Sari Luostarinen is a Senior Research Scientist at the Natural Resources Institute of Finland (Luke) and is the current Chair of the HELCOM Agri group

Aren’t nutrients supposed to be good? What’s wrong with nutrients? 

Nutrients are vital for humans, animals and the environment as a whole. They are also vital for agriculture and food production. No crops can grow without nutrients. But as with most other compounds, too much in the wrong place causes problems. In our region for instance, the excess of nutrients has led to the eutrophication of the Baltic Sea.

In terms of eutrophication and nutrients, what is the current status in the Baltic Sea region?

The Baltic Sea is a vulnerable sea for many reasons. The nutrients it has received in the past are bound in the sediments and released under certain conditions, causing internal nutrient loading. At the same time, nutrient runoff from current human activities is adding to the problem. Of the latter, many point sources have been reduced, for example due to improved wastewater treatment. But it is more difficult to restrict diffuse loading such as from agriculture. Depending on the weather conditions and due to increasing temperatures, eutrophication and its consequences are worsening. More actions to control the nutrient load are needed.

In general, what would need to be done to curb eutrophication and nutrient inputs, especially in regard to agriculture?

As said, crops cannot grow without nutrients. Both phosphorus and nitrogen need to be available for crops on the fields to achieve good yields. Good yields also mean that most nutrients given as fertilizers end up in the harvested crop and little is lost to the environment. The amount of nutrients spread as fertilizers should be adequate, for instance adjusting quantities depending on the crop, the soil type and its nutrient content, as well as the timing of the spread. The use of animal manure as a fertilizer is the traditional way to recycle nutrients in food production. However, due to segregation of animal and crop production it may be either available in excess or in deficit depending on the region. More precise utilisation of manure nutrients, including replacing mineral fertilization with manure, is important for reducing agricultural nutrient load. Also, other measures, such as reduced tillage, catch crops, water protection zones, are also needed to manage nutrient losses.

What concrete steps is HELCOM currently taking on the nutrient issue from the agriculture perspective?

HELCOM is efficiently driving several measures to reduce agricultural nutrient losses to the Baltic Sea. As an example, HELCOM is preparing the introduction of recommendations for national manure standards. The aim is to ensure the availability of updated, scientifically proven data on manure quantities and nutrient contents in the Baltic Sea countries so that the manure data used in fertilization planning and thus the amount of manure spread on fields becomes more precise. This is expected to reduce nutrient runoff from the fields. Furthermore, on resource efficiency, HELCOM is also preparing a strategy for nutrient recycling in the Baltic Sea Region. Again, the aim is to introduce more efficient measures to make better use of the nutrients already available and to reduce the need to introduce new mineral nutrients into the cycle. For example, this could be achieved by processing manure, different wastes and their by-products into recycled fertilizers.

Dr Susanne Heimüller works for the Federal Maritime and Hydrographic Agency (BSH) and is the Chair of HELCOM Maritime Working Group

Overall, what’s the current state of the management of wastewater from ships in the Baltic Sea, also compared to other seas?

The Baltic Sea is a highly sensitive sea area and eutrophication is one of its major problems. Therefore, following a lengthy preparation process within HELCOM, the International Maritime Organization (IMO) designated the Baltic Sea as “Special Area for sewage discharges from passenger ships under Annex IV of the MARPOL Convention.” Worldwide, it is the only region so far regulating these discharges. 

The more stringent Special Area regulations, which already applies to newly built vessels, require passenger ships to either discharge their sewage into port reception facilities (PRF) or to treat sewage with an advanced on-board sewage treatment plant capable of reducing nutrients to a safe level for discharging at sea. 

This is an important step forward towards a healthier Baltic Sea, while, at the same time, showing how a MARPOL Annex IV Special Area may be implemented.  

Why the Technical Guidance? What’s its objective, background?

Handling big volumes of sewage in ports requires new and innovative approaches. Initial experiences show that there is no “one size fits all” solution. Almost each port, with its own, specific infrastructure requirements, needs a tailored solution. 

To facilitate proper management of wastewater from ships, we therefore developed the “Technical Guidance for the Handling of Wastewater in Ports of the Baltic Sea Special Area under MARPOL Annex IV.”

