Global environmental change Flashcards
define global change
planetary-scale changes in the earth system
what causes global change (7)
solar variation plate tectonics volcanism proliferation and abatement of life meteorite impact resource depletion changes in the earths orbit
what is the main driver for global change
growing population causes increased demand for energy, food, services and disposal of waste
what is the result of global change
climate change
species extinction
desertification and ocean acidification
ozone depletion and pollution
define pollution
introduction of contaminants into natural enviro that causes adverse change
can be: energy, heat, noise, light or chemical substances
how do we measure toxic?
Lethal concentration: concentration of chemicals in the air/water that will kill 50% of test animals in single exposure
lethal dose: the single dose of a chemical that, when fed to group of test animals/ applied dermally will kill 50% of the animals
additive pollution
effects of each pollutant add together to produce overall effect (A+B=AB)
antagonistic pollution
one pollutant cancels out/reduces the impact of another (A+B+A)
synergistic pollution
pollutants combine in a way that the environmental effects are greater than would be expected additively
point source pollution
e.g. sewage outlet
multi source pollution
e.g. chimney stacks
seeping pollution
e.g. fertiliser runoff
spreading pollution
e.g. volatiles in air flow
what are the characteristics of acute pollution
large volume of pollutant released into enviro
- often from one point source (one off/accidental)
- commonly toxic affect
- afterwards ecosystem begins to recover and return to original situation
what are the characteristics of chronic pollution
low level input but almost constant = ecosystem under stress with no chance to recover = cumulative effect
acute pollution: crude oil
blend of chemical compounds:
- aliphatic hydrocarbons
- aromatic hydrocarbons
- polar compounds
- sulphur compounds
biotic effects of crude oil
around 90% sunlight intercepted
division of algal cells inhibited at oil levels of 0.1ppm
oceans dependent on phytoplankton
food chains modified (directly and indirectly)
chronic pollution: pesticides
toxic chemicals introduced into ecosystem to kill/reduce population size/growth of particular pests or weeds
Benefits:
saves many human lives (improved harvest)
reduces weeds/pests
fewer storage losses
control livestock and crop diseases
what are the different methods of applying pesticides
direct contact secondary contact ingested repellent lure and kill fumigant
direct contact pesticide
spraying pest
secondary contact pesticide
spraying plant
ingested pesticide
taken in by root = killed when pest eats it
repellent pesticide
deters pest
problem: pest may relocate
lure and kill pesticide
artificially toxic and attracts pest to ingest it
fumigant pesticide
fumes are toxic
don’t need to ingest or have contact
what are the 3 main types of pesticides
organochlorine:
- broad spectrum toxins
- remains in enviro for a long time
chlorophenoxy:
- chemistry resembles plant auxins
- broken down in soil in matter of days
organophosphates:
- highly toxic to humans
- biodegradable and non-persistent, readily broken down
chronic pollution: DDT and peregrine falcons
- peregrine egg thickness decreased and breaking
- high levels DDE (metabolite of DDT) found in fatty tissues peregrine carcasses
- more DDE = thinner shells
- realised DDT was reducing calcium deposition
biomagnification
when element/chemical moves from one compartment to another and occurs at higher concentration in the second
occurs when concentration factor > 1
concentration factor
concentration of the pollutant in the consumer / concentration of the pollutant in the diet
pollution: plastic
accumulation of plastic in enviro neg impact wildlife/habitat/humans
slow to degrade
affects: bodies of water, marine animals, humans, wildlife
pollution: microplastics
usually <5mm in diameter
sources include: cosmetics, clothing, industrial processes
primary microplastics
manufactured
direct result of human material and product use
secondary microplastics
fragments derived from breakdown of larger plastic debris
what are the main causes of extinction
habitat fragmentation agriculture human over population deforestation poaching and hunting
genetic diversity
total number of genetic characteristics in the genetic makeup of a species
genetic variability
tendency of genetic characteristics to vary
species diversity
number of different species
consists of species richness and evenness
species richness
count of species
species evenness
quantifies how equal the abundances of the species are
ecosystem/ecological diversity
variation in ecosystems found in region or variation in ecosystems over the whole planet
is the largest scale of biodiversity
gamma diversity
total species diversity in a landscape
determined by alpha and beta diversity
alpha diversity
the mean species diversity in sites or habitats at a more local scale
beta diversity
the differentiation among habitats
endemism
describes usually limited geographical distribution of a taxonomic group. usually at family, genus or species level (group only found in a certain area)
biodiversity hotspot
area of species richness and high level of endemism
have high conservation value
direct use value
direct role of biological resources in consumption and production
e.g. food, medicine, ecotourism, biocontrol, industrial resources
indirect use value
derives form the function biodiversity perform and is critical to human well being e.g. pollination
non use value
aspects of biodiversity that do not aid human life e.g. aesthetics
what is biocontrol
use of natural enemies to control species regarded as pests
would avoid pollution and toxicity aspects of pesticides
give to e.g. of poor sustainability today
global fish harvest
fuel wood
what are the pros and cons of ecotourism
pros: education tourism improving economy enriching life
cons:
damage caused via travel
indirect environmental harm due to poor awareness
ecosystem processes
actions or events that link organisms to their environment
e.g. decomposition, nutrient cycling, primary productivity
ecosystem services
the benefits provided by ecosystems to humans grouped into: provisioning regulating supporting cultural
provisioning service e.g.
