Climate Feedback Flashcards
POSITIVE climate FEEDBACK
Increasing warming of cooling rates
-Snow & Ice Cover. Small increase in snow/ice raise surface albedo so more solar energy is reflected back into space leading to further cooling which could lead to further snowfall and ice cover
-Melting of snow/ice cover by CO2 emissions decreases albedo; methane is emitted as permafrost melts, and warming seas lead to calving of ice sheets, which cover and of surface albedo, decreasing reflectivity and accelerating further warming
NEGATIVE climate FEEDBACK
Decreasing warming or cooling rates
-Increasing global warming leads to more evaporation and, over time, pollution from industrialisation adds to global cloud cover
-Ice sheet dynamics can disrupt thermohaline circulation (THC). Warming water in Arctic disrupts ocean currents; less warm water from Gulf Stream drawn north, which could lead to global cooling in northern Europe
Thermohaline Circulation (THC)
Global system of surface and deep-water ocean currents driven by differences in temperature (thermo) and salinity (haline) between areas of oceans.
Sometimes know as ocean conveyor
Calving
Breaking up chucks of ice at glacier snout or ice sheet front to form icebergs as glacier reaches a lake or the ocean
Long term causes of climate change
Obliquity
Eccentricity
Precession
Obliquity Cycle
Tilt of Earth’s axis varies between 21.5 and 24.5 degrees over 41,000 cycles
This changes the severity of the seasons
Eccentricity cycle
Shape of the earth’s orbit varies from circular to elliptical over 100,000 year cycles
Earth receives less solar radiation in the elliptical orbit when the earth is farthest from the Sun
Precession of the equinoxes
Earth wobbles as it spins on its axis, which means that the season during which the earth is nearest to the Sun varies
This varies over approximately 21,000 year cycles resulting in changes in the intensity the seasons
Short-term causes of climate change
Variations in solar output
Volcanic emissions
Volcanic emissions
injection into atmosphere large quantities of sulphur dioxide gas, which remains in atmosphere for as long as three years
Sulphate aerosols are formed, remains which increases reflection of radiation from the Sun back into space cooling Earth’s lower atmosphere
Solar output
Sunspots are dark patches on the face of the Sun. These sunspots are caused by intense magnetic activity in the sun’s interior
An increase in the number of sunspots means that the Sun is more active and giving off more energy, so sunspot numbers indicate levels of solar output
They appear to vary over 11 year cycle
Volcanic emissions example
1815, Mount Tambora year without summer
