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geog 272 > chapter 11 > Flashcards

chapter 11 Flashcards

1
Q

Climate change science

A

the interdisciplinary study of the causes and consequences of changing climate for all Earth systems and the sustainability of human societies

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2
Q

@ Paleoclimatology

A

the science that studies the climates, and the causes of variations in climate, of past ages, throughout historic and geologic time

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3
Q

Proxy methods

A

information about past environments that represents changes in climate, such as isotope analysis or tree ring dating; also called a climate proxy

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4
Q

@ Past climate

A

paleoclimatology, using proxy indicators (ice-core date, sediments, coral reefs, ancient pollen, tree-ring)

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5
Q

@ Current climate

A

weather station data, remote sensing data, numerical modelling using General Circulation Models (GCM)

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6
Q

@ Future climate

A

numerical prediction using GCMs

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7
Q

Isotope analysis

A

a technique for long-term climatic reconstruction that uses the atomic structure of chemical elements, specifically the relative amounts of their isotopes, to identify the chemical composition of past oceans and ice masses

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8
Q

« light » oxygen, 16O

A

evaporated more easily but condenses less easily

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9
Q

« heavy » oxygen, 18O

A

evaporated less easily but condenses more easily

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10
Q

Oxygen Isotope Analysis

A

Since 16O evaporates more easily, over time the atmosphere becomes relatively rich in « light » oxygen. As this water vapour moves toward the poles, enrichment with 16O continues, and eventually this water vapour condensed and falls to the ground as snow, accumulating in glaciers and ice sheets. At the same time, the oceans becomes relatively rich in 18O partly as a result of 16O evaporation at a greater rate and partly from 18O condensing and precipitating at a greater rate once it enters the atmosphere

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11
Q

@ how scientists can determine the isotope ratio of seawater at the time the shells were formed

A

by extracting a core of these ocean-floor sediments and comparing the ratio of oxygen isotopes in the CaCO3 shells
- shells with a high 18O/16O ratio were formed during cold periods; this with low ratios were formed during warm periods

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12
Q

explain how can we defined layers based on horizons of dust and volcanic ash that landed on the ice surface and mark specific time periods

A
  • Lower 18O/16O ration (less « heavy » oxygen in the ice) suggest colder climates, where more 18O is tied up in the oceans and more light oxygen is locked into glaciers and ice sheets
  • Higher 18O/16O ratio (more « heavy » oxygen in the ice) indicates a warmer climate during which more 18O evaporates and precipitates onto ice-sheet surface
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13
Q

@ causes of the dissociation of large gas hydrate deposits - breakdown of the solids into liquids and gases

A

can destabilize seafloor sediments, causing a loss of structural support that can lead to subsidence and collapse in the form of submarine landslides
- hydrate deposits; wherever methane occurs in the presence of water under elevated pressures and at relatively low temperatures

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14
Q

Carbon Isotope Analysis

A

scientist can use the carbon isotope ration of dead plant material to determine past vegetation assemblages and their associated rainfall and temperature conditions

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15
Q

Radioactive isotope

A

an unstable isotope that decays, or breaks down, into a different element, emitting radiation in the process. The unstable isotope carbon-14 has a constant rate of decay know as a half-life that can be used to date plant material in a technique called radiocarbon dating

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16
Q

@ Lake Cores

A

The sediments at the bottom of glacial lakes provide a record of climate change extending back as far as 50 000 years

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17
Q

@ Tree Rings

A

Wider rings suggest favourable growth conditions, and narrower rings suggest harsher conditions or stress to the tree (often related to moisture or temperature)

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18
Q

@ Dendroclimatology

A

the study of past climates using tree rings. The dating of tree rings by analysis and comparison of ring widths and colouration is dendrochronology

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19
Q

Speleothem

A

a calcium carbonate mineral deposit in a cave or cavern, such as a stalactite or stalagmite, that forms as water drips or seeps from rock and subsequently evaporated, leaving behind a residue of calcium carbonate that builds up over time

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20
Q

Stalactites

A

grow downward from a cave roof

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21
Q

Stalagmites

A

grow upward from the cave floor

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22
Q

Limestone

A

is a sedimentary rock that is easily dissolved by water. Natural chemical processes at work on limestone surfaces often form caves and underground rivers, producing a landscape of karst topography. Within caves and caverns