production of food and water
regulating service e.g.
control of climate and disease
supporting service e.g.
nutrient cycles and crop pollination
cultural service e.g.
spiritual and recreational benefits
climate change definition
large scale long term shift in planets weather patterns or average temp
earths climate temp
14c but recently increasing
what are the natural causes of climate change
solar activity
earths orbit - Milankovitch cycles
continental drift
describe solar activity
sunspot activity and how strong it is e.g. little ice age when reduced
describe Milankovitch cycles
cyclical movement related to earths orbit around the sun combines to affect solar heat
eccentricity cycle = ellipsical
axial tilt = between 22.1 and 24.5 degrees
precession = wobbles like a tilt
describe continental drift
continents once joined and now drifting apart due to circulating heat of earths interior and has large effect on climate
recent causes of climate change
el nino = water in eastern/central pacific warmer due to winds. change in ocean conditions changes weather volcanic eruptions
greenhouse effect
1827
jean baptiste joseph fourier 1st recognised existence of greenhouse effect
1860
john tyndall measured absorption of infrared radiation by carbon dioxide
1896
svante Arrhenius calculated effect of increasing concentration of greenhouse gases
1940
G S Callender first to calculate the warming due to increasing CO2 from burning fossil fuels
1957
Roger revelle and Hans suess first expression of concern about climate change
pre industrial global average concentration of CO2
260-280 ppm
1990 level CO2
350ppm
predicted level co2 in 2060
600ppm
what are the greenhouse gases
CO2, H20, CH4, CFCs
- co2 major contributor and less effective absorber
signs of climate change in wales
sea levels at Holyhead increased over past 50 yrs
wheat crops at Aberystwyth flower 1-2 weeks earlier
blackcap arriving earlier on skokholm island
sea level rise in the netherlands
50% country below sea levels
400km of dunes provide protection
10,000 million estimated cost of protection against 1m sea level rise
sea level rise in bangledesh
30% of land 2m below sea level
estimated 1m rise by 2050, 2m by 2100
120 mil people located in delta region
sea level rise low lying islands
- 5 mil people
0. 5 m rise would remove 50% groundwater
how sea level rise would affect freshwater
effect ground water supplies and reserves
yet increasing pop
worlds major water sources shared
co2 effects on plants
- c3 plants respond positively and increase photosynthesis but do acclimate. growth increase about 40% (vs C4 plant by 20%)
- plants commonly increase ratio of carbon to nitrogen = more nitrogen based defences against herbivores
- insects that eat plants limited by nitrogen, need to eat more and would develop more slowly
- causes partial closing of stomata making plants more efficient in water usage
- leaves of plants may become thicker and have more starch
effects of climate change on agriculture
- neg effect partially compensated by increased productivity from fertilization effect of co2
- increased disparity in cereal production between developed and less developed countries (developed increased 5%, less developed declined by 10%)
- some crops require cold to germinate
impacts of climate change in human health
- impacted by pollution, inadequate water supplies and poor soil
- main direct effect = heat stress
- potential increased spread of disease e.g tropical diseases could spread mid latitude (malaria)
- 150 mil environmental refugees
define invasive species
living organism that’s not native to an ecosystem and can harm the enviro, economy or human health
E.g invasive species Japanese knotweed
introduced from eastern asia
now across most of uk
forms dense strands and hard to control
illegal to sell house and not inform buyers its present
e.g. invasive species rhododendron
introduced from Iberian peninsula
blocks light
carries diseases fatal to native trees
characteristics of invasive species
fast growth rapid reproduction high dispersal ability phenotypic ability (alter growth to suit conditions) tolerance of enviro conditions can live of wide range of food types association with humans prior successful invasion history
define urbanisation
pop shift from rural to urban areas
how towns/cities formed
environmental effects of urbanisation
urban heat islands (urban areas retain and produce heat)
rural areas solar energy evaporated by eater from soil/vegetation
cities often warmer
define land use
management and modification of natural enviro
impacts local and global biodiversity
greatest cause of extinction e.g. deforestation
different types of land use
recreational transport agricultural residential commercial
