climate change i - climate change & its impact on the env, plants & animals

Question 1

define weather

Answer 1

weather is the combination of day-to-day variations in temperature, humidity, precipitation, wind, cloudiness and other atmospheric conditions occurring at a specific place and time

Question 2

define climate

Answer 2

cilmate is the long-term average weather patterns and may be measured at many different geographic scales (local, regional, global etc).
it refers to the statistical description in terms of the mean & variability of relevant quantities over a period of time ranging from months to thouseands/millions of years

Question 3

define climate change

Answer 3

climate change is a large-scale, long-term shift/change in average weather patterns or average temperatures. it refers to a statistically significant variation in the mean state of the climate or in its variabiltiy, persisting for an extended period of time

Question 4

define global warming

Answer 4

global warming refers to the overall warming of the planet, based on the long-term increase in earth’s average surface temperatures.
the main cause of global warming is the increased concentration of GHG in the atmosphere, directly leading to more heat being retained in the atmosphere and thus an increase in global average surface temperatures

Question 5

define biomes

Answer 5

biomes are global-scale biogeographic regions characterised by their distinctive climate, soil conditions & dominant species

Question 5

not in LOs: what are the 5 major components of the climate system?

Answer 5

1. atmosphere
2. hydrosphere
3. cyrosphere
4. land surface
5. biosphere

Question 6

define biodiversity

Answer 6

biodiversity is the number, variety and variability of living organisms. this includes diversity within & between species, and also diveristy of ecosystems

Question 6

define ecosystem

Answer 6

an ecosystem is a biological community and all of the abiotic factors influencing that community

Question 6

define endemic species

Answer 6

endemic species are unique to a particular place, and are not found elsewhere one earth

Question 7

define food web

Answer 7

a food web is a complex network of many interconnected food chains and feeding relationships

Question 8

define food chain

Answer 8

a food chain is a sequence of organisms, each of which serves as a source of energy for the next

Question 9

define habitat

Answer 9

a habitat is a place or type of place where an organism or population of organisms lives

Question 10

what is an ecological niche?

Answer 10

an ecological niche is a total way of life, or role of a species in an ecoystem. it includes all environmental factors that a species needs in order to grow, survive & reproduce

Question 11

what are the 4 biomes of interest to the h2 bio syllabus

Answer 11

tropical rainforest

• located near equator, uniformly high temperature that varies very little throughout the year
• very large diversity of living things
• most under threat

arctic tundra

• located far north towards the north pole
• cold & dry climate
• permafrost (underground soil in which captured water stays frozen for >2 years) forms

polar ice region

• refers to sheets of polar ice caps found at the north & south poles
• responsible for 70% of the earth’s freeshwater supply

mountain

• regions of high altitude
• often the habitat for endemic species
• climate varies at different latitudes

Question 12

what is albedo

Answer 12

• albedo is used to describe the proportion of solar radiation reflected back into space by an object or surface
• albedo is expressed as a proportion of the shortwave radiation striking a surface
• earth’s average albedo is 0.3, meaning 30% of shortwave radiaiton is reflected back into space and 70% is absorbed
• fresh snow has an albedo of 0.8. for many years, the arctic has been mostly white, reflecting most energy that has reached the icy surface. due to melting sea ice as a result of global warming, open water (albedo of 0.5 and 0.05 for low and high sun respectively) increasingly captures & stores that energy, further accelerating ice melting.

Question 13

what is the greenhouse effect and how does it work?

Answer 13

the greenhouse effect is a natural atmospheric process that is essential to keeping the earth’s surface warm

• as solar energy (shortwave radiation) hits the earth, most of it is absorbed. energy is then re-released frmo the earth’s warmed surface as longwave radiation
• GHG in atmosphere absorb & redirect some of this energy downward, keeping heat near the earth’s surface
• some energy absorbed by the earth’s surface is emitted back into space as terrestrial longwave radiation.
• the difference between incoming shortwave radiaiton & outgoing longwave radiation define the net radiation and determines surface temperatures
• shortwave radiation > longwave radiation -> surface temperature increases

Question 14

2 categories of causes of climate change

Answer 14

1. natural factors
2. anthropogenic factors

Question 15

what are the 3 natural factors that affect climate change

Answer 15

1. earth’s changing orbit
2. ocean-atmosphere interactions
3. volcanic eruptions

Question 16

how does the earth’s changing orbit cause climate change?

Answer 16

• changes in the tilt of the earth can change the amount and seasonal distribution of solar radiation reaching the earth’s surface
• more tilt = warmer summers and colder winters
• less tilt = cooler summers and milder winters
• this factor is not thought to play any significant role on the shorter timescales relevant to modern climate change

Question 17

how do ocean-atmosphere interactions cause climate change?

