Volcanoes Have Greater Impact on Climate than Thought

Scientists know less about geological influences
on climate than the popular press claims

Volcano eruption in Tonga Jan 15, 2022. (Earth Observatory satellite, NASA)

The Hunga Tonga eruption of 15 Jan 2022 caught scientists off guard. It was huge – one of the biggest ever observed. Fortunately, it occurred in a relatively remote place in the South Pacific, so few people were affected. But its plume reached into the stratosphere, caused a bang that was heard halfway around the world, and generated a tsunami that reached distant continents. Now, Nature reported on June 22 that it triggered the most intense lightning ever recorded: 2,600 bolts per minute!

Volcanoes can be exceptionally violent events that affect the whole planet. Do volcanoes cause climate change? Many remember the eruption of Mt. Pinatubo in the Philippines in 1992 that lowered average temperatures by half a degree Celsius for two years. Believers in Deep Time admit that volcanoes caused climate swings in the past, and may have caused mass extinctions.

It’s hard to measure the effects from volcanoes, because they can cause cooling as well as warming: cooling from release of particulates like sulfur dioxide that reflects solar radiation, cooling from dust that forms cloud condensation nuclei that can increase precipitation, and warming from adding carbon dioxide (CO₂) and other greenhouse gases into the atmosphere.

Who’s to Blame?

A majority of scientists still strongly believe that humans are to blame for current warming trends, but that depends on imperfect models that use poorly-constrained inputs. The models cannot by definition account for “unknown unknowns” in the world. We occasionally report some of these as they are discovered (e.g., 22 Sept 2020). Is there a lag time between the discoveries and the updates to climate models? Most likely, yes—a significant lag. This would mean that today’s climate models and graphs touted by the media as “settled science” are already out of date by the time politicians gather at climate conferences.

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

Take a look at these new studies that suggest a greater role for volcanoes on climate than previously thought.

Research reveals sources of CO2 from Aleutian-Alaska Arc volcanoes (University of Alaska Geophysical Institute, 28 June 2023). Geophysicists at U of A in Fairbanks believe that the amount of CO₂ released by volcanoes during subduction has been underestimated. As usual, press releases like this do not like to say that current climate models could be off. Instead, they couch the findings in unoffending promises like, “The finding can improve long-term projections about Earth’s climate.” But look what they say:

A study led by a University of Alaska Fairbanks Geophysical Institute scientist has shown that volcanoes of the Aleutian-Alaska Arc return more subducted slab carbon to the atmosphere as carbon dioxide than previously thought….

“While we now have a fairly good idea of how much carbon is driven into Earth’s interior through subduction and how much is released to the atmosphere by volcanoes, we still have a lot to learn about what happens to the carbon after it is subducted and what fraction is returned to the atmosphere,” Lopez said.

Climate scientists had believed that most of the carbon in subduction zones is recycled down into the mantle. From gas measurements at 17 volcanoes in the Pacific ring of fire, Lopez and team estimated how much CO₂ is released into the air. It was more than thought.

Lopez and colleagues instead found that approximately 43% to 61% of sediment-derived organic carbon is returned to the atmosphere through volcanic degassing in the central Aleutians and that approximately 6% to 9% of inorganic carbon from the slab crust is returned to the atmosphere by degassing of western Aleutian volcanoes….

“These results indicate less carbon is returned to the deep mantle than we previously thought,” Lopez said. “These results help clarify our understanding of the fate of subducted carbon and can help improve global climate models.”

When will that happen? Are the climate activists even reading this report?

Effect of volcanic eruptions significantly underestimated in climate projections (University of Cambridge, 23 June 2023). As stated above, volcanoes can cause both cooling or warming, depending on the conditions. This press release reveals that small-scale volcanic eruptions—not just the big ones—have a larger effect on climate than previously thought. Climate models have not been taking this into account.

Researchers have found that the cooling effect that volcanic eruptions have on Earth’s surface temperature is likely underestimated by a factor of two, and potentially as much as a factor of four, in standard climate projections.

Notice the surprise in their reactions to the data:

“We found that not only is volcanic forcing being underestimated, but small-magnitude eruptions are actually responsible for as much as half of all volcanic forcing,” said Chim. “These small-magnitude eruptions may not have a measurable effect individually, but collectively, their effect is significant.

“I was surprised to see just how important these small-magnitude eruptions are – we knew they had an effect, but we didn’t know it was so large.”

The estimate, however, comes only from measurements of volcanic aerosols (dust particles) that have a cooling effect. The scientists mistakenly assume that the bulk of warming CO₂ in the atmosphere was emitted by humans. What do they really know about the net effect from volcanoes?

“Volcanic aerosols in the upper atmosphere typically stay in the atmosphere for a year or two, whereas carbon dioxide stays in the atmosphere for much, much longer,” said Chim. “Even if we had a period of extraordinarily high volcanic activity, our simulations show that it wouldn’t be enough to stop global warming. It’s like a passing cloud on a hot, sunny day: the cooling effect is only temporary.”

The researchers say that fully accounting for the effect of volcanoes can help make climate projections more robust. They are now using their simulations to investigate whether future volcanic activity could threaten the recovery of the Antarctic ozone hole, and in turn, maintain relatively high levels of harmful ultraviolet radiation at the Earth’s surface.

If they are wrong about the amount of carbon released into the atmosphere, like the first article claimed, then they have not looked at the whole picture.

Do Volcanoes Add More Carbon Than They Take Away? (EOS, 26 April 2023). Short answer: yes. Measurements at volcanoes in northeast China show more carbon is released into the atmosphere than buried in the mantle by subduction. The subtitle reads, “Slow carbon seep long after eruptions have ceased could shape the carbon cycle on geological timescales.”

The researchers found that the Changbaishan region is a small net carbon source. Every year, the region releases at least 600 more tons of carbon than it incorporates—about the amount that 41 average Americans put into the atmosphere on an annual basis. That seems small, but over geological timescales, the impact could be significant.

How trustworthy is that finding? It only comes from one location in China at a small volcano. How long would it take for scientists to measure every active volcanic zone on earth? And then, how long would it take for climate models to catch up?

The Changbaishan volcanic region is just one of many around the world, the researchers point out. Future work should examine wider areas to gain a full understanding of how volcanoes contribute to Earth’s carbon cycle.

Our reporting on climate change comes almost entirely from secular sources that strongly believe in anthropogenic global warming (e.g., 15 Oct 2022). When scientists within the consensus discover new unknowns and recalculate measurements that show significant errors, citizens need to ask journalists and politicians if they know about these things. If they don’t care, because the “science is settled” in their minds, then they are guilty of spreading misinformation.

This is another field where knowledge of the philosophy and history of science is valuable. Drop scientism in the trash where it belongs. Real world science is done by fallible humans who don’t know everything, and are strongly liable to groupthink. Search on “climate change” in these pages, and use our links and sources to evaluate the likelihood that the consensus is right. If you accept the consensus, at least you will be better informed. Uninformed opinion is the definition of prejudice.

For a different take on climate change, read Bjorn Lomborg’s latest article at Imprimis from Hillsdale College, “Thinking smartly about climate change.” Lomborg accepts that the climate is warming and that it is a problem, but he gives some numbers about history and policy that can inform a well-rounded position.