Regarding the article in DN

”Sprid inte bilden av att det är för sent att rädda klimatet”




John Hassler

Rodrigo Caballero

Deliang Chen

Per Krusell

Thorsten Mauritsen

Jonas Nycander

Michael Tjernström


LennartBengtsson  is also warmly welcome as well as anyone who wants to take the challenge of

the most important issue of our time: climate sensitivity



I ask to challenge each of you to a duel.


1. Black curve is NASA measurements of actual global temperature anomaly.

2. There are many calculations (A) , made by climate experts on how the NASA curve is likely to continue.

Pick any such prediction, such as the one Exxon made in secret 42 years ago,

or one of the more recent ones, such as


Earth Syst. Dynam. Discuss, Professor Peter Nightingale,

The temperature anomaly data of NASA/GISS can be used for a linear regression, two-parameter

least-squares fit. This yields the following expression



3. Curve B is the Earth's temperature anomaly, as a mathematical consequence of

climate sensitivity=3 . This corresponds to the blue text below of the IPCC, which during

last 40 years asserted this climate sensitivity. No change in the last report in 2021.


Task: Calculate the climate sensitivity that drives curve A.

This task may be the most important in the whole climate change effort as the world's climate policy NetZero

policy stands or falls on its outcome.





The importance of the result is that two things happen if the climate sensitivity goes above 3.


1. Earth's temperature does not stop when emissions stop

Thus the NetZero policy falls. It will not work.


2. IPCC forecast +2C by 2100 at 450 ppm falls. This can already be seen at NASA

global temperature curve. This proves that climate sensitivity is above 3.



The results of the various calculations can be published here

or even better under DN debate.