CLIMATE CHANGE Flashcards
definition of weather?
day to day condition of atmosphere, focuses mainly on temperature and rainfall
definition of climate?
the long term average of weather, typically over 30 years
how does the curvature of the earth effect temperate?
-most intense solar radiation in face of earth as there’s a deficit of heat energy.
-colder at poles as there’s a surplus of heat energy
-concentration of energy/surface area
describe the greenhouse effect
-SW solar radiation from sun travels through atmosphere to earth where 51% is absorbed by surface and 20% is reflected by clouds
- as the surface is warm it bounces off earth as LW infrared radiation
-some of this radiation is absorbed by GHG in the atmosphere
-less heat escapes as more GHG due to human activity
what are the 3 cells called in the 3-cell model?
-polar
-ferrell
-hadley
between the polar and ferrell cells what is there?
rising air
LP
wet weather
what is there between ferrell and hadley cells?
-sinking air
-HP
-dry and hot weather
what is there between two hadley cells?
-rising air
-LP
-wet and hot weather
what are the three types of rainfall?
-convectional
-frontal(different air masses coming together
-relief
what is the ocean gyre?
the circulation of current in the ocean
what does red line in sea ocean circulation mean?
flows along surface in warmer regions
what does blue line in sea ocean circulation mean?
flows along floor in colder regions
what does paleoclimate mean?
the climate of the past prior to human record keeping or measurement
what is a proxy
a preserved record or geologic past that scientists used to infer some aspect of the past climate such as temperature or CO2 levels
name the 6 proxies
1-tree rings
2-ice cores
3-fossils
4-lake sediment
5- diagnostic rock types
6- glaciers and ice sheets
how can tree rings be used as a proxy?
scientists can date past events such as climate change through the tree rings (annules) which vary in width each year depending on temperature conditions and moisture availability
-more warm and moist, the wider the annules)
-cross dating allows us to date specific events
how can ice cores be used as proxies?
ice cores from polar regions contain tiny bubbles of air which gives us records of the gaseous composition of the atmosphere in the past
scientists measure the fx of 16O and 18O isotopes, the colder the climate the lower the fx of 18O isotopes
how can fossils be used as proxies?
plants and animals need specific conditions to thrive
eg/where coral reefs lived can be used as proxies as they need specific conditions
-some dinosaur species only survived in certain climates
how can lake sediment be used as a proxy?
-pollen-tells us past vegetation which tells us the climate they grew in
-diatoms- single felled algae found in lakes, evidence of past climate in shells
-varves- layers of lake sediment comprised of light and dark bands
light=summer =courser sediment
dark=winter= fine sediment
how can diagnostic rock types be used as proxies?
-certain rocks are diagnostic of certain climate conditions
eg/coal tells us yk once had tropical climate as coal is made from dead ferbs that grow in tropical conditions
how can glaciers and ice sheets be used as proxies?
from current glaciers geologists have figured out where they existed in the past which tells us the climate of that area
what is the 12800BD North Atlantic conveyer?
breakout of fresh water from melted glaciers into the salt sea water into the north atlantic gyre causing it to slow/stop which caused temperatures in Northern Europe to plummet as no warm ocean currents
during the mid-cretaceous period how much higher were average global temperatures?
6-8*C higher
what did the warm phase coincide with ?
CO2 levels being 5x higher than today
what happened 55mya ?
there was a spike in global temperatures
-peaked at 23*C
when global temperatures spiked what was this phase called?
palaeocene-eocene thermal maximum
what happened 35 mya?
start of the oligocene period
what conditions did antarctica experience 40mya?
fossil records show sub-tropical conditions
why did antarctica go into permanent ice house state?
-CO2 levels dropped from 1000-1200ppm to 600-700 ppm
-continental drift- movement of antarctica towards south pole isolated continent and allowed circumpolar current to insulate antarctica from warmer waters further north
-growth of south sandwich islands submerged volcanic arc disrupted deep water ocean currents which isolated continent from warmer water
when does the quaternary period span?
last 2.6 million years
in the past 450000 years how many glacial and interglacial periods have there been?
4 glacial
4 interglacials
what’s the holocene ?
the current geological period which began 11,700 years ago
how much have sea levels rises in the holocene
over 100m due to ice sheets melting
what happened between 1550 and 1850?
little ice age where global temps fell by 1*C
what do scientists believe about the climate change ?
it has been hugely driven by human activity in the past 200 years
what do scientists believe the new geological period is called?
the anthropocene
examples of external forcings
-astronomical shifts in earths orbit and axial tilt
-procession of equinoxes
-fluctuations in solar output
examples of internal forcings
-volcanic eruptions
-continental drift
-changes in ocean circulation
-fluctuations in atmospheric CO2
what is obliquity
-the tilt of earths axis
-over 40000 years it varies between 22-24.5 degrees
-when closer to 22 seasonal temperature differences are reduced
-so ice sheets done melt in summer so they expand which increases reflection of incoming solar radiation which lowers temps further
-negative feedback
what is eccentricity of earths axis ?
