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Climate Change Statistics - Coggle Diagram
Climate Change Statistics
Stats
For past 800kyr, CO2 170-300ppm vs 420ppm today (Hand, 2017)
IPCC Special Report on 1.5C (released 2018): gives us until about 2027 of unabated CO2 emissions for a 66% chance of staying below 1.%C
"Warming hiatus" 2004-2014
no apparent warming since 1998 despite CO2 increases
GHGs increased -> greenhouse effect increased (higher energy input to climate system) -> but same GMST (energy output)
'missing energy' (Trenberth and Fasullo, 2012)
Why?
El Nino changes?
1997/8 was strongest El Nino on record -> then switched to mostly La Nina years, which tend to be colder overall. Atmospheric heat gain (loss) corresponds to decreases (increases) in ocean heat uptake during El Nino (La Nina) years.
Strengthening of Pacific trade winds (England et al., 2014)
Stronger Pacific trade winds -> increased subsurface ocean heat uptake -> slowdown in surface warming
Why stronger Pacific winds?
Atlantic warming linked to positive phase of Atlantic Meridional Mode (AMM) but drivers unclear
Peaked in 2013, near normal in 2015 then back to warm in 2016
McGregor et al. (2014)
Interdecadal Pacific Oscillation (IPO)
low-frequency El-Nino-like pattern
negative phase so cool tropic pacific, strong trade winds
Drier stratosphere (Solomon et al., 2010)
Strato water vapour incr 1980-2000 then decr post-2000
Cools stratosphere but warms troposphere i.e. we're colder at lower parts of the atmosphere but missing heat stored higher up
Aerosol cooling
Favours negative IPO phase (Smith et al., 2016)
Changes in measurements taken (Karl et al., 2015)
Sea water temps measured by bucket -> engine intake -> buoys
Correction via interpolation removes hiatus
Following this, last decade has been warmest on record! (NASA)
El Nino (amplifies global warming) state since 2023 but weaker than 2015/16
Water-holding capacity of atmos as function of temp
Clausius-Clapeyron function
7% water increase per degree C
4% increase since 1970
recent decades have seen greater humidity but weakened circulations
Spatial climate variability
Latitudinal amplifications since 1980 (NASA Gistemp models)
Tropics warmed by 0.9C
SH extratropics warmed by 0.7C
NH extratropics warmed by 1.5C
Reasons for Arctic amplification (Pithen and Mauritsen, 2014)
ice-albedo feedback
seasonal signal where most warming in winter months
At cold temps, more warming needed for same change in Planck radiation. A slight temperature increase in cold environments means that much more thermal radiation is needed from the cold environment to return it to equilibrium, than would be for the same temp increase in a warmer environment.
Land vs ocean warming since 1980 (NASA Gistemp)
Land warmed 0.3C per decade
Oceans warmed 0.1C per decade
Latitudinal interactions
Arctic amplification -> extreme mid-latitude weather (Cohen et al., 2014)
Warm polar regions and increased Siberian snow cover -> favours negative NAO
Negative NAO favours increased warm air advection to poles
Reduced temp gradient between Arctic and mid-latitudes weakens the polar jet stream and makes it meander more
Weather systems travel eastwards slower -> more persistent weather patterns
Ridges in jet stream elongate polewards. Meridional wind component becomes more dominant over temperature differences -> more weather extremes
e.g. Feb 2017 saw extreme snowfall in Pakistan and Afghanistan, meanwhile very high polar temps