Climate Change Flashcards
How does the past climate change
Hot and Cold periods
Examples of proxy data
Tree rings, ice cores, fossil pollen, ocean sediments, corals and historical data
How are corals used to determine the past climate
Corals are made from Calcium Carbonate, Carbonate contains isotopes of oxygen as well as trace metals that can be used to determine the temp of the water om which the coral grew
How are tree rings used to determine the past climate
Climatic conditions influence tree growth, patterns in tree-ring widths, density and isotopic composition reflect variations in climate. Trees generally produce one rings a year
How are ice cores used to determine the past climate
Snowfall layers contain dust, air bubbles, or isotopes of oxygen, differing year to year based on the surrounding environment
Name the two types of earths climate conditions
Greenhouse
Icehouse
What occurs during ice house conditions
Glacial and inter-glacial periods occur but on a much shorter timescale
Conditions during the mid-Cretaceous (100 million years ago)
Average global temperatures 6-8 degrees higher than today
No polar ice caps
Sub-tropical conditions extended from Antarctica to Alaska
What is the new geological period called
Anthropocene
What are the three types of natural forcing and explain them
Natural forcings - induce change in climate
External forcing - These are linked to changes in the orbital parameters of the earth
Internal forcing - changes which occur within the Earths system itself
External forcing - Milankovitch Cycles what are they
Changes in the earths orbit and axis and the precession of the equinoxes
These changes affect the amount of solar radiation reaching the planets surface
Explain Obliquity and what affect it has on climate
Tilt of the Earths axis
More tilt = more seasonality, warmer polar summers, glaciers less likely to survive
Less tilt = the opposite
Explain Eccentricity and what affect it has on climate
Eccentricity of Earths orbit
Less eccentricity = less seasonality, cooler polar summers, glaciers more likely to survive
More eccentricity = the opposite
Explain precession of the equinoxes
affects seasonality and extent of glaciation
What affect does volcanic eruptions have on climate
Sulfur dioxide has a cooling effect
Increased albedo - reflects solar radiation back into space
Continental drifts affect on climate
As larger continental areas occupy higher latitudes, the land area with permanent ice cover expands increasing global albedo = positive feedback = forces global cooling
Ocean circulation
Vital component in the Earths energy budget, transferring surplus energy
Formation of the isthmus of panama consequences
Intensified the gulf stream
Increasing evaporation and precipitation in the North Atlantic
Decreasing the salinity of the North Atlantic and Arctic Oceans
This slowed thermohaline circulation
onset of the glaciation 3 mya
Melt water plus consequences
Melting of ice sheets in the Arctic reduces ocean salinity
Weakening the down welling of the North Atlantic Conveyor
Led to the return to glacial periods for 1000 years
What have the influences of humans been for climate
Growing population
Technological advances
Rising sea level-evidence for climate change
Currently 3 mm per year
Causes: thermal expansion and melting land ice
since 1900 average rise has been 1-2.5 mm/yr
currently at 3 mm/year
Shrinking valley glaciers-evidence for climate change
Retreated or disappeared
1961-2005 thickness of valley glaciers reduced by average of 12m
Shrinking of ice sheets-evidence for climate change
Antarctic and greenland contain 97 percent if global ice store
both are shrinking fast
Losses of ice-evidence for climate change
Warming of atmosphere
Meltwater penetrates the ice and increases the velocity of glacier flow
Ocean warming which accelerates the melting of ice sheets in coastal regions
increasing atmospheric water vapour
Most important GHG
Traps huge amounts of energy radiated from Earths surface
Warmer condition=more evaporation=more water vapour
This leads to a positive feedback
Decreasing sea ice
Overall decrease since 1997
Summer reduced 8 percent per decade
Winter reduced 3-4 percent per decade
Thickness has also declined
Carbon dioxide-Anthropogenic
Second most important GHG
75 percent of anthropogenic GHG
Before 1800 stable at 280 ppm
2015 passed 400ppm, increase in 40 percent in 200 years
Methane-Anthropogenic
measured in ppb 1984, 1735ppb 2009, 1890ppb more potent than CO2, 25 TIMES POTENT 15 percent of all GHG emissions
Reasons for rising GHG emissions since the pre-industrial era
Huge surge in demand for energy Industrialisation and tech advancements Especially manufacturing and transport Massive population growth 1800 1 billion, 7.4 billion in 2015 Increase in living standards Deforestation and drainage of wetlands Rely heavy on fossil fuels 87 percent
Dependance on fossil fuels
Two thirds of anthropogenic GHG emissions come from burning fossil fuels
10 billion tonnes of CO2 annually
Coal
Coal is no longer the leading fossil fuel
China and india are largely powered by coal
Coal is the dirtiest fossil fuel- twice as much co2 as natural gas/20 percent more co2 than oil
Cause of the Enhance greenhouse effect
Volume of GHG has increased rapidly in atmosphere
exaggerated by positive feedbacks which led to further warming