-earths orbit around the sun follows an elliptical path
-this varies from near circular to elliptical
-there’s a change in solar radiation of 30% between perihelion and aphelion
-when earths at max eccentricity there are ice ages
what is precession of equinoxes?
-earth gyrates on an axis
-point of earths orbit when it’s closest to the sun changes over 22,000 years due to gravitational influence of the moon and jupiter
-affects intensity of seasons
how does precession of equinoxes trigger glacial periods?
if perihelion occurs during northern hemispheres winter, winters will be warmer and summers cooler so the ice doesn’t melt in summer so the cover expands and triggers glacial periods
what is perihelion?
when earth is closest to sun
what’s aphelion?
when earth is furthest from sun
how do volcanic eruptions affect climate change?
they pump huge amounts of volcanic ash and sulphur dioxide into the stratosphere which change global climates
-sulphur dioxide has a cooling effect
what happens in the atmosphere when volcanoes erupt
-SO2 is converted to sulphuric acid
-forms sulphate aerosols
-these reflect solar radiation back into space and lower the temperature in the stratosphere
how have the distribution and configuration of continents changed?
-plate tectonics and sea-floor spreading
-explain extreme shifts in earths climate between greenhouse and ice house conditions
what was the single land mass called 250mya?
pangaea- since then continents have drifted
what is ocean circulation and what does it do?
-vital component of global energy budget
-transfers surplus energy from tropics to poles
what can modify ocean circulation and energy transfer ?
continental drift
what event intensified the gulf stream?
5mya the formation of the isthmus of panema joined N+S american continents closed the gateway between the pacific and atlantic oceans
how did this event intensify the gulf stream?
-conveyed warm surface water from the Caribbean to the N atlantic
-meant evaporation and precipitation increased which diluted the salinity of the N atlantic and arctic oceans
-weakened the downwelling of water driving the gulf stream and global thermo-valine circulation
what do less saline surface waters mean?
-there’s a reduction of heat transferred by the gulf stream led to more sea ice which is amplified by positive feedback
-increased reflection of solar radiation and insulation of water below sea ice created an onset glaciation 3mya
how does solar output contribute to climate change?
—suns output varies over time these variations are shown to contribute to climate change
-solar output follows an 11 year cycle
-in the past 50 years activity has been high which coincides with climate change
what’s the difference in energy output between maximum and minimum?
0.1%
-not enough to impact global climate
what happened near the end of the 17th century?
number of sunspots declined rapidly to almost 0 for several decades
-called the maunder minimum which gave severe winters in europe called the little ice age
what happened in the early 19th century?
low solar activity called dalton minimum
natural ghg- what’s there a close relationship between?
atmospheric CO2 levels and average global temperatures
-ice house earth corresponds with low levels of CO2 which reduces earths natural greenhouse effect
what did mountains made by tectonic plate movement increase?
rainfall , erosion and chemical weathering by rainwater charged with CO2
how was CO2 extracted from the atmosphere ?
large volumes were removed and transferred to storage in carbonate sediments in oceans. increase in ocean nutrients = phytoplankton which extracted CO2 from the atmosphere
what’s the evidence the world has warmed since the 19th century
-increased global surface and atmospheric temperatures
-shrinking of valley glaciers and ice sheets
-rising sea levels
-increase in atmospheric water vapour
-declining snow cover and sea ice
what two processes account for rising sea levels ?
- thermal expansion of oceans as climate warms
- melting of land-based ice sheets and glaciers
what are losses of ice due to?
- warming of atmosphere melts ice surface
- meltwater which penetrates ice and increases velocity of glacier flow towards lower, warmer altitudes resulting in calving into oceans
- ocean warming accelerating melting of ice sheets in coastal areas
how is increasing atmospheric water vapour evidence the world is warming ?
