D4.3 Climate change Flashcards

Question

What is the correlation between carbon dioxide levels and global temperature? And what releases CO2?

Answer 1

A clear correlation can be seen between increasing levels of CO2 since the industrial revolution & increasing global temp, providing evidence for role of human activities in causing global warming. Note that a correlation alone is not enough to prove causation, but this evidence can be taken alongside what we know about GHG & other evidence to provide a growing body of proof. In addition to burning of fossil fuels, CO2 is also released into atmosphere when natural stores of carbon are damaged or destroyed by human activities These carbon stores are known as carbon sinks. Carbon sinks include trees, soils, peat bogs, & oceans. Deforestation, soil degradation, peat harvesting, & ocean warming all contribute to addition of CO2 to atmosphere.

Answer 2

Melting permafrost releases methane through methanogens in swamps & waterlogged soils, as well as landfill sites where organic wastes have been dumped. Methanogenic bacteria in guts of ruminants release methane during excessive cattle farming. Natural wetlands & paddy fields also release methane.

Answer 3

Methane (CH4) is a simple hydrocarbon. It is present as a gas in atmosphere, & underground, & is main component of natural gas fossil fuel.

Answer 4

Methane can be produced by naturally occurring processes in some types of bacteria, but levels have risen significantly in last 150 yrs due to human activities. Methane can be produced by several human activities. Methane is released from guts of ruminant mammals, such as cattle, that are farmed by humans. Intensive farming of such animals has greatly increased their contribution to atmospheric methane. Landfill sites release methane when organic matter such as food waste decomposes Extraction of fossil fuels from underground releases methane. Anaerobic bacteria in waterlogged rice paddy fields release methane. In addition to the list above, the warming of poles that results from global warming also leads to release of methane from natural stores such as permafrost Permafrost is ground that remains frozen all yr round.

Answer 5

Positive feedback is when end product of a process results in the amplification of process that created it. Global heating is associated with a number of positive feedback cycles.

Answer 6

Negative feedback is when end product of a process results in reduction of process that created it. There are very few changes that bring about negative feedback in global warming.

Answer 7

Positive feedback is any mechanism in a system that leads to additional & increased change away from equilibrium. Positive feedback loops occur when output of a process feeds back into system in a way that moves system increasingly away from average state. In this way, positive feedback is destabilising; it amplifies deviation from equilibrium & drives systems towards a tipping point where the state of system suddenly shifts to a new equilibrium. Global warming has a positive feedback effect on Earth & its atmosphere. This means that global warming leads to more global warming, which further increases global warming, etc. There are several factors that contribute to positive feedback cycle of global warming. Positive feedback mechanisms involve, e.g. , increasing temperatures, thawing permafrost & release of methane. As methane is a GHG, it has potential to increase temp, thereby reinforcing rise in temp.

Answer 8

Extent to which a surface reflects light is known as its albedo; higher albedo, more light is reflected. Light coloured surfaces such as snow & ice have a high albedo, while dark surfaces such as rock & soil have a low albedo. As polar ice caps melt due to global warming, earth's overall albedo decreases, & more of sun's energy is absorbed by exposed rock, soil, & dark surface of oceans; this increases global warming. This cycle continues, further increasing global warming.

Answer 9

Methane is bubbling up from thawed permafrost at bottom of lake through ice at its surface. Positive feedback further affects permafrost. Permafrost is ground that remains frozen all year round. As global heating accelerates, permafrost melts & waterlogged detritus begins to decay, releasing methane. This in turn further accelerates global warming. (Melting permafrost can also lead to release of methane (CH4), a potent GHG. This is due to activity of methanogenic microorganisms in frozen soil, which increases as permafrost melts. Methanogenic microorganisms are species of archaea that produce methane as part of their metabolism)

Answer 10

Increased heating of atmosphere caused by positive feedback cycle has brought about CC with an increased number of droughts & wildfires. As global warming increases frequency of extreme weather events, droughts occur more often. Dry vegetation that results from drought can catch fire easily, & wild fires become more likely. Combustion of plant material releases carbon dioxide into atmosphere, where it increases global warming. Resulting reduction in number of photosynthesising plants (carbon sinks) means that less CO2 is removed from atmosphere.

