Climate Change

Question 1

What is global warming?

Answer 1

Increase in global temperatures through natural response or human activity e.g. industrialisation, caused by GHG emissions

Question 2

How does GHG contribute to the greenhouse effect & global warming?

Answer 2

• 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

Question 3

How does combustion of fossil fuels contribute to global warming?

Answer 3

Combustion of fossil fuels for increasing energy usage: electricity, transport, production of chemicals etc. –> CO2, a GHG

Question 4

Explain how forests and peatlands are carbon sinks

Answer 4

• CO2 absorbed stored as organic material in plants (biological carbon sequestration)
• Undisturbed waterlogged peatlands store large amts of C (small net sinks).

Question 5

How does the clearing/drainage of forests/mangroves/peatlands contribute to global warming?

Answer 5

• 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

Question 6

How does the growth in meat consumption (due to rising incomes) contribute to global warming?

Answer 6

• 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

Question 7

With reference to biochemical details, explain how planting young trees helps to counteract CO2 emissions

Answer 7

• 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

Question 8

Explain why stations should include CCS or CCU facilities

Answer 8

• 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)

Question 9

Describe the impact of global warming on frozen organic matter

Answer 9

• 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

Question 10

What causes the rise in sea levels?

Answer 10

• melting of land ice: polar ice caps, glaciers, ice sheets

- thermal expansion of water

Question 11

Describe the impact of global warming on freshwater supplies

Answer 11

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

Question 12

Describe the impact of climate change: change in weather, heatwaves, heavy rainfall

Answer 12

• 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

Question 13

What are the negative effects of rise in sea levels?

Answer 13

• 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

Question 14

Explain how a positive feedback mechanism may affect global climate change.

Answer 14

• (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

Question 15

Describe the physiological/morphological changes in plants under water stress (drought, high temp)

Answer 15

• 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

Question 16

What are the morphological adaptations of plants in response to high temp/water stress?

Answer 16

• 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

Question 17

Explain why during high temperatures, there is low CO2: O2 ratio in the airspaces of the leaves

Answer 17

• 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

Question 18

What problem occurs when there’s a low CO2: O2 ratio in the airspaces of the leaves?

Answer 18

Photorespiration: RuBisCO fixes O2 (competitive inhibitor of RuBisCO) instead of CO2 → less photosynthesis

Question 19

How do C4 and CAM plants adapt to high daytime temp and intense sunlight (photorespiration)?

Answer 19

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

Question 20

How do high temp affect physiology of plants?

Answer 20

• 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

Question 21

What is a thermal safety margin

Answer 21

Diff between thermal optimum and current climate

Question 22

Describe the effect of global warming on plant and animal distribution

Answer 22

To stay within their ideal temp range→ move to areas with cooler temp
Shift to higher elevations and northern latitudes

Question 23

What is the life cycle of Aedes aegypti?

Answer 23

• 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

Question 24

Describe how global warming affects the transmission of dengue virus

Answer 24

• 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

Question 25

Describe the development and virulence of dengue in humans

Answer 25

• DENV infects Langerhans cell (dendritic cell), which secrete cytokines and limit spread of infection and travel to lymph nodes-> display viral antigens on sf–> activate monocytes and macrophages–> instead of ingesting and destroying pathogens, they are targeted and infected by virus
• Infected monocytes and macrophage travel through lymphatic system→ virus spreads and infects more cells→ Viremia: high lvl of virus in bloodstream
• Infected cells secrete cytokines (interferons) → activate innate and adaptive immune system

Question 26

Describe the symptoms of dengue

Answer 26

DF: Viraemia, headache/pain, fever, rash

Severe dengue: DHF (lowered blood pressure) DSS (death)

Question 27

Why is there a higher risk of severe dengue upon infection from 2nd serotype?

