23 Climate Change (DIY)

• Suggest how coastal areas that are high enough to avoid flooding may still be threatened by sea level rise (1m)

  1. Increase soil salinity/ reduce freshwater sources (wells, streams, lakes) OR changing soil pH due to saltwater intrusion
  2. Colonisation of suitable habitats by displaced populations of animals
  3. Increased coastal erosion due to increased wave action
• Explain how a positive feedback mechanism may affect global climate change (Points 1-3)

  1. Positive feedback mechanism is where initial change results in further change of the same factor
  2. Increased temperatures causes increased decomposition of organic matter in soil, thus increases CO2 in the atmosphere and there is more infrared radiation absorbed and temperature increases
  3. Increased temperatures causes reduced solubility of CO2 in oceans and seas, increases CO2 in the atmosphere and more infrared radiation absorbed which increases temperature
• Explain how a positive feedback mechanism may affect global climate change (Points 4-5)

  1. Increased temperatures causes the melting of permafrost, increasing CH4 in the atmosphere, more infrared radiation is absorbed and increases temperature
  2.  increased temperatures causes the melting of land and sea ice which causes less radiation from the sun to be reflected, more sunlight is absorbed and temperature increases
• Explain how a positive feedback mechanism may affect global climate change (Point 6)

  1. Increased temperatures can cause a drier climate, causing more forest fires, more CO2 released in the atmosphere and more infrared radiation is absorbed , causing an increase in temperature
• Explain why blood is a good source of protein (2m)

  1. Blood has RBCs that contain protein haemoglobin
  2. Blood has WBCs that contain proteins such as major histocompatibility complexes/ cytokines/ perforins/ granzymes
  3. Blood has plasma proteins such as antibodies/ protein hormone/ enzymes
• Anthropogenic Activities - Combustion of Fossil Fuels 1

  • For ELECTRICITY and HEATING
  • Coal, petrol and natural gas are burnt to produce electricity and heat buildings, and this is the largest single source of GHG emissions
  • Electricity is a significant source of energy → the type of fossil fuel used to generate electricity will emit different amounts of GHG
  • Generation of electricity and heat worldwides relies heavily on coal
• Anthropogenic Activities - Combustion of Fossil Fuels 2

  • For TRANSPORTATION
  • Many industrialised nations are beginning to curb their CO2 emissions, by more efficient fuel use or by using alternative sources of fuel
  • While petroleum reserves are limited, there are still hundreds of years of coal reserves worldwide
  • Fulfills growing energy demand of those developing countries where energy-intensive industrial production is growing rapidly and large coal reserves exist with limited reserves of other energy sources
• Anthropogenic Activities - Combustion of Fossil Fuels 3

  • Natural gas also serves a source of energy for heating, cooking and electricity generation
  • Mostly made of methane and this can be released if there are even small leaks in gas pipes during the production and transportation of the natural gas
• Anthropogenic Activities - Deforestation (Role of Trees)

  • Trees play a huge role in the carbon cycle
  • Take in CO2 and give out O2 through the process of photosynthesis → a natural regulator of CO2
  • The more trees, the less CO2 in the atmosphere and the more O2
  • Storage of carbon: biological carbon sequestration
  • Plants absorb CO2 from the atmosphere as they grow, and they store some of the carbon throughout their lifetime
  • Soils can also store CO2 depending on how the soil is managed
  • Biological sequestration takes CO2 out of the atmosphere: called a Carbon Sink
• Anthropogenic Activities - Deforestation (CO2 gas)

  • Abundant in the atmosphere; vital for trees to take excess CO2 out of the air
  • Undisturbed peatlands store carbon and act as small net sinks
  • Drainage for agriculture results in a rapid increase in decomposition rates and increased risk of fires, leading to increased emissions of CO2 and N2O
  • Clearing of forests and mangroves
  • Decomposition and burning of biomass from the cleared forests releases more GHG
  • Increased CO2 in the atmosphere, more of the sun’s radiation is being reflected back to Earth, causing our average temperature to rise
• Anthropogenic Activities - Food Choices (intro)

