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Future Projec+ons
• Temperature • Deep Ocean heat transfer • Climate sensi+vity • Tropical storms • Other variables
IPCC, AR5, Fig. 12.44
IPCC, AR5, Fig. 12.41
IPCC, AR5, Fig. 12.40
Baker and Roe, 2009
€
R dΔTdt
+ λΔT = ΔF (11.2)
€
ΔT (t) = ΔTeq 1− e−tτ%
& ' (
) * (11.3)
€
τ = R λ
€
ΔTeq = ΔFλ
e-folding time
thermal inertia damping
radiative forcing
Mixed layer-only response
€
ΔT (t) = ΔTeq 1− e−tτ%
& ' (
) * (11.3)
€
τ = R λ
€
ΔTeq = ΔFλ
Greater sensitivity: • greater ΔT • slower to final change
3.75 Wm-2
7.5 Wm-2
3.75 Wm-2
2K
4K
2K
Effect of heat exchange between mixed layer and deep ocean
Atmosphere warms
IR
SH LH
Mixed-layer
Deep ocean
+ -
-
- themohaline overturning decreases
Steady State With mixed-layer warming
0.52Wm-2
-1.96Wm-2
1.44Wm-2
- diffusion increases - convection decreases
Net Effect: heat transfer from mixed-layer to deep ocean
advection
Sudden CO2 doubling
Net radiation at TOA = flux into deep ocean
IPCC, AR5, Fig. 12.42
IPCC, AR5, Fig. 12.35
Baker and Roe, 2009
Energy to deep-‐ocean serves as nega+ve feedback (0.15)
Narrower climate sensi+vity (transient)
Baker and Roe, 2009
Which feedbacks dominate uncertainty (oceanic or atmospheric)?
Reducing atm. uncertainty is more important
IPCC, AR5, Box 12.2, Fig. 1
IPCC, AR5, Box 12.2, Fig. 2
Baker and Roe, 2009
When will temperature reach a given value? (with a ramped 4 Wm-‐2 forcing)
Baker and Roe, 2009
How do emissions affect projec+ons of climate change?
Climate Matters w/ Jim Gandy Chief Meteorologist WLTX Columbia
hWp://www.wltx.com/weather/climate/default.aspx hWp://www.wltx.com/video/default.aspx?bc+d=610279275001
Tropical Cyclones and Climate Change
Challenges in detec+ng trends and anthropogenic influence in tropical cyclone ac+vity Ø Large amplitude fluctua+ons in frequency and intensity Ø Short term records Ø Quality of record
Future projec+on of tropical cyclones AO GCMs resolu+on too low, so we need 1. Reliable simula+ons of climate variables influencing
tropical storm ac+vity and reliable sta+s+cal rela+onships between these variables and tropical cyclone metrics
2. Or higher resolu+on models capable of resolving more processes
Detection and AttributionIntensity
Poten+al Intensity Theory: Local ambient thermodynamic environment determines the maximum intensity that a hurricane can achieve.
Indirect aWribu+on CO2 à SSTà Hurricanes
1. Warming SSTs due to GHG emissions
2. SST influence on tropical cyclonic ac+vity
Attribution Intensity
Power Dissipa+on Index : Seasonally integrated metric for storm dura+on, intensity, frequency
1. Atlan+c TC power dissipa+on and local SST
2. Atlan+c TC power dissipa+on and rela2ve SST (Diff between local SST and mean tropical SST)
0
3maxPDI V dt
τ≡ ∫
(Swanson, 2008)
Sta+s+cal es+ma+on of Atlan+c Hurricane Ac+vity from GCM projec+ons of sea surface temperatures
Projections Intensity
(Vecchi et al., 2008)
Detection and Attribution Frequency
No significant trend detected in tropical cyclones or landfalling hurricanes (1970-‐2004)
Quality of Historical Records
Mul+decadal variability
(Vecchi and Knutson, 2008)
Projections Frequency
(Villarini and Vecchi, 2012)
Stat/dyn downscaling (obs. SSTs)
Regional modeling (obs. SSTs, nudging)
100-‐km AGCM (obs. SSTs)
50-‐km AGCM (obs. SSTs)
(Knutson et al., 2008)
observed
10 least-‐ac+ve years, 1980-‐2006 10 most-‐ac+ve years, 1980-‐2006
Simulated (control)
Simulated (warm climate)
Global TC ac+vity change (2081-‐2100) rela+ve to 2000-‐2019
(IPCC AR5 WG1 Fig. TS.26 )
References
• IPCC, 2013. Working Group I Contribu+on To The IPCC Fihh Assessment Report (AR5), Climate Change 2013: The Physical Science Basis. Drah Report
• IPCC, 2012: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adapta+on. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-‐K. PlaWner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, UK, and New York, NY, USA, 582 pp.
• Knutson, T. et al. 2010. Tropical cyclones and Climate Change. Nature Geoscience. 3:157-‐163 • Swanson, K. 2008. Nonlocality of Atlan+c tropical cyclone intensi+es. Geochemistry
Geophysics Geosystems. 9 • Vecchi, G., Knutson,T. 2008. On es+mates of historical North Atlan+c tropical cyclone ac+vity.
Journal of Climate. 21:3580-‐3600 • Vecchi, G., Swanson, K.,Soden, B. 2008. Whither hurricane ac+vity. Science. 322:687-‐689 • Villarini, G. and Vecchi, G. 2012. Projected increases in North Atlan+c tropical cyclone
intensity from CMIP5 Models.