Impact of Climate Change on Animals and Plants

Question 1

explain how burning of fossil fuels linked to increasing energy change have contributed to climate change through increased emission of greenhouse gases

Answer 1

• burning of fossil fuels largest contributor of carbon dioxide emissions from human sources
• 3 types of fossil fuels most widely used are coal, natural gas and oil
• coal largest source of CO2 emissions, followed by oil, and then natural gas bc coal is the most carbon-intensive fossil fuel of all the different types of fossil fuels and coal is also used at a high rate
• fossil fuels used in electricity/heat, transportation and industrial sectors

Question 2

explain how clearing of forests have contributed to climate change through increased emission of greenhouse gases

Answer 2

• diminishing carbon sink: trees act as carbon sinks by removing carbon dioxide from atmosphere through photosynthesis. when forests are cleared for agriculture, crops that are grown in place of trees are less effective carbon sinks than trees, hence they remove less carbon dioxide from the atmosphere
• burning of trees (cheap and fast way to clear forest to make way for agricultural land) during deforestation releases a lot of carbon dioxide into the atmosphere since trees are mostly made of carbon compounds
• as carbon is also stored in soil, disturbances during deforestation will lead to further carbon emissions. disturbances also lead to soil erosion and nutrient leaching, which leads to loss of plants, further reducing area’s ability to act as a carbon sink

Question 3

explain how food choices have contributed to climate change through increased emission of greenhouse gases

Answer 3

• ruminant aminals create large amounts of methane during their normal digestion process
• as humans include meat in their diets, methane emissions from livestock farming make it the second largest contributor of methane emissions frmo human sources
• large increase in livestock populations (meat consumption increased due to increase in human population and people are increasingly affluent, and are eating more meat)
• greenhouse gas emissions from livestock production is much higher than crop production
• forests cleared for livestock farming, indirectly increasing greenhouse gas emissions
• animal production requires 10 times more land than crop production
• increase in demand for soy and cereal crops for animal feed have grown exponentially, leading to clearance of vast land area for farming

Question 4

explain effect of climate change in terms of heat waves and heavy rains

Answer 4

• increase in greenhouse gases leads to trapping of more longwave radiation, resulting in an increase in global temperature
• extreme weather conditions (hot weather) have been happening at a higher frequency and intensity
• higher temperature results in longer duration of heat waves, more intense and frequent heavy rain, increased rate of evaporation also leads to an increase in precipitation and hence increases risks of floods and more extreme weather conditions (more floods and droughts at different parts of the world)

Question 5

explain effect of climate change in terms of melting of polar ice caps and rising sea levels

Answer 5

• increase in greenhouse gases leads to trapping of more longwave radiation, resulting in an increase in global temperature
• increased temperature leadsd to melting of polar ice caps, exacerbating the ice-albedo feedback, further increasing temperatures
• melting of land-based ice could lead to increased sea levels, putting coastal communities at low lying countries at risk
• increase in temperature results in thermal expansion of ocean water leading to increase in sea level

Question 6

explain effect of climate change in terms of stress on freshwater supplies

Answer 6

• increase in greenhouse gases leads to trapping of more longwave radiation, resulting in an increase in global temperature
• higher temperature results in more precipitation in the form of rain, and not snow
• more snow will melt earlier in the spring
• since less snow is available at lower elevations, less water will be available to feed rivers
• there is too much water runoff (melted snow) through early spring, when it is not needed, and hence less water runoff in summer, when it is needed
• impacts hydropower output, fish migration and water availability in the dry summer season for crops, fish and people

Question 7

explain the effect of climate change in terms of release of greenhouse gases in frozen organic matter

Answer 7

• climate change resulted in thawing of permafrost at polar regions
• organic matter that was previously frozen in permafrost would start to decompose when permafrost thaws, releasing carbon dioxide and methane
• large amounts of methane previously trapped is released in gaseous form or in solution by rivers

