{
  "@context": "https://schema.org",
  "@type": "Dataset",
  "name": "Ocean plastic stock and flow model",
  "description": "A stock-and-flow model of plastic accumulating in the ocean from 1950 onward. Because plastic persists in the environment, the stock integrates: parameter choices change when a given quantity is reached rather than whether it is reached.",
  "version": "1.0",
  "dateModified": "2026-08-20",
  "creator": {
    "@type": "Organization",
    "name": "Hoskins Circular",
    "url": "https://www.hoskinscircular.com"
  },
  "license": "Reuse with attribution to Hoskins Circular and a link to the source page.",
  "disclaimer": "Illustrative model, not a forecast. Outputs depend entirely on user-selected assumptions and on published estimates that disagree with one another. Not professional, technical, regulatory, investment or policy advice. Provided without warranty; Hoskins Circular accepts no liability for reliance on it.",
  "scope": {
    "does_not_argue": [
      "No comparison is made between materials, and no case is made for substituting one material for another.",
      "Leakage is modelled as a property of the collection and waste-management system, not of the polymer.",
      "No claim is made that any material is inherently harmful."
    ],
    "endorsement": "Reference values are drawn from published sources whose authors have neither reviewed nor endorsed this tool or its outputs.",
    "material_coverage": {
      "description": "All plastic reaching the ocean, not packaging alone. The leakage rate is an effective, all-source rate fitted to estimates of total ocean plastic stock, so it already includes fishing gear, agricultural film, textile microfibres and tyre wear.",
      "named_pathways": {
        "tyre_wear": {
          "emissions_kg_per_capita_year": 0.81,
          "range_kg_per_capita_year": [
            0.23,
            4.7
          ],
          "global_emissions_tonnes_per_year": 6000000.0,
          "share_of_ocean_plastic_percent": [
            5,
            10
          ],
          "source": "Kole et al., Int. J. Environ. Res. Public Health (2017)",
          "note": "Released as microplastic; never a macro item, so not reachable by deposit schemes, beach cleans or surface collection."
        },
        "synthetic_textile_fibres": {
          "emissions_g_per_capita_year": [
            25,
            500
          ],
          "source": "European Environment Agency, Microplastics from textiles (2022)",
          "scope_note": "European estimate.",
          "note": "Also released as microplastic; the parent fibres are within the plastics production series."
        }
      },
      "known_inconsistency": "Tyre rubber is an elastomer and lies outside the plastics production series the model grows, so tyre-derived ocean plastic is expressed as a share of a production figure that excludes it. At 5-10% of ocean input the effect is small against the factor-of-two spread in stock estimates, but the leakage rate therefore slightly overstates the loss rate of conventional plastics.",
      "unit_note": "Bottle-equivalent figures are a unit of mass for visualisation. They do not imply the plastic in question is packaging."
    }
  },
  "key_finding": "Across the plausible parameter range the accumulated stock continues to rise, and a growing share of it is microplastic that no clean-up can recover. Changing production growth, leakage rate, removal capacity or fragmentation rate alters the year a given quantity is reached rather than whether it is reached, and delaying removal permanently reduces how much is recoverable at all. Closing the leakage pathway is the only intervention that changes the endpoint rather than the schedule, which is an argument for investment in collection, recovery and closed-loop design.",
  "model": {
    "time_step": "1 year",
    "start_year": 1950,
    "max_year": 2300,
    "units": "tonnes",
    "equation": "Two pools. macro[y] = macro[y-1] - fragmented + (leak[y] - primary[y]) - removal[y]; micro[y] = micro[y-1] + fragmented + primary[y]; stock[y] = macro[y] + micro[y]",
    "terms": {
      "fragmented": "macro[y-1] * (1 - 0.5^(1/fragmentation_half_life)); a transfer from macro to micro, not a loss",
      "primary[y]": "leak[y] * primary share; the share is the fixed historical ramp before 2026 and the user-selected value from 2026. Enters the ocean already as particles.",
      "production[y]": "observed 1950-2015; thereafter production[y-1] * (1 + growth) until the peak year, then held flat",
      "leak[y]": "production[y] * leakage_rate; the rate is the calibrated historical value before 2026 and the user-selected value from 2026",
      "removal[y]": "a flat annual tonnage from the chosen start year, applied to the macro pool only and floored at zero",
      "micro pool": "has no outflow: microplastic is neither removable nor lost on the timescales modelled"
    },
    "simplifications": [
      "single well-mixed pool per size class",
      "no sediment burial or beaching sink",
      "mass basis only; particle counts are not tracked, so exposure grows faster than the curve shows",
      "removal assumed to act on all macro plastic, not only floating or accessible material",
      "no regional or polymer detail",
      "world population held constant for per-capita figures"
    ]
  },
  "parameters": {
    "starting_stock": {
      "type": "enum",
      "default": "wef",
      "options": {
        "oecd": {
          "stock_2019_t": 140000000,
          "calibrated_historical_leakage": 0.014832,
          "implied_leakage_percent": 1.5,
          "source": "OECD, Global Plastics Outlook: Policy Scenarios to 2060 (2022)"
        },
        "wef": {
          "stock_2019_t": 181000000,
          "calibrated_historical_leakage": 0.01917,
          "implied_leakage_percent": 1.9,
          "source": "WEF / Ellen MacArthur Foundation, The New Plastics Economy (2016) \u2014 over 150 Mt at 2015. Often requoted as 165 Mt, which is the same figure in US short tons.",
          "note": "181 Mt is a model output, not a measurement: it is the 2016 estimate carried forward to 2019."
