..but why?

(Where is Ajax and lee and the copper internet loving brigade btw?)

(oh noes, they are waiting for everyone else to do their homework so they can replay high school but better this time  )

lee wrote on Jun 8^th, 2015 at 2:14pm:


No mention of the thermohaline cycle either: wow, what a thorough researcher you are 

http://itg1.meteor.wisc.edu/wxwise/AckermanKnox/chap14/climate_spatial_scales.ht...
     

Quote:

lee wrote on Jun 8^th, 2015 at 3:58pm:

lee can't handle the idea of complexity and so simply says "Good post John" in the hope he won't get attacked for his previous inability to accept the complex nature of the climate system.

Looking at the graph, you can see that between 1950 and 2015, you can see a temperature increase of about 0.6 degrees C.

During that time, the CO2 level in the atmosphere has gone from about 300 to about 400. It has not doubled, but increased by a factor of 1.333.

Plugging those figures into the radiative forcing equation,

ΔT = λ*ΔF = λ * 5.35 * ln(400/300) = 1.53 * λ

- where λ is climate sensitivity, ΔT is the change in temperature and ΔF is the change in radiative forcing.

For a temperature rise of 1 degree C for a doubling of CO2, or, using the equation, this gives us 0.27 degrees per (W/m2)

A climate sensitivity of 0.27 gives an equilibrium ΔT of 0.41 degrees rise. (1.53*0.27) for this period. (Note that the actual ΔT will be higher due to the inertia in the ocean temperature etc.)

Even though the current temperature is not at equilibrium, we can see straight away that the warming for this period (1950-2015) is 0.6, which is still higher than the 0.4 from a low climate sensitivity of 0.27, which is what is predicted by the likes of Roy Spencer.

The most likely climate sensitivity is between 2 and 4.5 degrees for a doubling of CO2 (or 0.54 to 0.81degrees per (W/m2))

lee wrote on Jun 9^th, 2015 at 3:21pm:


There hasn't been any change in Avogadro's constant either. Not bizarre.

1.5 to 4.5 is correct.

lee wrote on Jun 9^th, 2015 at 7:02pm:


A lot depends on the papers that are presented and the data that is available. The overall confidence level must reflect the data. Another factor that can cause changes like this is remote sensing data from satellites. If a satellite malfunctions or is not replaced due to launch failures, then the data will reflect this.

so yes, things change.

Realistically the bottom end (1.5) of the climate sensitivity scale is extremely unlikely given historical data and empirical studies during during major volcanic eruptions.  The top end (4.5) is more likely, but the IPCC is notoriously conservative in their estimates.  There are positive feedbacks (for example methane emissions from Tundra) that were not well enough understood to have been included. That may change yet.

Bobby. wrote on Jun 10^th, 2015 at 7:25am:


Your eccentricity figure is correct, and you're right in saying that aphelion occurs in July, with perihelion in January.

However, the greater influence of the ocean in the southern hemisphere has an overall tempering effect that means that the Southern hemisphere has fewer extremes than the North.

There are a lot of factors in play. The eccentricity of the Earth's orbit is just one factor. 

Of course, the ellipse rotates once every 112,000 years. That's called the precession of the perihelion, or apsidal precession.

The other long term effect is called Precession of the Equinoxes. The axis of the Earth gradually spins like a top. It traces a circle in the sky every 26,000  years. 

Superimposed, the two effects together with the axial precession (or wobble) cause the Milanković Cycles, which cause long term variation in climate.