The Technical Guidance sets out probable problems a port may encounter, and presents possible solutions on the different aspects of the management of wastewater from ships, be they of infrastructural or technological nature, or related to planning and communication.

Who is the Technical Guidance meant for?

The Technical Guidance offers recommendations to port operators and shipping companies. It can also be useful for administrations and municipal wastewater companies dealing with the issue.  

How do you expect the Technical Guidance to improve wastewater management in the Baltic Sea?

The Technical Guidance will hopefully aid all involved stakeholders to better understand the major and various challenges ports and ships face when it comes to managing wastewater. Awareness and good communication is a first step in working together on practical solutions, and ultimately, on improving the environment of the Baltic Sea.

Download the Technical Guidance:

The handling of wastewater from ships in ports of the Baltic Sea just got easier with the newly published Technical Guidance for the handling of wastewater in Ports of the Baltic Sea Special Area under MARPOL Annex IV.

Intended for shipowners, port operators, local administrations as well as municipal wastewater companies, the Technical Guidance was developed to facilitate the management of wastewater from ships to better comply with IMO regulations on wastewater handling in the Baltic Sea region. 

In 2011, the IMO designated the Baltic Sea a Special Area for sewage discharges from passenger ships, directing passenger ships operating in the Baltic Sea and not equipped with an on-board sewage treatment facility to discharge their sewage – or black water – at port, in a so-called port reception facility (PRF). 

“Initial experiences show that there is no ‘one size fits all’ solution,” said Susanne Heitmüller, the Chair of HELCOM Maritime, the HELCOM working group that deals with shipping-related topics. “Almost each port, with its own, specific infrastructure requirements, needs a tailored solution,” she added.

The current lack of experience with sewage handling in ports requires the development of new and innovative approaches to manage these new challenges. The Technical Guidance for the handling of wastewater in ports was produced to fill this gap and offer a wide range of possible options to several scenarios ships and ports may face. 

“The Technical Guidance sets out probable problems a port may encounter, and presents possible solutions on the different aspects of the management of wastewater from ships,” said Heitmüller.

Under the IMO regulations, all newly built passenger ships after June 2019 are required to comply to stricter rules on wastewater discharges, while older passenger ships will have to comply to the same rules by June 2021, with some exceptions until June 2023 for ships en route directly to or from a port located outside the Baltic Sea and to or from a port located east of longitude 28˚10′ E.

According to the rules, passenger ships which carry more than 12 passengers will have to either discharge sewage into port reception facilities, or alternatively at sea – provided that nutrients have been reduced by 70% for nitrogen and 80% for phosphorus through on-board treatment. 

Untreated wastewater has been identified as an important source of both hazardous substances and nutrients, the main cause of eutrophication leading to unwanted growth of blue-green algae that upset the Baltic Sea’s biodiversity.

Published by HELCOM, the Technical Guidance was developed by the Development and Assessment Institute in Waste Water Technology at RWTH Aachen University (PIA) on behalf of the Federal Maritime and Hydrographic Agency of Germany (BSH) and in collaboration with the German Federal Ministry of Transport and Digital Infrastructure (BMVI).

• Download the Technical Guidance for the handling of wastewater in Ports of the Baltic Sea Special Area under MARPOL Annex IV. 

If not their waters, then at least the experts of the world’s regional seas converged in Helsinki in late November to share best practices on the Sustainable Development Goal related to oceans and seas, SDG 14, and to start preparations on its joint outlook report to be presented at the Ocean Conference 2020.

The HELCOM-hosted workshop that took place in Helsinki from 25 to 27 November was a follow up of the UN Regional Seas Programme‘s Annual Meeting held in Berlin earlier in October and also co-hosted by HELCOM. 

“Our organisations are truly the best place to translate the global visions into action at the regional level,” said the Executive Secretary of HELCOM, Rüdiger Strempel, during his opening remarks in Helsinki, referring to the driving role of the regional sea conventions and bodies on advancing the global environmental targets.

Two of the global frameworks, the SDGs and the Aichi targets, have long been important guidelines for HELCOM in working to conserve the global marine environment. 

