Baltic Marine Environment
Protection Commission

 

Baltic Marine Environment
Protection Commission

Towards a climate-resilient Baltic Sea

rudiger-strempel-climate-change.jpg

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 20th 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).

HELCOM expert interview: Markus Meier on climate change

markus-meier-climate-change.jpg

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.

HELCOM expert interview: Jannica Haldin on climate change and the SROCC report

  

Q: WHAT’S IN THE IPCC REPORT?

Jannica Haldin: The Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) assesses the latest scientific knowledge about the impacts of climate change on ocean, coastal, polar and mountain ecosystems, as well as on us humans who depend on them. It is a mirror, with which we can look back to see what has changed from past to present. However, it also lets us look into the future, projecting what changes we can expect in the sea, depending on the amount of greenhouse gases we continue producing.

When looking at what has already changed, we can see that the rate of ocean warming – the sea taking in and storing heat – has more than doubled, as has global mean sea level rise. In fact, to date, the ocean has taken up more than 90 percent of the excess heat in the climate system. It is also clear that over the last decades, global warming has led to mass loss of ice sheets and glaciers, reductions in snow cover, and Arctic sea ice extent and thickness. In response to ocean warming, sea ice and biogeochemical changes such as oxygen loss, marine species have undergone shifts in geographical range and seasonal activities. This has already resulted in changes in species composition, abundance and biomass production of ecosystems and altered interactions between species, causing cascading impacts on ecosystem structure and functioning.

But the report also looks forward, up to 80 years into the future. Our future ocean is projected to transition to unprecedented conditions, a combination of increased temperatures, greater upper ocean stratification, further acidification, oxygen decline, and altered net primary production – for instance linked to algal blooms – as well as reduced sea ice extent. As a consequence, over the 21st century, we can expect a further decrease in global biomass of marine animal communities and in their production, a shift in species composition, and a decline in fisheries catch potential. In turn, this is projected to affect income, livelihoods, and food security. Projected ecosystem responses include further losses of species habitat and diversity, and degradation of ecosystem functions.

The SROCC report also makes clear that impacts of climate change are already a reality, and when the pressures exerted by climate change are combined with pressures stemming from other human activities, the latter have the potential to intensify the warming-induced ecosystem impacts. The capacity of organisms and ecosystems to adjust and adapt to change is better the lower the total pressure on the system is. This means that the sea has a better chance to handle the changes under lower emissions but it also means that we need to work to manage other human activities to limit their negative effects, to give the ecosystem a fighting chance.

HOW DOES THAT RELATE TO THE BALTIC SEA?

Although the report looks at the global situation, it is highly relevant for our own sea. The Baltic Sea is a shallow, Northern sea, partially covered by sea ice and with a high coast to sea ratio. If they changes outlined in the report come to pass, they will impact a significant proportion of the approximately 85 million people living in the catchment. The report directly states that the effects of warming will be more pronounced on high latitudes and for temperate shallow estuaries with limited exchange with the open ocean, of which the Baltic is used as prime example. This translates into that the changes outlined globally will occur faster and with more impact here than in other places.

In addition to the changes which affect larger areas, the report outlines some changes where Baltic Sea specific information is available. This includes increased risk of water-borne disease in the Baltic Sea, with a nearly two-fold predicted increase in suitable conditions for Vibrio bacteria which can cause cholera. Wave height in the Baltic is also predicted to increase, and extreme sea level projections show a rise of up to 0.35 m towards the end of the century along the Baltic Sea coast. Long-term loss and degradation of marine ecosystems compromise the sea’s role in cultural, recreational, and intrinsic values important for our identity and well-being.

WHAT IS HELCOM DOING ABOUT CLIMATE CHANGE?

Overall, HELCOM aims at strengthening the sea’s resilience and own coping mechanisms, by improving the capacity of the Baltic Sea’s ecosystem to recover from stress and disturbance resulting from climate change impacts. HELCOM is a regional environmental policy maker, working on developing common environmental objectives and actions for the whole region, as well as providing information about the state of and trends in the marine environment. Both the objectives and the trend information can then form the basis for decision-making in the Baltic Sea countries and in other international fora. HELCOM strives to make climate change increasingly visible in marine policy making, as well as incorporate it into the day to day work of the Commission.

In practice, climate change work within HELCOM is focusing on understanding and communicating what climate change means for the marine and coastal environment. Climate change has a multitude of effects so it needs to be approached in that way, not from one single topic, but from every angle of possible importance to the sea.

To compile the available climate change information, HELCOM, together with Baltic Earth, earlier this year established a Joint Climate Change expert network (EN CLIME), currently consisting of over 60 experts from the entire region. Right now, EN CLIME is working on a Baltic Sea climate change fact sheet, to make sure that decision makers have the latest science on climate change and its impacts. Similarly to the IPCC report, the fact sheet will provide key messages on what has already happened and what we can expect in the future. However, the fact sheet will look specifically at our own region, covering a large number of topics, from how much it might rain, to what we can expect for seabirds, to possible impacts on maritime traffic.

What the IPCC report did on a global scale, the fact sheet will do at the regional level – empowering decision makers to tackle the transition facing the region and help underpin timely, ambitious and coordinated action. The statement from the IPCC report is as valid for the Baltic Sea as it is globally:

“The more decisively and earlier we act, the more able we will be to address unavoidable changes, manage risks, improve our lives and achieve sustainability for ecosystems and people – today and in the future.”