you're reading...

Climate Change

Pacific flushing leads to carbon dioxide surges

Article: Du, Haley, Mix, Walczak, and Praetorius, “Flushing of the deep Pacific Ocean and the deglacial rise of atmospheric CO2 concentrations” (2018), Nat. Geoscience, doi:10.1038/s41561-018-0205-6

The United States released its fourth National Climate Assessment in November this year (2018). Some of the dire warnings within this report remind us why it is important to understand climate change, including what can cause atmospheric CO2 increases.

Another recent publication that also looks at climate change comes from scientists at Oregon State University and the United States Geological Survey, but this time the scientists are discussing climate 19,000 to 9,000 years ago. This was a time on Earth when glaciers were melting and the climate was warming after the ice age of Pixar fame. In addition to being warmer, Earth’s atmospheric concentration of CO2increased by about 80 ppm (parts per million) during this time. For comparison, today’s atmospheric CO2 is ~410 ppm (https://www.CO2.earth/daily-CO2).

CO2 and temperature increase over the last deglaciation (PC: Jeremy Shakun)

It is not known exactly how this CO2increase post-ice age happened, but scientists have found evidence that a large amount of CO2dissolved deep in the Pacific Ocean was released during deglaciation. It is thought that the Southern Ocean, the ocean around Antarctica, played an important role in the CO2release. There are still a lot of unanswered questions though, and many of the ways scientists have previously used to study this phenomena give partially confusing results.

Wooley mammoths were around during the time period discussed here, but went extinct as the climate warmed. Rendition from wikipedia.org


One of these methods, radiocarbon dating, has been used to look at carbon in marine sediments (the mud at the bottom the ocean) to try to understand what causes this CO2spew from the Pacific. To explain a bit more, we should explain a bit about isotopes and radiocarbon. Isotopes occur when one element will have atoms with different numbers of neutrons. Though it sounds trivial, isotopes are used by lots of different types of scientists to investigate questions. A very common isotope that is used in oceanography is radiocarbon. Radiocarbon is a type of carbon atom with 2 extra neutrons compared to normal carbon. The radiocarbon turns into normal carbon at a known rate. This allows scientists to estimate the date of something by comparing the amount of radiocarbon versus the amount of normal carbon, i.e. radiocarbon dating. In the case of this study, the radiocarbon in sediment gives some information of how quickly water at the bottom of the Pacific was moving during this time. However, since there are many sources of radiocarbon to the deep Pacific, and these sources are associated with different ages, this is not always a good indicator of water movement. The Southern Ocean in particular has ‘old’ radiocarbon, which makes radiocarbon at the bottom of the Pacific look older than the water.

To get around this, a team of scientists led by Jianghui Du used a different method to look at how quickly or slowly water moved at the bottom of the Pacific during deglacial times. They examined neodymium (Nd) isotopes present in Pacific sediments from near Alaska. You might know Nd, element number 60, from the strong magnets you can make out of it. In this case, the authors used Nd isotopes to us how fast the water at the bottom of the ocean moved over the sediment. Then, the scientists used radiocarbon dating to figure out how old the water looked when it was moving along the bottom of the seafloor.

The Nd isotopes showed that water movement along the seafloor got faster, while the radiocarbon showed that the seawater was probably partially from the Southern Ocean (the ocean around Antarctica). This might have been because at this point, the Southern Ocean was getting warmer and the sea-ice was melting. The scientists think this means that the Southern Ocean water movement at least partially caused the ‘flushing’ of CO2from the Pacific Ocean into the atmosphere, but making water move faster and eventually make CO2come out from the bottom of the ocean and into the atmosphere.

Why do ocean movements thousands of years ago matter to us today? Well, as the world warms, we see some of the same events happening now as happened in the deglaciation – the Earth is getting warmer and sea ice is melting. But right now we are not sure what the future holds for the Pacific Ocean, which still holds a lot of CO2. Could we expect more CO2 from the Pacific to be released in the future? Or will the oceans and sediments hold more carbon and help mitigate climate change? There is no one answer that all researchers agree on, but hopefully more research in the future will help us know!



No comments yet.

Post a Comment


  • by oceanbites 2 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 3 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 4 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 5 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 7 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 8 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 9 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 9 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 9 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 10 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 11 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 11 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com