//
you're reading...

Climate Change

Skating on Thin Ice

Reviewing Article: : Guarino, M. V., Sime, L. C., Schröeder, D., Malmierca-Vallet, I., Rosenblum, E., Ringer, M., … & Wolff, E. (2020). Sea-ice-free Arctic during the Last Interglacial supports fast future loss. Nature Climate Change, 1-5.

Twilight in the Arctic

Of all the environments being impacted by climate change, the Arctic is particularly susceptible. For the past few decades, sea ice in the Arctic has been melting at a staggering rate, so much so that it appears the disappearance of permanent Arctic sea ice is quickly upon us.

At the current rate that we are emitting CO2 and increasing the amount of heat we retain in the atmosphere, the debate in the scientific community is not if we will see an ice-free Arctic in the future, but when. Global climate models are one way scientists are developing a better understanding of sea ice loss in the Arctic. Dr. Guarino and colleagues recently published in Nature Climate Change results from a latest generation global climate model, called HadGEM3, that furthers our understanding of Arctic sea ice stability and overturn much of what we previously believed about our timeline for sea ice loss.

Late summer sea ice from 2019 compared to the late summer sea ice at the end of the 20th century in red, highlighting how much sea ice has retreated in just a few decades. (Image Source: NASA/Katie Jepson)

Global climate models like HadGEM3 simulate the oceans, atmosphere, land and ice of the entire Earth based on mathematical equations that describe the natural world (see example of a global atmospheric model here).

Schematic of global climate model. The Earth’s surface is divided into thousands of grids. In each grid, scientists model the important physical interactions (Image Source: NOAA)

As you might guess, these climate models are incredibly complex, requiring thousands of processors and hundreds of hours to run. We can test how accurate these models are by running simulations of past climate conditions and comparing their results to historical observations, a technique called “hindcasting”. Dr. Guarino and her team were confident in HadGEM3’s predictive abilities was because it performed much better than previous models in hindcasting the Last Interglacial, which spanned from 130 to 120 thousand years in past.

Simulating the Last Interglacial Period

So why did the researchers focus on validating their model during the Last Interglacial of all times? The reason is because the Last Interglacial was the most recent time in Earth’s history that the global climate was as warm as it is today. The Last Interglacial is therefore in some ways a good case study to test some of our predictions of global warming.

Based on microfossils found in marine sediments of the region, summers during the Last Interglacial were ice-free in the Arctic. This is supported by pollen and ice core records that also suggest a warmer, ice-free Arctic during this time. However, many models of the previous generation were unable to simulate ice retreat to this extent. In addition, these older models weren’t able to recreate air temperatures as cold as the pollen and ice core records suggested.

A Next Generation Climate Model

Dr. Guarino and others were eager to report that HadGEM3 was able to both simulate the loss of summer sea ice during the Last Interglacial as well as the warmer Arctic temperatures in agreement with paleo-records. Compared to its predecessors, HadGEM3 boasts more accurate cloud physics and an updated ocean model but the authors emphasize that the main reason for the discrepancy between model results is that HadGEM3 explicitly models melt ponds atop the sea ice.

Melt ponds over sea ice in the Arctic. The melt ponds are much darker than the surrounding sea ice and therefore reflect much less energy (Image Credit: Karen Frey, Clark University)

Sea ice has high albedo, which means that because it’s so white and shiny it reflects much of the sunlight it receives back into space. When the sea ice melts into pools of water, it no longer becomes as reflective. These melt ponds have much lower albedo and therefore trap more heat in the ice than if they were not there. Because HadGEM3 explicitly models these melt ponds that contribute to heating the ice, the simulated Arctic more closely resembles the Last Interglacial observations.

Polar bears are one of the many species threatened by sea ice loss in the Arctic (Image credit: Chris Linder, Woods Hole Oceanographic Institution)

According to HadCM3, a predecessor model of HadGEM3, if we make no efforts to reduce our carbon emissions into the atmosphere, then we are likely to see a disappearance of permanent sea ice by the year 2086. However, with the inclusion of the melt ponds and other more accurate climate physics, HadGEM3 predicts the first ice-free summer will occur as early as 2035. This difference highlights how important the work of climate scientists and oceanographers are. A keen understanding of our climate system is crucial for predictions of global warming.

Discussion

No comments yet.

Post a Comment

Instagram

  • by oceanbites 10 hours 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 1 week 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 2 weeks 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 3 weeks 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 1 month 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 2 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 2 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 2 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 2 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 3 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 3 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 4 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 4 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 5 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 5 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 6 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 6 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 
  • by oceanbites 7 months ago
    Feeling a bit flattened by the week? So are these summer flounder larvae. Fun fact: flounder larvae start out with their eyes set like normal fish, but as they grow one of their eyes migrates to meet the other and
  • by oceanbites 7 months ago
    Have you seen a remote working setup like this? This is a photo from one of our Oceanbites team members Anne Hartwell. “A view from inside the control can of an underwater robot we used to explore the deep parts
  • by oceanbites 8 months ago
    Today is the day of  #shutdownacademia  and  #shutdownstem  and many of us at the Oceanbites team are taking the day to plan solid actions for how we can make our organization and the institutions we work at a better place
WP2Social Auto Publish Powered By : XYZScripts.com