geography worksheet 2

�if the quantity of carbonic acid increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression� (1896)

ΔF (Wm-2) = α ln(C/C0) α = 5.35

ΔT(K) = λ*ΔF

Svante Arrhenius Climate Sensitivity: change in global mean temperature in response to a doubling of CO2 volume mixing ratio.

Let’s talk about climate sensitivity with a little more specificity in terms of CO2 emissions. Once again, as shared in previous lecture slides, this slide shows the “greenhouse law” formulated by Svante Arrhenius.

CO2 carbon dioxide CH4 methane

N2O nitrous oxide

It is important to note that, although we are focusing on CO2 to examine climate sensitivity here, we all know that there are other molecules that can absorb long wave back radiation: water molecule (H2O), methane (CH4), nitrous oxide (N2O), etc.

What is a logarithm? • logbX “the log to base b of X” is the power that b

must be raised to get X

• So, what is log10100? (= 2)

• Logs with the base e (LogeX) are written in Ln X (natural logarithm)

• e=2.71828…. (mathematical constant)

• Definition:

Arrhenius’s greenhouse law tells us that the relationship between climate

sensitivity and carbon dioxide (CO2) concentration is a natural logarithm.

ΔF (Wm-2) = α ln(C/C0)

This means that… (see next slide)

Radiative ‘forcing’ of CO2 is logarithmic!

Increasing CO2 concentration à

In cr

ea si

ng ra

di at

iv e

fo rc

in g

in W

m 2

Radiative forcing, defined as the difference between radiant energy received by the Earth and energy re-radiated to space logarithmically increases with increasing CO2 concentration. More importantly, the increase in radiative forcing slows down as CO2 concentration increases.

�if the quantity of carbonic acid increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression� (1896)

ΔF (Wm-2) = α ln(C/C0) α = 5.35

ΔT(K) = λ*ΔF

Svante Arrhenius Climate Sensitivity: change in global mean temperature in response to a doubling of CO2 volume mixing ratio.

At the beginning of the industrial revolution, CO2 concentration was 280 ppmv (parts per million by volume)

As of May 2013, CO2 concentration was 398 ppmv.

How much extra radiative forcing is the Earth’s surface getting in 2013, relative to 1850?

�if the quantity of carbonic acid increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression� (1896)

Radiative forcing since 1850 AD

5.35Wm−2 •ln 398ppm 280ppm "

# $

%

& '

=1.9Wm−2

We must multiply this times a “sensitivity factor” λ to calculate temperature change

λ is usually assumed to be about 0.8 per (Wm-2). So, 0.8 * 1.9 = ~1.5K (kelvin).