“The SDGs and Aichi targets are, in fact omnipresent in our everyday work,” said Strempel, adding that “both have proven to be key to advancing the ocean agenda, and decisively influence the policies we develop, the strategies we devise, the actions we implement.”

“At HELCOM and in the Baltic Sea, we believe that the various regional seas mechanisms can learn a lot from each other,” said Strempel, further stressing that despite HELCOM not directly being linked to the UN system, it continually takes account of the relevant UN goals and processes.

Increasing collaboration with the UN Regional Seas Programme was one of the four HELCOM commitments made during the UN Ocean Conference 2017. 

The other commitments were to establish a NOx Emission Control Area (NECA) in the Baltic Sea, to strengthen the implementation of the HELCOM Baltic Sea Action Plan to support ocean-related SDGs, and to identify Ecologically or Biologically Significant Marine Areas (EBSAs) in the Baltic Sea.

Organised by the UN Regional Seas Programme, facilitated by the UN Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) and hosted by HELCOM, the workshop attracted 16 regional sea organisations from all over the world.

Not just one or two but three events on maritime spatial planning (MSP) were combined in the “Global meets regional” Maritime Spatial Planning Forum in Riga between 19 and 21 November, showing the importance that MSP is gaining in the Baltic Sea region.

The event that attracted 300 participants from over 40 countries was a grouping of the 4th International MSP Forum, the 3rd Baltic MSP Forum, and the final conference of the Pan Baltic Scope project. It focussed heavily on the ecosystem approach as well as transboundary planning between countries and frameworks.

“For HELCOM, maritime spatial planning is one of the tools at our disposal for achieving good environmental status of the Baltic Sea,” noted Rüdiger Strempel, the Executive Secretary of HELCOM, in his recap remarks.

“By promoting the ecosystem approach, [we] add the human dimension to the ecosystem, both in terms of the benefits we derive from the sea, and regarding the pressures our activities exert on the marine environment,” he said.

According to Strempel, the forum also impressively demonstrated “the broad range of disciplines and topics of relevance to and affected by MSP.” Indeed, legal issues, environmental impacts, economic and social dimensions, green infrastructure, and ecosystem services all prominently featured on the forum’s agenda, confirming the complexities and the multidisciplinary nature of MSP.

The forum furthermore served as the final conference of the EU-funded Pan Baltic Scope project on advancing MSP in the Baltic Sea region and where HELCOM led the work on economic and social analyses, and cumulative impacts.

In the project, HELCOM also collaborated on a data sharing activity to support regional cooperation and transboundary coherence in MSP. At the forum, HELCOM presented BASEMAPS, a web-based tool showing decentralized MSP data through open standard services.

“With BASEMAPS, planners can finally access a catalogue of transnational MSP data published by official data providers,” said Joni Kaitaranta, HELCOM’s data manager. The tool seeks to facilitate the development of coherent plans across the Baltic Sea region.

BASEMAPS is the result of both the Baltic LINes and Pan Baltic Scope projects, with the first focussing on input data – the data needed to produce the plans –, and the second on output data, showing national MSP plans in a harmonized way following HELCOM-VASAB guidelines on transboundary MSP output data structure in the Baltic Sea to support cross-border coherence of plans.

The forum was organized in conjunction with UNESCO’s Intergovernmental Oceanographic Commission (IOC UNESCO), VASAB, Pan Baltic Scope and the European Commission’s Directorate-General for Maritime Affairs and Fisheries (DG MARE).

And who said three: in a MSP-dominated week, the forum took place back to back with an EU MSP expert meeting on Monday, 18 November and the Capacity4MSP project partner meeting on Friday, 22 November – bumping up the count to an actual five MSP events in Riga. 

Watch Rüdiger Strempel’s recap video

Smarter use of nutrients in agriculture will be key to curb eutrophication in the Baltic Sea, as was emphasized during the last meeting of the HELCOM Group on Sustainable Agricultural Practices (HELCOM Agri) that took place in Berlin, Germany from 5 to 6 November 2019.

Consisting of representatives from environmental and agricultural stakeholders such as national authorities, industry associations and NGOs, the HELCOM Agri group primarily aims at reducing the nutrient inputs from agriculture to the Baltic. Excessive nutrient concentrations in the sea remain the lead cause for eutrophication and toxic algal blooms.