Answer 27

• antibody-dependent enhancement of infection: antibodies from 1st infection bind to infecting virus particle, cannot neutralise virus→ higher overall replication of virus; non-neutralising ab facilitates virus entry into host cells→ increasing viremia
• cytotoxic T cells provide only partial immunity against new serotype/don’t effectively clea virus + release excess cytokines→ serious inflammation and tissue damage
  > ↑ vascular permeability→ leakage of plasma, fluids collect in body cavities; severe bleeding: stomach and intestinal bleeding→ death
  > Loss of plasma and protein→ shock: lack of blood circulation, undetectable blood pressure and pulse

Question 28

Suggest why it may be difficult for species displaced by a rise in sea level to colonise new habitats–> unable to adapt, higher risk of extinction

Answer 28

• No other suitable habitat/not able to adapt
• No biological corridor for species to move from one habitat to another
• Rate of sea rise too high, time taken for colonisation is insufficient
• Lack of other species for its survival e.g. prey / New predators
• Niches already filled
• Compete with native species for food & resources
• Exposure to new forms of disease

Question 29

How does climate change affect corals?

Answer 29

• Higher
  > thermal stress on corals
  > more bac multiplication and infection of corals by bac–> stress
  > zooxanthellae leaves corals–> coral bleaching etc.
• More CO2 and acidification of oceans–> calcification rates and growth rates of corals reduce
• Over-fishing of herbivorous fish that eat macroalgae→ corals under more threat from macroalgae
• ↑sea level and sedimentation→ smothering of coral
• Stronger and more freq storms→ destory coral reefs
• ↑ runoff of freshwater, sediment, pollutant→ algae bloom→ blocks light
  ⇒ loss of coral reefs = loss of habitats for marine organisms, disrupt ecosystem, loss of diversity

Question 30

Describe the benefits to zooxanthellae of the coral-algae symbiotic rs

Answer 30

• CO2 from coral respiration can be used for photosynthesis
• nitrogenous waste from corals–> nutrients for algae
• Physical support and shelter provided by corals

Question 31

Describe the benefits to corals of the coral-algae symbiotic rs

Answer 31

• Algae photosynthesise, produce food for corals

- Algae absorb light light energy, protecting corals from harmful effects of sunlight

Question 32

Why does the loss zooxanthellae lead to coral death?

Answer 32

• As zooxanthellae produce food, no algae–> less source of food
• Loss of inorganic ions for deposition of skeleton
• loss of protective algal layer

Question 33

How does climate change affect salmon?

Answer 33

• Warmer water temp
  → affects life cycle of salmon
  → ↓ cardiovascular capacity→ more vulnerable to disease & predators→ death
• Expanded industrial activities→ decline in salmon populations
• Loss of snowpack, shrinking glaciers→ ↓ stream flows in summer & fall
  → water levels in rivers and streams ↓→ bears snap at spawning salmon more easily→ ↓ survival of salmon
  → more difficult to return to spawning grounds/juvenile fish to enter ocean in summer
• Intense spring floods→ wash away salmon eggs laid in stream beds
• Salmon return to native rivers to spawn, don’t migrate to cooler waters to spawn

Question 34

What are the effects of the loss of biodiversity?

Answer 34

• Loss of biomedicines
• Loss of genetic diversity in food
  > Without genetic diversity in crop production/consistent mutation→ species cannot continue to thrive in face of disease and pestilence→ ↓sustainability of food source

Question 35

Describe the impact of climate change on global food supply: crops

Answer 35

• reduce crop yield:
  > droughts, change in ppt–> less water
  > High temp–> poor anther dehiscence, low pollen production→ sterility and no seeds
  > Warming→ shorter periods of low winter temp→ low flower bud initiation
• Alter patterns of weeds, plant pests and pathogens/diseases
  > high temp–> more pests and weeds
  > new pests
• Loss of arable land
  > high ppt and flooding–> soil erosion–> destroy veg plots–> lower yield

Question 36

Describe the impact of climate change on global food supply: fisheries

Answer 36

• Migration towards poles
  > → catches more dominated by warm-water species
  > Tropics: less catches→ ↓ food security
• Acidification of ocean
  > → death of coral reefs, the foundation of many fisheries
  > Harm shellfish by weakening their shells

Question 37

Describe the impact of climate change on global food supply: livestock

Answer 37

• High temp→ heat stress in animals→ vulnerable to disease, reduced fertility & milk production, high mortality
• High temp→ drought→ loss of pasture grazing land (food) for livestock