you're reading...

Climate Change

A Small Pool Makes a Big Splash

Reviewing: Dang, H., Jian, Z., Wang, Y., Mohtadi, M., Rosenthal, Y., Ye, L., … & Kuhnt, W. (2020). Pacific warm pool subsurface heat sequestration modulated Walker circulation and ENSO activity during the Holocene. Science advances, 6(42), eabc0402.

Global Warming Took a Hiatus

In the early 2000s, the public was just beginning to actively engage with the idea that burning fossil fuels was disrupting the climate and could have devastating consequences (think Al Gore and the Kyoto Protocol). Coincidentally, it was right around then that the trend of rising global temperatures that had been visible for the past 50 years suddenly flattened for a bit. This apparent “Global Warming Hiatus”, which lasted from 1999 to 2013, created much debate among climate scientists and was used as ammunition by climate denialists that climate change itself was a hoax. 

After 2013, the warming trend of global temperatures continued. 2016 was the warmest year ever recorded. However, climate scientists are still actively trying to understand the cause of the Global Warming Hiatus.

Global temperatures based on multiple sources of the last 150 years with the Global Warming Hiatus shaded in grey (Image Credit: NASA; UC Berkeley)

Current theories to explain the hiatus propose that the ocean played a role in offsetting surface warming. Because water has such a high heat capacity, it can absorb the excess heat energy produced from global warming and store it below the ocean’s surface. This has motivated oceanographers to study how the ocean’s heat storage has changed in the past, and what’s behind those changes. 

The Indo-Pacific Warm Pool: Earth’s Hot Tub

The Indo-Pacific Warm Pool (IPWP) is the ocean’s largest body of high-temperature waters. Because of all the heat energy stored in the waters here, oceanographers are interested in learning how this warm pool has changed over time. In a recent study, a group of oceanographers reconstructed the history of the IPWP over the last 25,000 years to understand how its heat capacity affects the climate.

The Indo-Pacific Warm Pool (IPWP) is defined based its warm seawater temperatures (Image Credit: NOAA Climate.gov)

To do this, the authors analyzed more than 30 sediment core samples retrieved from the ocean floor in the Indo-Pacific region. Within each sediment sample, the scientists picked out tiny fossil shells of amoebas that had once lived in the shallow warm waters of the Indo-Pacific. By carefully analyzing the elemental concentrations within the shells of these ancient amoebas, the scientists were able to reconstruct the temperature of seawater that the amoebas once lived in. They compiled multiple records to create a holistic view of temperature in the IPWP. 

Earth’s Wobble, El Nino, and the IPWP

So what did this compiled record of seawater temperature look like? Researchers were interested to find two distinct peaks of warming: one at around eleven thousand years ago, and another at roughly six thousand years ago. This provides strong evidence that the IPWP heat storage was influenced by the precession and obliquity of the Earth’s axis. 

Now you might be wondering what “precession” and “obliquity” are. Imagine that the Earth is like an old-fashioned top, spinning as it orbits the Sun. Unlike most tops that spin around an axis that is straight up, the Earth’s rotational axis is tilted. This axial tilt, called obliquity, leads to uneven warming of the Northern and Southern Hemispheres. Obliquity accounts for why we have seasons. Precession, on the other hand, is the wobbling of the Earth’s rotational axis, like the wobbling of a top that is starting to slow down. This influences how extreme the seasons are in each hemisphere. Both the precession and obliquity of the Earth’s axis vary on timescales of tens of thousands of years. Variation in these factors impacts how much sunlight hits different parts of the Earth.

Diagram showing how obliquity and precession change the Earth’s rotation, which influences how much sunlight different parts of the Earth receives (Image Credit: The Skeptical Scientist)

Both the eleven thousand year and six thousand year record matched times when precession and obliquity were configured optimally to warm the waters that feed into the IPWP. Coincidence? Probably not. Instead, the alignment between obliquity, precession, and hot seawater conditions in the IPWP suggests that these factors are important to consider when thinking about climate variability on long timescales.

Not only did the scientists find a relationship between the IPWP temperatures and these orbital changes, but they also found a strong link between IPWP temperatures and El Nino strength. During periods of extreme warmth in the IPWP, the El Nino was a lot weaker and occurred less frequently. This is important because the El Nino is a significant climate pattern (see more here) that affects rainfall, storms, and ocean temperatures globally. 

The IPWP’s Role in Our Climate (And Our Future)

The strong influence of the IPWP’s temperatures on the El Nino might explain the global warming hiatus in the early 2000s. During El Nino years the eastern Pacific surface waters release a lot of heat to the atmosphere. If the IPWP is warmer, and the El Nino events are weaker, more heat storage is available in the eastern Pacific. That can result in an apparent reduction in global warming. As we continue to warm the IPWP due to climate change, we might expect even more hiccups in global air temperatures as the eastern Pacific temporarily sequesters more heat.  

This study shows just how complex our climate system really is, with feedbacks and mechanisms between the oceans, atmosphere, and land that we are just beginning to uncover. We will need the continual collaboration of scientists from all different backgrounds (chemistry, physics, biology, and computer science etc.) if we hope to accurately predict and mitigate the impacts of climate changes.


No comments yet.

Post a Comment


  • by oceanbites 4 weeks 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 2 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 3 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 4 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 4 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 4 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 4 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 5 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 5 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 6 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 6 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 6 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 6 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 7 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 7 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 8 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 8 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 9 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 10 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 10 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