Answer 11

When all environmental changes & positive feedback cycles overwhelm resilience of an ecosystem, a tipping point is reached whereby ecosystem is converted from one stable form to another.

Answer 12

Boreal (coniferous) forests (also known as Taiga) in northern areas of world (Alaska, Canada, Russia) are important carbon sinks, as cold temp slow down cellular respiration of detritus & other organism, while photosynthesis captures CO2 in tree biomass. They store more CO2 than tropical rainforests globally as they are distributed over a greater area. Boreal forests, or taiga, form a biome that covers much of North America, Europe, & Russia, & though they have relatively low productivity, these forests are an important carbon sink due to their size.

Answer 13

Climate change has brought these forests to a tipping point, in where they might turn from carbon sinks to carbon sources. Warm, dry summers have led to droughts & forest fires releasing CO2 stored in detritus in large quantities, & preventing it to store carbon.

Answer 14

Boreal forests are at risk of switching from being a carbon sink to being a carbon source due to effects of global warming on their ecosystem processes. This switch from sink to source is known as a tipping point. This further increases the positive feedback effects of global warming. Reduction in water availability that is caused by global warming is a huge problem for boreal forests. Less snow falls due to increased temp, meaning that less water is available from snow melt water. This leads to drought, reducing rates of photosynthesis in coniferous trees of boreal forests. Reduced photosynthesis means reduced productivity, & over long periods can kill trees. Lack of water initially leads to a loss of green pigment & a process called forest browning, where trees become brown. Eventually trees will die. Dead trees dry out & risk of forest fires increases. Loss of boreal forest reduces removal of CO2 by photosynthesis, & increases release of CO2 by combustion. Combustion can release carbon that has been locked up for many yrs in living trees, dead needles on the ground, and within the soil itself; this is known as legacy carbon combustion. This can tip forests from carbon sink to source, & can be irreversible.

Answer 15

Many species rely on ice that forms at poles for their habitat. Sea ice forms when ocean freezes. Sea ice that is attached to land is known as landfast ice. Global warming means that there is less sea ice, & ice that does form breaks apart & detaches from land earlier in yr than previously, causing problems for breeding animals. Animals such as emperor penguin & polar bears use it for hunting, nesting sites and breeding grounds. Melting of landfast ice has many negative consequences.

Answer 16

- CC increase by GHG --> increase 2°C - increase temp cause that delays in ice formation & early ice breakup can reduce rates of successful breeding & offspring & colony survival, even to point of local extinction - Further, if we do lose that must sea ice, it could disrupt Antarctic food web, making emperors at risk of starvation & pop decline - sea ice recession may also bring make new species to emperor breeding sites, resulting in more frequent predation & resources competition.

Answer 17

- limiting amount of space available for walruses to congregate. Floating summer sea ice is also receding further north to where the water is too deep for animals to dive & feed. This forces them to desert ice & seek refuge ashore - massive haulouts can be incredibly dangerous for walruses. Crowded animals are easily spoked; any sound or scent e.g. an airplane flying by, a human, or a whiff of a predator can cause a deadly stampede --> trample other walruses, especially young calves, which are susceptible to injury & death.

