Global environmental change Flashcards
global environmental change
planetary scale changes in earth system (climate, urbanization, economy, sea ice loss)
causes and effects of global environmental change
past causes : solar variation, plate tectonics, volcanism, meteorites, change in orbit, resource depletion
present causes: growing human population, demand for energy , goods, services, information, disposal of waste products
effects: climate change, extinction, desertification, ocean acidification, ozone depletion, pollution
pollution
introduction of contaminants into natural environments that cause adverse change
chemicals/ energy (noise, heat, light)
2015 - killed 9 million globally
measuring toxicity
effect of a chemical depends on concentration
lethal concentration (Lc) = conc of chemical in air + water that will kill 50% within single exposure
lethal dose (Ld) - single dose of a chemical test that when fed/applied dermally will kill 50 %
effects of pollutants
additive = effects of each added together to overall effect
antagonistic = one pollutant cancel out/ reduce impact of another
synergistic = combine in such a way that effects greater than additively
sources of pollutants
point sources (eg sewage outlet)
multi-source (chimney stacks)
seeping (fertiliser runoff)
spreading (volatiles in air flow)
acute pollution
large amount of waste enters environment
usually common from point source after accident
toxic effect however ecosystem recovers + returns to original
oil - intercepts 90% sunlight, division of algal cells inhibited at levels of 0.01ppm. modifies food chains directly + indirectly
chronic pollution
low level input into environment through continous/frequent pulses
constantly under stress, no opportunity to recover
pesiticdes - highly toxic + deliberate, saves human lives and improves harvests however DDT found to decrease thickness of perigrene falcon eggs
organochlorine - broad, remain
chlorophenoxy - resemble auxins, broken down in days
organophosphates - highly toxic to humans, biodegradable + non persistant
biomagnification
when chemical compound moves to another compartment and causes higher concentration factor
CF= conc of pollutant in consumer / conc pollutant in diet
biomagnification when CF>1
plastic - slow to degrade, only 24% recycled, entanglement or ingestion
microplastics - 5mm>. primary (manufactured) or secondary (fragments from breakdown)
can accumulate in body tissues
biodiversity
attempt to capture complexity of life
genetic diversity = total no. of genetic characteristics in the genetic makeup of a species
genetic variability = tendency of genetic characteristics to vary
species diversity = no. different species
-species richness = count of species
-species eveness - how equal abundances are
species extinction
> 90% all species to ever exist now extinct
100-150 species extinct daily
anthropocene extinction - ongoing extinction event mainly due to humans
main causes of species extinction
habitat fragmentation
agriculture
human over population
deforestation
poaching + hunting
simpson’s reciprocal diversity index (1/D)
yeah do this one lmao
ecosystem diversity
variation in ecosystems found in a region or variation in ecosystems over planet
takes into account variation in complexity of community, no. of trophic levels + other processes
largest scale of biodiversity - considerable species + genetic diversity within each ecosystem
total species diversity in a landscape
gamma diversity, determined by:
alpha diversity = mean species diversity in sites or habitats
beta diversity = differentiation among those habitats
hotspots
endemism = limited geographical distribution of a taxonomic group (at species, family or genus level)
areas of high species richness + endemism generally of high conservation value
36 areas globally support 60% species
importance of biodiversity (direct use value)
direct use value- direct role of biological resources :
food - 80% from 20 types of plants + many animal species
medicine - 35% all prescriptions based on plants, only about 5,000 species investigated
biocontrol - use natural enemies to control pests eg weeds or insects (africa control mealybug saved £350 m annually)
industrial resources - tree export worldwide £4.5 billion
ecotourism - 250 million people anually, £80-250 bn income
sustainability
global fish harvest: 66% marine fish stocks fished beyond level of maximum productivity
fuel wood: developing countries consume faster than replenished, if trends continue 1 billion face chronic shortages by 2050
importance of biodiversity (indirect use value)
providing services critical to human wellbeing, worth £25 trillion
ecosystem processes - eg decomposition, nutrient cycling, primary productivity
ecosystem services - benefits provided to humans
-provisioning - food+water
-regulating- climate + disease control
-supporting- crop pollination + nutrient cycles
-cultural- spiritual + recreational benefits
importance of biodiversity (non use value)
feel good/warm glow
value of ensuring availability of biodiversity + ecosystem functioning for future generations
aesthetic
climate change
natural + recent causes
large scale long-term shift in the planets weather patterns or average temps
natural causes : solar activity, earths orbit (milankovitch cycle), continental drift
recent causes : el nino, volcanic eruptions (block sunlight + release sulfur dioxide), greenhouse effect
greenhouse gases
CO2, CH4, H2O, CFCs
CO2 major contributor
-measure concentrations in ice cores: pre industrial revolution 270ppm -> 2024 430ppm
CH4 is 25x as effective
42% from livestock + rice farming (deforestation for cattle ranching, coal burning, waste)
consequences of climate change
sea level rise
effects on species
distribution of species
effects on agriculture
patterns in disease
human migration
CC - sea level rise
predicted to rise 12cm by 2030
50% humanity inhabits coastal zones
lowest lying lands v fertile
Netherlands - 50% land below present sea leve, 400km dykes + coastal dunes
cost of protection against 1m rise - £10,000 million
bangladesh, low lying islands - 0.5m rise reduce habitable area + remove 50% groundwater
