Oil spills

Reported spill incidents greater than one tonne have decreased in number and as a proportion of the total number of spills over the assessment period. The evidence supports the conclusion that the UK target is currently being met.

Background

UK target

This indicator is used to assess progress against the target set out in the Marine Strategy Part One (HM Government, 2012), which requires that the occurrence and extent of significant acute spills (such as spills of oil and oil products or spills of chemicals) and their impact on biota should be minimised through appropriate risk-based approaches.

Key pressures and impacts

The key pressures causing from the shipping industry spills include increased marine traffic, larger vessel sizes and increased navigational pressures in key areas such as approaches to ports and harbours. The UK oil and gas industry is under unprecedented pressure to improve productivity against a background of low oil price and maturing oil fields. In addition, the shift towards enhanced efficiency, late life operations and decommissioning requires a general adaption of working practices. While these pressures provide a changing operational environment, there is no evidence suggesting any subsequent impact on the occurrence of significant acute spills.

In the event of a major spill the potential impacts can be highly significant and potentially cause major impact to key ecological habitats, commercial fishing and aquaculture, and leisure/business use of the marine and coastal environment.

Measures taken to address the impacts

Measures taken to address spills of contaminants including oil and chemicals are set out in the UK Marine Strategy Part Three (HM Government, 2015). The shipping, port and harbours, and offshore oil and gas industries are effectively regulated in UK waters with implementation of key national and international regulations focusing on both safety and the minimisation of marine pollution.

In the event of spill occurrence, the UK has a well-developed and exercised process of response, including measures set out in the UK National Contingency Plan (HM Government, 2014). All spill reports from the oil and gas industry are followed up by the Department of Business, Energy and Industrial Strategy, to gather further information on the cause, the potential environmental impact, the response strategy and the measures being taken to prevent a recurrence. These measures, procedures and risk-based approaches help ensure that the occurrence and extent of significant acute spills and their impact on biota are minimised.

Monitoring, assessment and regional co-operation

Areas that have been assessed

The assessment scales used were the Greater North Sea and the Celtic Seas.

Monitoring and assessment methods

The base dataset for the numbers of spills in UK waters is collated annually by the Advisory Committee on the Protection of the Seas on behalf of the UK Maritime and Coastguard Agency using data collected from the shipping, ports and harbours, and offshore oil and gas industries. This provides a consistent and long-term dataset that enables assessment of status and trends, though it cannot correct for changes in incident reporting practices. Further in-depth analysis of this dataset is conducted to investigate trends on a spatial and a significance basis (currently related to spill volume) for the purposes of this indicator.

Assessment thresholds

No specific assessment thresholds are established for this indicator and the definition of ‘significant’ acute pollution in the context of spills is not yet available. For the purposes of this assessment, a spill volume of greater than one tonne is used for trend analysis.

Regional co-operation

The UK Government is fully engaged with European and international partners across a range of groups and initiatives relating to the prevention of spills including those presided over by OSPAR, International Maritime Organization and European Maritime Safety Agency.

Further information

The introduction of contaminants, including oil and chemicals, into the marine environment presents a potential threat to marine resources and biodiversity. Acute, short-term releases in sufficient volumes or numbers, could therefore contribute to an overall deterioration of Good Environmental Status.

This assessment has focussed primarily on the reported spills of oil and oil-based products in UK waters and draws on information gathered from pollution report returns gathered by the UK Maritime and Coastguard Agency and the Department for Business, Energy and Industrial Strategy, for spills originating from marine incidents (primarily shipping and ports) and offshore oil and gas industry incidents respectively. Spills of chemicals are also assessed, though the available reports are primarily from the offshore oil and gas sector. These data are checked and compiled into a standard format by the Advisory Committee on Protection of the Sea on an annual basis (at the time of writing the data is only available to 2014).

Datasets from the Advisory Committee on Protection of the Sea allow some analysis by spill position, numbers and volume. However, no assessment is made as to the environmental ‘significance’ of any given spill and, therefore, assessment and trend analysis is primarily limited to the numbers of reported incidents.

