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Northern Europe’s Mild Winters. Keywords: Human maritime activities, sea temperature
increase, North Sea and Baltic warming, change in seasonality, sea ice
decrease. 1. Introduction Northern European
winters are getting warmer and warmer at a rate higher than global average.
Last winter 2014/15 hardly occurred. Can anthropogenic activities in the North
Sea, Baltic and coastal seas be made partly responsible? Presumably yes!
Stirring liquids will cool them down. 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 [1]. This view is too
narrow. More mechanisms are at work. Not only ‘winds and storms’ have an impact
on the various sea layers over the entire depth of the sea; Several thousand
offshore facilities on 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. 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. Long distant implication, as far away
as the Eastern U.S. in January and February 2015, cannot be excluded. Climate
research or agencies overseeing marine activities pay little attention for such
considerations. 2. Stronger than Global The situation at the
beginning of the evaluation is obvious. Over the past 25 years the rate of
increase in sea surface temperature in all 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[3]. According
to the latest BACCII Report [4] in recent years
(1990-2004) all ·
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) occured 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. The Helsinki 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.” [5].
3. The effect of Stirring 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 [1]. 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. For example:
According to HELCOM ‘2000 sizable ships’ navigate the Baltic at any time [6]. 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
For a more detailed review of the situation at the end of the summer
season, when intake of heat ends and reverse, the next two graphs 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 is 6°C. On the other hand early September data (14 days-2015) from Arkoma Basin
Buoy, in the Western Baltic (details next section) (Fig.6) indicate that the
interior of the sea is much more complex as one might assume from Figure 5. In
the example, Figure 6, the temperature difference is up to 12°C in the range of
less than 50 meters depth.
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. The measuring device,
operated by the Federal Maritime and Hydrographic Agency (BSH), is located at
Position 54°53’N, 13°52’E, covering a depth of about 45 meters. Many offshore
wind farms have been erected in the Western Baltic in recent years. Ship
traffic is very high. The next two graphs
give the temperature and salinity profile of 9 respectively 8 levels during the
last 12 months, November 2014 to November 2015 (Fig. 7, 8). From January to the
end of March temperature decreased combined from14°C to the annual minimum of
3-4°C until March/April, still significantly too high to freeze. Since May a
gap between upper and lower level emerged, culminating in August to about 12°C,
narrowing the margin during the 4thcalendar Quarter.
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). Last winter 2014/15 the Gulf of Bothnia remained
almost free of sea ice, and reached by mid-March only a fraction of normal (Fig.
9). 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.”[7]. 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. 4.4
Warmer Europe’s distant implication by the ‘Siberian Express’? Europe is not the
world. However Western Europe is under the influence of the weather system from
West to East. Atlantic low pressure areas move east, unless cold continental
high pressure air blocks them. These are the winters that Europe talks about.
This succeeds very well when the North Sea and Baltic do not assist the
Atlantic weather because they cannot release enough heat or are hindered by sea
icing. During last winter 2014/15 they served as perfect helpers and keep the
cold from Siberia at a safe distance.
The more the Atlantic
weather governs the situation beyond the Ural the further Polar and Siberian
cold will be pushed eastwards, called ‘Siberian Express’(Fig.10). This was felt
in Alaska, Canada and Eastern U.S. Many days were extremely cold with
deviations from the mean of 20°C and beyond. Perhaps North Sea and Baltic have contributed to the extreme cold in the U.S.A., at least a bit (Fig. 11), which should not be ignored but the mechanism must be understood.
5. Discussion 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 matters. 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. If SST rise in the
North Sea more than elsewhere (section 2) and human activities rise as well,
the influence on the temperature profile Fig. 4-8 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 (Fig. 4, 7), 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 less vapor, 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, as provided by
theArkoma Basin buoy (Fig. 6-8) in a high number, presumably from many hundred
stations. 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 4.3).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 nineteenth century [8] the impact by human activities in the marine
environment received hardly any attention.
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 (Fig.12).
6. Summary 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 logical consequence. This is a revised text first published in February 2015 at: www.climate-ocean.com
http://climate-ocean.com/2015/K.html
[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). [5]
HELCOM; 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
[6].
HELCOM, Response-Group; http://www.helcom.fi/helcom-at-work/groups/response. [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. [9].
Bernaerts, Arnd; 2012; “Failures of Meteorology! Unable to Prevent Climate
Change and World Wars? Oceans Make Climate!”, BoD Norderstedt, pages 232,
online: http://www.seaclimate.com/
. The same: 2005; “Climate Change & Naval War”, Trafford Publishing,
CA/USA, pages 236, http://www.2030climate.com/
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