The group is currently revising the Annex to the Helsinki Convention that sets legally binding requirements for sustainable practices of agricultural production for all Contracting Parties to the Helsinki Convention.

Growing ammonia emissions, regularly reported by the European Monitoring and Evaluation Programme (EMEP), and their subsequent deposition of nitrogen in the Baltic Sea are of particular scrutiny to the group as agriculture is the main source of emission of this gas.

The group compiled information on measures to reduce ammonia emissions which can be applied in agricultural practices, revealing that only a few of them have been implemented in almost all Baltic Sea countries.

“Ammonia emissions could be reduced through improved management of manure and better agricultural practices such as covering manure storage facilities, as well as injection and fast incorporation of manure to soils,” said Susanna Kaasinen, the project manager handling agriculture at HELCOM.

The group agreed that the currently valid HELCOM Recommendation on reduction of ammonia emissions is outdated, does not reflect modern state of scientific knowledge and is to be revised.

The group is also promoting smart nutrient management in the HELCOM countries by developing the Baltic Sea Regional Nutrient Recycling Strategy with the aim to close nutrient loops, return these valuable components to the food production and minimize their losses to the aquatic environment.

To advance smart nutrient management – one of the pillars of sustainable agriculture – the group has drafted HELCOM Recommendation on the use of national manure standards. 

In Berlin, the Agri group also elected its new Chair, Ms Sari Luostarinen, a senior research scientist at the Natural Resources Institute Finland (Luke).

Read the outcome of the AGRI 8-2019 meeting

As maritime spatial planning is sharpening up in Baltic Sea region, planners and policy makers advanced on environmentally-friendly management of human sea-based activities during the last HELCOM-VASAB meeting held in St Petersburg, Russia from 28 to 29 October 2019.

“The HELCOM-VASAB Working Group is a unique platform for developing ecosystem-based management, pooling the efforts of both planners and environmentalists for better maritime spatial planning (MSP) in the Baltic Sea region,” said Dmitry Frank-Kamenetsky who oversees MSP at HELCOM.

In MSP, ecosystem-based management, or the ecosystem approach, aims at linking the conservation of marine resources with an integrated management of different human maritime activities. This approach helps to reduce the cumulative impacts on the environment caused by multiple human activities.

In St Petersburg, ecosystem-based management was a central topic as reflected by the meeting outcome, along the exchange on the state of national maritime spatial plans.

All Baltic Sea countries are currently developing maritime spatial plans or looking into the matter, with the majority already having adopted their plans and some even embarking on their revision.

As laid out in its roadmap for MSP, HELCOM-VASAB promotes the coordination between national MSP efforts to avoid incompatibilities of plans between countries within the Baltic Sea region.

MSP is also expected to feature more prominently in the update of the Baltic Sea Action Plan (BSAP), HELCOM’s strategic programme of actions to reach a good environmental status of the Baltic Sea and that is due to be updated by 2021. When the initial BSAP was adopted in 2007, there weren’t many concrete MSP activities in the region yet. At HELCOM-VASAB, it was therefore agreed that MSP finds its rightful place in the updated BSAP.

“In the Baltic Sea area, most MSP activities came to life because of the commitments made under the BSAP. Now that the region has advanced on MSP, we can see its full potential for helping us to reach our environmental goals for our sea,” said Frank-Kamenetsky.

Presented by Pan Baltic Scope during the meeting, the concept of green infrastructure (GI) showed possible ways on how to integrate MSP in the update of the BSAP. By mapping habitats and biotopes that provide essential ecosystem services, green infrastructure is an attempt to effectively link biodiversity to spatial planning.

Green infrastructure is a network of natural or semi-natural ecosystems that offer valuable services. They provide natural resources – think clean air, water and food –, regulate the environment and climate, as well as add a cultural and social value, for instance through recreational opportunities. 

Further development of the green infrastructure concept was included in the HELCOM-VASAB Work Plan for 2020-2021 to be submitted to the HELCOM countries for final approval.

The 19th meeting of joint HELCOM-VASAB Working Group on Maritime Spatial Planning (MSP) took place during the XVIII Annual Strategic Planning Leaders Forum that, every autumn, attracts over 1000 participants from Russia and beyond.

