September 21, 2020 | David F. Coppedge

Unknowns Found in Climate Change Models

“Follow the science!” the consensus demands, and many politicians fall in line to look good. These stories cast doubt on the science.

As a major US election draws near, politicians are taking their party’s sides on matters of science (so-called). One of the most heated controversies involves global warming or “anthropogenic climate change”. Democrats tend to line up with the consensus, and Republicans maintain the right to doubt. On September 14, California governor Gavin Newsom (Democrat) gently rebuked President Trump (Republican) about this matter, and Trump meekly suggested that scientists may not know all the science. Newsom undoubtedly felt secure in his position by trusting in the powerful international consensus. Trump, it is well known, took the US out of the Paris Climate Accord, to the horror of Europeans and American Democrats. Newson blamed the wildfires on climate change (e.g., BBC’s position); Trump blamed them on bad forest management (e.g., Prager U video). Who’s right? Who knows?

Keep in mind that the real question is not global warming per se; it could be a natural cycle. The question is to what extent humans are causing it with carbon emissions.

Readers are free to pick whatever position they feel is best supported by the evidence; CEH does not take a firm position on the issue, other than to make two observations: (1) the same ones believing the consensus about climate change also overwhelmingly (but not uniformly) tend to believe the consensus about Darwinian evolution (see Bergman, 26 March 2020); and (2) from our vantage point of daily reading the journals and news, the science is not as settled as the consensus says it is. We have documented this fact several times over the years from papers in leading journals (see big rethink last month, 8 Sept 2020). The first observation touches on the sociology of science. The second observation touches on the philosophy of science. Both of those disciplines overlap with CEH’s primary focus on origins. That makes this important subject worth looking into.

New findings continue to cast doubt on what climate scientists know. It’s hard to find papers critical of anthropogenic global warming, given the social and political power behind the consensus field and the difficulty of getting funding if a researcher adopts a maverick position. Nevertheless, these findings seem to cast significant doubt about what climate scientists think they know.

Volcanic ash may have a bigger impact on the climate than we thought (University of Colorado). Climate models assume that particles from volcanic ash fall out of the atmosphere at a particular rate. This team found that particles stay aloft much longer than thought. This is significant because atmospheric particles cool the climate. It’s clear they were not trying to buck the consensus, because they found this phenomenon by chance.

When volcanos erupt, these geologic monsters produce tremendous clouds of ash and dust—plumes that can blacken the sky, shut down air traffic and reach heights of roughly 25 miles above Earth’s surface.

A new study led by the University of Colorado Boulder suggests that such volcanic ash may also have a larger influence on the planet’s climate than scientists previously suspected.

The new research, published in the journal Nature Communications, examines the eruption of Mount Kelut (or Kelud) on the Indonesian island of Java in 2014. Drawing on real-world observations of this event and advanced computer simulations, the team discovered that volcanic ash seems to be prone to loitering—remaining in the air for months or even longer after a major eruption.

“What we found for this eruption is that the volcanic ash can persist for a long time,” said Yunqian Zhu, lead author of the new study and a research scientist at the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder.

Pyroclastic flows and ash from Mayan volcano, Philippines 1984. (WikiBooks)

The paper in Nature Communications (open access) begins with a rather embarrassing admission. “Volcanic ash is often neglected in climate simulations because ash particles are assumed to have a short atmospheric lifetime, and to not participate in sulfur chemistry.” The team looked at a major eruption from Mt. Kelut in Java, and another in Alaska, and found that both assumptions are wrong. Notice that major policy decisions at global climate conferences that affect the lives of potentially billions of people have been based on these erroneous assumptions.

In science, numbers matter. How big an effect are they talking about? The paper is not clear, because teasing out all the effects is difficult, with many factors to consider. What they do say is that their findings call for updates to the climate models trusted by the consensus:

Further studies of the heterogenous chemical reaction of SO2 on ash following other large and small eruptions are warranted since the ratio of ash to SO2 injections is variable. Also, climate models with higher resolution can reproduce the spread of volcanic ash and SO2 better. Finally, climate models need to better quantify the contribution of volcanic ash particles to the energy balance and heterogeneous ozone loss.

The press release treats this as something important:

Just what the impact of those clouds of ash are on the climate isn’t clear. Long-lasting particles in the atmosphere could, theoretically, darken and even help to cool the planet after an eruption. Floating ash might also blow all the way from sites like Kelut to the planet’s poles. There, it could kickstart chemical reactions that would damage Earth’s all-important ozone layer.

But the researchers say that one thing is clear: When a volcano blows, it may be time to pay a lot more attention to all that ash and its true impact on Earth’s climate.

“I think we’ve discovered something important here,” Toon said. “It’s subtle, but it could make a big difference.”

Climate is a hugely complex and dynamic system challenging to model for a year, let alone for centuries.




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