Thursday, December 07, 2023

Climate science and the Montana climate lawsuit

by Jerry Elwood
| September 7, 2023 12:00 AM

In his Aug. 23 guest opinion article about Montana Republicans losing the Held v Montana climate lawsuit, Ed Berry suggests that if Montana’s attorney general had presented Berry’s story of climate science to the court, the presiding judge would have ruled in favor of the state instead of the plaintiffs.

But his story is refuted by a vast body of published scientific evidence on the subject that he either willfully ignores, misinterprets, or misrepresents.

Berry suggests that Montana lost the climate lawsuit because the state’s assistant attorney general acknowledged, for the purpose of the case, the scientific consensus that global warming is a direct result of greenhouse gas emissions from human activities. It’s a consensus Berry refuses to accept. Instead, he chooses to believe the cause is due mostly to natural emissions.

But he offers no credible scientific evidence to support his belief.

He ignores the fact that annual increases in atmospheric CO2 are consistently less than the annual emissions from human activities alone. The only logically deduction to draw from this fact is that nature is absorbing more CO2 from the atmosphere each year than it emits. It is acting as a net global sink of atmospheric CO2, not a source. And direct measures of CO2 uptake by both the oceans and terrestrial biosphere confirm this fact.

Berry holds a mythical belief that human emissions can’t be the cause of increasing atmospheric CO2 because human CO2 accounts for only a small fraction of the CO2 present in today’s atmosphere. His reasoning defies common sense, is scientifically baseless, and is logically flawed.

First, his assertion that IPCC carbon cycle data show human CO2 is only 8% of today’s atmospheric CO2 is false. In fact, IPCC data show no such thing.

The reason is the fraction of CO2 in the atmosphere today — or at any time — that originated from human activities is unknowable because CO2 molecules emitted from human and natural sources are indistinguishable from each other.

Secondly, were it even possible to measure the fraction, it would not tell you how much human emissions are contributing to the rise in atmospheric CO2. This is because the fraction of atmospheric CO2 that originated from human vs natural sources is continuously altered by exchanges of CO2 between the atmosphere and the ocean and land.

Lastly, Berry’s argument is a logical fallacy because it is based on a false premise that a proportionally small amount of material, i.e., small fraction of atmospheric CO2 that originated from human activities, can’t have a large effect on a system, i.e., can’t be the source of rising atmospheric CO2.

Another of Berry’s bogus arguments is that because atmospheric CO2 continued to increase in the pandemic year of 2020 while global CO2 emissions exhibited a large decline, human emissions don’t control atmospheric CO2. His argument is based entirely on his incorrect claim that global CO2 emissions from human activities in 2020 declined by 20%. The actual decline in emissions in 2020, however, was only 5.4 %.

Moreover, the increase in atmospheric CO2 in 2020 was within the normal range of its year-to-year variation, which is caused by annual variation in both human CO2 emissions and environmental factors and natural processes that affect the net absorption of CO2 from the atmosphere.

It’s well documented that atmospheric CO2 increased by 2.0 parts per million (ppm) in 2020. This increase was almost the same as the average growth rate of CO2 during the first decade of the 21st Century. Further, CO2 increased by 2.5 ppm in 2019, by 2.0 ppm in 2014, and by 3.0 ppm in 2017. Thus, despite the 5.4% reduction in CO2 emissions globally from human activities in 2020, the increase in atmospheric CO2 in that year was not markedly different from that in years prior to the pandemic. And while the 2020 decrease in global CO2 emissions from human activities reduced the increase in atmospheric CO2 in that year compared to what it would have likely been without the pandemic, it didn’t stop the increase.

This means the decrease in human-caused emissions in 2020 due to the Covid pandemic was too small and too brief to cause a significant reduction in the growth of atmospheric CO2. Human emissions continued to be the cause of the increase, and Berry’s claim that they aren’t the primary control of atmospheric CO2 levels is scientifically baseless.

But Berry would rather purvey misinformation about the cause of rising atmospheric CO2 than acknowledge this fact.

Montana’s attorney general has indicated his intent to appeal the Held v Montana decision of the court. But neither his appeal nor its outcome will change the scientific fact that emissions of greenhouse gases, especially CO2, from human activities are driving climate change at global, regional, and local scales.

It begs the question of whether individuals, societies and governments in this country and abroad will find the necessary collective will to do what is needed to change this trajectory.

Jerry Elwood lives in Kalispell.

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