  • Agriculture is one of the main contributors to the emission of GHG
  • Industrial style agriculture replaced traditional small-scale farming
  • Pasturage and use of animal manure as fertiliser was abandoned
  • The increasing efficiency of industrial agriculture has led to reduced prices for many of our daily products
  • This helps to reliably nourish large populations, and turned a food that was an occasional meal - meat, into an affordable, everyday product for many
• Anthropogenic Activities - Food Choices (Sources of GHG emissions from raising livestock 1)

  • Enteric fermentation produces methane
  • Certain animals produce methane as they digest food (Cows and sheep)
  • Enteric fermentation is a digestive process by which carbohydrates are broken down by microorganisms into simple molecules for absorption into the bloodstream of an animal
  • Nitrogenous fertilisers produces nitrous oxide
  • Application of chemical fertilisers to increase production of animal feed for livestock
• Anthropogenic Activities - Food Choices (Sources of GHG emissions from raising livestock 2)

  • Nitrogenous fertilisers produces CO2 and nitrous oxide
  • Production of chemical nitrogenous fertilizers
  • Manure produces methane
  • Stored manure from livestock releases methane when it decays
  • Manure produces nitrous oxide
  • Application of manure as fertilisers
  • Deforestation and conversion of grassland into agricultural land produces CO2 and nitrous oxide
  • Decomposition of carbon and nitrogen-rich humus
• Anthropogenic Activities - Food Choices (Alternative methods)

  • Beef produces the highest GHG emissions in comparison to other products such as pork, poultry and milk
  • Changes in human diet may be a practical tool to reduce GHG emissions
  • It has been suggested that the inclusion of protein extenders from plant origin would be a practical way to replace red meats
  • Still more dependent on grain and soy products and may still have a negative impact on GHG emissions
  • Grass-fed meat and resulting dairy products may be more environmentally friendly than factory-farmed or grain-fed options
• Greenhouse Effect (Greenhouse analogy)

  • Short-wave radiation from the sun (sunlight) passes through the glass
  • Everything in the greenhouse, such as plants, surfaces and ground, absorbs the short wavelength light and becomes warmer
  • Warmed objects now give off long-wave radiation (infrared)
  • Glass of greenhouse absorbs the long-wave radiation and warms up
  • Glass re-emits most long-wave radiation into the greenhouse, thus warming the interior of the greenhouse
• Greenhouse Effect (World analogy)

  • A natural process by which heat radiated from Earth’s surface is trapped by greenhouse gases
  • Short-wave radiation from the sun passes through the atmosphere, and some is reflected by the clouds, atmosphere and surface of the Earth
  • Half is absorbed by the Earth’s surface and warms it
  • The heated surface radiate heat/ infrared/ longwave radiation
  • Some of the infrared long-wave radiation passes through the atmosphere but most is absorbed and re-emitted by greenhouse gases
  • Maintains Earth’s average surface temperature at a life-sustaining 15degC
• Effect on Environment (Rise of Sea Levels 1)

  • Melting of the Greenland and Antarctic ice sheets, glaciers and polar ice caps
  • World’s 2 major ice sheets → contain about 75% of the world’s fresh water,can raise the sea level by over 75m if all the ice returned to the oceans
  • Implications:
  • loss of sea ice = animals will lose access to their feeding grounds for long periods → difficult for these populations to be sustained
  • important resource of freshwater → glaciers retreat communities lose this resource → experience floods, avalanches, or landslides triggered by glacial melt
• Effects on Environment (Rise of Sea Levels 2)

  • Thermal expansion of seawater
  • Occurs when the ocean temperature rises and the particles that make up the ocean start to move more vigorously
  • Expansion of water occurs, increasing the overall volume of the ocean, causing a rise in average sea levels
  • Sea level rise affects populations living near the seashore (almost 50% of the world’s population lives close to the coast)
• Effects on Environment (Heat Waves & Heavy Rains - Definitions)

