Post: December 17, 2020, About 15 minutes read
oceans are still the greatest unknown in the climate change scenario. Oceans cover 71% of Earth and they contain 99.93% of the thermal energy (“heat”) on the
surface. Is it a too big issue for increasing understanding the matter?
Certainly if you lump everything together! Progress requires selection! Focus
on smaller regions, distinction between the seasons and on observations where
people are particularly active. Then you would quickly look at the North and
Baltic Seas. So the question could be: What is the contribution of the
wind-offshore industry, shipping, and fishery towards the Northern Europe’s
temperature of the North Sea has risen twice as fast as the oceans of the world over the past 45
years. In the last 100 years, the Baltic Sea has warmed 0.3°C per decade, however after 1990 significantly
faster at 0.59°C per decade.
European winters are getting warmer and warmer at a rate higher than global
average. Can anthropogenic activities in the North Sea, Baltic and coastal seas
be made partly responsible? Presumably yes! Stirring the sea during autumn and
winter the sea increase the release of heat stored during the summer season.
A recent paper
assumes: In the North Sea and Baltic, the
thermal air-sea coupling is strongly controlled by the seasonal cycle of the
air-sea temperature difference, which changes its sign twice a year. In
addition to that, winds and storm have an active large impact on the mixed
layer depth. The mixed layer thickness in turn controls how fast the ocean will
adapt to changes in the atmosphere and how fast a new equilibrium is reached
This view is too
narrow. More mechanisms are at work. Several thousand offshore facilities reach
the bottom of the sea or anchored offshore wind turbines, divert currents at
sea and influence tides and currents as a permanent resistance against the
normal flow of huge amounts of ocean water. Many ship propellers are plowing
through the sea stirring the surface layer to a depth of 15 meters. In the
North Sea and Baltic there are continuously ten thousand motor ships at sea.
The result is like stirring soup, or a baby bathing
water. During the winter season warm
water will come to the surface and the heat will supply the atmosphere with
warmth. The air will become warmer and the winters will be milder. The
correlation is not to be underestimated. Climate research or agencies
overseeing marine activities pay little attention for such considerations. They
actually ignore it completely.
2. Stronger than
The situation at the
beginning of the evaluation is obvious. Over recent years the rate of increase
in sea surface temperature in all European seas has been about 10 times faster
than the average rate of increase during the past century. In five European
seas the warming occurs even more rapidly. In the North and Baltic Seas
temperatures increased five to six times faster than the global average, and
three times faster in the Black and Mediterranean Seas. .
In about 1995 SST
(sea surface temperature) between the North Atlantic, North Sea and Baltic were
at the same level (Fig. 1), while the latter show a dramatic increase since.
With 11.4 ° C as annual average, the temperature of the North Sea surface water
was 1.5°C higher than the long-term average (Fig.2).
The same is reported about the Baltic. This had a
direct influence on air temperatures. During the period 1871 – 2004 there were
significant positive trends in the annual mean temperature for the northern and
southern Baltic Sea basin, being 0.10 °C/decade on average to the north of 60°
and 0.07°C/decade to the south of 60°N. The trends are larger than for the
entire globe which amount to 0.05 °C/decade (1861 – 2000), assessed a BALTEX
Conference in 2006.
According to the BACCII Report 2015  in recent
years (1990-2004) all years except for one, 1996, had a mean temperature above
normal for most of Europe, and that daily minimum temperature has increased
much more than the daily maximum. This interesting aspect with regard to
shipping is – inter alias – discussed later on. The Report furthermore suggests
changes in seasonality:
The length of the growing season and the sums of
positive degree days have previously been shown to increase, whereas the length
of the cold season and the frost days has decreased. The start of late autumn
(i.e. the end of the growing season, indicated by a continuous drop in daily
mean air temperature below 5°C) occurred 8 days later and the start of winter
(indicated by the formation of a permanent snow cover) 17 days later. The
duration of summer increased by 11 days and of ‘early winter’ by 18 days, while
the duration of winter proper has decreased by 29 days. The length of the
growing season (defined by a daily mean air temperature permanently above 5°C)
increased by 13 days.
