A carbon sink shrinks in the arctic

UD researchers show Canada Basin’s diminished capacity to absorb carbon dioxide

University of Delaware

IMAGE
Melting ice in the Arctic Ocean is a bellwether for climate change, an apt illustration of environmental changes in a warming world. view more  Credit: Photo courtesy of Zhangxian Ouyang

New research by University of Delaware doctoral student Zhangxian Ouyang and oceanographer Wei-Jun Cai, and an international team of researchers, demonstrates that rapid warming and sea-ice loss have induced major changes in the western Arctic Ocean.

The research team’s findings — published Monday, June 15 in Nature Climate Change — show that the Arctic Ocean’s ability to remove carbon dioxide from the atmosphere can vary greatly depending on location.

Arctic Ocean sea-ice loss is a critical consequence of climate change. As sea ice continues to melt in the western Arctic Ocean, more fresh water is entering the upper portion of the water in the Canada Basin, which sits off the coast of Alaska and Canada, south of the Chukchi Shelf.

This summertime melt cycle is exacerbating seasonal changes and increasing the amount of carbon dioxide present in the water’s topmost layer, which comprises the upper 70 feet of the water column. This is reducing the basin’s capacity to remove carbon dioxide from the atmosphere.

Prevailing thought, based on data measurements from under the ice and in newly melted ocean margin areas in the 1990s and early 2000s, had suggested that when the ice melted it would allow the Arctic Ocean to draw large amounts of carbon dioxide out of the atmosphere, acting as a carbon sink and helping to mitigate greenhouse gases. However, this may not be the case in all places, particularly in the Canada Basin where summer ice retreat has advanced into the deep basin since 2007.

The research team’s latest findings are based on an analysis of over 20 years of global data sets collected between 1994-2017 by researchers across the United States, China, Japan and Canada. They provide a more accurate depiction of what is happening in this region and build on Cai’s previous work from 2010, which indicated that carbon dioxide levels at the sea surface increase rapidly and unexpectedly toward levels found in the atmosphere in newly ice-free Arctic Ocean basins.

For example, the research team’s work showed that as the ice breaks up and melts in the Canada Basin, this meltwater lays on top of the sea surface, creating a “blanket” of sorts that inhibits the ocean’s ability to absorb carbon dioxide from the atmosphere into the deep ocean and store it there. Cai’s team refers to this phenomenon as a “new normal” that is created by extreme seasonal warming and meltwater in the region.

“As carbon dioxide accumulates in the surface layer of the water from melting ice, the amount of carbon dioxide this area of the Arctic Ocean can take from the atmosphere will continue to shrink,” said Cai, the Mary A.S. Lighthipe Professor in the College of Earth, Ocean and Environment. “We predict by 2030, the Canada Basin’s ability to serve as a carbon sink will be really minimal.”

Additionally, this rapid increase of carbon dioxide content in the basin may have rapidly acidified the surface water, a process that can endanger marine calcifying organisms and disrupt ecosystem functioning there.

In stark contrast, farther south in the shallow Chukchi Sea, the amount of carbon dioxide in the water’s topmost layer remains very low, much lower than what is present in the atmosphere. This means that as air passes over the water’s surface, the sea can more quickly absorb carbon dioxide from the air.

The researchers suggest that this difference is the result of high biological production in the Chukchi Sea due to rich nutrients being transported there on currents coming from the Pacific Ocean since the Bering Strait has opened up due to earlier ice loss. These nutrients enable abundant growth of phytoplankton and other marine organisms that form the base of the marine food web and feed the broader ecosystem. Phytoplankton also consume carbon dioxide dissolved in the water during photosynthesis, allowing more carbon dioxide to be taken from the surrounding atmosphere.

The research team suspects that the Chukchi Sea will become a larger carbon sink in the future and impact the deep ocean carbon cycle and ecosystem, while the Canada Basin likely will remain less so as sea ice in the region continues to melt and change the water chemistry.

