MB FUTURE SCIENCE BRIEF 
In 2008, the uncertainty around the distribution and abundance 
of sound sources was ‘high’ (Boyd et al., 2008). At that time, 
very little research had been done on the topic, partly due to a 
lack of resources but also due to a lack of appropriate methods 
to record and map sound over large spatial scales (such as AIS, 
sound (propagation) modelling, and mapping). In 2009, a first 
assessment of the environmental impact of underwater noise in 
the Northeast Atlantic was provided by OSPAR, the Convention 
°or the Protection of the Marine Environment of the North- 
East Atlantic? (OSPAR Commission, 2009a). The available data 
indicated that pressures due to underwater noise emissions 
might be relatively high in the Greater North Sea and Celtic 
Seas. This is attributed to the comparably high level of human 
activities in those areas. OSPAR also concluded that this trend 
might increase with the development of maritime activities in 
Europe such as wind farm deployment, construction of harbour 
infrastructures, ongoing seismic surveys, etc. Since then, the 
European Commission’s Marine Strategy Framework Directive 
{MSFD; European Parliament and the Council of the European 
Union, 2008) has triggered a variety of projects aimed at 
systematically monitoring both impulsive and continuous sources 
of underwater noise. 
Continuous noise monitoring projects have been, or are being, 
conducted in the Baltic Sea (BIAS project‘; Baltic Sea Information 
on the Acoustic Soundscape), the wider North Sea (JOMOPANS®; 
Joint Monitoring Programme for Ambient Noise North Sea), the 
Atlantic JONAS®; Joint Framework for Ocean Noise in the Atlantic 
Seas), the Mediterranean Sea (QuietMed’ and QuietMed2®), and 
the newly started Quiet Seas? in the Mediterranean and Black Sea. 
These programs have deployed sound monitoring stations in their 
respective study areas to document baseline sound levels (and trends 
over time) and contributed to the development of standards both 
for the measurement and analysis of underwater ambient noise. 
An important step forward is the development of sound maps, as 
proposed in Dekeling et al., (2014), making use of numerical modelling, 
AIS data, and the use of source models (e.g. MacGillivray & de Jong, 
2021). These sound maps provide insight into spatial and temporal 
distribution of sound that individual measurements cannot provide, 
and they can be used as the basis for assessments. Sound maps can 
also be used for other purposes, such as predicting the effect of noise 
mitigation measures. Figure 6 is an example of a sound map for the 
North Sea showing sound levels from shipping and background sound 
(wind, waves etc.), based on modelling underwater sound from these 
sources, and supported by a year of measurements at 15 locations. 
Broadband - shippina + wind 90 percentile 
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Figure 6. Estimated sound from 
shipping and wind in the North 
Sea, presented using a colour-blind 
1ccessible colour scale where white 
s the highest level and black is the 
lowest 
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