Releases of greater than one tonne (of which only 2 to 5% are oil releases) are investigated in more detail, and a range of factors will be taken into consideration when determining whether a formal investigation or enforcement action is appropriate, as set out in the Business, Energy and Industrial Strategy enforcement policy (HM Government, 2018). These factors include the observed or likely environmental impact, the previous compliance history of the installation and the level of culpability relating to the release. All operators are required to maintain an approved Oil Pollution Emergency Plan and may be required to undertake immediate aerial surveillance, an independent assessment of the environment impact and post-spill monitoring.

Understanding the environmental impact of spills is supported through the Pollution Response in Emergencies: Marine Impact Assessment and Monitoring (Premiam) initiative which details post spill monitoring guidelines and procedures for initiating and co-ordinating monitoring and impact assessment surveys.

Assessment method

All the source spill data used as the basis of this assessment has been received from the Advisory Committee on Protection of the Sea, which provides a definitive spill dataset that is comparable across years. This dataset is further analysed to ascertain metrics relating to numbers of spills both regionally for the Greater North Sea and Celtic Seas regions, and in size categories (0.01 to 0.1, 0.1 to 1.0, 1 to 10, 10 to 100 and 100 to 1000 tonnes).

The Marine Strategy Framework Directive (European Commission, 2008) target for acute spills refers to the assessment of ‘significant’ spills. However, no specific definition of significant is provided. A wide range of issues would contribute to whether a spill could be considered as ‘significant’ from an environmental impact perspective, including volume, toxicity of spilled material, potential for dilution/dispersion at spill site, proximity of vulnerable marine resources (and their relative sensitivity), time of year and the effectiveness/availability of treatment options (for example, chemical dispersion).

A standardised process for taking these issues into account is not available. The assessment is, therefore, based on an evaluation of total numbers of spill incidents occurring annually with an additional analysis of numbers of spills above certain size categories. Temporal trends are then assessed in terms of total reported spills and compared to previous data/assessments to provide a qualitative analysis in relation to Marine Strategy Framework Directive targets.

Results

Findings in the 2012 UK Initial Assessment

No major marine oil spills have occurred in UK waters since 2005, and whilst there were a significant number of accidental discharges, only a very small percentage were greater than 2 tonnes, which was used as the threshold for large spills in the earlier assessment report (HM Government, 2012).

Latest findings

During the period 2000 to 2014, the annual number of reported spills from vessels has steadily reduced from approximately 300 to 200 incidents, but the number of reported spills from offshore oil and gas installations has increased from about 300 to 600 annually. However, the vast majority of the offshore oil and gas spills are less than 100 kg. While this has resulted in a very slight overall upward trend in spill numbers the data are too variable to make strong statements in relation to overall trends. The overall spill trends are provided in the Advisory Committee on Protection of the Sea annual report on discharges and releases of oil in the UK Exclusive Economic Zone for 2014, which included chemical and oil spills between 2000 and 2014 (Figure 1; Dixon, 2015).

Figure 1. Annual totals for reported discharges and releases attributed to vessels and offshore oil and gas installations 2000 to 2014. Figure from Dixon (2015).

There was a general upward trend in the number of reported spills over the period 2012 to 2014. This is thought to be driven by more stringent reporting practices. However, the numbers of oil spills greater than one tonne has showed a downward trend both in terms of numbers and as a proportion of the total reports (Tables 1 and 2).

Table 1. Numbers of reported oil spill incidents (not including chemical spills) from 2012 to 2014 sorted by source sector and size. Oil and Gas data from Department for Business, Energy and Industrial Strategy. Shipping and Ports data from UK Maritime and Coastguard Agency.

Source	Size (tonnes)	2012	2013	2014
Oil and Gas	0.01 to 0.1	207	259	323
	0.1 to 1.0	39	46	41
	1.0 to 10	8	9	9
	10 to 100	7	3	0
	Over 100	2	0	0
	Unknown	11	18	37
	Sector Total	274	335	410
Shipping and Ports	0.01 to 0.1	57	44	52
	0.1 to 1.0	6	9	9
	1.0 to 10	7	5	4
	10 to 100	1	1	1
	Over 100	0	0	0
	Sector Total	71	59	66
Total		345	394	476

Table 2. Analysis of reported oil spill incident data (2012 to 14) to show the percentage of spills over one tonne as a proxy for ‘significant’ spills.