Answer 18

Emperor penguins, Aptenodytes forsteri: - These birds breed on Antarctic sea ice, laying & incubating their eggs, and raising their young - Early melting of sea ice is not giving them enough time to raise their young Walruses, Odobenus rosmerus - These mammals rely on Arctic sea ice, where mothers can alternate periods of feeding their young & hunting for food in ocean nearby - Early loss of ice means that nursing mothers need to care for their young further from water's edge, leaving young without protection for longer periods when mothers hunt for food

Answer 19

Weather & climate are strongly influenced by water movement in oceans, which also play an essential role in distributing nutrients that support marine life. Ocean currents, driven by factors like wind, temp, & salinity gradients, redistribute heat across Earth's surface. Warm ocean currents carry heat from tropics towards poles, moderating temps in coastal areas. E.g. Gulf Stream, a warm ocean current in Atlantic, means that Europe has a warmer climate than Canada, despite being at a similar latitude. Cold ocean currents transport cold water from polar regions towards tropics, resulting in cooler coastal temperatures & affecting marine ecosystems.

Answer 20

Upwelling occurs when cold, nutrient-rich water rises to surface, primarily driven by wind that moves surface waters out of way, allowing deeper waters to rise up to replace them. Upwelling brings deep, nutrient-rich waters to surface, supporting abundant marine life & contributing to productivity of fisheries in coastal areas.

Answer 21

Changes in oceanic currents, such as alterations in current strength or shifts in their paths, can have significant implications for regional & global climates, & for marine life. E.g. El Niño events, part of El Niño-Southern Oscillation (ENSO) cycle, have significant impacts on global weather patterns. El Niño events involve warming of central Pacific Ocean. Warm surface water prevents nutrient upwelling in waters off Central & South America, reducing primary production & flow of energy through marine food chains in these regions. El Niño can also cause shifts in atmospheric circulation, leading to droughts, floods, & other extreme weather events.

Answer 22

-Warmer, less salty water is less dense and floats on top of denser, colder, saltier water. - Diff layers mix as heat slowly seeps deeper into ocean by action of current, winds & tides. This = upwelling. - With greater difference in densities between layers mixing becomes more difficult, resulting in oceans to become more stable.

Answer 23

- Nutrient upwelling is important, as it brings up nutrient rich water to surface where consumers can feed on them contributing to nutrient cycling. - This is also the most active zone, bc sunlight can only penetrate this far into ocean. - Carbon containing detritus & faeces sink to deep ocean by gravity.

Answer 24

- CC is leading to warmer temp at each elevation. - Species whose habitat is on mountains migrate upslope to find their optimal climate

Answer 25

Species exist within tolerance limits, meaning that they can only survive in habitats where environmental conditions fall within their range (or zone) of tolerance. E.g. a marine species may only be able to survive in seawater that falls within certain temp limits

Answer 26

CC is causing changes to many local environmental factors; when this causes conditions of a habitat to change beyond what a species can tolerate, species must either migrate to a new habitat or face extinction.

Answer 27

Migration may involve a shift in range distribution towards poles, or to a higher altitude, to an area where temp are cooler. A range shift towards poles is described as a poleward shift. A range shift to a higher altitude is an upslope shift. Research has shown that distributions of many terrestrial organisms are currently shifting in latitude or elevation in response to changing climate. Range changes in elevation include species that move upwards in mountain ranges as warming conditions cause habitat ranges to shift higher. Species have zones of tolerance & so need to shift higher, to colder areas, as areas they live in warm. As conditions required by their niche change, so too does distribution of species. These shifting geographic distributions have been recorded in temp species & correlated to anthropogenic temp increases.

Answer 28

In the tropics of Papa New Guinea species have been found to react more strongly to changes in temp than species from temp regions. Strong upslope shifts of bird species on two independent New Guinean mountains were found when comparing data from 1985 to data surveyed from 2017. Evidence gathered in mountains of Papua New Guinea over a 50 yr period shows that many bird species have migrated to higher altitudes over this time period. (This is not the case for all species; a few have stayed in the same place or moved downslope). Data were collected from 2 mountains in Papua New Guinea in 2012-13 – Mt Karimui and Karkar Island – & compared with historical data from 1960s. On both mountains, bird species shifted their upper limits upslope significantly. On Mt Karimui by 113 metres & on Karkar Island by 152 metres. Upslope shifts also occurred at species’ lower limits on Mt Karimui by 95 metres.