Commission (HELCOM) confirmed in 2013 that “On average since the late 19th
century” the increase in annual average surface air temperature has been 0.11˚C
per decade in the northern Baltic and 0.08˚C in the southern Baltic compared to
the global average of 0.05˚C per decade.” .
between North and South can be explained by the fact that the southern Baltic
is shallower than the eastern Baltic. That means there is less volume of water
available for storing heat (summer) and releasing it (winter). The over
proportional warming of water and air is self-evident. To link this to global
warming cannot be convincing. How can global warming lead to specific higher
warming in these regional seas? During winter when the nights are long and
sun-ray remote? Rather, it should be asked; have shipping and offshore
activities contributed to pronounced reginal warming?
3. The effect of
Wherever variant water temperatures consist in a sea
water column, due to internal or external forcing, an exchange between the sea
layers happens at any time. As already mentioned winds and storms are observed
factors . But about human forcing ‘obstacles’ little is taken into account,
although it is well known that there is a strong interaction between a physical
structure and a flow field (Fig.3).
All offshore wind
turbine units are connected with the sea floor, either by platform or anchored
as floating units. The former is usually used for water depth of up to 60
meters. A floating structure consists of one or more steel cylinder filled with
ballast of water and rocks, which can extend 100 meters or more beneath the
sea’s surface. Currently used on most offshore wind projects, the foundation
consists of a large base constructed from either concrete or steel which rests
on the seabed, whereby one or more piles are driven 10 to 20 meters into the
seabed. Every pile has several meters in diameter. A ‘natural’ current system,
whether due to temperature difference and salinity (density currents) or tide,
will be significant affected.
Of not less impact is
shipping. On one hand the vessel draught effects directly only the sea surface
layer accordingly, on the other hand much more intensive as offshore
structures due to motor propulsion. At a speed of 18 knots a ship travels about
800 kilometers in 24 hours, leaving a mixed water column behind down from few
to a dozen meters.
According to HELCOM ‘two thousand sizable ships’ navigate the Baltic at any
time . By rough calculation this means, that the entire Baltic sea surface
down to 10 meters and more is mixed in about two weeks’ time, or 30 times per
year. That means: During the summer season more heat will be forced into deeper
layers, in winter more heat comes out of the water body.
4. More heat input –
More heat output.
4.1 General overview
The mean water depth of the Baltic is 52m (Nord Sea
94m) and is less in the south-west than in the eastern Baltic. The salinity is
very different from location to location, but in average considerable higher in
the North Sea (32-35psu), low in the western Baltic (about 8psu), and Gulf of
Bothnia near zero. As a general rule the water temperatures vary over the
seasons in the upper 50 meters water column, below that depth the water is cold
and remains fairly unchanged throughout summer and winter. That applies either
to the North Sea as well as to the Baltic Sea. As an example may serve a
quarterly vertical profile from the Eastern Baltic (close to Gdańsk Bay) (Fig.
For a more detailed
review of the situation at the end of the summer season, when intake of heat
ends and reverse, the next graph indicate the temperature profiles in the two
seas. In a North Sea cross section along Latitude 56,5° North during September
the huge temperature the difference between the warm and cold water body is
well indicated (Fig.5). Below about 40-50 meters the heat
intake in summer is very moderate, as the statistical minimum from March to May
Since mankind, during
the course of a year, agitates the water column of North Sea and Baltic by
stirring, more warmth is taken to deeper water in the summer season and rises
to the surface from lower layers in the winter period, where heat is exchanged
with the air until sea icing is observed. This is a process that can be seen
from the beginning of September until the end of March.
4.2 Sea Ice as indicator for human activities
Sea ice conditions in
the Baltic have been systematically monitored for more than a century. But
never the question has been raised whether human activities have ever
contributed to the fact, that the last near complete ice-cover in the Baltic
Sea occurred one quarter Century ago (1986). During most recent winters the
Gulf of Bothnia remained almost free of sea ice, and reached by mid-March only
a fraction of normal.
Marine activities play a much bigger role in time
factor and duration of ice formation. If the sea surface temperature has
already reached the freezing point, any vessel shovels warmer water to the
surface, or vice versa, forcing a more rapid melt. Some indications can be
found in this respect, mentioned by the BACCII-Report:
“Ship-induced waves are known to prevent the formation
of a permanent ice cover in autumn and also to enhance break-up of the ice
cover in spring, and so an increase in the size of vessels and the intensity of
shipping activity could also affect ice conditions.”.