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23
Q

The rate of growth of speleothems depends on several environmental factors

A
  • amount of rainwater percolating through the rocks that form the cave
  • Water acidity
  • Water temperature
  • Caves humidity conditions
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24
Q

Corals

A
  • Corals are marine invertebrates with a body called a polyp that extracts calcium carbonate from seawater and then excretes it to form a calcium carbonate exoskeleton. These skeletons accumulate over time in warm, tropical oceans, forming coral reefs
  • During the last glacial maximum and the Younger Dryas, temperature rise occurring about 14 000 years ago and again about 12 000 years ago at the end of the Younger Dryas
  • X-rays of core samples extracted from coral reefs reveal seasonal growth bands similar to those of trees, yielding information as to the water chemistry at the time the exoskeletons were formed
25
Q

Earth’s Short-Term Climate History

A
  • The last glacial period lasted from about 110 000 years ago to about 11 700 years ago, and the abrupt warming marked the end of the Pleistocene Epoch
  • the capacity of cold air to absorb water vapour is less than for warm air, resulting in decreased snowfall during glacial periods
  • Greenland ice cores: past 20 000 years of temperature and snow accumulation
25
Q

variation in the earth’s elliptical orbit around the sun

A

earth’s elliptical orbit about the sun, known as eccentricity, is not constant and changes in cycles over several time scales. The most prominent is a 100 000 year cycle in which the shape of the ellipse varie by more than 17.7 million km, from a shape that is nearly circular to one that is more elliptical

26
Q

Milankovitch cycles

A

the consistent orbital cycles - based on the irregularities in Earth’s orbit around the Sun, its rotation on its axis, and its axial tilt - that relate to climatic patterns and may be an important cause of glacials and interglacials. Milutin Milankovitch (1879-1958), a Serbian in insolation that affected temperatures on Earth

27
Q

variation in the earth’s axial title

A

Earths axial title, at present about 23.5°, varies from 21.5° to 24.5° during a 41 000 year period

28
Q

Continental Position and Topography

A

the position of the continents also impacts ocean currents, which are critical for redistributing heat throughout the world’s oceans
The movement of continental plates causes episodes of mountain building and spreading of the seafloor

29
Q

what is the primary natural source of CO2 emissions in the atmosphere

A

outgassing from Earth’s interior through volcanoes and vents in the ocean floor

30
Q

what happen when theres an accumulations of aerosols ejected into the stratosphere

A

can create a layer of particulates that increases albedo so that more insolation is reflected and less solar energy reaches Earth’s surface, like a volcanic eruption

31
Q

Climate feedbacks

A

a process that either amplifies or reduces a climate trend toward either warming or cooling

32
Q

Carbon sinks

A

an area in Earth’s atmosphere, hydrosphere, lithosphere, or biosphere where carbon is stored; also called a carbon reservoir

33
Q

Global carbon budget

A

the exchange of carbon between sources and sinks in Earth’s atmosphere, hydrosphere, lithosphere, and biosphere

34
Q

how can the ocean dissolves CO2 in seawater

A

by biological processes through photosynthesis in microscopic marine organisms called phytoplankton

35
Q

how does ocean acidification happen

A

dissolved CO2 mixes with seawater, carbonic acid (H2CO3) forms

36
Q

what is the most abundant natural greenhouse gas in the Earth

A

water vapour

37
Q

explain the positive feedback of water vapour in the atmospheric system of earth

A

As air temperature rises, evaporation increases, because the capacity to absorb water vapour is greater for warm air than for cooler air, As atmospheric water vapour increases, higher rates of condensation will lead to more cloud formation, and thin clouds can cause warming, and then more evaporation happen

38
Q

explain the carbon positive feedback

A

Rising atmospheric CO2 leads to increased plant growth and microbial activity, and eventually leads to a greater amount of carbon emitted to the atmosphere rather than stored in the ground
- initial warming leads to increases in gas concentrations; elevated gas concentrations then amplify warming, and so on