Answer 29

Combination of higher maximum temps in summertime & lengthened growing season has increased frequency of droughts. Based on predictions & modelling, lower elevations & southern latitudes will no longer provide cool, wet habitats preferred by some species like sugar maple & hemlock, as well as other Northern American tree species. Various studies of North American tree species have shown range contraction, i.e. ranges of these trees have shrunk, & northward spread for many species. One study sampled 92 species in 43000 plots across eastern North America. Latitudinal differences were compared with 20th-century temp change. More than 1/2 of tree species showed indications that their ranges were shrinking at both their northern & southern habitat boundaries. Slightly more species showed their ranges were shifting just north, & only a few species indicated an increase at both north & south limits of their range.

Answer 30

Corals are colonies of small animals embedded in a calcium carbonate shell that they secrete. They form underwater structures, known as coral reefs, in warm, shallow water where sunlight penetrates. Specific microscopic photosynthetic algae (zooxanthellae) live sheltered & protected in cells of tropic corals. Coral reefs are most diverse of ecosystems known &, although they cover less than 0.1% of surface of oceans, these reefs are home to about 25% of all marine species. Marine organisms take dissolved carbon in form of CO2 or HCO3- ions out of water & use some of it to make their carbonate shells. Organisms that build coral reefs are called coral polyps, & they combine Ca2+ from sea with carbon to form molecules of calcium carbonate (CaCO3). This molecule is basis of coral reef, & it is sturdy like rock. (Ca2+ + 2HCO3 – → CaCO3 + CO2 + H2O)

Answer 31

Coral bleaching is whitening of corals that happens when a coral is stressed from a variety of factors, including poor water quality due to pollution, or more frequently warmer oceans, as a result of global warming due to increased carbon emissions.

Answer 32

Increased conc of CO2 in oceans has also led to another problem in addition to warmer waters – ocean acidification.

Answer 33

Coral bleaching is caused by loss of symbiotic algae (zooxanthella) from tissue of corals as a result of pollution of increased water temp.

Answer 34

- Linkages between buildup of atmospheric CO2 from burning fossil fuels & slowing of coral calcification due to ocean acidification. - Atmospheric CO2 is absorbed by ocean & results in a decrease in carbonate ion conc, making carbonate ions unavailable to corals & other marine calcifies.

Answer 35

- There are many consequences of ocean acidity, including dying of coral reefs, molluscs, crustaceans, as well as photo- & zooplankton such as foraminifers & coccolithophores, which are forming an essential component of ocean food chains. - The acidity is also responsible for decrease in immunity of organism, increase in water noise & even cloud formation.

Answer 36

Coral reefs are built from hard calcium carbonate deposits that are secreted by organisms called coral polyps. Note that not all corals build reefs; reefs are built by corals described as reef-building corals. These polyps live in a symbiotic relationship with algae, in which the algae provide carbon compounds through photosynthesis, & coral polyp provides shelter & protection within its body.

Answer 37

Coral reefs are some of most diverse ecosystems in world; complex structures produced by reef-building corals provide habitats for many species, supporting complex food chains & providing suitable places to breed & raise young. Around 25 % of world's ocean fish species are dependent on coral reefs for survival.

Answer 38

Corals are highly sensitive to factors such as water temperature & pH, & global warming can have highly damaging effects on life processes of coral polyps. Death of coral polyps will have a knock-on effect on all other species that rely on reef, disrupting food webs, reducing the availability of niches & therefore reducing reef biodiversity. Many species will die off or migrate to other habitats. This leads to ecosystem collapse.

Answer 39

- High water temps cause coral polyps to expel their algae symbionts; this causes reefs to lose their bright colours & leads to coral bleaching - Bc polyps rely on algae for their carbon compounds, extended bleaching events can lead to death of polyps

Answer 40

Carbon sequestration = capture & storage of carbon through geological (peat formation) & biological (photosynthesis, biomass storage…) processes.

