global warming 2 Flashcards
what GHG contributes most to CC?
Methane
its stored in hydrate deposits and in permafrost eg high arctic and siberia
positive feedback examples
temps warm > permafrost thaws> co2 and ch4 released
GHG increases> earth warms > increase in water vapour
negative feedback example
more clouds> more sunlight reflection> less radiation
define anomaly
amount of deviation from accepted normal value of that quantity
data - mean = anomaly
what year did we hit 1.5 degree warming
2016
what tells us cold and warm years
striped graphs
5 warmest years are recent
coldest years are in past
how is it hard to predict climate change?
as warming not evenly distributed
warming usually higher in high latitudes
earth climate is non linear dynamical system
what was the warming pause in 2000?
here there was no real trend in temp
it wasn;t predicted
don’t know why is happened
lots of energy stored in oceans and linked to el nino and la nina
name 2 ways we see climate change impact?
glacier recession -169 glaciers all show same trend - problem for water sources and tourism
arctic sea ice reduction - ice cover shrunk by 9% over 1976-2000 and thats increased to 13.5% decrease
if east antarctic ice sheet melted how much would sea evel rise?
65m
if west antarctic ice sheet melted how much would sea evel rise?
3.4 m
if greenland ice sheet melted how much would sea evel rise?
7.5m
if arctic sea ice melted how much would sea evel rise?
0m
sea ice doesn’t contribute to sea level change - only land ice does
name 2 ways sea level rises
ocean exppansion
melting glaciers
how much does ocean expansion contribute to sea level rise 2005 data?
2/3 from ocean expansion
how much does melting glaciers contribute to sea level rise 2005 data?
1/3
howevr melting glaicers contribute more to sea level rise than in the past
why is sea level rise not globally unifrom?
eg isostatic rebound - removal of glacial weight from continent, the crust will rebound after losing the weight, land rises relative to the sea, other side of land subsides eg North of uk lifting and south is subsiding
describe the impact of global warming on coral reef?
bleaching.
coral get nutrients from photosynthetic algae.
when water is too warm the coral expel algae living in their tissue.
bleaching can be reversible if water cools down
happens in warm waters and when ocean acidifies
give examples of bleached coral reefs
great barrier reef worst bleaching in 2016
japans biggest reef - 75% of it has died from bleaching
describe ocean acidification
1 half of co2 released over 200yrs has been absorbed by oceans.
co2 in sea water creates carbonic acid which lowers waters PH making it more acidic
this raises hydrogen ions in water and limits organisms acess to carbonate ions which are needed for shells
how do we predict cc?
climate computer models - solve math equaltions and asses land/ocean/cryosphere interactions
however not all accurate
data takes a while to process
what are the IPCC scenarios
RCP2/4.5/6/8.5
Possible climate futures - all possible depending on how much GHG emitted
what is the prediction of global surface temp?
1.5 - 4 degrees
what is radiative forcing?
difference of insolation absorbed by earth and energy radiated back to space
what is the prospected seal level rise by end of 2100?
40-83 cm
increased recently by 20-60cm
what is the prospected sea ice extent by 2100?
worse case scenario is ice free by 2070
“All models are wrong. Some are useful”
attempt to stimulate reality
all have errors - comparable to proxy data
all tested, comapres and evaulated