-water vapour which is a GHG which traps huge amounts of energy radiated from earths surface and creates a natural greenhouse effect
-estimated for every 1*c increase caused by enhanced CO2 levels, rising levels of water vapour will double the warming
-positive feedback
what does decreasing snow cover and ice mean?
it effects climate as snow has a high albedo reflecting 70-80% of incoming solar radiation compared to 10-20% for soil and vegetation surfaces
-diminishing snow cover increases absorption of solar radiation
-suns energy is warming the ground not melting the ice so air temps rise
what do GHGs do
warm the earth and its atmosphere by intercepting outgoing, terrestrial radiation and re radiating it back to the surface and to the atmosphere
what are the greenhouse gases
-carbon dioxide (CO2)
-water vapour
-methane (CH4)
-nitrous oxide (N2O)
what 3 sets of factors explain the increase in GHGs
- huge surge in demand for energy due to industrialisation and technological advances
- massive global population growth (1billion to 7.8 billion) and rising living standards
- land use changes- deforestation and draining of wetlands for food production and urban development
explain the changing valence of anthropogenic emissions of GHGs around the world
- most CO2 and other GHGs from 1850-1960 originated from industrialised economies of North America and Europe
-since then, Asia has increased massively, north america and europe have stabilised and germany and ik have declined
-china overtook USA as worlds leading emitter of CO2 with its friends of coal and its demand for energy to sustain its explosive economic growth
what’s the effectiveness of different GHGs in trapping terrestrial radiation measured in and how does it work
Global Warming Potential (GWP)
-CO2 is used as a baseline measure and other gases are compared to it
What is positive feedback?
it amplifies a change and increases disequilibrium
what are seven positive feedbacks?
-increased evaporation
-Reduced albedo
-Declining forest cover
-Increased cloud cover
-Release of methane hydrates
-Melting of permafrost
-Increased ocean acidity
how is increased evaporation an example of positive feedback
-Global warming, intensifies evaporation from ocean land surfaces
-As a result, atmospheric water vapour increases
-Raises global temperatures
-Creates Further evaporation
How is reduced albedo an example of positive feedback
-melting of glaciers sea, ice, and snow fields decreases albedo
-More solar radiation is absorbed at the surfaces
-Temperatures increase
-Further melting
how is declining forest covering example of positive feedback?
-As global temps rise, tropical forest, trees become stressed and die
-Releases CO2 from stores
-Results in higher temperatures
-Threatens the future of forests
how is increased cloud covering example of positive feedback
-More water in atmosphere, increases cover of high altitude cirrus clouds
-Helps retain radiated heat from earth
-Contributes to further temperature rises
-More evaporation, equals more clouds
How is the release of methane hydrates, and an example of positive feedback
-locked away in Ocean sediments
-As oceans warm methane is released
-Methane= 20 times stronger than CO2
how is melting of Permafrost an example of positive feedback?
-CH4, and CO2 are stored in vast quantities in the arctic and subarctic permafrost
-Thawing of permafrost release these greenhouse gases
-Creates enhanced greenhouse effect
-Results in more melting
how is increased ocean acidity an example of positive feedback
-As oceans, absorbs CO2, they become more acidic
-Increased acidity reduces oceans capacity to absorb CO2
-Increases CO2 in atmosphere
-Enhances the greenhouse effect
what does negative feedback do?
It restores balance in the system
what are three examples of negative feedback
-Expansion of forests
-Increased cloudiness
-Increased aerosol in atmosphere
How is the expansion of forests an example of negative feedback
-as temperatures rise
-Tree line advances polewards
-Expansion forest will absorb more CO2 from atmosphere
How is increased cloudiness an example of negative feedback
-higher levels of evaporation and water vapour increase cloud cover
-Increases reflection of incoming solar radiation (albedo)
-lowers temperatures
-associated with stratocumulus clouds
how is increased aerosol in atmosphere an example of negative feedback
-burning fossil fuel releases aerosol such as smoke, dust and sulphur
-Reflect incoming solar radiation back to space
-Lowers global temperature
-Known as global dimming
What does the carbon cycle operate in a state of?
Dynamic equilibrium as carbon moves continuously between stores
what does the carbon cycle consist of?
A number of carbon stores in pathways where carbon moves in and out of the stores
what is five examples of stores in the carbon cycle?
-Ocean
-Atmosphere
-Carbonate rock
-Soil
-biosphere
what are four examples of pathways in the carbon cycle?
-photosynthesis
-Respiration
-Decomposition
-Chemical weathering
How are carbon cycles crucial to life on the planet?
-organisms depend on carbon
-Green plants and phytoplankton extract carbon from atmosphere by photosynthesis, which support all consumer organisms
-Carbon stores look away carbon to help maintain atmospheric CO2 levels
-Decomposition and oxidation is CO2 is recycled rapidly
-CO2 and C4, important greenhouse gases and absorb wave radiation from earth surface and contribute to the natural greenhouse effect
What is media misrepresentation?
many people people rely on popular media reporting through newspapers, magazines in the TV
-these outlets play huge role in forming public perception and opinion
-Depending on the political leanings of media organisations reporting may be deliberately slanted
what is false balance?
giving disproportionate coverage to contrains and sceptics. They suggest climate changes is more controversial than it is.