Answer 41

- Afforestation - Forest regeneration - Restoration of peat forming wetland

Answer 42

This involves planting trees in areas where they currently do not exist. A number of countries have committed to achieving numerical goals for planting as an initiative to reverse desertification & to enhance carbon sequestration.

Answer 43

Forest regeneration or reforestation is restocking of forests that have been depleted through clearcutting. Usually this is achieved through planting seedlings in form of monocultures of trees which are commercially meaningful.

Answer 44

Combines agriculture with forestry, allowing farmer to continue cropping while using trees for animal food, fuel & building timber. Trees protect, shade & fertilise soil, decreasing rates of decomposition & related rates of respiration & increasing photosynthesis. Such practices improve carbon sequestration in agricultural soils & above-ground biomass through a range of soil, crop & livestock management practices, & protect existing carbon in system by slowing decomposition of organic matter & reducing erosion.

Answer 45

- Peat is partially decayed organic matter that comes from unique waterlogged ecosystems such as bogs, muskegs & moors. - It is commercially useful, as it services as a fuel, domestic heating, fertilizer & gardening soil. - Globally, these wetlands form world’s largest carbon sinks.

Answer 46

Restoring peatlands requires the restoration of water levels, blocking drainage & re-establishing native species such as sphagnum moss.

Answer 47

From 1640 onwards, large areas of wetland, such as East Anglian Fens in UK, were drained for farming, which degraded peat. No longer waterlogged, peat shrank, decomposed & became eroded by wind, which increased flux of carbon dioxide into atmosphere. Restoring rich peatlands that were lost during agricultural development would enhance carbon sequestration of these wetland ecosystems. Restoring these wetlands increases land carbon store & decreases atmospheric store. Degraded & drained peatlands emit more than 2 gigatons of carbon dioxide annually.

Answer 48

Hinewai reserve, New Zealand.

Answer 49

Phenology is study of timing of seasonal activities in animals & plants. Word “phenology” is derived from Greek words “phainestain” (= to appear) & “logos” (= study).

Answer 50

Photoperiodism & temp.

Answer 51

- Day length is an important environmental signal which triggers developmental transitions like flowering in plants. - Some crop plants only flower when day length is longer.

Answer 52

- Decreasing temp (together with short daylengths) in autumn are largely responsible for a cessation of growth in deciduous trees. - Increasing temp in spring are for many plants a trigger for budburst (emergence of new leaves).

Answer 53

- change in leaf colour in autumn - flowering in plants - migration of birds - ripening in fruits - leaf bud formation

Answer 54

Changes in day length & associated light availability (photoperiod) & temp initiates or stops growth phases in most plants, resulting in bud burst or bud set.

Answer 55

For a long time it has already been observed that phenological events such as budburst start differently when comparing rural with urban areas. Warmer temps in urbanised areas lead to different & extended seasonal growth periods. This also has an effect on synchronised interspecific relationships between animals & plants.

Answer 56

CC can disrupt timings of biological events. Environmental cues may no longer function as they should, e.g. Temp may be diff to previous years, Day length, known as photoperiod, may not coincide with events that may have occurred in the past. If events do not occur at right time, species will be left without resources that they need, & food chains will be disrupted. Trophic levels may be missing from food chain. This is known as a trophic mismatch.

Answer 57

CC can lead to a disruption of synchrony of phenological events. Because migratory animals depend on food availability of plants & insects, changes to seasonal appearance of those causes a de-synchronisation, leaving animals with inadequate supplies of food.

Answer 58

- Reindeer (Rangifer tarandus, also known as caribou) has changed its migratory pattern in accordance with growing season of shrub, of which it mostly feeds on. - Shrub arctic mouse ear (Cerastium arcticum) grows as a native plant in Greenland, northern Canada, parts of Norway & Siberia. - Due to CC spring growth of this plant is advancing (i.e. coming earlier in year).