According to Lisa Robbins, a retired senior scientist with the United States Geological Survey (USGS) and a co-author on the paper, these changes could have important implications for organisms in the Arctic. For instance, Arctic cod is an important fishery in the western Arctic that contributes to the region’s overall economy and serves an important role in the marine food web as a food source for other organisms, such as Beluga whales and ringed seals. Biologists have noted that as temperature and sea ice melt have increased, Atlantic cod are responding by moving farther north. Changing water chemistry also may be playing a role, said Robbins, who led three expeditions to study the region’s water chemistry in the Arctic aboard the United States Icebreaker R/V Healy while with the USGS.

Long-term data sets, such as those used in this study, are key to understanding and predicting future changes in the Arctic.

“The amount of insight we get from these data sets into how our earth-ocean works is tremendous. If scientists hadn’t collected data in 1994, we wouldn’t have a place to start and compare with,” said Robbins, now a courtesy professor in the College of Marine Science at University of South Florida.

A 2019 article in Wired magazine found that in northern Canada near Greenland, glacial meltwater seems to be aiding watersheds in absorbing carbon dioxide from the atmosphere. While alone it cannot counterbalance the amount of carbon dioxide in the atmosphere due to carbon emissions, it is an important illustration that the changes aren’t uniform and the subsequent effects — positive and negative — are the result of a complex combination of multiple different drivers. Further research and more international collaborative efforts can help to answer challenging unanswered questions.

As sea-ice loss accelerates, the researchers expect these seasonal variations will cause the ocean water in the Canada Basin to have high levels of carbon dioxide and become increasingly acidic. This will further reduce the basin’s capacity to take up carbon dioxide from the atmosphere and potentially reduce its capacity to mitigate climate change.

While this problem might seem very far away from Delaware, it’s important to remember that the ocean is one global system with circulation currents that transport water around the world, even to the Atlantic Ocean on the East Coast. And greenhouse gases are a global issue.

Understanding how fundamentally important ice melt is to driving carbonate chemistry and seasonal changes in carbon dioxide in this region of the Arctic Ocean will help advance the science in this area, maybe not immediately but over the long-run, said Cai.

“We are trying to understand the processes at work and if the Arctic Ocean will continue to be a large carbon sink, while providing data that can help Earth systems modelers to predict global changes to the carbon cycle, and the ocean’s biology and water chemistry,” Cai said.

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This work is funded by multiple nations, including Cai’s work which is supported through the National Science Foundation’s Arctic Natural Science Program.

Co-authors on the paper include researchers at The Third Institution of Oceanography (China), Columbia University, University of Montana, Ocean University of China, Japan Agency for Marine-Earth Science and Technology, University of South Florida and the International Arctic Research Center.

From EurekAlert!

33 thoughts on “A carbon sink shrinks in the arctic

  1. It always amazes me how the AGW promoters are always right as proven by their research. You’d think by now they could turn lead into gold.

    • Yes, the Climate Alarmists are really trying to practice Alchemy, turning leaden weather into golden climate…

    • They have turned charter into gold. After all, Mark, the UN Did set up the IPCC to go forth and find an adverse link between man and his environment. Was it 1988? And the IPCC still exits nearly half way into their 3rd decade with a significant taxpayer budget despite the fact that they have proven, beyond any Skeptics doubt, that the climate is changing and it is all of us taxpayers who are to blame.

      Lots of bureaucratic hangers on have also improved their net worth position thanks to this
      Chrysopoeia where you turn federal credit card debt into assets for ex politicians like ALGORE the lab assistant to Dr. Frankenstein 2000.

  2. This summertime melt cycle is exacerbating seasonal changes and increasing the amount of carbon dioxide present in the water’s topmost layer, which comprises the upper 70 feet of the water column. This is reducing the basin’s capacity to remove carbon dioxide from the atmosphere.

