MB FUTURE SCIENCE BRIEF 
Addressing the issue 
A of underwater nolse 
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The last decade has seen the issue of underwater noise 
acknowledged in a series of international agreements. 
n Europe, the most significant driver in tackling this 
aressure is the Marine Strategy Framework Directive 
adopted in 2008; 
nternational standards for measuring and reporting 
underwater noise have been published, facilitating 
'nternational collaboration on the issue; 
n the last decade there has been some progress 
towards the reduction of noise from shipping. Regional 
Nonitoring programmes in European waters started in 
the last decade will inform policy and regulation in years 
to come; 
As the plans for a Blue Economy have intensified in the 
past decade, so has the development of best practices 
for marine environmental impact assessment of noise- 
‘nducing activities; 
Regulation, management and mitigation measures have 
gradually been tailored to noise sources, such as pile- 
driving and military sonar, and to the species affected, 
but further research is needed to develop more cost 
effective measures; 
New technologies such as drones, modelling approaches 
and more multi-disciplinary studies appear promising 
in terms of increasing our understanding of underwater 
noise and our ability to manage it. 
Boyd et al., (2008) did not go into detail on the risk management 
aspects of underwater noise. This was partly because up until that 
time there was very little international or regional regulation on 
he issue. In addition, although noise mitigation measures had 
been well-established for example in seismic surveys, only during 
the last decade did noise management really start to be more 
widely developed and applied for other noise producing activities. 
In this chapter, we discuss regulations and other policy drivers, 
environmental impact assessments and mitigation strategies. We 
also outline emerging technologies applicable for each step of the 
risk framework (Figure 1). 
may lead to noise-associated risks for marine mammals. In 2017, 
‘t reaffirmed the need for further internationally coordinated 
research on the impact of underwater noise on cetaceans and other 
nigratory species. This resolution also proposed that environmental 
mpact assessments take full account of the effects of all activities 
on cetaceans, and that the issue of underwater noise be integrated 
nto the management plans of marine protected areas. At the 
CBD 12* Conference of Parties in 2014, Decision XIl/23 included 
a section on the impacts of anthropogenic underwater noise on 
marine and coastal biodiversity, asking Parties to, among other 
measures, carry out further research on the remaining significant 
knowledge gaps and to combine acoustic and habitat mapping 
of sound-sensitive species in order to identify areas where those 
species may be exposed to noise Iimpacts. 
4.1 Regulations and other drivers 
4.1.1 International 
In 1982, the United Nations Convention on the Law of the Sea 
{UNCLOS) (United Nations, 1982) provided a definition of marine 
pollution and urged countries to act in a transboundary approach, 
taking measures to control it. However, it was not until three decades 
later that underwater noise was acknowledged as a pollutant 
and started to appear explicitly in international environmental 
conservation agreements, conventions and fora. In the last decade 
in particular, a series of resolutions have been agreed on the issue 
of anthropogenic underwater noise, recognising it as a threat to 
marine organisms that need to be understood and managed. This 
is the case for both the Convention for Biological Diversity?® (CBD) 
and the Convention on the Conservation of Migratory Species of 
Wild Animals?® (CMS). For example, in 2008, the CMS adopted a 
resolution on the adverse impacts of anthropogenic underwater 
noise on cetaceans and other biota, calling on Parties to undertake 
environmental assessments when introducing systems which 
The 2017 United Nations (UN) declaration 'Our ocean, our 
ruture: call for action‘ included a specific reference to addressing 
ınderwater noise. This was followed in 2018 by the UN Informal 
Consultative Process on Oceans and the Law of the Sea, which 
focussed on the issue, with contributions from both governmental 
and non-governmental stakeholders, resulting in a Secretary- 
General report on 'Oceans and Law of the Sea' (UN, 2018a). In 2019, 
JN General Assembly resolution 74/19 also explicitly included 
underwater noise and encouraged the International Maritime 
Organization?’ (IMO) to take action on shipping noise, in particular 
by looking at energy efficiency and noise reduction measures in 
tandem (see below). 
ın 2018, the International Whaling Commission?® (IWC) made a 
resolution to continue its work on exposure, impact assessment 
and management of underwater noise. Furthermore, it aimed to 
5 https://www.cbd.int/ 
S https://www.ems.int/ 
7 https://www.imo.org/ 
8 https‘ /Awe int /nnuate/dawnlands /Oumu0CVhMNO SYWST-OTFu/RFESOLUTION. 20178 NOISE ndf