Climate Change: Future Projections And Extreme Sceanios Flashcards
Equilibrium climate sensitivity
If you double CO2 emissions, what would the change in temp be?
Use instrumentations (past climate data), climatological constraints (physics of atmosphere) ,raw models range (global climate model), paleoclimate (reconstructions of observations in past, not very reliable) Combination - best estimate
1 1/2- 4 1/2 degree rise
RCP
Representative Concentration Pathways - what might humans do in future, what will force (put energy in eg the sun, volcanos, CO2) the atmosphere in the future
CO2 concentration projections
Mitigation pathways (will humans stop emitting CO2, geoengineering etc)
If we continue as we are - RCP 8.5
RCP 6.0
RCP 4.5
RCP 2.6
Radiative forcing
Climate change is caused by radiation from the sun
Gets absorbed by atmosphere
Forcing- energy coming in
Cumulative emissions are key
It’s not just the CO2 that we’re emitting right now, but what we have emitted in the past
If you want to predict temp- need to consider all CO2 emitted throughout human history
Cumulative emissions of CO2 largely determine global warming
Climate change will persist
This represents a substantial commitment to addressing climate change
Need a long term climate change plan- multi-centuries (govs are only 4 years)
Future predictions
RCP 2.6 - 1/2 degree
RCP 4.5 -
RCP 6.0 -
RCP 8.5 - 8 degrees increase
Paris Agreement 2015 - ratified by 122 countries
Public perception important for success
Agreement on emissions of greenhouse gases
Aim- holding the increase in globally averaged temperature to well below 2 degrees C above preindustrial levels and to pursue efforts to limit the temperature increase to 1.5 C
Future climate predictions - regional
Temperature
Temperature quite uniform across continents
Temperature may increase more regionally than globally- especially on land
Higher northern latitudes warming more than equatorial regions and Southern Hemisphere
Future climate predictions - regional
Precipitation
Indirect effect of climate change
Warmer atmosphere can hold more moisture and so it can rain more
RCP 8.5 - not uniform increase - some regions increase, some decrease
Because precipitation acts in a very different way to temp - dynamics of the systems
E.g. Storm track- if storm track changes, some parts will be dryer, some parts will be wetter
Future climate predictions - regional
Sea ice
Northern hemisphere- sea ice decreases
Some people dont care- opens up shipping routes, can drill further north
Future climate predictions - regional
Cloud cover
Really poor reproducing in climate models- dynamics crucial
Structure of cloud system very complex, changes differently in different areas
Future climate predictions - regional
Ocean currents
Vital for our current climate - warm water pumped from equator, goes towards pole, sink as they get cooler, over turning Circulation
If this breaks down, we wouldn’t get energy pumped to higher latitudes
Projections : extreme temperature magnitude
Rare, small sample sizes, but they’re important as that’s what we feel
Clear trend for warming
Relatively uniform throughout the global
Coldest day in winter will get much warmer, warmest day in summer will get much warmer
Difficult sleeping and some temps unliveable
Extreme temperature duration
If heatwave occurs for extra day, more strain on bodies trying to recover
Fewer frost days
More tropical nights
Extreme precipitation
Far more structure than temperature metrics
5 day precipitation (flood) increases
Increases in consecutive dry days
More extreme weather in future
Droughts - depend on where you are
Hurricanes
Very difficult to predict (processes involved in hurricane movement, dispersions are very small scale, models have got to understand small scales of weather and climate to understand/ predict) also often get to bifurcation (move one way or other but not in middle)
Globally - fewer category 1, increase in 3 & 4