    What exactly am I missing here…
    Because increasing Arctic Ocean open water area is INCREASING the amount of CO2 present in the waters topmost layer it is REDUCING the capacity to absorb more.

    So in short, the Arctic ocean can’t absorb more CO2 because it has absorbed more CO2

  3. Oh dear!! Not another load of armchair surmises and conjectures based on erroneous assumptions, such as the arctic ice melt is accelerating etc. I wonder how much this article cost to produce. Quite a few expensive grants involved here methinks.

  4. Doesn’t the consensus claim that relative land and ocean sinks are 50/50? Doesn’t the consensus also claim that net natural flux is perfectly balanced at most time scales? That sounds realistic (sarc.).

  5. And exactly how much CO2 passes through the sea ice that has not melted and into the water column below? I’m thinking floccinaucinihilipilification.

  6. The Arctic Oceans sink ability is not being reduced. The cold open water will always be a sink and the area of the open water increases as the ice melts. This change in area should more than compensate for the difference in solubility between fresh and salt water. Even if not, the big Arctic sink is only being moved a little further South where there are phytoplankton blooms.

  7. ‘…as sea ice loss accelerates.,,,,’. Oh dear. Surely they’ve noticed ice at third week in September has been above four million sq km since 2007 (save 2012). They must be lying.

  8. Are they showing this data and how it was collected? I am sceptical.
    I am imagining extrapolation based on assumptions. Not actual measurement of what is claimed.

  9. Went to the source. Found this: “The code used for 𝑝CO2 simulations is available in the Supplementary Information. R programming software was used to generate all the results. As I surmized it’s all modelling. Assumptions in = climate change out.

  10. Lets see if I’ve got this right. So, if the ice melts, it creates a fresh water layer that traps the dissolved CO2, preventing its getting into the salt water, so this means less CO2 sequestering by the seawater. Check!

    So if the ice does NOT melt, this prevents atmospheric CO2 from getting into the seawater, so this means less CO2 sequestering by the seawater. Errr..Check!

    So, whether it melts or not, less CO2 can be sequestered in the seawater. I can see, I’m going to need re-education in the camps if I don’t get to understand this Post Normal Science.

  11. Change? Data from 1994 to 2917, or 23 years of a variable collection of different data types? 23 years is a popcorn fart on the timescale of us geologists.

  12. “As sea-ice loss accelerates, the researchers expect these seasonal variations will cause the ocean water in the Canada Basin to have high levels of carbon dioxide and become increasingly acidic.”

    Not even wrong.

    • To me, it’s like they completely ignore the biology of what is happening to that dissolved CO2 and how phytoplankton blooms and increasing as well. The Arctic is undergoing an explosion of life that is feeding the entire food chain there. Thank you Mr CO2. Can we have some more, please?

  13. Unfortunately for these climate dowsers the observations of CO2 seasonal cycles in the Arctic shows the opposite is actually happening in the atmosphere above the sea (where it matters for the GHE). The Arctic overall is continuing to expand its CO2 sink rate uptake as fossil fuels burning does push the secular (annual) CO2 trend upwards.
    This can be seen in NOAA/ESRL’s data in several ways.
    One way to see this increasing sink rate of the Arctic is in thius NOAA/ESRL graphic:

    https://www.esrl.noaa.gov/gmd/ccgg/about/gm_figure4.png
    This graphic depicts latitudinal distributions for 16 September 1980 and 2009. Those 29 years of course depicts the high mark for Arctic Sea ice (1980) and a low mark period (2009). 1980 difference between the equatorial reading (339 ppm) to the Arctic (333 ppm) is a 1.7% differential (delta 6 ppm over a 339ppm base). The 2009 difference is delta 8 ppm over a 386 ppm, or 2.1% differential. The differential is increasing between those periods, implying the Arctic sink rate has increased.

