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This is how climate change will affect in the Nordics

NORWAY
Thursday, March 02, 2023, 07:00 (GMT + 9)

Climate change will change the ecosystem and fishery resources in the Nordic sea areas. New report provides answers to how.

Source: Havforskningsinstituttet

The new report "Climate changes and effects in the Nordic sea areas" is the first delivery in the project Nordic climate scenarios, initiated by the Nordic Council of Ministers.

"The reports to the UN climate panel are comprehensive, thorough and important. But they should provide an overview of literally the entire world", says researcher Geir Ottersen at the Institute of Marine Research (HI).

He leads the project in which a number of marine scientists from HI and Nordic partners have contributed.

"The Nordic sea areas have characteristics that stand out from other sea areas, and make them extra vulnerable. Therefore, it is crucial that we investigate how climate change will take shape here in the Nordics, and what consequences it will have", explains Ottersen.

"This work constitutes an important knowledge base for decision-makers in the Nordic countries."

Hits hardest in the north

The report states that there are major challenges for each of the Nordic sea areas.

Climate change will hit hardest in the far north.

"Some of the biggest changes in the world are expected in the Barents Sea and the northernmost parts of the Greenland, Icelandic and Norwegian Seas. These are sea areas that have been very cold and covered in ice for most of the year, and the ecosystems have adapted to this."

Projected change in annual temperature (°C) from the period 1971-2000 to 2031-2060 ("2045") and 2071-2100 ( "2085") for emission scenarios RCP2.6 (yellow), RCP4.5 (blue) and RCP8.5 (red) for different regions. ESD simulations are made for all scenarios; RCM simulations for RCP4.5 and RCP8.5. Median projections are indicated with a bold black line, while low and high projections are respectively lower and upper part of the boxes. The figure includes graphs for six temperature regions, and for the Norwegian mainland (“Norway”, bottom right). The background map shows annual temperature (°C) in the reference period 1971-2000, and boundaries between the different temperature regions are marked with black lines. Source: miljodirektoratet

"When the Arctic is now changing, the effects on the ecosystems will be very large", says the HI researcher.

"This works out differently for different species. For cod and haddock, a slightly warmer Barents Sea is good news, while arctic species such as polar cod are already in trouble."

The North Sea: In cross pressure

In the North Sea, the main challenge is "the sum of everything".

<-- Already in climate trouble: Arctic cod. Photo: Erling Svensen/HI

"This is one of the most heavily stressed sea areas in the world. There are many different industries and activities here, and an incredible number of people live in the catchment area of the sea area. Climate change thus comes on top of an already large footprint", explains Ottersen.

In the Baltic Sea, species diversity is under severe pressure. Here, there is a problematically high level of nutrient supply, combined with too little oxygen and too low a salt content for species such as cod and herring to thrive.

"We fear this will be reinforced by climate change."

From rising sea levels to less salty seas

In the report, the Nordic researchers go through the regional results on known "consequential errors" of climate change, such as rising sea levels and warmer oceans. In some places, the salt content in the seawater will also be lower.

What remains is that the Nordic region is not one size either.

"For example, we see that only along the Norwegian coast are there big differences in how rising sea levels will play out, due to what is called land uplift. During the last ice age, there was tremendous pressure on the land here in the Nordics, from enormous amounts of ice. When the ice disappeared, the land rose slowly and in some places this still continues", explains the HI researcher.

"This applies, for example, in the Oslo area, but little on the Westland coast. Thus, the sea will rise more in the west than in the east."

Zooplankton: Temperature rise pushes one out, to the advantage of the other

The major upheavals in the environment will of course also affect those who live there. It is already happening now.

Calanus finmarchicus is outcompeted by a less nutritious relative. Photo: Terje van der Meeren/HI-->

A clear example is the fate of the tiny but important zooplankton species Calanus finmarchicus in the North Sea - popularly known as ruddåte.

Over several decades, it has slowly but surely been outcompeted by its own "cousin" - Calanus helgolandicus.

The latter thrives better than the former, when the sea gets warmer.

Smaller reds lead to large tracking errors

"hey look very similar, you have to be an expert to tell the difference. Nevertheless, this has enormous ripple effects", says Geir Ottersen.

"The red trout is the most important dinner food for the youngest North Sea cod. The "cousin" has a lower nutritional value and appears too late in the season to be an equally good snack for small cod."

This means that an already vulnerable cod stock in the North Sea gets even worse odds.

"This is an example of how higher sea temperatures lead to poorer survival, because the time for the fish to grow up no longer coincides with when there is the most food available in the sea."

Source: miljodirektoratet Click on this link to enlarge the sizeThe way forward

The Nordic researchers hope that the brand new report gives politicians and the administration a basis for making informed decisions. But the work is not finished here.

"In this report, we summarize much of what we know today. Further in the project, we will generate new knowledge", says Ottersen.

"With the help of advanced models and historical data, we will "recreate the past" and see how the sea and coastal areas have historically developed. We will then use that knowledge further to be able to form an even clearer picture of how the future may turn out."

Source: Institute of Marine Research (Translated from the original in Norwegian)

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