Several estimates about the
amount of plastics entering the ocean each year exist. Jambeck et al. (2015)
estimate that amount to be about 8 million t, Hammer et al (2012) say it is 6.4
million t and Plastics Europe (2015) state it to be 10% of the plastics
produced, thus 31 million t. Further, Eriksen et al. (2014) estimate that more
than 260 000 t float on the surface while Cózar et al. (2014) say the floating
mass should be some 10 000 t - and that it should be more, so a lot is removed
by nano-fragmentation and ingestion, other sinks. So their number is still by
far within the Eriksen estimate.
If these estimates are
combined now - about 260 000 t floats (15%), then 260 000 t is washed ashore (15%)
and 1 200 000 t sinks to the sea floor (70%) (Barnes et al, 2009). This is then
1.7 million t in total - but the annual input, according to Jambeck then is 8
million t. If any of the 3 input estimates here (6.4 million t, 8 million t or
31 million t) is anywhere near correct, then the total mass already existing in
the ocean from about 50 year of incessantly increasing plastics production
cannot be in the order of 1,7 t in total. With 15% washed ashore, where the
waste still is in a marine ecosystem, maybe half of that is cleaned up. But a
tiny part of the floating debris is cleaned up now and then as well and some
other processes remove plastics that are ingested etc. Then in total
approximately 10% of the debris entering the ocean is actually removed some way
or another, which likely is an optimistic estimate. This would mean that 90% of
the debris entering the ocean stays there. With lifetimes of the order of
hundreds of year, the plastic can only be fragmented, but not biodegraded.
Global annual plastic production started off with 1.5 million t in 1950,
increasing steadily to over 300 million t nowadays (see Figure 2). The estimates from literature could probably be averaged to 10
million t for 2015, which is about 3% of the plastics produced. This number can
then be used to calculate the total amount of plastic waste that must have
entered the ocean since plastic production began in the 1950ies, which is
approximated to be about 200 million tons (see Figure 3). So instead of the given 1.7
million t of total marine debris from literature, the more fitting number of
200 million t in total will be used for illustrations and considerations of the
marine debris picture.
Figure 2: Growth in global plastic production 1950-2014, from Plastics Europe,
the facts 2015
|
Year
|
plastic amount
|
estimated waste
|
Year
|
plastic amount
|
estimated waste
|
1950
|
1.5
|
0.045
|
1983
|
77
|
2.31
|
1951
|
2
|
0.06
|
1984
|
80
|
2.4
|
1952
|
3
|
0.09
|
1985
|
82
|
2.46
|
1953
|
4
|
0.12
|
1986
|
85
|
2.55
|
1954
|
5
|
0.15
|
1987
|
90
|
2.7
|
1955
|
6
|
0.18
|
1988
|
96
|
2.88
|
1956
|
7
|
0.21
|
1989
|
100
|
3
|
1957
|
8
|
0.24
|
1990
|
107
|
3.21
|
1958
|
9
|
0.27
|
1991
|
112
|
3.36
|
1959
|
10
|
0.3
|
1992
|
120
|
3.6
|
1960
|
11
|
0.33
|
1993
|
125
|
3.75
|
1961
|
12
|
0.36
|
1994
|
130
|
3.9
|
1962
|
13
|
0.39
|
1995
|
137
|
4.11
|
1963
|
14
|
0.42
|
1996
|
140
|
4.2
|
1964
|
15
|
0.45
|
1997
|
150
|
4.5
|
1965
|
16
|
0.48
|
1998
|
155
|
4.65
|
1966
|
18
|
0.54
|
1999
|
160
|
4.8
|
1967
|
20
|
0.6
|
2000
|
172
|
5.16
|
1968
|
25
|
0.75
|
2001
|
185
|
5.55
|
1969
|
28
|
0.84
|
2002
|
200
|
6
|
1970
|
30
|
0.9
|
2003
|
208
|
6.24
|
1971
|
32
|
0.96
|
2004
|
215
|
6.45
|
1972
|
35
|
1.05
|
2005
|
225
|
6.75
|
1973
|
38
|
1.14
|
2006
|
230
|
6.9
|
1974
|
40
|
1.2
|
2007
|
240
|
7.2
|
1975
|
44
|
1.32
|
2008
|
245
|
7.35
|
1976
|
50
|
1.5
|
2009
|
250
|
7.5
|
1977
|
55
|
1.65
|
2010
|
270
|
8.1
|
1978
|
62
|
1.86
|
2011
|
279
|
8.37
|
1979
|
65
|
1.95
|
2012
|
288
|
8.64
|
1980
|
68
|
2.04
|
2013
|
299
|
8.97
|
1981
|
70
|
2.1
|
2014
|
311
|
9.33
|
1982
|
75
|
2.25
|
2015
|
320
|
9.6
|
|
|
|
|
6773
|
203
|
Figure 3: Approximated marine debris
amount in million t, calculated with 3% of the plastics produced enter the
ocean
|
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