The HELCOM-VASAB Working Group was established in 2010 to ensure cooperation among the Baltic Sea Region countries for coherent regional maritime spatial planning processes in the Baltic Sea.

Read the meeting outcome

By Rüdiger Strempel, HELCOM Executive Secretary

Polaris is an impressive vessel. Built in 2016, she is the most recent addition to the sizeable fleet of ice breakers based a mere ten-minute walk away from the HELCOM Secretariat in Helsinki. But does the fact that Finland maintains a fleet of heavy-duty ships to break the sea ice in her waters mean that climate change has not reached the Baltic Sea? Unfortunately not. In fact, this region is warming faster than Earth as a whole, and the sea ice cover has decreased dramatically since the middle of the 20^th century. And there is more to come. Over the next 100 years, precipitation is expected to increase, but the snow season will likely become shorter and the sea ice cover could decline even further. Other effects of climate change in the Baltic Sea could include higher air and water temperatures, lower salinity, decreased oxygen levels and shifts in habitats and species distribution.

In other words, climate change is adding more pressure to a fragile ecosystem already affected by a wide variety of anthropogenic impacts, such as eutrophication, pollution, overfishing and habitat loss. But HELCOM is working to tackle this issue. A priority of the current Finnish presidency of HELCOM, climate change has long been on the agenda of our organization. Since 2007, HELCOM Ministerial Meetings have stressed that climate change will impact on the region’s marine environment and should therefore be reflected in HELCOM policies. In 2007, HELCOM published its first thematic assessment of climate change, jointly with BALTEX. More recently, in the Declaration of the Ministerial Meeting held in Brussels, Belgium in 2018, HELCOM Ministers not only reiterated their concern about the impacts of climate change but also stressed “the need for research and adaptive management to strengthen the resilience of the Baltic Sea in the face of climate change impacts”. They also agreed “to increase HELCOM’s preparedness to respond to climate change impacts, by taking foreseen climate change impacts into account when updating the Baltic Sea Action Plan and by exploring the needs and possibilities to further adapt HELCOM’s policies and recommendations 1) in line with existing objectives of protection of the marine environment and sustainable use of marine resources, also under the changing climate, and 2) to maximise the capacity of the Baltic Sea ecosystem to contribute to mitigation of climate change through blue carbon storage.”    

In plain language: The Contracting Parties to HELCOM share the view that the ultimate aim of HELCOM’s work on climate change should be increased resilience of the Baltic Sea system to the impacts of climate change and that a long-term, multidisciplinary approach to understanding and communicating its implications for the region’s marine and coastal environment is needed. We are therefore working to establish HELCOM as a regional platform for policy-science dialogue on climate change, to provide robust, policy-relevant and research-based knowledge on the state, impacts and vulnerabilities of the Baltic Sea with respect to climate change and we are reviewing our policies with a view to promoting climate change adaptation.

While HELCOM’s various Expert Groups and networks already strive to take account of climate change, HELCOM has now taken the topic to the next level by establishing a dedicated Network on Climate Change (EN-CLIME), jointly with Baltic Earth, a focal point for technical marine climate change information and expertise in the region. Working in the context of our State and Conservation Working Group and consisting of experts from both organizations, EN-CLIME cooperates closely with both other HELCOM Groups and networks and external partners. One of EN-CLIME’s deliverables will be a climate change fact sheet. As a science driven exercise, the fact sheet is intended to offer policy makers a concise and easily accessible resource providing a consensus view by the region’s experts regarding relevant abiotic and biotic parameters, thus helping to bridge the science-policy gap. The fact sheet will then continually be updated to reflect advances in science and understanding of climate change as it relates to our region. Based on the best available science, we will also broaden the scope of the Baltic Sea Action Plan, HELCOM’s ambitious program of action for a healthier Baltic Sea, to encompass climate change when updating the plan for the post-2021 period.

Whether Polaris and her fellow icebreakers will still be needed 50 or 100 years from now is difficult to predict. But as we gain a better understanding of the dynamics and implications of climate change for the Baltic Sea, a clearer picture will emerge of what needs to be done to ensure a sustainable and liveable future for the Sea that defines our region and for the region as a whole.     