Source	Size category	2012	2013	2014
Oil and Gas	Greater than 1 tonne	17	12	9
	Sector Total	274	335	410
	% greater than 1 tonne	6.2	3.6	2.2
Shipping and Ports	Greater than 1 tonne	8	6	5
	Sector Total	71	59	66
	% greater than 1 tonne	11.2	10.2	7.6
Total greater than 1 tonne		25	18	14
Total		345	394	476
% Total		7.2	4.6	2.9

Chemical spills

The vast majority (over 99%) of chemical spills are reported from the offshore oil and gas industry but the overall numbers of spills covering the reported period are generally steady with no discernible trend (Tables 3 and 4). Note that the total incident numbers are slightly lower than in Table 4 due to 3 reports unattributed to a sea region.

Table 3. Numbers of reported chemical spill incidents from 2012 to 2014 sorted by source sector and size. Oil and Gas data from Department for Business, Energy and Industrial Strategy. Shipping and Ports data from UK Maritime and Coastguard Agency.

Source	Size (tonnes)	2012	2013	2014
Oil and Gas	0.01 to 0.1	121	94	106
	0.1 to 1.0	63	65	68
	1.0 to 10	31	40	28
	10 to 100	9	6	4
	Over 100	1	1
	Unknown	4	5	6
	Sector Total	229	211	212
Shipping and Ports	0.01 to 0.1	1	3	0
	0.1 to 1.0	0	0	1
	Over 1.0	0	0	0
	Sector Total	1	3	1
Total		230	214	213

Further information

Oil Spills

A more detailed analysis has been conducted on the datasets for 2012 to 2014 (at the time of writing the 2015 dataset is not available). Table 1 shows the frequency of recorded oil spills from 2012 to 2014, sorted by the source (offshore industry and shipping/other) and the size category (tonnes). Over this period, there is a general upward trend in incident reports, primarily driven by increased reports from the oil and gas sector. However, this trend may be driven by more stringent reporting practices for the sector (a positive development) rather than any real increase in spill numbers. The incidents from shipping appear more stable over the recent term.

The relative number of oil spills in from each sectoral source in the two sea areas covered by the assessment, the Celtic Seas and the Greater North Sea, are shown in Table 5. As expected, given the primary locations of oil and gas activity and major shipping routes, the majority of incidents from both sectors have taken place in the Greater North Sea. Over the analysed period spill reports in the Greater North Sea accounted for 82%, 82% and 78% of the total reported spills for 2012, 2013 and 2014, respectively. Maps showing the spatial extent of the spills for 2012, 2013 and 2014, including their size and source, are reproduced as Figures 2, 3 and 4 respectively.

Table 5. Numbers of reported oil spill incidents from 2012 to 2014 sorted by source sector and sea region. Note that total incident numbers are slightly lower than those in Table 1 due to 10 reports unattributed to a sea region.

Area	Source	2012	2013	2014
Greater North Sea	Oil and Gas	236	280	328
	Shipping and Ports	44	41	38
	Total	280	321	366
Celtic Seas	Oil and Gas	36	53	80
	Shipping and Ports	27	17	25
	Total	63	70	105
Total		343	391	471

Figure 2. Spatial distribution, size (tonne) and source for reported oil spills in 2012.

Figure 3. Spatial distribution, size (tonnes) and source for reported oil spills in 2013.

Figure 4. Spatial distribution, size (tonnes) and source for reported oil spills in 2014.