  • Global warming results in change in weather
  • Rise in temperature and warmer air
  • Greater evaporation from land and water into atmosphere
  • More water vapour in the air
  • Increased precipitation (more rain and snow)
  • Weather: Short term changes in the atmosphere
  • Climate: describes the average daily weather for an extended period of time at a certain location
• Effect on Environment (Heat Waves & Heavy Rains - 1)

  • More precipitation
  • Parts of North and South America, northern Europe and Asia has been experiencing increasing precipitation while other parts experienced less
  • Rainfall increase in the tropics and at high latitudes (vice versa)
  • Increase will produce more pollution
  • Increase will increase water-borne diseases and lower water quality
  • Increased risk of flooding in urban areas
  • Number of frost days decreases at high latitudes, increasing the growing season, thus increasing food production for the high latitudes
• Effects on Environment (Heat Waves & Heavy Rains - 2)

  • Stronger storms and hurricanes
  • They get their energy from warm ocean water, as the top layer of the ocean gets warmer, hurricanes and other tropical storms grow stronger, with faster winds and heavier rain
  • Higher temperatures and increased evaporation results in other types of storms to get stronger too
• Effects on Environment (Heat Waves & Heavy Rains - 3)

  •  more areas affected by droughts
  • The areas of the planet affected by droughts appears to have increased
  • Increases in temperature will affect the amount and duration of snow cover, which affects the timing of ice melting and water flowing into waterways, impacting groundwater recharge
  • Heatwaves are expected to become more frequent as average temperatures rise (may cause more heat-related deaths)
• Effects on Environment (Stress on Fresh Water Supplies - Intro)

  • Freshwater is any naturally occurring water except seawater and brackish water
  • Includes water in ice sheets, ice caps, glaciers, icebergs, bogs, pongs, lakes, ricers, streams and even underground water
  • These supplies are scarce since the vast majority of the Earth’s water resources are salt water
  • Scarcity is expected to become an ever-increasing problem
• Effects on Environment (Stress on Fresh Water Supplies - 1)

  • Groundwater depletion (global-warming → change in rainfall patterns → shorter duration of rainfall combined with increased sum of evaporation and plant transpiration from the earth’s land surface, replenishment of groundwater will be negatively affected)
  • Some areas may even have increased pumping of groundwater for irrigation during less rainfall
• Effects on Environment (Stress on Water Supplies - 2.1)

  • Decline in water quality (increased precipitation → increase runoff → residual water that remains is often of inferior quality)
  • Leakage of saline/ contaminated water from the land surface/ adjacent water bodies that have highly concentrated quantities of contaminants due to decreased precipitation and runoff results in high concentration of pollution and nutrients in the water → high level of nutrients tend to increase load of microbes
• Effects on Environment (Stress on Water Supplies - 2.2)

  • Increase in water temperature → bloom in microbial populations in freshwater supplies/ reduces the amount of dissolved oxygen in the water → when water warms, its ability to hold oxygen decreases as it is dependent upon its ability to effectively self-purity through biodegradation
  • For coastal populations, water quality is affected by salinisation/ increased quantities of salt in water supplies
• Effects on Environment (Release of Greenhouse Gases in Frozen Organic Matter - Intro)

  • Permafrost: layer of soil/ rock that is frozen all year round
  • Found throughout much of North America, Scandinavia, Russia and China
  • Stores an immense amount of carbon and methane, twice as much carbon as contained in the atmosphere
  • Plants can still grow in the soil at the surface which is not frozen during warmer parts of the year
  • Warming of the environment causes permafrost to degrade and these gases which have been in storage will be released
• Effects on Environment (Release of Greenhouse Gases in Frozen Organic Matter - Carbon)

  • Carbon is also stored in permafrost
  • A third of the Earth’s soil carbon is found in the permafrost of the Arctic where the soil carbon is stored in frozen organic matter
  • Thawing of permafrost releases carbon into the atmosphere when organic matter within the permafrost decomposes
  • Process is sped up as air temperature increases and the ground warms
• Effects on Environment (Release of Greenhouse Gases in Frozen Organic Matter - Methane)