This article was originally published in Open Access Government (October 2019). View the publication (article is on page 340).

​Marine litter, underwater noise and chemical contamination of the marine environment were prominently featured on the agenda of the PRESSURE 11-2019 meeting held in Brussels from 22 to 25 October. The meeting was further complemented by two workshops on hazardous substances and marine litter.

“Marine litter is posing a threat to the Baltic Sea’s biodiversity, so it needs to be solved rapidly,” said Dmitry Frank-Kamenetsky, adding that the issue is being successfully addressed through the implementation of the HELCOM Regional Action Plan on Marine Litter.

In Brussels, progress in the implementation of the plan was particularly acknowledged, and further steps were outlined to deal with derelict fishing gear, to improve stormwater management – crucial in addressing microplastics – and to address expanded polystyrene, one of the top litter items found on the entire Baltic Sea coast.

“Since rivers are significant pathways bringing litter and all sorts of substances to the sea, we also need to look upstream and beyond our shores,” said Frank-Kamenetsky, echoing the common view that further cooperation with river basin management authorities needs to be strengthened to address the marine litter issue.

Furthermore, a new draft of the action plan to mitigate manmade underwater noise was presented at PRESSURE 11-2019. “Although the document is still in a drafting phase, it is a first step in the HELCOM process that may eventually lead to concrete measures to ease the effects of man-made sound and noise on aquatic wildlife,” said Frank-Kamenetsky.

Marine mammals and certain type of fish are particularly affected by underwater noise since they rely heavily on hearing throughout their entire life, such as for geolocation, communicating, feeding or mating.

Chemical contamination of the marine environment was another of the key environmental pressures emphasized at PRESSURE 11-2019, highlighting the vast variety of chemicals currently used in industries and households. New products are continuously flooding the markets, and their effects on the marine environment aren’t always clear.

At the meeting, the HELCOM members therefore welcomed the progress on a knowledge base on micropollutants including pharmaceuticals currently in development, and concluded that the HELCOM framework on hazardous substances might require a significant revision to be able to respond to threats posed by these new chemicals.

Moreover, a new assessment of the input of nutrients to the Baltic sea was presented at PRESSURE 11-2019, illustrating the substantial reduction of nutrient inputs since the reference period. The assessment shows that inputs of nitrogen and phosphorus to the Baltic Sea were reduced by 14 and 24 percent respectively since early 2000.

The highest nitrogen input reduction in this period was observed in the Danish Straits (24 percent) and Kattegat (21 percent), while the highest reduction of phosphorus load was noted in the Gulf of Finland (51 percent) and Baltic Proper (22 percent).

The reduction indicates the joint effort of all HELCOM countries to reduce input of nutrients and commitment to abate eutrophication – the major threat for the Baltic Sea. But the assessment shows that the nutrient input targets for the whole Baltic Sea have not yet achieved.

PRESSURE 11-2019, the “11th Meeting of the Working Group on Reduction of Pressures from the Baltic Sea Catchment Area (HELCOM Pressure Group),” was hosted by the European Commission in Brussels.

The HELCOM Pressure Group seeks to provide the necessary technical background to the work on inputs of nutrients and hazardous substances from both diffuse and point sources on land, including follow-up of the implementation of the HELCOM nutrient reduction scheme. It currently also works on emerging challenges such as underwater noise and plastic pollution.

Read the outcome of PRESSURE 11-2019

Prof. Dr. Markus Meier is the Head of Department of Physical Oceanography and Instrumentation at the Leibniz Institute for Baltic Sea Research in Warnemünde, Germany. He also is the co-Chair of the HELCOM Expert Network on Climate Change (EN CLIME) and the Chair of the Baltic Earth Science Steering Group (BESSG).

