4.a Flashcards
what are some examples of positive feedback scenarios?
global warming in the polar regions could be higher due to a reduced albedo effect
clouds, particularly high clouds such as cirrus, can also trap outgoing heat and act as a blanket
higher temps = more evaporation = therefore more water vapour which is a GHG…
as temps increase in tropical regions, soil, plants and trees will become more heat stress, potentially releaseing the huge amounts of carbon they store
rising sea temps could trigger the release of methane from methane hydrates stored on ocean floor
what are some examples of negative feedback scenarios?
rising global temps increase evaporation which increase cloud cover. clouds, particularly low clouds such as stratocumulus, reflect sunlight
increased burning fossil fuels releases particulate into the atmosphere.
absorption and reflection of insolation by these particles can reduce the amount of incoming energy.
as temps increase, the areas in which trees can grow will extend north to higher latitudes. new trees will absorb more CO2
how will past and present day GHG emissions affect the climate far into the future?
many GHGs stay in the atmosphere for long periods of time
as a result, even if emissions stopped increasing, atmospheric GHG concs would continue to increase and remain elevated for 100s of years.
surface air temps would also continue to warm
because oceans, which store heat, take many decades to fully respond.
what are the 3 key global projections for temperature changes?
increases in avg global temps are expected to be w/in the range of 0.5F to 8.6F by 2100
global avg temp is expected to warm at least 2x as much in the next 100 years as it has during the last 100 yrs
ground level air temps are expected to continue to warm more rapidly over land than oceans.
what are the 4 key global projections for precipitation and storm events?
global avg annual precipitation through the end of the century is expected to increase, although changes in the amount and intensity of precipitation will vary significantly by region
the intensity of precipitaion events will likely increase on avg. particularly pronounced in tropical and high latitude regions
strength of winds associated with tropical storms likely to increase.
annual avg precipitation projected to increase in some areas and decrease in others
what are the 3 key global projections for future ice, snowpack and permafrost
for every 2F of warming, models project about a 15% decrease in the extent of annually avgd Arctic sea ice and a 25% decrease in the area covered by arctic sea ice at the end of summer. this decrease DOESN’T contribute to sea level rise
coastal sections of greenland and antarctic ice sheets expected to continue to melt/slide into ocean. if the rate of this ice melting increases in the 21st c, ice sheets could add significantly to the global sea level rise
glaciers are expected to continue to decrease in size = sea level rise.
future ocean acidification projections?
ocean acidifcation adversely affects many marine species, including plankton, mollusks, shellfish and corals.
if atmospheric CO2 concentrations double, coral calcification rates are projected to decline by more than 30%
what are RCPs?
the IPCC uses four scenarios called “Representative Concentration Pathways” (RCPs)
how does an effective response rely on knowing what the future holds?
we don’t know how severe future impacts will be because we don’t know what pathway we are on/what decisions future policy makers will make.
(good AO2 point)
what might a 2C world look like?
raised sea level by thermal expansion alone 0.51-1.4m
storm surges and increased hurricane destruction
cities more likely to suffer from catastrophic flooding/super storms. impacts to infrastructure
affect places we assume would be safe (not prepared)
once in a century storms increase by 5x
35 mill Bangladeshi will become climate refugees
superstorm sandy 2012 caused huge amounts of damage. could become more common
what might a 3C world look like?
possibility of releasing carbon locked in permafrost. 1500 billion tonnes of carbon (methane) 20x more powerful
if it all melted from greenland = 7m sea level rise
coastlines completely changing under this SL rise.
what are the predicted impacts on global temperatures?
many GHGs stay in the atmosphere for long periods of time.
as a result even if emissions stopped rising, atmospheric gas concs would continue to rise and remain elevated for 100s of years
moreover, if we stabilised concs, surface air temps would continue to warm
this is because oceans store latent heat.
except under the most aggressive mitigation scenarios, global temps are expected to warm at least twice as much as in the next 100 years as it has during the last 100 yrs
ground level air temps are expected to continue to warm more rapidly over land than oceans. some parts of the world are projected to see larger temp rises than the global avg
what are the predicted impacts on sea levels?
warming temps contribute to sea level rise by expanding ocean water, melting mountain glaciers and ice caps and causing meltwater to flow from Greenland and antarctic ice sheets
since 1870 global SL has risen by 7.5 inches
estimates of future SL rise vary for different regions, but global SL for next century is expected to increase at a greater rate than during the past 50 years
the contribution of thermal expansion, ice caps and small glaciers to SL rise is relatively well studied, but the impacts of climate change on ice sheets in Greenland and Antarctica are less understood and represent an active area of research.
Changes in ice sheets are currently expected to account for 8 inches of SL rise by the end of this century
what are representative concentration pathways?
projections of what impacts climate change will have in the future under different emissions scenarios
the IPCC uses 4 scenarios called RCPs.
the numbers in the names represent radiative forcing = a measure of how the gases in the atmosphere affect the balance between the energy absorbed by the earth and the energy radiated back out to space.
the bigger the number, the bigger the ratio of radiation in to radiation out.
RCP 8.5 impact
this emissions pathway assumes that CO2 emissions will continue to rise in the next 100 years.
the Arctic Ocean will be completely ice free in Sept by the 2080s