  • Methane is also stored in permafrost
  • Methane has 20 to 25 times more warming power than carbon dioxide
  • Methane can exist in the form of methane hydrates (methane gas frozen into ice structures)
  • Formed at cold temperatures and under high pressure
  • Methane can either be released directly into the atmosphere or bacteria will break it down into carbon dioxide which are then released
  • Bacteria and viruses can be preserved in the frozen permafrost soil
• Effects on Plants (Water availability - Water Stress 1-4)

  • Water stress:
  • Reduction of water content and turgor, cell expansion slows down or ceases
  • Alteration in level of photosynthetic pigment
  • Rapid decrease in the amount of Rubisco, which leads to lower activity of the enzyme
  • Increasing the ratio of roots to shoots, developing more roots in order to access more water
• Effects on Plants (Water Availability - Water Stress 5-7)

  • Reducing leaf number and leaf area to lower transpiration rates
  • Stomatal closure
  • Decrease in number of stomata per leaf to reduce transpiration → reduced CO2 uptake (a plant that could get enough CO2 with fewer stomata would have selective advantage since it would be better able to conserve its water
• Effects on Plants (Reproduction)

  • High temperatures of flowering time reduce pollen viability in cereals
  • Deviation from optimal temperature disrupts flowering process and affects seed production in plants
• Effects on Animals (Body Size)

  • In warm-blooded animals, races from warm regions are smaller than races from cold regions
  • Smaller body size allows general warming VS larger with cooling
  • The larger surface area to volume ratio of smaller body sizes serve as efficient heat dissipators in warm climates
  • The smaller body surface area to volume ratio may help in heat conservation in cold climates
• Impact on Global Food Supply

  • Effects are unevenly distributed across the world
  • In mid- to high-latitude regions, moderate warming benefits crop and pasture yields, but even slight warming decreases yields in seasonally dry and low-latitude regions
  • Rain-fed crops in low latitude countries are near their maximum temperature tolerance
  • Yields for major cereals are likely to fall sharply for even small temperature increases
• Impact on Global Food Supply - 1

  • Effects on crops in northern latitudes may be positive/ negative
  • Marginal increases in temperature in temperate regions/ regions of higher altitude may benefit leafy vegetable production as temperature moves towards optimum for seed germination
• Impact on Global Food Supply - 2

  • Water is essential for plant growth
  • With droughts occurring more frequently, the changes in the amount and pattern of precipitation and evaporation will have a significant effect on global crop development and yield
  • E.g. Rice Spikelets exposed to temperatures of more than 35degC are sterile and set no seed → reduces grain yield → caused by poor anther dehiscence and low pollen production
  • Low flower bud initiation results and this ultimately reduces the yield of the crops
• Impact on Global Food Supply - 3

  • Alters patterns of weeds, plant pests and pathogens
  • Increased pressure from insects and disease vectors - insect pests and weeds may survive/ even reproduce more often each year if cold winters no longer keep them in check
  • New pests may also invade each region as temperature and humidity conditions change
  • Lower latitude pests may move to higher latitudes
  • Increased use of pesticides and fungicides may negatively affect human health
• Effect on Global Food Supply 4

  • Leads to loss of arable land
  • Leads to a more vigorous hydrological cycle, including more extreme rainfall events
  • High precipitation and flooding can result in submergence and soil erosion that destroys vegetable plots, resulting in yield reduction
• Impact on Livestock - 1

  • High temperatures lead to heat stress in animals
  • In cattle. Farmers can expect their livestock to have:
  • Reduced grazing time
  • Reduced feed intake
  • Increase in body temperature
  • Increased sweating and panting
  • Weight loss
  • Can increase vulnerability to disease, reduce fertility and reduce milk production
  • Higher summer temperatures can lead to increase in livestock mortality, especially during transportation
• Impact on Livestock - 2

  • Can affect the food availability of livestock
  • Drought can result in the loss of pasture grazing land for livestock
  • For animals that rely on grain, decline in crop production yields due to drought can be a problem