1. Q: Climate change and the Baltic Sea: what are the facts and trends, what do we know?

Markus Meier (MM): According to the conclusions of the BACC II Author Team (2015), water temperatures of the Baltic Sea have been increasing during the past 100 years and are projected to further increase during the 21st century. According to recent future scenario simulations, ensemble mean changes in sea surface temperature averaged over the Baltic Sea between 1978-2007 and 2069-2098 range between 1.8 and 3.1°C depending on the underlying greenhouse gas emission scenario. Correspondingly, the annual maximum sea-ice extent has significantly declined during the past decades and will further decline in the future. Projections suggest that at the end of the century the Bothnian Sea and large areas of the Gulf of Finland and Gulf of Riga will become ice-free during normal winters. Past salt water inflows and observed salinities in the Baltic Sea do not show statistically significant trends but large multi-decadal variations on the time scale of about 30 years. According to the BACC II Author Team (2015), it is still unclear whether Baltic Sea salinity will increase or decrease as climate models have severe biases with regard to the freshwater balance. Since the beginning of Baltic tide gauge measurements in 1886, the mean sea level in the Baltic Sea has increased by more than 0.2 m and, for the 21st century, an accelerated sea-level rise is projected. However, the projections are highly uncertain and in the northern Baltic Sea glacial isostatic adjustment may counteract also the accelerated sea-level rise in the future.

1. Q: What are the implications on biodiversity?

MM: Changing temperature and salinity in future climate may have large impacts on species distributions and food web interactions. According to the BACC II Author Team (2015), species distributions and biodiversity of the Baltic Sea are particularly sensitive to changes in salinity due to the large salinity gradients and due to the fact that salinities of large areas are in a critical range of approximately 5 to 7 g kg-1. In this range, the numbers of both freshwater and marine species are at their minima. Hence, any systematic changes in salinity would considerably affect the habitats of marine and freshwater ecosystems. Further, the projected increase in water temperatures would enable the invasions of warm water species which have already been observed, but also the decline of other species. An example for the latter might be the potentially vulnerable, ice-breeding Baltic ringed seal (Phoca hispida botnica). Climate change might be a major threat to all southern populations in the Archipelago Sea, Gulf of Finland and Gulf of Riga and only the fairly good winter sea-ice habitat in the Bothnian Bay might guarantee the survival of the northern populations.

1. Q: What needs to be done, both short and long term?

MM: Today, the largest environmental threat of the Baltic Sea as a whole might probably be anthropogenic eutrophication. Hypoxic sea bottoms in the Baltic without higher forms of life have today approximately the size of the Republic of Ireland. According to the BACC II Author Team (2015), climate change is likely to exacerbate eutrophication effects in the Baltic Sea because of (1) increased external nutrient loads due to increased runoff, (2) reduced oxygen flux from the atmosphere to the ocean and (3) intensified internal nutrient cycling due to increased water temperatures. Hence, nutrient load abatement strategies as already agreed within the Baltic Sea Action Plan (BSAP) should rigorously be implemented. With the help of large coupled environment-climate model ensembles that allow us to estimate uncertainties, management questions can today successfully be addressed. Despite the large spread in future projections, the realization of the BSAP will lead to a significant improvement of the environmental status of the Baltic Sea. This result is independent of the applied climate model or the greenhouse gas emission scenario. Assuming an optimistic scenario with perfect implementation of the BSAP, projections suggest that the achievement of a Good Environmental Status will take at least a few more decades. To assess the status of the Baltic Sea environment and its changes and to further improve and evaluate Baltic Sea models, coordinated long-term measurement programs are indispensable.

About climate change assessments within Baltic Earth

Within the Baltic Earth programme, regular assessments of our knowledge about climate change in the Baltic Sea region are performed in order to synthesize scientifically legitimate literature. So far, two comprehensive books have been published (BACC Author Team, 2008 and BACC II Author Team, 2015) and, currently, a third assessment is underway. These sources of condensed information on climate change have previously been used by HELCOM for own climate reports and will also be used for the fact sheet on climate change that is currently under development by experts from HELCOM and Baltic Earth networks (EN CLIME).

References

BACC Author Team (2008). Assessment of climate change for the Baltic Sea basin. Regional Climate Studies, Springer, Berlin Heidelberg, 474 pp. https://doi.org/10.1007/978-3-540-72786-6.

BACC II Author Team (2015). Second assessment of climate change for the Baltic Sea Basin. Regional Climate Studies. Cham: Springer. https://doi.org/10.1007/978-3-319-16006-1.