ENSC425/625 Climate Change and Global Warming

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ENSC425/625

Climate Change and Global Warming

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Level of confidence is higher

CO2, more warming (1.68 vs 1.66)

Surface albedo, less cooling (-0.15 vs -0.2)

Aerosols & precursors, less cooling (-0.27 vs -0.4)

Cloud albedo due to aerosols, less cooling (-0.55

vs -0.7)

Solar radiation, less warming (0.05 vs 0.12)

Total anthropogenic, more warming (2.29 vs

1.6)

4

• AR4

5

• AR5

6

7

8

No ◦ Tremendous interannual and interdecadal variability in

the climate system (ENSO, PDO, AO, etc)

◦ Evidence that the extra heat is in the oceans (ocean

warming dominates the increase in energy in the climate

system)

◦ Decadal averages show increasing temperatures

“Warming of the climate system is unequivocal”

It is “extremely likely that human influence has

been the dominant cause of the observed

warming since the mid-20th century”

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10

Example

RCP8.5: Constant emissions after 2100 and constant concentrations

after 2250 with smooth transition of emissions between 2150 and

2250.

RCP2.6

2.6 W m-2 RCP4.5

4.5 W m-2 RCP6.0

6.0 W m-2 RCP8.5

8.5W m-2

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12

AR4

AR5

15

AR5

16

AR4

AR5