How can it be ignored
that the water body below a sea surface of zero degrees is usually warmer, and
ships and other obstacles force warmer water to the surface. The shrinking ice
cover correlates well with an increase in human activities, and subsequently
leading to higher air temperature throughout the region.
A. Regional seas in
Northern Europe are minor from size and volume in global ocean affairs. Weather
is “done” elsewhere, but every location contributes to the global picture. In
the case of N-Europe it may be more significant as weather can be divided in
maritime and continental influence, and due to the global air circulation from
West to East, it is a gate. It may support the flow of warm wet air eastward
(low pressure), or stem it by dry and cold continental air (high pressure), by
diverting low pressure areas – in extreme circumstances - towards the Bering
Sea or Mediterranean. In so far the North Sea and Baltic play a crucial role in
how to open or close this gate.
But according to SST
statistics, the gate sea area warming increase more than in other sea areas in
Europe, and here stronger than the oceans worldwide (Fig.1). This phenomenon is
not explained with a general reference to ‘global warming’. A reasonable
explanation is pending. Many “weather factors” may play a role, such as river
runoff, precipitation, cloudiness, sea ice cover, but that has not yet lead to
a sufficient conclusion, as none of them can be regarded as a driver in climatic
The major player in
this respect is water, and the genuine mass of it is contained by the oceans
and seas. Smaller water bodies are no exception. Geographical features, as the
Norwegian high mountain range, which hinders the free flow of Atlantic air
eastwards, provide a particular scenario to study and understand how much the
water body in lee of the barrier contributes to the regional weather and
climate. The sea water condition in the North Sea is not less interesting, as
it is the main gate on how the west-wind flows.
B. Basically only
three facts are established: higher warming, a small shift in the seasons, and
a decreasing sea ice cover. In each scenario the two sea’s conditions play
a decisive role. These conditions are impaired by wind farms, shipping,
fishing, off shore drilling, under sea floor gas-pipe line construction and
maintenance, naval exercise, diving, yachting, and so on, about little to
nothing has been investigated and is understood. The little that can be done is
to do fundamental considerations:
If SST rise in the
North Sea more than elsewhere (section 2) and human activities rise as well,
the influence on the temperature profile is a serious issue. During summer more
heat is pushed down, but available for release during the winter season. The
down push is a merrily mechanical exercise, while the interaction between the
sea surface and the atmosphere is a highly complex matter requiring certain
conditions. Thus it is easier to force heat mechanically into the sea body, while
it takes some time until ‘natural processes’ release the ‘additional’ heat
according the laws of physics.
It is almost
unthinkable that the seasons remain stable (section 2). Until June the water
body is still fairly cold, whereas the upper surface layer gets lots of sun
rays and warms. Any moving vessel replaces the warm layer with colder water.
The air gets fewer vapors, which support high pressure, continental condition
with fewer clouds and more sunshine. For famers the growing season may start earlier.
For a clearer picture one would need data, from many hundred stations alone in
the Baltic, with many dozen collectors from the sea surface to the sea bottom.
The winter season is
a much easier situation for climate research. The reason is simple. The
ultimate factor in the climate system, the sun, has a low inclination, the
nights are long, and the sea receives only a moderate amount of sunrays. The
scene is governed by lows from the Atlantic, continental highs, and the heat
release from North Sea and Baltic. The surface layer transfers more heat to the
atmosphere as it receives from the sun, and cools down quicker than sub-layers
(Fig. 7). The interchange between the layers depends primarily on internal
physical processes (temperature, salinity, and others), and on external forcing
such as wind and numerous human activities. Both factors force a much higher
and rapid heat transfer. The winters are getting warmer. It surprises that
science pays so little attention on the mechanism during the winter season, and
neglects the impact of human activities.
Presumably an even
more convenient case for studies is sea ice condition. The annual period for
analyses is shorter (about December to April). From the moment sea ice has
established, the influence by wind diminishes. Human activities rise to a big
player in the sub-surface temperature and salinity water structure. Motor
vessel impact goes much further than: “Ship-induced
waves prevent the formation of a permanent ice cover in autumn and also to
enhance break-up of the ice cover in spring” (section 4.2).They churn a
water column down to ten meters and more.
