A new study from The University of Alabama in Huntsville addresses the most crucial of all climate questions: How much warming can be expected from adding carbon dioxide to the atmosphere?
UAH Earth System Science Center Research Scientist Dr Roy Spencer and UAH Earth System Science Center Director and Alabama State Climatologist Dr John R. Christy have spent the past decade developing a climate model to answer this very question.
Their latest research, “Effective climate sensitivity distributions from a 1D model of global ocean and land temperature trends, 1970–2021”, was published in the September 2023 issue of Theoretical and Applied Climatology.
Spencer and Christy’s comprehensive climate model, which is based upon objective measured data, found that carbon dioxide does not have as big of an effect of warming of the atmosphere when compared with other IPCC-backed models.
“For over 30 years, dozens of highly sophisticated computerized climate models based upon theory have been unable to agree on an answer. That’s why we developed our own one-dimensional climate model to provide an answer,” said Dr Spencer.
Today’s climate models are not in agreement when it comes to the level of warming produced by a doubling of atmospheric carbon dioxide–what’s known as “effective climate sensitivity.” Despite mainstream proclamations of ‘settled science’, determining this crucial factor has remained elusive for decades.
While the current range rides as high as +5.6C for a doubling of CO2, Spencer and Christy’s one-dimensional climate model comes in near the bottom-end, at just +1.9C. The lower UAH value indicates that the climate impact of increasing carbon dioxide concentrations is much less that that based on other climate models, reports phys.org.
“An important assumption of our model, as well as the more complex models used by others, is that all climate change is human caused,” said Spencer, carefully wording: “If recent warming is partly natural, it would further reduce climate sensitivity.”
What distinguishes this model developed at UAH from others is that it is driven by actual observations, rather than theoretical assumptions about how the climate system responds to increasing greenhouse gases — the only logical way to conduct such a model.
The UAH model uses a variety of observational datasets between 1970 and 2021 of the deep ocean and land. These datasets produced a range of estimates of climate sensitivity based upon basic concepts of energy conservation.
The results of Spencer and Christy’s research showed a period of the most rapid growth in atmospheric carbon dioxide, continues phys.org. This is due to their climate model accounting for heat storage in deeper layers of land, which other climate models ignore.
“This should be a requirement that any physics-based model of global warming should meet,” Spencer asserted. “Current computerized climate models continue to have difficulty achieving this aspect.”
“If we assume ALL *observed* warming of the deep oceans and land since 1970 has been due to humans, we get an effective climate sensitivity to a doubling of atmospheric CO2 of around 1.9 deg. C. This is considerably lower than the official *theoretical* model-based IPCC range of 2.5 to 4.0 deg. C.”