39
Q

explain the CO2 positive feedback

A

the subsequent increase in precipitation and enhancement of chemical increase in precipitation and enhancement of chemical weathering then acts to buffer warming by removing CO2 from the atmosphere and transferring it to the oceans
- which create acid water, can chemically break down rocks, affected marine sediments and corals

40
Q

@ what pourcentage of the ice sheet’s surface was melting, in Greenland

A

97%

41
Q

@ how much of Arctic permafrost will thaw over the next 200 years, if not sooner

A

between one and two thirds

42
Q

@ sea ice

A

sea ice is composed of frozen seawater, which forms over the ocean, it helps to cool the planet by reflecting sunlight

43
Q

problems with sea ice

A

summer sea ice may disappear sooner than predicted by most models; some scientists estimate an ice-free summer Arctic Ocean within the next few decades
Scientists think that the decline of multiyear ice causes an overall thinning of the Arctic pack ice that this becomes vulnerable for further, accelerating melt

44
Q

Sea-Level Rise

A

Sea level is rising more quickly than predicted by most climate models, and the rate appears to be accelerating
From 1993 to 2013, satellite data show that sea level rose 3.16mm per year

45
Q

what causes sea-level rise

A

roughly two-thirds of the rise comes from the melting of land ice in the form of glaciers and ice sheets
The other third comes from the thermal expansion of seawater that occurs as oceans absorb heat from the atmosphere and expand in volume

46
Q

what can cause a greater amount of water vapour in the atmosphere

A

affects weather in a number of ways and can lead to « extreme » events involving temperature, precipitation, and storm intensity

47
Q

carbon dioxide

A
  • Principale greenhouse gas produced by human activities
  • Come from the combustion of fossil fuels, biomass burning, removal of forest, industrial agriculture, cement production
  • A residence time of 50 to 200 years in the atmosphere, but can take tens of thousand of years if it goes in the marine sediments
48
Q

methane

A
  • Second most prevalent greenhouse gas produced by human activities
  • Concentration are ncrease faster than CO2
  • Residence time of about 12 years in the atmosphere
  • 25 times more effective at trapping atmospheric heat than CO2
  • 72 times more effective than CO2
  • Two-thirds of the total methane in the air is anthropogenic caused
  • Mining of coal, oil, and natural gas, processes in flooded fields associated with rice cultivation
49
Q

nitrous oxide

A
  • third most important greenhouse gas produced by human activity
  • A lifetime in the atmosphere of about 120 years
  • Fertilizer in agriculture, wastewater management, fossil fuel burning, some industrial practices
50
Q

halogenated gases

A
  • Produced only by human activities; fluorine, chlorine, bromine
  • Are ozone-depleting substances
  • The most important of these are chlorofluorocarbons
51
Q

Radiative forcing

A

the amount by which some perturbation causes Earth’s energy balance to deviate from zero; a positive forcing indicates a warming condition, a negative forcing indicates cooling; also called climate forcing

52
Q

@ General circulation model (GCM)

A

complex, computer-based model that produces generalizations of reality and forecasts of future weather and climate conditions. Complex GCMs (three-dimensional models) are in use in the United States and in other countries

53
Q

@ Atmosphere-Ocean General Circulation Model (AOGCM)

A

a sophisticated general circulation model that couples atmosphere and ocean submodes to simulate the effects of linkages between specific climate components over different time frames and at various scales

54
Q

consequenses of sea-leavel getting higher

A

higher water levels, higher tides, and higher storm surges to many regions, particularly impacting river deltas, lowland coastal farming valleys, and low-lying mainland areas, national and international migration

55
Q

what is the paris agreement

A

in 2016, 195 countries signed to keep the increase in global mean temperature in the 21st century to less than 2 Celsius degrees above pre-industrial levels, as well as strengthening the ability of countries to respond to the impacts of climate change

56
Q

what to be careful of when taking a position on climate change

A

Media misinformation often comes from corporate interests whose financial gains are at stake if climate change solutions are imposed
Growing number of blogs and other social media that often present results not yet evaluated by other scientists

57
Q

no regrets movement

A

Taking action on climate change must focus on lowering atmospheric CO2, societies have little to lose and much to gain by employing these strategies

58
Q

how to save the planet from climate change

A

Not only as individuals, but also as an international community

geog 272 (11 decks)

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