SST can easily change
from zero to several plus degrees. Very critical is the impact of vessels
navigating in ice-fields, when the water body is cut-off from interaction with
the atmosphere. As warmer water is less heavy as colder water any vessel’s wake
spreads below the ice bottom. Although sea ice mechanism and duration is
intensively observed and studied in the Baltic Sea since the 19th Century
 the impact by human activities in the marine environment received hardly
C. The biggest
impediment to explain the disproportionate warming convincingly is of a
fundamental nature. The dominant role of the sea in climatic affairs needs to
be more recognized. Without this requirement, a sustainable scientific work
cannot be organized. So an organization then requires a major effort in terms
of concepts, data, computer capacity, competent researchers and a lot of money.
A much cheaper way – at least about the role of the
sea in climate affairs – to analyze and explain the extraordinary war winters
in Europe, particularly 1939/40, 1940/41 and 1941/42 (Fig.8) most likely primarily
caused by naval warfare. Although with the start of naval war in September 1939
also a pronounced global cooling commenced lasting until the mid-1970s science
has not shown any interest.
From September 1st, 1939 until Pearl Harbor in
December 1941 naval warfare was primarily a European affair, and the bulk of
naval activities took place in North Sea and Baltic, releasing too much heat
stored in the sea too early, thus allowing cold air from Siberia to take reign
over Western Europe up to the Ireland (section 5.A.). Across large parts of
Europe temperatures dropped to Little Ice Age level.
The facts are conclusive. ‘Global Climate Change’
cannot cause a special rise in temperatures in Northern Europe, neither in the
North Sea nor the Baltic or beyond. Any use of the oceans by mankind has an
influence on thermo-haline structures within the water column from a few cm to
10m and more. Noticeable warmer winters in Europe are the inevitable consequence.
Summary: The marine
environment of North Sea and Baltic is one of the most heavily strained by
numerous human activities. Simultaneously water and air temperatures increase
more than elsewhere in Europe and globally, which cannot be explained with
‘global warming’. The climatic change issue would be better understood if this
extraordinary regional warming is sufficiently explained. The regional features
are unique for in-depth studies due to different summer-winter conditions,
shallowness of the seas, geographical structure, and main pathway for maritime
weather patterns moving eastwards. The impact of sea activities on the seasonal
sea water profile structure is contributing to stronger regional warming,
change in growing season, and less severe sea ice conditions. The impact of the
man, whether small or large, should be understood very soon and very thoroughly.
shorted version of a paper published 2015:
1. Gröger, Matthias; Dietrich, Christiab; Meier Markush
H.E.; Schminake, Semon, 2015; „Thermal air–sea coupling in hindcast simulations
for the North Sea and Baltic Sea on the NW European shelf”; Tellus A 2015, 67,
26911, http://dx.doi.org/10.3402/tellusa.v67.26911; PDF, page 2.
2. European Environment Agency (EEA), 2015;”Rising sea
surface temperature: towards ice-free Arctic summers and a changing marine food
chain”; http://www.eea.europa.eu/themes/coast_sea/sea-surface-temperature BALTEX
Assessment of Climate Change for the Baltic Sea Basin, 2006; International
Conference Göteborg, Sweden 22 – 23 May 2006; http://www.baltex-research.eu/BACC/material/IBS_No35_BACC; PDF, page 7.
3. The BACC II Author Team (Editor), 2015; “Second
Assessment of Climate Change for the Baltic Sea Basin, Regional Climate
Studies”, Open access at SpringerLink.com, pages 501 (Chapter 4, A. Rutgersson
et al, p. 83f).
4. The BACC II Author Team (Editor), 2015; “Second
Assessment of Climate Change for the Baltic Sea Basin, Regional Climate
Studies”, Open access at SpringerLink.com, pages 501 (Chapter 4, A. Rutgersson
et al, p. 83f).
2013; “Sea Surface Temperature in the Baltic Sea in 2013”; Press release
27/09/2013 11:01; http://www.helcom.fi/news/Pages/Warming-in-the-Baltic-Sea-region-is-expected-to-continue-and-alter-the-marine-ecosystem.aspx
7. The BACC II
Author Team (Editor), 2015; op. cit.; (Footnote 4), Jari J. Haapala et. al.,
Chapter 8, p. 153
8. op. cit. (Footnote 7), p. 145.