Answer 17

• on a shorter time scale, there are oscillations (periodic shifts) in ocean currents and atmosphere circulation over years or decades
• eg el nino (warming of ocean surface leading to higher global temperatures) & la nina (cooling of ocean surface leading to lower global temperatures) oscillation
• these short term climatic fluctuations are periods of natural warming & cooling in the pacific ocean -> have a large effect on the climate -> associated witih significant year-to-year changes in temperature & rainfall patterns across many parts of the world

Question 18

how do volcanic eruptions cause climate change?

Answer 18

• explosive volcanic eruptions modify the composition of the atmosphere by injecting aerosols into the stratosphere
• sulfate aerosols reflect incoming solar radiation back to space, reducing solar energy and contributing to a decrease in global temperature which cools the earth’s surface
• such a cooling effect lasts until the volcanic particles and aerosols are finally cleansed from the atmosphere, and the earth’s surface temperature rebounds soon after. (i.e. effect is short term)

Question 19

LO: what are the 3 anthropogenic factors that affect climate change

Answer 19

1. burning fossil fuels due to increasing energy usage
2. clearing of forests
3. food choices (increasing consumption of meat)

anthropogenic climate change refers to the increased emission of greenhouse gases caused by human activities

Question 20

LO: how does increase in energy usage cause climate change?

Answer 20

• the combustion of fossil fuels to generate electricity is the largest source of CO2 emissions. electricity must be generated to power homes, businesses and industry
• combustion of fossil fuels to transport people and goods is another source of CO2 emissions, eg in vehicles, air travel, marine transportation & rail
• industrial processes also emit CO2 through fossil fuel combustion, eg production of cement, metals, chemicals etc
• burning of fossil fuels has a huge impact on the carbon cycle; oil, coal & natural gas combustion introducing 9 billion tons of carbon to carbon cycle in 2008.

Question 21

LO: how does deforestation for land-use change cause climate change?

Answer 21

• the 2nd biggest source of CO2 emissions is the clearing of forests for agricultural activities.
• forests are cleared to create space for cultivation of crops as feeds for farmed animals, to supply grazing land for animals or for livestock farming to feed our increasing populations
• forests are important carbon sinks as they absorb carbon dioxide and lock carbon away. cutting down & burning of forests releases carbon stored in standing trees into the atmosphere. the exposure of organic material in exposed soil oxidises and decays, producing more CO2 and CH4.

Question 22

LO: how do changes in food consumption habits (increase consumption of meat) cause climate change?

Answer 22

- increased consumption of meat due to increasing income of consumers, especially in LDCs -> increased rearing of domestic livestock that produce large amounts of CH4 (ruminants) as part of their normal digestive process. during **enteric fermentation**, carbohydrates are broken down by microorganisms and CH4 is released. with **continuing expansion of meat consumption around the world**, demand for ruminant livestock, and hence the size of this CH4 source, has grown rapidly - ruminant animals also require **significantly more resources** like larger grazing land, fertiliser and energy-intensive feed, and also generate more manure, than other farmed animals like chicken - when animals' manure is stored or managed in lagoons or holding tanks, CH4 is produced - clearing of forests for animals to graze and to grow feed crops increases CO2 emissions - meat processing like **freezing & packaging** also contributes to carbon emissions, with electricity used to run the plants being the main source of greenhouse gases. - transportation also contributes to emissions due to **fossil fuel combustion**. buying locally can significantly reduce the climate impact of vegetable production, but has a relatively smaller impact for meat - discarded food also contributes to emissions, with most coming from **producing food that is ultimately discarded**, and CH4 produced during decomposition at landfill waste ## Footnote lamb & beef have the highest GHG emissions as they are ruminant animals that constantly generate CH4 in enteric fermentaiton

Question 23

LO: apart from rearing livestock, what 3 other human activities that contribute to rising CH4 emissions?

Answer 23

- **rice cultivation.** rice grows in **rice paddies**, and the warm, waterlogged soil of rice paddies block oxygen from penetrating the soil, providing the **ideal conditions** for bacteria to decompose organic material in order to produce CH4 by methanogenesis. - **industry**. CH4 is released into atmosphere during the **extraction, production, storage, transportation & combustion of fossil fuels** - **landfill waste** from residential, commercial & industrial activities. CH4 is generated in landfills as **waste decomposes, and in the absence of oxygen** (eg manure or sewage treatment)

Question 24

what are the 2 major greenhouse gases?

Answer 24

1. carbon dioxide (CO2) 2. methane (CH4)

Question 25

what 3 factors affect the degree to which any GHG will influence global warming?

