Shrinkage due to COVID-19 may provide case in point
Earth Institute at Columbia UniversityShare Print E-Mail
Volcanic eruptions and human-caused changes to the atmosphere strongly influence the rate at which the ocean absorbs carbon dioxide, says a new study. The ocean is so sensitive to changes such as declining greenhouse gas emissions that it immediately responds by taking up less carbon dioxide.
The authors say we may soon see this play out due to the COVID-19 pandemic lessening global fuel consumption; they predict the ocean will not continue its recent historic pattern of absorbing more carbon dioxide each year than the year before, and could even take up less in 2020 than in 2019.
“We didn’t realize until we did this work that these external forcings, like changes in the growth of atmospheric carbon dioxide, dominate the variability in the global ocean on year-to-year timescales. That’s a real surprise,” said lead author Galen McKinley, a carbon cycle scientist at Columbia University’s Lamont-Doherty Earth Observatory. “As we reduce our emissions and the growth rate of atmospheric carbon dioxide slows down, it’s important to realize that the ocean carbon sink will respond by slowing down.”
The paper, published today in the journal AGU Advances, largely resolves the uncertainty about what caused the ocean to take up varying amounts of carbon over the last 30 years. The findings will enable more accurate measurements and projections of how much the planet might warm, and how much the ocean might offset climate change in the future.
A carbon sink is a natural system that absorbs excess carbon dioxide from the atmosphere and stores it away. Earth’s largest carbon sink is the ocean. As a result, it plays a fundamental role in curbing the effects of human-caused climate change. Nearly 40 percent of the carbon dioxide added to the atmosphere by fossil fuel burning since the dawn of the industrial era has been taken up by the ocean.
There’s variability in the rate at which the ocean takes up carbon dioxide, which isn’t fully understood. In particular, the scientific community has puzzled over why the ocean briefly absorbed more carbon dioxide in the early 1990s and then slowly took up less until 2001, a phenomenon verified by numerous ocean observations and models.
McKinley and her coauthors addressed this question by using a diagnostic model to visualize and analyze different scenarios that could have driven greater and lesser ocean carbon uptake between 1980 and 2017. They found the reduced ocean carbon sink of the 1990s can be explained by the slowed growth rate of atmospheric carbon dioxide early in the decade. Efficiency improvements and the economic collapse of the Soviet Union and Eastern European countries are thought to be among the causes of this slowdown.
But another event also affected the carbon sink: The massive eruption of Mount Pinatubo in the Philippines in 1991 caused the sink to temporarily become much larger coincident with the eruption.
“One of the key findings of this work is that the climate effects of volcanic eruptions such as those of Mount Pinatubo can play important roles in driving the variability of the ocean carbon sink,” said coauthor Yassir Eddebbar, a postdoctoral scholar at Scripps Institution of Oceanography.
Pinatubo was the second-largest volcanic eruption of the 20th century. The estimated 20 million tons of ash and gases it spewed high into the atmosphere had a significant impact on climate and the ocean carbon sink. The researchers found that Pinatubo’s emissions caused the ocean to take up more carbon in 1992 and 1993. The carbon sink slowly declined until 2001, when human activity began pumping more carbon dioxide into the atmosphere. The ocean responded by absorbing these excess emissions.
“This study is important for a number of reasons, but I’m most interested in what it means for our ability to predict the near-term, one to ten years out, future for the ocean carbon sink,” said coauthor said Nicole Lovenduski, an oceanographer at the University of Colorado Boulder. “The future external forcing is unknown. We don’t know when the next big volcanic eruption will occur, for example. And the COVID-19-driven carbon dioxide emissions reduction was certainly not anticipated very far in advance.”
Investigating how the Pinatubo eruption impacted global climate, and thus the ocean carbon sink, and whether the drop in emissions due to COVID-19 is reflected in the ocean are among the research team’s next plans.
By understanding variability in the ocean carbon sink, the scientists can continue to refine projections of how the ocean system will slow down.
McKinley cautions that as global emissions are cut, there will be an interim phase where the ocean carbon sink will slow down and not offset climate change as much as in the past. That extra carbon dioxide will remain in the atmosphere and contribute to additional warming, which may surprise some people, she said.
“We need to discuss this coming feedback. We want people to understand that there will be a time when the ocean will limit the effectiveness of mitigation actions, and this should also be accounted for in policymaking,” she said.
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The study was coauthored by Amanda Fay and Lucas Gloege of Columbia University’s Lamont-Doherty Earth Observatory.
So I looked at the data. Mt Pinatubo’s effect is not visible on the graph, and must be smaller than 1/4 of the seasonal cycle. Therefore, this whole paper is meaningless since the data they use to calibrate their pile of models isn’t significant. To be meaningful, you would have to take the raw CO2 data, indicate eruptions and quantities of CO2 emitted without knowing this information ahead of time, and show that these values match historical data and our best estimates of CO2 emitted by these volcanoes (hopefully based on some real samples). Then your model might have some validity and you could calculate the slight change in the ocean’s take-up due to the human-caused slight change in CO2 production.
Ralph Keeling from Mauna Loa was interviewed: “Based on calculations of how many fewer tons of carbon dioxide would be added to the atmosphere if there were a sustained 10-percent decline, Keeling estimated CO2 levels in the atmosphere would deviate by roughly 0.5 ppm under that scenario”. So we have to wait one year? – No! – Ten years ago only 90% of today’s carbon dioxode was added. Both then and now the the accumulation in the atmosphere was/is 2 ppm per year. – His model fails. Where does the missing 0.5 ppm come from? From the sea water?
This is transparent political BS as is clear to anyone with an IQ larger than their shoe size. It’s as 100% fabricated as Surgisphere epidemiology. This is Surgisphere climatology – made up to order for a political message-du-jour. Falling CO2 from coronavirus can’t possibly lead to anything good, so make up data quick to get ahead of that narrative and stop it gaining traction. Repulsive and pathetic.
This paper has the comical feel of Fawlty Towers desperation about it. Any good news story involving CO2 has to be stamped out no matter what idiotic deceit and fabrication is needed. Black comedy at its best.
Possibly, the positive outcome of present pandemic is nature getting nurtured.Hope it continue in future as well
“The ocean is so sensitive to changes such as declining greenhouse gas emissions that it immediately responds by taking up less carbon dioxide”
This is a fancy way of saying that we can’t measure carbon cycle flows and that therefore we don’t really know these flows well enough to detect the effect of relatively small CO2 flows from fossil fuel emissions.
https://tambonthongchai.com/2018/05/31/the-carbon-cycle-measurement-problem/
And that is why we don’t have any empirical evidence that atmospheric composition is responsive to fossil fuel emissions.
https://tambonthongchai.com/2018/12/19/co2responsiveness/
And yet the whole of the basis for AGW climate change and climate action is based on this imagined relationship i which fossil fuel emissions change atmospheric composition.