IPCC_2022_0404_comment

In the scenarios we assessed, limiting warming to around 1.5°C (2.7°F) requires global greenhouse gas emissions to peak before 2025 at the latest, and be reduced by 43% by 2030; at the same time, methane would also need to be reduced by about a third. Even if we do this, it is almost inevitable that we will temporarily exceed this temperature threshold but could return to below it by the end of the century.

“It’s now or never, if we want to limit global warming to 1.5°C (2.7°F),” said Skea. “Without immediate and deep emissions reductions across all sectors, it will be impossible.”

The global temperature will stabilise when carbon dioxide emissions reach net zero. For 1.5°C (2.7°F), this means achieving net zero carbon dioxide emissions globally in the early 2050s; for 2°C (3.6°F), it is in the early 2070s.  

 

Jan. 2022

pending

417.99

2.84

Jan. 2021

pending

415.15

 

 

If we use climate sensitivity=6 from Prof James Hansen

and if all emissions are halved , from 2.84 ppm/year to 1.4 ppm/year, start 2025

then the Earth's temperature trend follows the green line.

 

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Same projection with climate sensitivity=36

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Same forecast with (wrong) climate sensitivity=3:

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Argumentation 2

 

 

IPCC:Global temperatures will stabilize when carbon dioxide emissions reach net zero. For 1.5°C (2.7°F), this means reaching net zero carbon dioxide emissions globally in the early 2050s; for 2°C (3.6°F), it is in the early 2070s.

 

The IPCC bases the concept of climate sensitivity on this logarithmic formula.

1.442695041*cs*ln(ppmCO2/275)

At climate sensitivity=3

In 2050, the Earth will have reached 500 ppm CO2 and the temperature will be aiming for 1.442695041*3*ln(500/275)= + 2.58 C Here, zero emissions after 2050 will not help. It will not remove any CO2 and the final temperature will be 2.58 C, not +1.5 as claimed by the IPCC.

 

At climate sensitivity=36

In 2050, the Earth has reached 500 ppm CO2 and the temperature then aims for 1.442695041*36*ln(500/275)= + 31 C Here, zero emissions after 2050 does not help. It does not remove any CO2 and the final temperature will be 31C, not +1.5 as the IPCC claims. If the above expression is made time-dependent and integrated along the time axis and divided by the time constant 630 years, a correct forecast between 2008-2022 is obtained.

 

Regardless of climate sensitivity, the IPCC claim is incorrect. The temperature cannot be stabilized at +1.5C

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