Answer 25

1. **concentration/abundance** in the atmosphere. larger emissions of GHGs -> higher concentrations of GHGs in the atmosphere 2. **atmospheric lifetime**, referring to the time a GHG remains in the atmosphere. different GHGs remain in the atmosphere for different amounts of time 3. **global warming potential (GWP)**, a measure of the total energy that a gas absorbs over a particular period of time compared to CO2. higher GWP = more energy the gas absorbs = more global warming caused

Question 26

global trends in CO2 emissions

Answer 26

- CO2 accounts for 76% of the GHG output. - there has been a 41% increase in atmospheric CO2 level since the industrial revolution - about half of CO2 emitted by human activities is absorbed by carbon sinks eg forests and oceans, with the rest remaining in the atmosphere - human activities like burning fossil fuels, industrial processes and deforestation emit CO2

Question 27

global trends in CH4 emissions

Answer 27

- CH4 accounts for 14% of GHG output (2nd after CO2) - there has been a 150% increase in atmospheric CH4 level since the industrial revolution - 40% of CH4 comes from natural processes, with the remaining 60% coming from human activities - natural processes that release CH4 include decay of plant material in wetlands, ruminant digestion and methan-producing microbes in the ocean

Question 28

define anthropogenic climate change

Answer 28

anthropogenic climate change refers to the **increased emission of greenhouse gases** caused by **human activities**

Question 29

define deforestation

Answer 29

deforestation is the **permanent clearing of forests in order to make the land available for other uses** such as agricultural activities.

Question 30

LO: what are the 7 deadliest sins impacts of climate change as a result of GHG emissions?

Answer 30

1. melting polar ice caps 2. rising sea levels 3. stress on freshwater supplies 4. extreme weather events: heat waves & heavy rains 5. death of coral reefs 6. migration of fishes & insects 7. release of GHG in frozen organic matter

Question 31

LO: what are the 4 effects of melting of polar ice caps caused by climate change as a result of GHG emissions?

Answer 31

**1- rise in sea level** - increase in average temp at the poles due to changes in climate -> **polar ice caps shrink** as they melt and break apart - temp increase -> melting ice sheets -> **extra water enters the ocean** -> increase sea level - melting sea ice does NOT increase sea level as it only replaces the volume of water it originally displaced. ice sheet = mass of glacier ice that covers land surrounding it **2- long term decline in freshwater resources** - ice sheets contain enormous amounts of frozen freshwater on land - increase temp -> polar ice caps melt into the sea -> freshwater turns into seawater -> decreases water availability **3- accelerated warming from albedo** - rising arctic temperatures -> major shrinking of arctic sea ice - sea ice is white, so majority (80%) of sunlight that hits the sea ice surface is reflected back into space - when climate is sufficiently warm to melt the sea ice, it **exposes dark, open waters** -> ocean surface is dramatically changed from one that is **highly reflective** to one that **absorbs most of the sun's energy** -> ocean surface warms, leading to more ice loss -> positive feedback loop that amplifies the original change **4- severe threats to polar communities** - many polar creatures depend on sea ice for their lives. this is done by: - sea ice **insulates the water beneath it**, keeping it from becoming too warm so life forms can be supported - sea ice provides **breeding & hunting grounds** for marine mammals and birds, such as the polar bear which depends on expansive sea ice cover to reach and feed their prey. retreat of sea ice due to climate change -> polar bears are forced to remain on tundra where they must fast. melting ice decreases available platforms that seals and walruses use to rest & hunt from - as sea ice melts in the summer, it **releases nutrients into the water**, stimulating the growth of phytoplankton, the centre of the marine food web

Question 32

LO: why does sea level rise with global warming, and what are the 2 effects of rising sea levels as a result of climate change due to GHG emissions

Answer 32

sea levels rise with warmer temperatures because - as the land & lower atmosphere of the world warm, heat is transferred into the oceans -> water becomes less dense as it warms, and **thermal expansion** of seawater occurs - melting ice, especially the melting of continental ice (ice sheets, ice caps, glaciers) **adds extra water to the ocean -> major impact on sea level**. (melting of ice sheets the most significant IMPACTS: **1- threat to coastal communities** - most of the world's largest urban areas are on coastlines -> rising sea levels may cause **destructive erosion & flooding** -> puts millions of lives & billions of dollars worth of property & coastal infra at risk. higher sea levels also force residents to abandon their homes & relocate - people living on **low-lying islands** like kiribati will be **increasingly vulnerable to storm events** due to the risk of rising sea levels submerging these islands - as seawater reaches farther island, **coastal wetland flooding & agricultural soil contamination** occurs, eventually resulting in habitat loss for fish, birds & plants **2- saltwater intrusion** - sea level rise -> **saltwater intrudes into fresh groundwater drinking supplies** -> supply of drinking water is reduced - saltwater also contaminates irrigation supplies or overruns agricultural fields

Question 33

LO: how does climate change cause stress on freshwater supplies?

