = releases methane + co2 from anaerobic decomposition -> more ghgs -> more climate change -> more global warming -> more permafrost melting = positive feedback loop

impact on coastal communities :

• property loss, damage, potential relocation = coastal communities (poorer ones) that can’t build up have to relocate

• seawalls just delay the inevitable

• loss of barrier islands = islands that buffer coastal communities form wind + waves but will be lost w/ sea level rise

impact on atmospheric currents :

• widening + weakening of the hadley cell = as temperature differs between equator + poles decrease, air ascends and expands further before sinking

• subtropical zone will shift further up (dryer weather)

• weakened, destabilized jet stream = as arctic warms faster than other areas temperature difference between equator + poles weakens

• basically temperature + pressure difference drives the polar jet so less difference = less polar jet

• e.g. extreme cold spells in eastern us + dry spells in western us

impact on marine ecosystems :

• altered range of marine ecosystems

• some new marine habitats will be formed

• some areas of ocean = too deep to receive sunlight

• altered range for organisms 

• fish population have to migrate to cooler water bc need oxygen that they have adapted to

suppression of thermohaline circulation :

• global ocean current that redistributed heat from the equator, salt, and nutrients, by mixing ocean water

• critical to earth’s climate

• e.g. ice melt from greenland -> especially cold, fresh water which is less dense than salt, preventing it from sinking

• cold water makes gulf stream waters colder

• cools down europe + slows thermohaline circulation

 unequal global warming :

• polar regions of earth are warming faster than other regions 

• arctic bc more land + less water to absorb heat

• ice and snow have high albedo they reflect more light so more ice melts = positive feedback loop

• distribution of tropical heat to poles by thermohaline circulation also warms poles

• melting of permafrost

• air pollution adds soot + other pm to atmosphere 

• darker pm covered ice has less albedo so absorbs heat

impact on polar ecosystems :

• arctic sea ice loss = habitat loss

• e.g. seals use it fro resting

• e.g. algae grow on ice (base of food web)

• e.g. polar bears not only live on it but need seals for food

9.6 - ocean warming

objective :

• explain the causes and effects of ocean warming

relationship :

• atmospheric warming + ocean warming = related

• as atmosphere warms, heat is transferred to the ocean

• ocean absorbs heat radiated back to earth by ghgs

• ocean absorb much of earth’s heat bc of high specific heat of water

• thermohaline circulation distributed heat absorbed at surface to other areas

• ocean can transfer heat back to atmosphere

effect on marine species :

• warm water = less o2

• means respiratory stress/suffocation

• migratory routes can be altered (e.g. whales)

• reproductive timing can be disrupted (e.g. fish)

• habitat loss = coral bleaching w/ heating ocean (shallow, sunny waters ideal for algae + coral become deeper from ice melt)

• toxic algae blooms = blue-green algae releases toxins into the water that can kill marine species

• can also block sunlight so hypoxia

coral reef ecosystems :

• among the most biodiverse

• brings tourism

• ocean warming causes thermal stress so coral bleaching + infectious disease risk

• sea levels rising causes sedimentation so smothers the coral

• changes in storm patterns causes more storms so destruction of the reef structure

• changes in precipitation so increases runoff of freshwater + algae blooms

• altered ocean currents so change in temperature lack of food

coral bleaching :

• coral reef = mutualistic relationship between coral + photosynthetic algae (zooxanthellae)

• algae give sugar + coral give co2 + nutrient containing organic matter

• algae have narrow temperature tolerance and leave the reef when temperature rises

• pollutants from runoff can also force algae from reef

• coral lose color bc no algae so very vulnerable (NOT dead)

9.7 - ocean acidification

objective :

• explain the causes and effects of ocean acidification

basics :

• comes from increased co2 in atmosphere -> more co2 in ocean

• co2 combines w/ ocean water to form carbonic acid 

• carbonic acid dissociate into bicarbonate ion meaning less carbonate ions

• carbonate ions = used for shells

calcium carbonate + marine organisms :

• marine organisms use calcium and carbonate ions to build their calcium carbonate shells (calcification)

• co2 increase + ocean acidification = less carbonate ions

• when ph of ocean decreases there are fewer carbonate ions bc more carbonic acid

• means marine shells breakdown as ph decreases

• fewer carbonate ions = less shells

climate change + ocean acidification :

• anthropogenic causes for ocean acidification = fossil fuel combustion, deforestation, and coal/gas combustion 

• co2 increase = direct negative correlation w/ ocean acidification

• already decreases by .1 in past 150 year (30% change)

9.8 - invasive species

objective :

• explain the environmental problems associated with invasive species and strategies to control them

basics :

• not native species introduced by human transport

• no natural predators to control population so they thrive

• highly competitive + can thrive in the non-native habitats (adaptive)

