More About the IPCC's Very Serious Climate Sensitivity Calculation Errors

Last Updated 11.13.23

A new major climate change  study has just been released which dramatically increases the IPCC's serious underestimation and error problems considerably. We strongly recommend you start with this article and then come back and read the page below.


Alvin Urquhart, a Job One advisory board member, created this article. It is recommended if you are a science person and want to see the complex and detailed science and mathematics behind how the United Nations Intergovernmental Panel on Climate Change (IPCC) has grossly underestimated our coming climate consequences and their time frames by significantly minimizing the Climate Sensitivity calculation amount. (Climate Sensitivity is a constant used in and relied upon in many of the most critical and complex calculations relating to predicting our climate change future.)

If you do not understand climate sensitivity, we strongly recommend you read this definition. Understanding it and having it correct is indispensable to predicting our climate future accurately

The following article is partially derived from the 2050 Goals of the IPCC. The article below also refers to James Hansen's (the world-famous former NASA climate scientist) most recent and scary article on climate change's climate-sensitive problems at the IPCC. (We did a brief review of Hansen's new climate sensitivity article here. Hansen's climate science in his climate sensitivity article was dense, so we tried to make it more understandable to the general public in this article here. This article links to Hansen's full paper as well.)

This article, along with James Hansen's original climate sensitivity article, helps to explain one of the biggest reasons why our organization consistently says that the IPCC's summary reports, on average, are underestimated between 20 to 40% or more.

And finally, Dr. Peter Carter, another climate scientist, has brought up the issue of climate sensitivity errors at the IPCC even before James Hansen. Dr. Peter Carter's earlier climate sensitivity article is found here.


Difficulties in reaching the 2050 goals of the IPCC

Report 11: June 1, 2023

The IPCC has presented several scenarios of global warming, only one of which, scenario (RCP 2.6), met the goal of having a 50% chance of remaining below an increase of 1.50 C by 2050. At the other extreme, scenario (RCP 8.5–which approaches a continuation of business as usual), has the possibility of reaching over 50C warming by 2100.(RCP stands for Representative Climate Pathways.)




The IPCC goals of keeping global temperatures below 1.50 C by 2050 and at net zero (00C) by 2021 are highly unlikely because of:

  1. difficulties in modeling and projecting the course of global warming;
  2. inadequate concern about ‘tipping points’ that herald unstoppable increases.
  3. inadequate pledges by national governments to reach the IPCC goals;
  4. cultural inertia that resists changing attitudes and actions of nations, industries, and people;
  5. and reliance on technology to solve the problems of global warming (I will discuss this in a later Report.)


Climate Forcing Gases. The growth of climate forcing greenhouse gases is shown in the diagram below. (Each gas forces the heat to rise and remain in the atmosphere differently.) If the present course of global heating is maintained, the climate forcing gases will increase temperatures. The red band (in Fig. 5 from Hansen et alia) represents trace gases including chlorofluorocarbons, which have declined since having been highly regulated since the late 1970s.







Global warming in the pipeline James E. Hansen,et alia

Even the low, unattainable climate-forcing scenarios of the IPCC, do not reflect the more recent modifications of global models, which create pathways closer to RCP8.5. The pathways are chosen based on estimates of their sensitivity to global surface warming.

Climate sensitivity is defined as the equilibrium warming resulting from a doubling of atmospheric CO2. It is assumed that, in the long run, the heat of the Earth is in equilibrium when the heat coming to the Earth from the sun equals the heat leaving the Earth. Equilibrium slowly changes as the orbit of the Earth around the sun changes, as ice sheets grow and retreat, as land area and cover change, as clouds and water increase or decline, etc. The diagram below shows that as global forcing changed over the past 400,000 years so did the temperatures measured in water isotopes in Antarctic ice. This represents over 400,000 years of long-term equilibrium of the Earth. Since 1750, however, global forcing has greatly exceeded the near equilibrium.



       (In the diagram, 40C was the assumed metric of climate sensitivity since 1750.)  Global warming in the pipeline James E. Hansen,et alia

The importance of the level of climate sensitivity is in knowing how climate deviates from long range equilibrium and how global temperatures react to levels of CO2. As an example, the next diagram indicates that when a sensitivity is determined to be 30C, (i.e. deviates from equilibrium by 30C) a recorded temperature of 20C would be relatively stable when the concentration of CO2 remained under about (350-400 ppm). Whereas with a sensitivity determined to be 4.50C, a temperature of 30C would be stable when the concentration remained in the realm of 445-490 ppm of CO2. When climate sensitivity is larger,  the temperature when CO2 is doubled (Equilibrium Global Average Temperature) will also be much higher.