In the absence of a clear definition of ‘significant’, this assessment uses spill volume as a proxy whilst fully appreciating that potential environmental impact (a preferred measure for significance) is dependent on a range of other factors. Table 2 shows an analysis of the data from 2012 to 2014 showing the number and percentage of oil spills that were greater than one tonne. In contrast to the total numbers of spills, this shows a generally downward trend over the 3-year period with total spills greater than one tonne being 25, 18 and 14 for 2012, 2013 and 2014 respectively. The downward trend over this period is even more evident when the figures are considered as a percentage of the total number of oil spill reports. Spills greater than one tonne were 11.2% and 6.2% of the total for the shipping and oil and gas sectors respectively in 2012 and had reduced to 7.6% and 2.2%, respectively in 2014. In the Marine Strategy Part One (HM Government, 2012,) it was stated that 6% of total reported spills were greater than 2 tonnes in 2010, by comparison only 2.9% of total spills were greater than one tonne in 2014.

Chemical Spills

Table 3 shows the total number of chemical spills by size category and sector. It is clear that the vast majority (over 99%) of chemical spills are reported from the offshore oil and gas industry, and the overall numbers of spills during the reported period are generally steady with no discernible trend. Table 4 shows the same data sorted by sea region, showing that the majority of spills occur in the Greater North Sea area (just over 80% of the total), and this distribution has been steady over the reported period. Even when the data are analysed from a ‘significant’ spill perspective (spills greater than one tonne) there is no discernible trend with the proportion of chemical spills from the oil and gas sector running at 18%, 22% and 15% of the total chemical spills for years 2012, 2013 and 2014, respectively. Figure 5 shows the spatial distribution, size (tonnes) and source for reported chemical spills in 2012. Similar numbers and distribution were found for 2013 and 2014.

Figure 5. Spatial distribution, size (tonnes) and source for reported chemical spills in 2012.

Conclusions

Since 2012, the volume of oil and chemicals accidentally spilled has varied from year to year but is generally small and of relatively minor significance.

Considering the oil and chemical spill data together, the overall number of reported spills is up from 575 in 2012 to 689 in 2014 but the overall number of spills greater than one tonne as a percentage shows a continued downward trend for 2012, 2013 and 2014 (11.5%, 10.7% and 6.7% for 2012, 2013 and 2014 respectively). These numbers and trends are heavily influenced by the oil spill data.

In 2010, 6% of spills were greater than 2 tonnes so the weight of evidence supports a slight downward trend in both the total and overall percentage of larger (greater than one tonne) spills since that time. The UK Marine Strategy Framework Directive target (HM Government, 2012) indicates that the occurrence and extent of acute spill events should be minimised through risk-based approaches. The evidence presented in this assessment supports the conclusion that the target is currently being met.

Further information

Since 2012, there has been a continuing upward trend in the total number of reported oil spills from the oil and gas sector and this has contributed to a slight upward increase in the overall UK total. However, this is considered to be in part due to changes in reporting behaviour which introduces uncertainty into any temporal trend analysis. The increased number is primarily attributed to greater frequency of reporting for small spills (less than 0.1 tonnes) from the oil and gas sector. Total incidents from the shipping and ports sector are generally stable.

A clearer indication of trends is obtained from the numbers of ‘significant’ incidents, for which spill volume is used as a proxy for potential environmental impact. Using an arbitrary threshold of spills larger than one tonne, the trend since the last assessment is generally down. Considering the number of spills greater than one tonne as a percentage of the total recorded spills, there is a downwards shift from 7.2% in 2012 to 2.9% in 2014.

There are no notable trends in the chemical spill data over the reported period, however, a higher proportion of chemical spills could be considered as potentially ‘significant’ (greater than one tonne). The average proportion of chemical spills greater than one tonne over the reported period was 18% compared to 5% for the reported oil spills.

Knowledge gaps

This analysis uses third party reporting of incidents as the key data source and the Marine Strategy Framework Directive (European Commission, 2008) assessment is not the primary driver for that process. As a result, there is little control over reporting practices which can have a significant effect on temporal inter-comparability for trend analysis. Understanding reporting practices and how they are influenced, and the promotion of standardisation would be beneficial for future assessments.

The use of spill volume as a proxy for environmental ‘significance’ is a blunt tool. Numerous other factors, such as proximity to sensitive/valuable resource, the type of oil spilled and seasonality, are potentially of greater importance. Consideration should therefore be given to the development of a more robust assessment of ‘significant’ spills, although this is accepted as problematic.