Question 8

explain how human activities could damage coral reefs

Answer 8

• human activities such as burning of fossil fuels/deforestation/food choices increases amount of greenhouse gas emission into the atmosphere
• increased greenhouse gases lead to increased temperatures of the earth surface/heat waves which leads to coral bleaching and/or death
• increased CO2 in the atmosphere increases amount of CO2 dissolved in the ocean while leads to ocean acidification which results in inability to form the calcium carbonate skeleton of the corals
• thermal stratification resulting in reduced upwelling affects nutrient fluxes and hence affect coral reefs
• shipping/fishing activities leading to coral damage

Question 9

suggest how the damage to the coral reefs could affect food security

Answer 9

• coral reefs are important habitats to many fish species/are often nurseries for fish fry
• damage to the coral reef habitats might result in a decrease in fish stock/marine organisms
• communities/countries dependent on marine organisms/fish stock for food supplies might be affected

Question 10

explain the mutual relationship between corals and zooxanthellae

Answer 10

• coral polyps produce CO2 and water as by-products of cellular respiration which the zooxanthellae cells use to carry out photosynthesis
• zooxanthellae produce sugars, lipids and oxygen, some of which are used by the coral polyps in respiration. zooxanthellae also gives coral polyp its vibrant colour
• light recycling of products between the polyp cells and the zooxanthellae is the driving force behind the growth and productivity of coral reefs

Question 11

describe coral bleaching

Answer 11

• increased temperature reduces photosynthetic ability of zooxanthellae, such that even normal amounts of light overwhelms the zooxanthellae, causing them to be released from corals
• removal of zooxanthellae results in loss of nutrition and colour for the corals. as zooxanthellae is usually coloured, its absence reveals the white coral skeleton. when there is a large scale loss of zooxanthellae from the corals, coral bleaching has occurred
• corals begin to starve and will die unless zooxanthellae are restored. bare skeleton of bleached corals makes them vulnerable to rapid colonisation by seaweeks, which block light from reaching the zooxanthellae that is left and accelerating their removal from the corals. over time, corals will die
• bare skeleton of bleached corals makes them vulnerable to slow degradation, especially during storm surges

Question 12

explain effect of climate change in terms of migration of fish and fishes

Answer 12

• large fluctuations in temperature might reduce growth and fertility rates, cause endocrine imbalance, reduce foraging range and disrupt migration patterns
• rapid environmental fluctuations may result in fish breeding and migration periods not coinciding with an abundance of food (food sources for fish use day length as a cue for hatching)
• as sea surface temperature rises, plankton are moving progressively northward where the waters are cooler, affecting the distribution of fish and marine mammals that feed on phytoplankton and zooplankton. this migration of fish and marine mammals into new areas may put these species into competition with other species over food and other resources
• blocking of waterways by human structures (dams) prevent the migration of fish to suitable habitats
• rising sea levels impact estuaries by causing some areas to become permanently covered with water
• changes to volume and timing of water flowing into the estuaries from coastal rivers will have potentially catastrophic impacts on fish migration, habitat use, breeding and food availability

Question 13

explain effect of climate change in terms of insects

Answer 13

• higher temperatures lead to more rapid development and higher survival rates in insects in mid to high latitudes, leading to a shift in the geographical range of inssect species
• due to their relatively short life cycles, high reproductive capacity and high degree of mobility, higher temperatures may cause insect populations to grow and spread quickly over a relatively short period of time
• as winter temperatures of regions near the poles are now higher, mortality of insect species may decrease, allowing poleward range expansions
• higher temperature also advances the onset of insect life cycles for many species, as they use thermal cues to match the timing of key events in their life cycles with the changing seasons

Question 14

explain how climate change affects vertical plant distribution

Answer 14

• as temperature increases, higher altitudes now have environments of higher temperature, that are now favourable to lower-altitude plants
• this leads to low-altitude plant species shifting its vertical distribution upwards
• higher-altitude plants which are adapted to lower temperatures may not be able to survive temperature increases/competition from lower-altitude plants, extinction of these higher-altitude species might occur

Question 15

explain how climate change leads to shift in latitude of plant distribbution

Answer 15

• at higher temperatures, plants that are suited for warmer temperatures will move towards the poles as temperate regions now experience a higher temperature
• due to competition from lower latitudes, temperate species might reduce in number/become extinct
• increase in amount of suitable agricultural land, as temperature in high latitude places will be expected to be above freezing more often in the year, leading to a longer annual growing season for crops

