Baltic Sea a Time Machine to Future Ocean Challenges

(CN) – At face value, the Baltic Sea seems insignificant to the research pursuits of scientists investigating global ocean topics. It’s comparatively shallow, has a narrow connection to the North Atlantic and a low salinity. But these factors obscure the Baltic Sea region’s value as a model for future changes in the ocean, according to a study published Tuesday in the journal Science Advances.

“This unique sea of brackish water can serve as a kind of time machine that allows us to better estimate future global changes,” said co-lead author Thorsten Reusch, a professor at the GEOMAR Helmholtz Center for Ocean Research Kiel in Germany.

The authors argue future changes projected for oceans are already occurring in the Baltic.

“This is because the small volume of water and slow water exchange with the open ocean, behaves like an amplifier, allowing many processes and interactions to occur at a faster pace,” said co-lead author Jan Dierking, a researcher at GEOMAR.

For example, the oceans have warmed by an average of nearly 1 degree Fahrenheit over the last 30 years. In the same time period, time-series measurements in the Baltic have documented warming of about 2.7 degrees Fahrenheit. In addition, there are massive oxygen-free zones in the deeper portions of the sea, which have spiked 900 percent over the past century.

And the pH of the Baltic routinely reaches values projected for oceans in the next century.

While these extremes are generated by the particular basin topography of the Baltic, significant human activity in the sea continues to accelerate negative changes.

Nine highly industrialized nations with densely populated coastal regions border the sea directly. Furthermore, intensive agriculture in the interior ensures considerable nutrient runoff, while equally demanding fisheries place pressure on the pelagic food web.

But it is not all bad.

The Baltic is one of the most thoroughly surveyed seas on Earth. Scientific observation and monitoring of biological and physical processes in the sea began around 1900, and there is a strong tradition of research collaborations among many nations surrounding the Baltic.

These partnerships led to the implementation of the European Union’s joint Baltic research and develop program BONUS, a dedicated macro-regional research agenda and funding program that also enabled the team to produce its study.

The findings from BONUS offer a sound basis for science-based resource management “on a level accomplished in only a few regions of the world,” according to Reusch.

Bordering nations have drastically reduced nutrient inputs since the 1980s in order to both curb overfishing and reverse the decline of large predators. This accomplishment was achieved through binding agreements within the framework of the European Union, in addition to the ambitious goals of the Baltic Sea Action Plan, which included Russia even before the end of the Cold War.

In fisheries, the safeguarding of capture fisheries and bird and marine mammal populations among the perimeter nations has led to measurable improvements of existing stocks.

“Overfishing, warming, acidification, pollution, eutrophication, loss of oxygen, intensive use of coasts – all these are phenomena that we observe around the globe,” said Reusch. “Because they have been particularly drastic in the Baltic, but also because some key problems were successfully addressed, the region can, for good and for bad, tell us what to expect and how to respond to the challenges of the future.

“The Baltic Sea, as a model region, can contribute to achieving the United Nation’s Sustainable Development Goal 14 – the conservation and sustainable use of the oceans, seas and marine resources.”


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