Of course, the relevance to humanity is that higher climate sensitivity means that temperatures will become higher and come faster when the levels of GHG increase. In the current climate crises, the use of a correct sensitivity determination is crucial to understanding the results of continued GHG emissions. Since 1979, the most used measure of ECS has varied from 1.50C to 4.50C. The IPCC uses 30C in the climate model on which it bases discussions about goal-setting and the ways to remain under their goal.

Factors in determining ECS



          (Climate sensitivity in the Anthropocene. M. Previdi, et alia Earth Syst. Dynam. Discuss., 2, 531–550, 2011)


Climate forcing initiates changes in atmospheric climate warming directly. But also, feedback mechanisms release stored heat as the Earth moves toward equilibrium as outlined in the description of Fig. 1a above. Especially notice the large amount of energy stored in the oceans and the potential for atmospheric climate warming through releasing its energy to the atmosphere. Studies of the possible feedback of heat stored in the oceans and the continents, and the melting of ice sheets and glaciers are in process.



K. von Schuckmann et al.: Heat stored in the Earth system Earth Syst. Sci. Data, 12, 2013–2041, 2020

One of these studies (J.Hansen et alia) has resulted in a ECS setting of about 100C.  [very far from the IPCC goal of net zero (00C) by 2100.] 

In addition studies of paleo-climates have led to refinements in understanding the ways aerosols affect global warming. An additional probable change from the present is that global heating may  increase because of a decline in cooling from aerosols. (Shown (Fig. 19) in the next diagram in yellow.) Before 1970, cooling by aerosols decreased global warming; although since then, reduced amounts of aerosols may even add to global warming. Overall, aerosol cooling may still reduce the possible  temperature anomaly by 30C , possibly resulting in an ECS of 70C.

(See Global warming in the pipeline James E. Hansen, Makiko Sato, Leon Simons, Larissa S. Nazarenko, Karina vonSchuckmann, Norman G. Loeb, Matthew B. Osman, Pushker Kharecha, Qinjian Jin, George Tselioudis, Andrew Lacis, Reto Ruedy, Gary Russell, Junji Cao, Jing Li).




Because heat is temporarily stored in the Earth, global equilibrium will remain out of balance for decades to come no matter what efforts humans can make to lower emissions of GHG. Eventual release of stored heat will result in increased feedback added to heat from CO2 that is directly emitted to the atmosphere.


2. Tipping Points (See the fuller explanation of tipping points in Understanding Critical Climate Change and Global Warming Tipping Points – Job One for Humanity)

Climate tipping points are the temperatures or levels of emission of energy that initiate or support radical further changes–often self reinforcing–to the Earth systems in which they are embedded. Once initiated, tipping points lead to further imbalances in the climate equilibrium and cannot be stopped until the climate system is greatly readjusted to an equilibrium. The Earth has already passed a tipping point where drastic climate changes have occurred such as increased flooding; heat domes, sea level rise, melting glaciers and ice sheets, etc.

The amount of greenhouse gases measured in carbon ppm indicates possible tipping points. Humanity is experiencing the first phase of a tipping point. The second chart below indicates probable consequences of passing a 1.50C or greater tipping point.







Some of probable tipping points and where on Earth they will occur.








3. IPCC Goals and National Determined Commitments NDC (2022).

GHG emission ranges. The most obvious problem of the climate model chosen by the IPCC–RCP2.6–that I discussed above is the disparity between the National Determined Commitments (NDC) and the selected goals. An illustration of part of the problem is shown by part of the projected increase in greenhouse gas emissions that outstrip the NDC pledges and far exceed the levels necessary to reach either a 1.50C or even a 20C goal. A simplified diagram indicates that even the National pledged reductions (NDC) are far above the 1.50 C goal of the IPCC and the projected increases in the emissions of continued ‘business as usual.’ increase of 2 times of CO2.





For over 50 years, conferences have alerted national leaders to the necessity of pledging and meeting those pledges if climate disasters were to be avoided or ameliorated.




To date, no progress has been reached in lowering the emissions of global atmospheric GHG; Greenhouse gasses continue to accumulate, delaying the possibility of meeting the IPCC goals.




Global warming in the pipeline James E. Hansen,et alia

The most recent report of the IPCC (2023) states that emissions of GHG need to be cut by almost half by 2030, if there is any chance that the 1.50C goal can be met. The diagram below showing predicted changes between 2020 and 2030 indicates that the gap between actual emissions and progress to the needed decline in emissions is widening. Thus indicating that the goals will not be met.






Other climate models that address the goal of 20C set by the IPCC fail to meet that goal.

One of the largest of these studies of climate models was done by The Washington Post in collaboration with the Potsdam Institute for Climate Impact Research.