References

Dixon T (2015) ‘Annual survey of reported discharges and releases attributed to vessels and offshore oil and gas installations operating in the United Kingdom’s Exclusive Economic Zone (UK EEZ) 2014’ ACOPS: Advisory Committee on Protection of the Sea (viewed on 12 December 2018)

European Commission (2008) ‘Directive 2008/56/EC of the European Parliament and of the Council of 17 June 2008 establishing a framework for community action in the field of marine environmental policy (Marine Strategy Framework Directive)’ Official Journal of the European Union L 164, 25.6.2008, pages 19-40 (viewed 21 September 2018)

HM Government (2012) ‘Marine Strategy Part One: UK Initial Assessment and Good Environmental Status’ (viewed on 5 July 2018)

HM Government (2014) ‘The National Contingency Plan - A Strategic Overview for Responses to Marine Pollution from Shipping and Offshore Installations’. UK Maritime and Coastguard Agency (viewed on 11 December 2018)

HM Government (2015) ‘Marine Strategy Part Three: UK Programme of Measures’ December 2015 (viewed on 5 July 2018)

HM Government (2018) ‘Business, Energy and Industrial Strategy Enforcement Policy’ (viewed on 12 December 2018)

Acknowledgements

Assessment metadata

Assessment Type	D8 Contaminants



Point of contact email	marinestrategy@defra.gov.uk
Metadata date	Tuesday, December 1, 2020
Title	Oil and chemical spills
Resource abstract
Linkage
Conditions applying to access and use	© Crown copyright, licenced under the Open Government Licence (OGL).
Assessment Lineage	The base dataset for the numbers of spills in UK waters is collated annually by the Advisory Committee on the Protection of the Seas https://www.acops.org.uk on behalf of the UK Maritime and Coastguard Agency using data collected from the shipping, ports and harbours, and offshore oil and gas industries. The assessment is, therefore, based on an evaluation of total numbers of spill incidents occurring annually with an additional analysis of numbers of spills above certain size categories.
Dataset metadata	please, see details in Dixon T (2015) ‘Annual survey of reported discharges and releases attributed to vessels and offshore oil and gas installations operating in the United Kingdom’s Exclusive Economic Zone (UK EEZ) 2014’ ACOPS: Advisory Committee on Protection of the Sea (viewed on 12 December 2018)
Dataset DOI	Marine Scotland. 2018. Contaminant and biological effect data to support MSFD Descriptor 8 1999-2015 by CSEMP Region. DOI: 10.7489/12111-1

The Metadata are “data about the content, quality, condition, and other characteristics of data” (FGDC Content Standard for Digital Geospatial Metadata Workbook, Ver 2.0, May 1, 2000).

Metadata definitions

Assessment Lineage - description of data sets and method used to obtain the results of the assessment

Dataset – The datasets included in the assessment should be accessible, and reflect the exact copies or versions of the data used in the assessment. This means that if extracts from existing data were modified, filtered, or otherwise altered, then the modified data should be separately accessible, and described by metadata (acknowledging the originators of the raw data).

Dataset metadata – information on the data sources and characteristics of data sets used in the assessment (MEDIN and INSPIRE compliance).

Digital Object Identifier (DOI) – a persistent identifier to provide a link to a dataset (or other resource) on digital networks. Please note that persistent identifiers can be created/minted, even if a dataset is not directly available online.

Indicator assessment metadata – data and information about the content, quality, condition, and other characteristics of an indicator assessment.

MEDIN discovery metadata - a list of standardized information that accompanies a marine dataset and allows other people to find out what the dataset contains, where it was collected and how they can get hold of it.

Recommended reference for this indicator assessment

Mark Kirby¹ 2018. Significant Oil spills. UK Marine Online Assessment Tool, available at: https://moat.cefas.co.uk/pressures-from-human-activities/contaminants/oil-spills/

¹Centre for Environment, Fisheries and Aquaculture Science