Question 16

explain how climate change affects plant morphology

Answer 16

• higher temperatures/decrease in rainfall lead to decrease in leaf size/number of leaves since broader leaves/plants with more leaves are more susceptible to high temperature as more water is lost through the stomata
• decrease in number of stomata per leaf to decrease water loss from transpiration when temperatures are high
• development of more and longer roots allows plant to take in more water to counter loss of water due to higher temperatures

Question 17

explain how climate change affects physiology of plants

Answer 17

climate change might change the length of the seasons which might affect flowering and growth season, affecting survivability of the plant if there are no suitable pollinators or dispersers at the time of the year

Question 18

explain how climate change affects plants in terms of their survivability and habitat

Answer 18

• changes in climate could lead to changes in environmental conditions of habitat change resulting in fewer suitable habitats
• increased temperatures and weather conditions could change beyond the tolerance of plants resulting in low survivability
• rising sea levels/flood events might lead to decrease in poplation of plants

Question 19

explain how temperature changes affect insect survival, metabolism and development

Answer 19

• narrow temperature tolerance of insects
• higher temperature increases metabolic rate of insects
• higher metabolic activity leads to more intensive and longer total day and night’s activity of imago, increased feeding, mating and time spend on finding proper place for laying eggs
• higher temperature shortens length of time most insects take to develop, earlier appearnce of some insect species in spring
• gradual warming above the upper development threshold results in loss of water from insect
• changes in host plant metabolism and physiology due to climate change affects life cycle of insects

Question 20

explain how temperature changes affect insect geographical range

Answer 20

• at higher temperatures, higher altitudes are now warmer, leading to an expansion in geographical range of insects towards higher altitudes
• insect distribution moves poleward because of increasing temperature, insects originally found nearer the tropics may move towards the poles as temperate regions now experience a higher temperature

Question 21

explain how temperature changes affect insect population size

Answer 21

insect population size increases due to higher metabolic rate resulting in higher activity, so frequency of mating and egg-laying increases, shortening gestation periods so successive generations hatch more frequently and longer periods of warmth allow insects to be active for a longer period of time

Question 22

discuss the effects of environmental stress on habitat and organisms

Answer 22

• increased temperature results in thermal stratification and reduces upwelling in oceans, altering nutrient fluxes, affecting marine coral reefs
• changes in oxygen levels in the ocean, sea level rises, increased wave height, storm surges and loss of sea ice may occur
• environmental changes lead to organisms being unable to adapt to the new conditions in time
• being ill-adapted to the new environment, organisms often do not survive well/might become extinct
• e.g. since lizards grow more quickly in warmer conditions, they can spend more time each day looking for food, resulting in an overall larger body size. however, extremely high temperature may affect lizards’ ability to regulate body temperatures and hence limit the foraging hours. increased temperature may affect development of embryos in some species

Question 23

discuss the effect of environmental stress on food chains

Answer 23

• changes in abiotic factors will lead to changes in habitats and hence affect organisms which are dependent on the habitat
• there might be downstream effects on food chains as organisms have strong interactions with each other within an ecosystem

Question 24

discuss the effect of environmental stress on niche occupation

Answer 24

• as conditions change in a habitat, native species might become less suited for the environment and populations might decrease in number/become extinct, creating an empty niche (specific area where an organism inhabits, performing a role/function in an ecosystem) as there are more resources available than used
• invasions by alien species (organisms which are not native to a country/region but are introduced by human activity, tend to be more resilient to changes in environmental conditions, making it easier for them to establish a population) may occur as conditions become more suitable for them
• establishment of alien species often have adverse effects on native species as it competes for the same resources, preventing the reestablishment of native populations
• changes in range of plants and animals can lead to competition with species previously occupying that niche

Question 25

discuss the consequences to the global food supply of increased environmental stress resulting from climate change, including the effects on plants and animals of increased temperature and more extreme weather conditions

