I was a little bit skeptical of big changes in the Arctic Ocean in this area specifically,
but in front of my eyes the picture is changing.
And it’s changing so rapidly that in 10 years the ocean became completely different.
This is a completely different, new Arctic ocean.
When I became a part of IARC we had a wonderful spirit of camaraderie and friendship and everyone
from this time remembers this period.
Everyone was friendly, was open, was collaborative, and I was really happy to be there and NABOS
was conceived as a part of this period of time.
NABOS, this is our program, stands for the Nansen and Amundsen Basins Observational System.
We were doing a lot of climatological studies at this period of time, and for that we used
a lot of data to build climatological time series.
It became immediately obvious to us that some parts of the Arctic Ocean are just empty,
white spots with no data.
Particularly difficult, was that most of these white spots were in the Russian Economic Zone
where permission for observations is required from the Russian authorities.
And since we had a lot of roots in Russia, we had a lot of friends, a lot of collaborators
in Russia, it was pretty easy for us to organize this kind of project where we leveraged some
decisions from the Russian authorities to support our research in the economic zone
and we continued that for many years.
We started our program in 2002 with a desire to fill gaps in observational system.
We were deploying instrumentation with the expectation that if anything happens in the
ocean we will see that.
And we indeed found that, our moorings showed a very strong increase in temperature of the
ocean interior in the mid 2000s.
The Arctic Ocean has certain channels to conduct currents.
They are called boundary currents.
The major current system follows the topography.
Where the topography is steep, that’s where the currents are strong.
This steep topography is associated with the transition from shelf, shallow water area,
to the deep ocean, key locations for monitoring fluxes of water from the lower latitude regions
into the Arctic Ocean.
And the time series showed that we were correct to place our instrumentation there and monitor
major changes.
We were not seeing any changes at the beginning of the program, and then in 2003/2004, we
recovered several moorings and when we plotted the data we saw a very strong jump in temperature
of the ocean interior.
So the ocean started changing, started accumulating this heat since the mid 2000s.
And our moorings were tracing these changes.
But that was not the end of the story.
When we are talking about the Arctic Ocean we are talking about several natural layers.
One of the most important layers for the sea ice story is the Atlantic layer.
Atlantic water enters the Arctic ocean and it becomes an intermediate water occupying
the depth range of about 150 to 900 meters.
It carries a lot of heat from the Atlantic ocean.
This heat is enough to melt the Arctic sea ice several times over.
But this Atlantic water layer, Atlantic water heat, is covered by fresh surface Arctic waters.
The transition from this surface, fresh water layer to the Atlantic water layer forms a
very special Arctic water mass which is called the halocline.
The stability of the halocline regulates how much of the Atlantic water heat penetrates
to the bottom of the sea ice.
In 2010s we found that the halocline became weaker.
That was the second and the most critical stage of the changing system.
That’s the key now.
We want to establish and quantify how much of the Atlantic water heat penetrates this
surface layer and reaches the bottom of sea ice, melts it, and also warms the atmosphere.
For our observations we use a complex of instrumentation.
Moorings we deploy in Arctic waters monitor the state of the ocean temperature and salinity
and measure currents.
Mooring are stationary devices which are anchored to the bottom of the Arctic Ocean.
We put different instrumentation along this line measuring temperature, salinity, currents,
chemical properties, multiple parameters.
We also use the so called Lagrangian Buoys.
They are not anchored, they can drift with the ice, and during this expedition we will
deploy several complexes of these buoys as well.
ITP were invented a couple of decades ago, but now they are one of the major tools to
monitor the state of the Arctic Ocean.
An ITP is an ice-tethered-profiler.
It is mounted on the ice, but it has a wire below the ice in the ocean, 700 meters approximately,
and there is a profiler which runs up and down along this line measuring temperature,
salinity, and sometimes other parameters if the profiler is equipped with additional sensors.
Together, there are probably ten buoys drifting in the Arctic Ocean, monitoring the state
of the ocean, and this number of ITPs provides a variable picture of the state of the ocean
in general.
But in addition to these oceanographic buoys we will deploy ice-monitoring buoys, which
monitor temperature and thickness of ice nearby the ITP buoys.
So there will be a complex of instrumentation drifting in the Arctic ocean monitoring the
state not just of the ocean but the ice as well.
This program is one of the most important contributions of NABOS to overall Arctic community.
We found, thanks to our observations and our collaboration with international colleagues,
that the halocline state is now affected by a strong advection of denser water from the
Barents Sea.
The halocline is weakening because the Barents Sea sends denser water into this layer, and
as a result, the Arctic halocline becomes weaker and weaker, more penetrable to the
transport of heat fluxes from the ocean interior.
The weakening of the halocline and the release of Atlantic water heat is the major message.
This change is critical because it shifts the balance of forces maintaining Arctic sea
ice from the atmosphere as the major driver to the ocean in the Eastern Arctic.
Manabe was talking about sea ice albedo feedback, where the atmosphere interacts with ice and
surface of the ocean and creates a very strong positive feedback mechanism enhancing sea
ice disappearance.
But what we are seeing now is that this ice albedo feedback became a part of a more powerful
feedback where the ocean interior is involved.
Our moorings tell us the story about changes of water temperature and salinity, but ship-borne
observations, including chemical observations, help us to identify the sources of water and
produce chemical signatures of this water.
This helps us to interpret physical observations with more insight into the nature of the processes
driving changes in the Arctic.
That’s why the next step in our program is identifying the source of anomalous water
in the halocline layer and to present a chemical signature of this water.
If we want to identify the source of anomalous water in the Arctic Ocean, or in any ocean,
we need to operate not just with temperature and salinity, which are major parameters for
physical oceanographers, but we need to work with chemists in order to understand the chemical
signature of waters.
Chemical sensors start appearing in mooring equipment, but these sensors are still extremely
expensive and we don’t have many of them.
Instead, we use ship-borne observations to take water samples for chemical signatures.
Based on this chemical analysis we can identify the source of water, whether it comes from
ice melt, or from Siberian rivers, or from the Barents Sea.
Critical for the program and for climate research is repeated observations.
So we need to come to the same location year after year to see changes.
And we are happy to report that our first mooring was deployed in 2002, and now we are
sailing to the same location to recover another mooring and redeploy it for the next two years.
Yesterday I calculated and it happens that we maintained this mooring site for 20 years,
repeatedly.
I think it’s quite amazing.
I hope we will have this mooring for five more years, so it will be 25 years of observations
at the same spot.
I am very proud of what we have accomplished.
First of all, we were able to convince an international community to work together.
And this is great achievement.
I am really proud that I have colleagues, friends, all around the world thanks to NABOS.
There were a lot of skeptics who didn’t believe that the Atlantic water heat is an
important player in sea ice change because of the preventative role of the halocline
layer, but now we have evidence that this oceanic heat plays an important regulating
role to maintain Arctic sea ice cover at least in this region of the Arctic Ocean.