Climate Change Flashcards
(37 cards)
What is global warming?
Increase in global temperatures through natural response or human activity e.g. industrialisation, caused by GHG emissions
How does GHG contribute to the greenhouse effect & global warming?
- GHG allow short-wave radiation from sun to pass through & heat the earth sf→ heated sf radiate out-going, long-wave radiation/infrared which is absorbed and re-emitted by GHGs into atmosphere
- Increased conc of GHG→ increased trapping of radiation/heat
How does combustion of fossil fuels contribute to global warming?
Combustion of fossil fuels for increasing energy usage: electricity, transport, production of chemicals etc. –> CO2, a GHG
Explain how forests and peatlands are carbon sinks
- CO2 absorbed stored as organic material in plants (biological carbon sequestration)
- Undisturbed waterlogged peatlands store large amts of C (small net sinks).
How does the clearing/drainage of forests/mangroves/peatlands contribute to global warming?
- Reduces net photosynthesis, reduce amt of C sinks available
- Drainage of peatlands–> increased decomposition rates, risk of peatland fires–> more CO2 and N2O
- Burning of forests –> CO2
- Conversion to agriculture further increases GHG emissions
How does the growth in meat consumption (due to rising incomes) contribute to global warming?
- Beef produces the highest GHG emissions compared to other foods
- Source of GHG from raising livestock
> Enteric fermentation: carbohydrates digested by microorganisms into simple mlcs for absorption into bloodstream of animal ⇒ methane
> Nitrogenous fertilisers:
–> increases production of animal feed for livestock⇒ N2O
–> production of chemical N fertilisers⇒ CO2 + N2O
> Manure
–> Stored manure from livestock⇒ methane
–> Used as fetilisers⇒ N2O - Deforestation and conversion of grassland into agricultural land: decomposition of N-rich humus⇒ CO2 + N2O
With reference to biochemical details, explain how planting young trees helps to counteract CO2 emissions
- Photosynthesise to produce sugars for their growth and survival
- LD: Light energy→ ATP and NADPH
- LID: CO2 combines with RuBP to form GP, catalysed by enzyme, RuBP carboxylase→ GP (in the presence of ATP and NADPH) reduced to triose phosphate (G3P)* and subsequently to RuBP;
- G3P used in the formation of other carbohydrates/proteins/fatty acids, which can be used to form structural tissues that is incorporated into the growing trees;
- G3P also converted into storage molecules like starch or structural materials like cellulose
Explain why stations should include CCS or CCU facilities
- CO2 is a GHG→ global warming
- CCS and CCU limits CO2 emissions→ mitigate the effect of global warming
- To prevent coral bleaching/more extreme weather conditions (AVP: any other environmental effects of high CO2 concentration)
Describe the impact of global warming on frozen organic matter
- Permafrost stores immense amt of C (frozen organic matter) and methane (methane hydrates)
- Thawing of permafrost/warming→
> Organic matter in permafrost starts to decompose→ CO2
> Organic matter decomposes at a faster rate→ CO2
> Methane released directly or broken down into CO2 by bac before being released
> Increased microbial activities (even in winter; thawed regions between frozen layers) → new methane produced
What causes the rise in sea levels?
- melting of land ice: polar ice caps, glaciers, ice sheets
- thermal expansion of water
Describe the impact of global warming on freshwater supplies
Stress on freshwater supplies
1. Higher temp→ melting of ice sheets, glaciers and polar ice caps (land ice) → increase flood risk during rainy seasons, depletion of glaciers (water source)
2. Higher sea level→ saltwater intrusion into streams/lakes (increase salt conc in groundwater, extending areas of salinity, less freshwater)
3. Wetter rainy seasons
> more runoff→ more sedimentation→ contaminate freshwater supplies⇒ decline in water quality
> Flooding→ streams cannot contain water, wasted when water drains into sea⇒ depletes freshwater
4. Dryer dry seasons/drought→
> depletes groundwater and -vely affects replenishment of groundwater
→ ↑ evaporation and transpiration removes water from water from lakes/ground water
→ More pumping of groundwater for irrigation
→ Shorter duration of rainfall
> decline in water quality
→ More areas affected by drought, which depletes groundwater reserves→ residual water of inferior quality: leakage of saline/contaminated water from land sf/adj water bodies that are contaminated
→ Higher conc of pollution and nutrients in water→ increase load of microbes in waterways & drinking water reservoirs
5. Increase in temp→ Increased microbial growth
Describe the impact of climate change: change in weather, heatwaves, heavy rainfall
- Rise in temp and warmer air→ more evaporation of water into atmosphere→ more water vapour in air→ increased precipitation, but distribution of precipitation around the world is uneven
- Higher precipitation in tropics: Increased freq and intensity of rainfall / wetter rainy seasons
> → more pollution e.g. erosion and sedimentation due to run-off→
–> Water-borne diseases
–> More runoff→ more sedimentation→ contaminate freshwater supplies (e.g. drinking reservoirs)⇒ decline in water quality
–> Flooding→ streams cannot contain water, wasted when water drains into sea⇒ depletes freshwater
–> Eutrophication of water→ more algae→ less light/O2 → death of fish and other plants
> Increased risk of flooding in urban area - Lower precipitation in already dry subtropics / Dryer dry seasons: during drought/periods w less rainfall→
> Depletes groundwater & -vely affects replenishment of groundwater
> Flooding→ streams cannot contain water, wasted when water drains into sea⇒ depletes freshwater
4. Dryer dry seasons/drought→
> depletes groundwater and -vely affects replenishment of groundwater
→ ↑ evaporation and transpiration removes water from water from lakes/ground water
→ More pumping of groundwater for irrigation
→ Shorter duration of rainfall
> decline in water quality
→ More areas affected by drought, which depletes groundwater reserves→ residual water of inferior quality: leakage of saline/contaminated water from land sf/adj water bodies that are contaminated
→ Higher conc of pollution and nutrients in water→ increase load of microbes in waterways & drinking water reservoirs - Less amount and duration of snowcover→ affect timing of ice melting & water flowing into waterways→ less groundwater
- Less frost days at high latitudes→ increasing growing season and food production
- More freq & intense heatwaves→ more heat-related deaths
- Stronger storms and hurricanes: top layer of ocean gets warmer→ hurricanes and tropical storms grow stronger, w faster winds and heavier rain
What are the negative effects of rise in sea levels?