    Another way to see this increasing Arctic CO2 sink rate is in NOAA’s de-trended CO2 data from their Barrow Alaska station data.

    https://www.esrl.noaa.gov/gmd/ccgg/mbl/crvfit/figure8.png
    The above graphic shows the seasonal CO2 amplitude for each year is determined by finding the maximum value of the detrended cycle minus the minimum value of the detrended cycle. In 2000, the seasonal max(above trend, using smoothed red line) was +2.8 ppm, the seasonal min (below trend) was a-10.1ppm, a difference = 13.9 ppm. By 2011, the seasonal max was +3.0 ppm, the min was -11.7 ppm, a difference of 14.7 ppm in 11 years. Although this graphic ends at 2012, we can look at the data to 2018 and see that the seasonal difference is around 19 ppm. The sink rate is continuing to increase as the underlying trend (annual) increases.

    Conclusion, using actual measured data for 40 years (1980 thru 2019) the Arctic CO2 observed sink rate is increasing. This is telling us the sinks are expanding their ability to absorb CO2 during the summer growing season when sea ice is a minimum. Whatever the UD researcher’s computer computer models about the Candian basin sea are either wrong or they don’t matter in the bigger picture. The Arctic is continuing to expand its ability to take up increasing levels CO2.

    • Very interesting Mr O’Bryan, thanks for that.

      I was trying to wrap my layman’s brain around this last night, turns out melt water, sea water and sea ice interactions are more complicated than I had previously thought.

      Anyway with the Canadian Basin covered with ice for around 9 months of the year, I’ve added this computer model prediction to my “probably has very little real world interest” list.

  14. 1. They still haven’t shown us this dramatic ice loss in the Arctic. What we see is oscillating and cycle-bound changes across the years.

    2. I have a puzzle as to how Arctic ice loss is meant to change the climate – apparently as they lose ice (in their models anyway) it changes the albedo of Earth because ice reflects away more light.
    The problem with this is all that ice is well above 71° latitude. My understanding from high school is that 71° is the critical angle for water to reflect instead of refract – I would imagine, except for the vertical rise of ice sticking up above the water, it is the same for ice.

    Now, near as I can tell, that means loss of ice in the Arctic will COOL the Earth because instead of vertical rise of ice, you have more water and virtually all the light will be reflected and not absorbed. So as the ice melts, we would lose the small amount of light being absrobed by the vertical rise of ice.

    Is there a fault in my reasoning here that someone can explain?

  15. “Additionally, this rapid increase of carbon dioxide content in the basin may have rapidly acidified the surface water, a process that can endanger marine calcifying organisms and disrupt ecosystem functioning there.”

    “May have rapidly acidified the surface”? Can they not measure the PH of the surface water and know for sure instead of just making a conjecture? Is it all models now, no observations allowed?

  16. Melting ice in the Arctic Ocean is a bellwether for a centennial solar minimum. So any reduction in CO2 uptake there and in the warmer North Atlantic is effectively a negative feedback.

  17. “Arctic Ocean sea-ice loss is a critical consequence of climate change.”
    or
    “Arctic Ocean sea-ice loss is a normal consequence of ocean cycles.”
    Can prove or disprove either statement, which one is”more true”?
    The fact that the Arctic is warming faster than the global average seems to point away from a global cause.

    Are these numbers roughly true:
    Arctic ice loss 500 km^ 3 / year Canada Basin surface area 1,8E6 km^2
    5/1.8 E-4 km => 30cm/year

    Are the authors of that study trying to defend that there is a special surface meltwater over the Canadian Basin of 30cm or less, which remains mostly unmixed with the underlying sea water over the cause of a year?
    Maybe I misunderstand something here, but that seems unlikely.. was this article peer reviewed?

    • According to PIOMAS the annual Arctic ice volume loss is ~16,000 km^3.

      The low salinity layer (~50m) at the surface is separated from the deep water by a layer of rapidly changing salinity known as the halocline.

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