Answer 33

- 70% of the earth's supply of freshwater comes from ice caps & glaciers - water stress occurs when demand for water exceeds the available amount during a certain period, or when poor quality restricts its use EFFECTS OF CLIMATE CHANGE **1- global warming causes polar ice caps to melt** - higher temp -> **melting of glaciers and snow packs** -> increase water supply to rivers and lakes **initially**, but this will **cease** once they have melted -> results in **initial floods** and eventually **long drought periods** in areas dependent on melting of glaciers for water supply - rising temp -> snow melts **earlier** in spring -> **alters timing of streamflow** in rivers with sources in mountainous areas - rising temp -> **melting of polar ice caps** into the sea -> turns already scarce freshwater into seawater -> **decrease availability of freshwater** **2- higher temp increases rate of evaporation of water into the atmosphere** - increased evaporation due to higher temp **dries out some areas and falls as heavier rainfall on other areas** - higher temp -> more precipitation occurs as rain rather than snow -> **more rapid movement of water from atmosphere back into the oceans** -> reduces abiltiy to store & use water. - heavy rainfall also **increases runoff** into rivers & lakes -> reduces quality of water -> water is made unusable, unsafe or in need of water treatment - heavy rainfall -> saltwater moves into freshwater regions along the coasts, aka **saltwater intrusion** -> decreases freshwater supply -> increases the need for **desalination**

Question 34

LO: what are the 2 extreme weather events that become more frequent & severe due to climate change caused by GHG emissions, and their impacts?

Answer 34

**1- heat waves** - a heat wave is generally defined as period of several days to weeks of **very high temperatures**, resulting in **abnormally hot weather**. human-caused climate change is likely to cause an increase in the **frequency, intensity & duration** of such heatwaves IMPACTS - the combination of **high humidity & high night-time temperatures** offers no relief and poses a threat for infants & the elderly - high temp at night is also **damaging to agriculture**, and heat stress for livestock rises (heat stressed cattle can experience declines in milk production, slower growth and reduced conception rates) - **low-humidity heatwaves** may result in droughts and wildfires that can displace homes and destroy crops **2- heavy rains** - temp increase -> **air becomes warmer & there is a rise in evaporation** from oceans, lakes & soil -> **more water vapour in atmosphere** -> **more intense precipitation** in the form of heavy rainfall - extra precipitation is not spread evenly around the globe -> some places get more intense precipitation, some get less - climate change causes changes in the **amount, intensity and frequency** of rainfall IMPACTS - heavy rain **increases runoff** into rivers & lakes -> sediments, nutrients, pollutants, trash, animal waste and other materials into water supplies -> water becomes unusable, unsafe or in need of water treatment - increase heavy rain -> **higher incidence of floods** due to increased runoff or storm surges - increased spread of water-borne diseases - exacerbates pressures of rising sea level

Question 35

LO: what are coral reefs and the 2 effects of climate change caused by GHG emissions on coral reefs?

Answer 35

- coral reefs are some of the **most diverse and important ecosystems** on earth, and grow in **warm, clear shallow waters that receive plenty of sunlight** - corals contain zooxanthellae, an algae. zooxanthellae provide corals with food, while corals provide nutrients and shelter for zooxanthellae EFFECTS OF CLIMATE CHANGE **1- coral bleaching** - increase water temp -> stress corals, which are **very sensitive to changes in temperature** - coral bleaching occurs when photosynthesis in zooxanthallae is **disrupted at higher than usual temp** and they no longer produce food for corals -> affects metabolism of coral polyps -> corals **expel their symbiotic zooxanthallae and expose their exoskeletons** -> corals turn white (aka bleached) without zooxanthallae and are less able to combat disease - without nutrients provided by zooxanthallae, coral eventually **die of starvation and disease** - bleached coral may recover if water temp cools back enough for zooxanthallae to repopulate the cells of the coral host **2- ocean acidification affects hard corals** - hard corals build skeletons made up of calcium carbonate for protection and support - fossil fuel burning & deforestation -> rising conc of CO2 -> **increased CO2 absorption in the ocean** -> as CO2 dissolves in water, it is transformed into **carbonic acid**, making the water **acidic** and less conducive for coral growth, known as **ocean acidification** -> corals are unable to **absorb the calcium carbonate** required to create & maintain their exoskeletons -> their stony skeletons that support corals & reefs **dissolve** - increased CO2 conc will hence damange coral reefs -> major impact on oceanic ecosystems

Question 36

how does climate change affect the migration of fishes and insects?

Answer 36

**migration of fishes** - fishes are cold-blooded and control their body temperatures by movement to cooler/warmer water -> many fishes have a **very narrow preferred temperature** - rising temperatures can directly affect feeding, metabolism, digestion, sex life, growth, susceptibility to diseases and behaviour of fish - fishes exposed to warmer temperatures will **migrate to cooler water**; in oceans, they move polewards from the tropics, or to deeper and hence cooler water. this puts different fish species into competition over food & resources. commercial fisheries are