- Higher projected storm surge (less protection by seawalls)
- Infrastructure and sewers compromised
- Coastal areas high enough to avoid flooding still affected
> Saltwater intrusion→ increase soil salinity/reduce freshwater sources/ changing soil pH
> Colonisation of habitats by displaced populations of animals
> Increased coastal erosion/shoreline erosion
Explain how a positive feedback mechanism may affect global climate change.
- (defn) initial change results in further change of same factor
- Higher temperature will lead to increased CO2 in atmosphere in these activities→ more GHG→ more infrared radiation absorbed→ further increase in temperature
> Increased decomposition of organic matter in soil→ increased CO2 in atmosphere
> Reduced CO2 solubility in oceans and seas→ increased CO2 in atmosphere
> Melting of permafrost → increase of CH4 in atmosphere
> Melting of land and sea ice→ less radiation from sun is reflected (less albedo) → more sunlight & heat absorbed→ increase temperature
> Drier climate→ more forest fires→ more CO2 released in atmosphere
Describe the physiological/morphological changes in plants under water stress (drought, high temp)
- Reduction of water content and turgor→ cell expansion slows/ceases
- Less/no photosynthetic pigment
- Less RuBisCO→ less carbon fixation
- Incresed ratio of roots to shoots
- Stomatal closure & less stoma per leaf → reduce water loss through transpiration
⇒ photosynthetic rates decrease→ plant growth is retarded; dehydrate and die
What are the morphological adaptations of plants in response to high temp/water stress?
- Small sf area to vol ratio of leaf
- Thick waxy cuticle and epidermis
- Stomata only on bottom of leaf; only in grooves and surrounded by hair → high humidity at stomata opening→ reduce evaporation and water loss through transpiration
- Leaves that curl up on dry days e.g. marram grass using “hinge”/bulliform cells
Explain why during high temperatures, there is low CO2: O2 ratio in the airspaces of the leaves
- High temp→ significant transpiration→ water loss→ stomata closes to reduce transpiration→ prevent gaseous exchange
- Rate of photosynthesis is higher than rate of respiration
- LD rxn of photosynthesis continues→ photolysis of water, more O2 gas produced & accumulates
- Available CO2 is used up during carbon fixation
What problem occurs when there’s a low CO2: O2 ratio in the airspaces of the leaves?
Photorespiration: RuBisCO fixes O2 (competitive inhibitor of RuBisCO) instead of CO2 → less photosynthesis
How do C4 and CAM plants adapt to high daytime temp and intense sunlight (photorespiration)?
C4 plants: CO2 converted to 4C compounds by enzyme that doesn’t bind O2 → 4C goes to deeper tissue layer where less O2 is present → CO2 released and enters Calvin cycle
CAM plants: CO2 converted to 4C in the day. CO2 released, C fixation at night
How do high temp affect physiology of plants?
- drought and water stress–> C4 and CAM plants
- reproduction of plants: high temp→ reduced pollen viability, disrupt flowering process, affects seed production
- smaller body size of animals–> large sf area to v ratio–> efficient heat loss
- Body temp of ectoderms fluctuates w env temp. Higher temp→ faster rate of enzyme-catalysed biochemical rxn→ faster metabolism rate→ less time to maturity
- Higher temp→ affect fitness of insects
> Decrease relative fitness of tropical insects: small thermal safety margins as their envs are already close to their physiological optimum→ approach physiological optimum temp faster and risk extinction
> Increase relative fitness of temperate insects: larger thermal safety margins as their envs are on average cooler than their physiological optimal→ broader thermal tolerance→ warming enhances fitness - Change in timings of seasonal life cycle events: mismatch in timing of migration, hibernation, breeding, food availability, flowering timings etc.→ species out of synch with other species /impt natural events in ecosystem
What is a thermal safety margin
Diff between thermal optimum and current climate
Describe the effect of global warming on plant and animal distribution
To stay within their ideal temp range→ move to areas with cooler temp
Shift to higher elevations and northern latitudes
What is the life cycle of Aedes aegypti?
- Egg (1-2 days): can survive very long in dry ststae, and hatch almost immediately when water appears
- Larva (4 days): 1st to 4th instars
- Pupa (2days)
- Adult
Describe how global warming affects the transmission of dengue virus
- Mosquito vector, Aedes aegypti, lives and breeds in moist tropical regions.
- Dengue virus spread through human-to-mosquito-to-human cycle
Virus reproduces within mosquito. ↑ mosquito vector which transmits dengue→ higher transmission of dengue
- Higher temp in temperate regions/higher altitudes→ conditions more suited for survival of mosquitoes→ mosquitoes move to higher latitude, expanding their distribution + colonise higher altitudes
- Higher temp
→ Shorter life cycle (first instar to emergence shorter): ↑ rates of enzyme-catalysed rxns→ ↑ metabolism→ faster development, decreasing length of reproductive cycles→ stimulate hatching of eggs
→ more rainfall → more pools of stagnant water for mosquito breeding
⇒ more mosquitoes→ more transmission of dengue fever
Higher temp→ shorter extrinsic incubation period in mosquito