                                                                                                                             (Washington Post 12/1/2022; updated 5/22/2023)


Potsdam Institute researchers rated the ability of over 1,200 scenarios based on their progress in meeting the 1.5°C goal by 2050. Each of five dimensions were rated as to their probability of meeting each of five dimensions. The three categories used were 1. speculative, 2. challenging, or 3. reasonable.

The five dimensions are:

1. Carbon dioxide removal and storage underground

2. Carbon dioxide removal using land

3. Carbon intensity reductions

4. Changing energy demand

5. Fewer methane emissions

For various reasons only 112 possible scenarios could possibly reach the goal. Of those scenarios, 86 were rejected because they indicated that the predicted temperatures would highly overshoot the IPCC goals. 26 pathways would result in only a temporarily low or no overshot of the 1.50C goal. And only 11 pathways are left when only challenging or reasonable dimensions were considered.




Of those, only 4 pathways remained even if ‘carbon dioxide removal and storage underground’ was not considered ‘reasonable’ but still considered ‘challenging’. If all categories were considered as merely reasonable, zero pathways remain.





The Washington Post concludes with the following statement:

“At the U.N. Climate Change Conference late last month, world leaders reaffirmed the 1.5C goal. But these scenarios show that without dramatic action–action the leaders did not commit to taking–it most likely will not be possible.

“Or at least, not without a major overshoot first. That is where the world is currently heading.”

Job One for Humanity diagrams the problems (JOFH).

JOFH’s diagram shows that severe climate warming will occur when the underestimation of global climate sensitivity (20-40%) as well as the effects of tipping points are added to the current IPCC predictions.




4. Cultural inertia

The inertia of society, politics, and economy is the main reason that climate warming is continuing today.

It is impossible to deny the benefits brought about by the burning of fossil fuels. Who can not appreciate better health, living longer, being able to move and communicate over huge distances, having food, services and goods from all over the world, having the opportunity of better education, and on and on? An acceleration of the “good life” so that everyone can appreciate it is a large part of “progress, development, and growth” that underlies world views today. Even intelligent leaders who are aware of climate warming still want “economic growth” to support the continuation of the extraordinary economic profits and social benefits of modern times.

Perhaps President Obama summed it up best at the end of his presidency:

If you had to choose a moment in history to be born, and you did not know ahead of time who you would be—you didn’t know whether you were going to be born into a wealthy family or a poor family, what country you’d be born in, whether you were going to be a man or a woman—if you had to choose blindly what moment you’d want to be born, you’d choose now.

As a simple example of the ways this is playing out in its most basic form has been shown by studies of the ways the fossil fuel industry, knowing the probable consequences of global heating, continue to exploit irreplaceable fossil fuels that underlie modern life. I include only one very powerful example of current disregard for continuing and accelerating climate disasters.


Carbon Bombs. The Guardian newspaper shows the fossil fuel industry’s and governmental regard to growth in production of fossil fuels in an article by Damian Carrington and Matthew Taylor. (Wed 11 May 2022 Last modified on Mon 3 Apr 2023 ;” Revealed: the ‘carbon bombs’ set to trigger catastrophic climate breakdown”)


“The fossil fuel industry’s short-term expansion plans involve the start of oil and gas projects that will produce greenhouse gases equivalent to a decade of CO2 emissions from China, the world’s biggest polluter.”

The next two diagrams show fossil fuel reserves and the impact on the global carbon budget in relation to the IPCC goal of 1.50C.










“These plans include 195 carbon bombs, gigantic oil and gas projects that would each result in at least a billion tonnes of CO2 emissions over their lifetimes, in total equivalent to about 18 years of current global CO2 emissions. About 60% of these have already started pumping.”




“The dozen biggest oil companies are on track to spend $103m a day for the rest of the decade exploiting new fields of oil and gas that cannot be burned if global heating is to be limited to well under 2C.”




“The Middle East and Russia often attract the most attention in relation to future oil and gas production but the US, Canada and Australia are among the countries with the biggest expansion plans and the highest number of carbon bombs. The US, Canada and Australia also give some of the world’s biggest subsidies for fossil fuels per capita.”



The article also indicates that the production of fossil fuels receives large governmental subsidies.




The shortcomings of the political realm are not only failure to agree to the weak goals of the IPCC but also failure to produce legislation that might require acceptance of those goals. Instead, in the United States, the Congress produced some legislation, such as the IRA, which relies on technology that has little chance of addressing the major issues of growth and expansion of the consumption of energy.


6. Technology

I will delay, to another report, commenting on the dependence on new, more efficient, or otherwise improved technologies to reach the IPCC goals.

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