Climate Change From The Start Of The Quaternary Period And The Consequences Of Climate Change Flashcards
What are glacials
- historic cold periods associated with the build-up of snow, ice, the growth of ice sheets and glaciers
What are inter-glacials
Historic warm periods in-between glacial periods where conditions were much the same as today
What and when was the Little Ice Age
- 1300-1870
- a period of time when parts of Europe and Northern America experienced much colder winters than today
- coldest periods being 15th and 17th
What were the consequences of the Little ice Age (6)
- The price of grain increased and vineyards in Europe became unproductive
- Ice land surrounded by sea ice = prevented ships landing and crops were failing = almost half the population left (emigrated)
- The sea froze around parts of UK
- regular winter ‘Frost Fairs’ were held on frozen river Thames
- In Northern Europe, rivers froze and food supplies became limited = famine
- effects lingered until beginning of 19th century
What and when was the Medieval warm period
- it was associated with an unusual temp rise roughly between 750 and 1350 AD
- available evidence suggests that at times, som regions experienced temps exceeding those recorded during the period between 1960 and 1990
Where can we find evidence for global warming
- Global temp data
- Ice cores
- Tree rings
- Paintings and diaries
How does the Global temp data show evidence for climate change
- maps produced by NASA by using data collected over 1000 ground weather stations + satellite info
- there’s a warming trend for most of the world
- the warming is consistent with earlier maps produced over several decades
- avg global temps has increased by 0.6’C since 1950 and 0.85’C since 1880
Why might the maps produced by NASA not necessarily be accurate
- weather stations are not evenly distributed across the world and some regions (especially Africa)
- therefore the maps aren’t absolutely accurate and reliable
How can ice cores be used to show evidence for climate change
- extracted from Antarctic and Greenland
- when snow falls in polar environments, it builds up slowly, year by year
- buried layers of snow are compressed and gradually turned into ice
- scientists can drill to deep ice and extract cylindrical cores from ice, and then dated accurately
- they date them by analysing the trapped water molecules, then calculating the temp of the atmosphere when the snow fell
- this info can be used to create graphs from the past 400,000 years —> which show fluctuating temps
- this indicates past glacial and inter-glacial periods
How thick and old is the Antarctic ice sheet
- 5km thick in some areas
- the eldest ice at it’s base is thought to be 800,000 yrs old
How do tree rings show evidence of climate change
- every year, the growth of a tree is shown by a single ring
- if the ring is narrow it indicates a cooler drier year
- if it’s thicker it means the temp was warmer and wetter
- these patterns of growth are used to produce tree ring timescales, which give accurate climate info
How do paintings and diaries show evidence for climate change
- Ancient cave paintings of animals in France and Spain depict nature as it was between 40, 000 and 11, 000 years ago, a period of time when the climate change significantly.
- most evidence from little Ice Age comes from diaries and observations made at the time
- paintings and drawings of ice fairs and markets on the river Thames when it froze —> indicate Little Ice Age
What is the weakness with paintings and diaries for evidence of climate change
- it’s difficult to date accurately when cave paintings were drawn
- person accounts can lack objective accuracy
What are some of the natural causes of climate change
- Greenhouse effect
- Milankovitch cycles (Orbital forcing): Eccentricity, axial tilt, precession
- Volcanic activity
- solar forcing
what is the greenhouse effect is
- natural phenomenon
- maintains 15’C avg temp in lower atmosphere
Explain how the greenhouse effect works
- sun emits short wavelength radiation, greenhouse gases can’t absorb it
- the earth reflects these wavelengths as long wavelength radiation which the greenhouse gases can absorb
- They then re-radiate it in all directions-including back towards earth
- The long wave radiation is thermal radiation, so it results in warming of the surface of the Earth. This is the greenhouse effect
Explain how the Milankovitch cycles influence the Earth’s climate
—> Eccentricity:
- the Earths orbit
- when it’s more elliptical shaped = warmer periods
- when it’s more circular shaped = cooler periods
- a complete cycle take 100 000 years
—> Axial Tilt
- some parts get more intense solar radiation then others
- A greater degree of tilt = high avg. temp
- tilt of Earth moves back and forth over a period of 41, 000 years
—> Precession
- the Earth’s wobble
- 1 complete wobble takes 26, 000 years
- can cause very long days and very long nights
How does volcanic activity influence climate change
- produces Ash and SO2
- Ash: ash clouds go high into atmosphere = block solar radiation = leading to worldwide cooling for up to 2 yrs
- SO2: SO2 gas turns into sulphuric acid particles in atmosphere = reflects sun’s rays = reducing solar radiation
How does solar forcing influence climate change
- sun spots: dark patches on sun’s surface = indicate higher solar out put
- sun’s energy output isn’t constant
- periods when the sun’s activity is high correlates to warm climatic periods
- periods when the sun’s activity is low correlates to cooler climatic periods
What were the causes of the Medieval warming Period
- increase in solar radiation and decrease in volcanic eruptions
- The increase in solar radiation modified the atmospheric pressure system over the North Atlantic Ocean,
- which brought warmer and wetter conditions over Northern Europe and most of north-eastern part of North American continent (including Greenland).
What were the cause of the Little Ice age
- The weak sun in the 17th Ventura ray coincided with the little Ice Age
- Throughout the Little Ice Age, the world also experienced heightened Volcanic activity
What are the sources of Carbon dioxide
- burning of fossil fuels
- Deforestation (burning wood)
- Industrial processes (e.g. making cement)
What are the sources of Methane, CH4
- emitted from livestock and rice cultivation
- decay of organic waste in landfill sites
What are the sources of Nitrous oxides, NOx
- vehicle exhausts
- agriculture and industrial processes
What are the social consequences of climate change
- 600 million people live in coastal areas that are less than 10m above sea level
- people living in vulnerable areas may have to move home or even move to different countries. Some small islands states such as Tuvalu and Vanuatu are particularly at risk
- people may suffer from increased flooding and storm damage
- people may lose their jobs, e.g. fishing or tourism, so will have to learn new skills
- No. of environmental refugees will increase
What are the economic consequences of climate change (6)
- Cities like London, New York, Venice may be affected by flooding
- valuable agricultural land may be lost to sea/polluted by sea water (in areas like India or China)
- harbours and ports may be affected —> impact on fishing and trade
- transport systems, such as railways, roads and airports might be damaged or destroyed
- valuable land and property will need expensive coastal protection measurements
- countries that depend on coastal tourism as main source of income may have beaches eroded or flooded —> forcing hotels to close and reducing tourism
What are the environmental consequences of climate change
- fresh water sources might be contaminated by salty seawater: salinisation
- damage could occur to coastal ecosystems such as mangrove swamps, which form natural barriers to storms
- damage to coral reefs by storms and powerful waves will affect fish breeding grounds and ecosystems
- The IPCC estimates that up to 33% of coastal land and wetlands could be lost in the next 100 yrs
- Harbours may become blocked by sediment due to increased rates of coastal erosion