Answer 59

Common Cuckoo is only brood parasite among breeding birds in Switzerland, leaving smaller songbirds to rear its young. It overwinters more than 6000km away south of African Sahara. Because warmer temp lead to an earlier start of spring, brood synchronisation becomes more difficult. Earlier availability of caterpillars as food source due to a shift in phenological events has caused local bird species to initiate rearing of young already – so when cuckoo arrives it might already too late.

Answer 60

Other synchronised events include change of plumage in bird species. Warmer temp in Alpine regions have lead to a decline of Alpine Ptarmigan. A possible reason could be disrupted synchrony between loss of snow cover & camouflaging plumage, which results in it becoming an easier victim to predation.

Answer 61

- Increased number of generations - Expansion of geographical range - Outbreak of plant diseases transmitted by insects - Increased overwintering survival - Desynchronization of insects & their natural enemies - Loss of synchrony with host plant.

Answer 62

- Beetles (the order Coleoptera) are most diverse & abundant group of insects on Earth. - They inhabit every ecosystem except for the oceans. While most beetles provide vital roles in ecosystem dynamics, some species have become pests. - One group, bark beetles, feed on tree plantations, damaging & killing trees. - There are more than 2000 species of bark beetles. - Great spruce bark beetle (Dendroctonus micans) is a non-native (alien) pest of spruce & pine trees in Europe. - Eurasian Spruce bark beetle (Ips typographus) is one of most destructive forest insects in Europe, responsible for kiling of more than 50 million m³ of Norway spruce (Picea abies) since 1940s.

Answer 63

1. Development of nymphs from eggs followed by instars (intermediate developmental stages) to adults E.g. locusts & grasshoppers 2. Larvae are produced from eggs which then form a pupa (where developing organism is usually enclosed in a cocoon or protective covering). In pupa, organism undergoes internal changes (metamorphosis) where larval structures are replaced by those of adult. E.g. beetles

Answer 64

Bark beetles bore into bark of tree and tunnel through to phloem where they lay eggs. Emerging larvae feed on sap of phloem as well as tissue. New adults continue process, once they have pupated, making new holes through bark as they emerge. Phloem transports sucrose & other organic compounds around plant. Larvae damage this tissue, which weakens tree & can lead to its death. Large areas of forest have been affected by outbreaks of bark beetle.

Answer 65

Insects have short life cycles & are very mobile. Insect life cycles are very sensitive to temp. Changes in temp due to CC results in changes to their rate of development & geographical distribution. Warming summer & winter temp have a major effect on beetle populations & increase chance of outbreaks across USA & Europe. Temp also lead to range expansion in some species (e.g. beetles spreading to new areas as temperatures warm). CC may increase risk of bark beetle outbreaks, particularly in old forests in northern Europe. Research in Norway has shown that warmer winters also favour beetles & that, instead of one life cycle, two generations per yr could be formed (one in Spring & one in July/August), causing even more damage to trees.

Answer 66

Natural selection is driven by selection pressures in environment. Selection pressures are features of environment that limit the survival chances of an individual, e.g. presence of a predator, a lack of food, or antibiotics killing bacteria. CC introduces new selection pressures, so can drive evolution by natural selection.

Answer 67

Tawny owls show polymorphism, meaning that their alleles can give rise to diff phenotypes, or morphs. E.g. some tawny owls are grey in colour, while some are brown. A decades-long Finnish study has shown an increase in frequency of brown owls in pop from around 30 % to around 50 %; this is thought be due to natural selection. In a snowy environment, pale grey owls are less visible, so are more successful & have a better chance of surviving & reproducing. It is not known whether decreased visibility is relevant to increased success in catching prey or increased success in avoiding predators, or both. Global warming and milder winters mean that there is less snow, & owls that are brown in colour have increased success; these brown owls are more likely to survive, reproduce & pass on their alleles for brown feathers.