This NASA climate model chart certainly confirms why expert computer climate simulations are held in such contempt and ridiculed; and also why they should not be utilized for policy work performed by politicians and bureaucrats.
The failure of climate models at what they were originally intended to accomplish has forced the major climate research agencies into a constant state of both "upgrading" their wildly expensive climate models and "correcting" past actual temperature measurements.
This particular model was instrumental in starting the egregious and shrill propaganda war against economic growth and prosperity way back in 1988. It's creation has led to the point where today teenage doomsday cult personalities are provided top-level platforms to fear-rant - by those who should know better - to rail against the bountiful wonders of modern civilization.
This NASA model has had a long history being wrong, and when correct at specific periods, it's due more to blind luck of the natural temporary El Niño global warming phenomenon, which is not sustainable over lengthy time spans.
The model chart presents three simulated global temperature scenarios that portray the end result of growing greenhouse gas emissions, with the focus on fossil fuel CO2 emissions. The scenarios developed by NASA include:
Scenario 'A': The business-as-usual (BAU) scenario that represented total emissions growing without any constraints.
Scenario 'B': Representing the reduction of total emissions by moderate amounts.
Scenario 'C': Representing a scenario that had global emissions being maintained in the future at year 2000 levels.
As the observed NASA and HadCRUT global temperature plots on the chart reveal, the observed temperatures are not anywhere close to NASA's BAU scenario 'A'. Yet, as can be seen below, it's continued to be business-as-usual for a very long time, at least since the 1988 introduction of this model to the public.
This December 2019 article lays out the essentials of past greenhouse gas growth and the continuing growth of CO2, which shows no signs of a permanent global curtailment.
In summary, this NASA/GISS model was never an effective tool for climate change prediction, let alone establishing a realistic national or global policymaker climate strategy. And over the decades since 1988, all the later generations of climate models have been no better as they also way over estimate the warming impact of greenhouse emissions.
Prior climate model postings. Additional climate model charts.