• r-selected (generalists, lots of reproduce)

• high biotic potential + low parental care

zebra mussel :

• transported by ship ballast water

• aggressive filter feeders

• eat algae that others rely on

• can lay a million eggs per year (high biotic potential)

• clog intake pipes so economic = bad

kudzu vine :

• planted to limit soil erosion in southern us

• grows very rapidly

• outcompetes native plants for sunlight

• no herbivore control in us

asian carp :

• brought in to control algae growth in aquatic farms

• escaped to mississippi river

• outcompete native fish for food and space

• decreases fishery production + value

emerald ash borer :

• spread by wood packing materials of ships

• larvae laid in bark + eat way into phloem

• phloem = tree nutrient transport

cost :

• cost 120 billion a year

• lost agricultural productivity, tourism, property value decline, fishery decline, control and removal costs

control :

• laws preventing transport of invasives

• removal of hosts (e.g. dead ash trees from emerald ash borer) which reduces the likelihood of them getting spread

• inspection of boats (e.g. zebra mussels being attached)

removal :

• introduction of natural predator

• e.g. chinese wasps kill emerald ash borer

• biological control

• physical removal (e.g. hunting pythons, detaching zebra mussels)

9.9 - endangered species

objective :

• explain how species become endangered and strategies to combat the problems

poaching :

•  illegal hunting of exotic species for fur, tusks, horns

• may also be over harvested or hunted for food

• could be removed from wild into pets

special food/habitat needs :

• niche specialists are prone bc specific food/habitat needs

• e.g. koalas need eucalyptus

• less tolerant to changing climate (e.g. wildfires)

invasives :

• outcompete for resources

• e.g. zebra mussels

• have endangered 30 native mussel species

climate change :

• shifts habitat of many species

• migration to new habitat is harder bc fragmentation

• changes in temperature can be too fast + can’t adapt fast enough

protection :

• poaching (cut off valuable parts of the animal)

• have armed guards + give jail time

• protect habitats that wildlife need to survive

• legislation = international agreement for countries to monitor the endangered species

• endangered species act basically allows them to designate species as endangered + do what they want

iucn red list :

• determines on a scale of least concern to extinct

• least concern, near threatened, threatened, extinct in the wild, extinct

endangerment :

• 41% of amphibians bc vulnerable to climate change

• 25% of mammals

• 13% birds

specialists vs. generalists :

• obvi specialists bc they stay in one place

• generalist can adapt

competition + endangerment :

• interspecific competition amongst members of different species

• can cause species to be threatened

• can further threaten them bc of vulnerability from climate change

9.10 - human threats to biodiversity

objective :

• explain how human activities affect biodiversity and strategies to combat the problem

hippco :

• h = habitat fragmentation/loss

• i = invasive species

• p = population growth 

• p = pollution (pollutants)

• c = climate change

• o = over exploitation

habitat fragmentation :

• roads + pipelines fragment habitats 

• disrupt movement -> fatal collisions w/movement

• agricultural + urban land use

• clearing forest/grassland for agricultural fields or urbanization fragments those habitats

• logging removes trees + construction which fragments forests

• breaking of large, continuous habitats into smaller, isolated patches disrupts breeding, hunting + migration

• some species are more disrupted by fragmentation than others

• e.g. k-selected mammals

metapopulations :

• isolated subpopulations connected by habitat corridors

• can allow gene flow

• smaller subpopulations = less genetic diversity (bottleneck, inbreeding depression)

edge effect :

• edge habitat = where two ecosystems meet

• allow for expansion of specific species

• e.g. brown headed cowbird (brood parasite) that leaves eggs in nests of songbirds making them raise the bird

• increases brown headed cowbird range

• expense of songbirds (population decline)

temperature change :

• warming temperature can shift biomes

• e.g. boreal forest + temperate coniferous forests may shift north

• tundra may decrease bc temperature rise

precipitation change :

• warming global temperature will decrease precipitation

• leads to soil dessication + desertification

• increase in some areas (more tropical ecosystems)

sea level rise :

• estuary habitats become fully submerged + more saline

• coastal ecosystems become flooded

• climate change increase + decreases range

biodiversity + domestication :

• fewer plant species are grown bc selective breeding and gmos

• decreases genetic diversity bc gmos are clones

• many breeds of animals that humans eat are gone

• bc need productivity

• decreases genetic diversity bc only selective breeding

protecting + connecting habitats :

• protecting important by making national parks

• wildlife corridors allow movement + breeding

sustainable land use :

• urban growth boundaries + reducing urban sprawl

• expanding parks, urban gardens, green roofs

restoring lost habitats :

• replanting clear-cut forests

• reestablishing prairies on old agricultural fields or golf courses