Answer 25

• global food supply might be threatened in light of increased environmental stress in some areas
• however, in some other areas, it might result in an increase in food production
• crops grow best in climatic conditions they are adapted to
• higher average temperature will accelerate the growth and development of plants
• for plants with a higher optimal temperature for growth and reproduction, an increase in agricultural land because of increased temperatures might also increase the crop yield
• however, if warming exceeds a crop’s optimum temperature, yields can decline
• in grain crops, faster growth reduces the amount of time that seeds have to growth and mature
• increased temperature in the tropics reduces soil moisture, decreasing crop yield
• extreme weather conditions like floods and droughts can damage crops
• weeds, pest and fungi thrive in warmer and wetter conditions which might also damage crops
• furthermore, range of weeds and pests are likely to expand with climate change
• increased tempratures could also lead to unhealthy livestock as animals tend to reduce food intake
• fertility rates might also decrease, decreasing amount of livestock
• heat stress could also lead to vulnerability to disease
• droughts may threaten pasture and feed supplies, reducing the amount of quality forage available to grazing livestock
• climate change may also increase the prevalence of parasites and diseases that affect livestock
• increased temperatures could affect marine habitats like coral reefs
• which in turn would affect fish populations which many economies are dependent on

Question 26

outline the life cycle of Aedes aegypti

Answer 26

• adult female mosquito lay their eggs in water (must contain organic material). three days after feeding on blood, mosquito lays its eggs just above the water line. eggs are laid over a period of several days
• an average of 150 eggs per batch is laid and spread out above the water. they hatch in about 2-7 days. laid eggs are resistant to desiccation, can survive for very long periods in a dry state, often for more than a year. however, they hatch immediately once submerged in water
• larvae feed on organic particulate matter in the water (algae). most of the larval stage is spent at the water surface. larval development is temperature dependent, higher temperature shortens larval development. it can become a pupae at around 4 days
• mosquito pupae develop in the water, and are mobile and respond to stimuli. pupae do not feed and take approximately two days to develop into adults
• increased rainfall and high humitidy = more stagnant pools of water = increase in mosquito populations

Question 27

outline the development of viral dengue disease in humans

Answer 27

• host-pathogen interaction: when an infected mosquito feeds on a person, it injects the dengue virus into the bloodstream
• dengue virus causes WBCs to produce signalling proteins responsible for fever, flu-like symptoms and severe joint pains
• virus then replicates in the human body until the bloodstream contains a high level of dengue virus/viremia
• viremia lasts about 5 days. during this period, if the human is bitten by another mosquito, the mosquito is infected with the dengue virus and will transmit the virus in its next feeding

Question 28

explain why increasing temperature leading to increasing embryonic completion is a concern for countries plagued by vector-borne diseases in the light of climate change

Answer 28

• increased rates of embryonic completion result in shorter amount of time to mature leading to increased number of mature mosquitoes
• resulting in more viable vectors which increases the potential for spreading of vector-borne diseases

Question 29

state reasons why it is important to conserve plant species

Answer 29

• plant species represent a potential rich reservoir of biomedicines which will go extinct if species are not conserved
• genetic diversity is important to maintain the resilience of crop species in the face of climate change
• many plant species provide ecosystem services such as habitat for animals and oxygen

Question 30

explain how increase in temperature affects spread of mosquito-borne infectious diseases

Answer 30

• mosquito larvae development time shortens at higher temperature
• higher temperature at highlands allowed mosquitoes to proliferate at higher altitudes. at lower altitudes where malaria and dengue are alreadya problem, warmer temperatures will only shorten development time and hasten the growth cycle of the parasites in the mosquito
• increase in temperature in temperate regions allow mosquitoes to expand their geographical range poleward
• increased rate of replication of dengue viruses in mosquitoes at higher temperatures
• no increased rate of replication of dengue viruses in humans at higher temperatures as humans can conduct homeostasis (constant body temp)
• increases in temperature might have a greater impact on selecting for virulent virus genotypes that are already being transmitted by mosquitoes

Question 31

explain how excessive monsoon rainfall and high humidity affects the spread of mosquito-borne infectious diseases

Answer 31

creates more stagnant pools of water, making it more favourable for mosquito breeding and establishment of new populations, increasing number of mosquito populations dramatically in locations where mosquitoes already exist and in new locations