        },
        "sciadv": {
          "stock_2019_t": 317000000,
          "calibrated_historical_leakage": 0.03362,
          "implied_leakage_percent": 3.4,
          "source": "Kaandorp et al., Science Advances (2025) \u2014 263 Mt marine pool at 2015",
          "note": "317 Mt is a model output, not a measurement."
        }
      }
    },
    "production_growth_percent": {
      "type": "number",
      "default": 2.4,
      "min": -3,
      "max": 6,
      "reference": 2.4,
      "reference_source": "Implied by the OECD baseline: 460 Mt in 2019 rising to 1,231 Mt by 2060 (2.43%/yr compound)"
    },
    "peak_year": {
      "type": "integer",
      "default": 2045,
      "min": 2026,
      "max": 2101,
      "null_value": 2101,
      "reference": 2045,
      "reference_source": "Modelled peak in land-to-sea transport under the OECD's ambitious policy scenarios (Kaandorp et al., 2025)",
      "note": "Production is held flat from this year on. That is a peak only while growth is positive; below zero it is the year the decline levels off; at zero growth it has no effect."
    },
    "leakage_percent": {
      "type": "number",
      "default": null,
      "min": 0,
      "max": 5,
      "note": "Defaults to the rate implied by the chosen starting stock. Applies from 2026; earlier years use the calibrated historical rate.",
      "references": [
        {
          "value": 1.5,
          "source": "OECD baseline, in which the mismanaged share of waste falls from 22% to 15% by 2060 without new policy"
        }
      ]
    },
    "removal_tonnes_per_year": {
      "type": "number",
      "default": 25119,
      "min": 0,
      "max": 100000000,
      "reference": 25000,
      "reference_source": "The Ocean Cleanup's best year to date (2025), ~25 million kg; ~53 million kg cumulative since 2013",
      "note": "For scale, UNEP estimates roughly 11 Mt of plastic enters the ocean annually."
    },
    "primary_microplastic_share_percent": {
      "type": "number",
      "default": 23,
      "min": 0,
      "max": 45,
      "reference_range": [
        15,
        31
      ],
      "reference_source": "Boucher & Friot, Primary Microplastics in the Oceans, IUCN (2017) \u2014 15-31% of ocean plastic, nearly two-thirds of it from synthetic textiles and tyre abrasion",
      "note": "Enters as particles and can never be collected.",
      "applies_from": 2026
    },
    "removal_start_year": {
      "type": "integer",
      "default": 2026,
      "min": 2026,
      "max": 2100,
      "note": "Delay compounds: macro plastic left in the water keeps fragmenting, so waiting reduces how much remains recoverable at all."
    },
    "fragmentation_half_life_years": {
      "type": "integer",
      "default": 450,
      "min": 5,
      "max": 600,
      "reference": 450,
      "reference_source": "Commonly cited persistence for common polymers in seawater",
      "note": "Renamed fragmentation half-life. It governs the transfer of mass from the macro pool to the micro pool; it destroys no mass, so a shorter half-life worsens the outcome by moving mass beyond recovery sooner."
    },
    "historical_primary_share_percent": {
      "type": "number",
      "default": 15,
      "min": 0,
      "max": 31,
      "applies_to": "1950-2025",
      "reference_range": [
        15,
        31
      ],
      "reference_source": "Boucher & Friot, IUCN (2017) \u2014 the range for ocean plastic entering as microplastic",
      "note": "The share ramps linearly from zero in 1950 to this value in 2026. The ramp shape is an assumption reflecting the growth of vehicle fleets and synthetic textile production; no published historical series exists. The endpoint is user-selectable within the IUCN range. Separating this from the forward share prevents an assumption about the future from rewriting how much of today's stock is already beyond recovery."
    }
  },
  "historical_production_tonnes": {
    "1950": 2000000,
    "1951": 2000000,
    "1952": 2000000,
    "1953": 3000000,
    "1954": 3000000,
    "1955": 4000000,
    "1956": 5000000,
    "1957": 5000000,
    "1958": 6000000,
    "1959": 7000000,
    "1960": 8000000,
    "1961": 9000000,
    "1962": 11000000,
    "1963": 13000000,
    "1964": 15000000,
    "1965": 17000000,
    "1966": 20000000,
    "1967": 23000000,
    "1968": 27000000,
    "1969": 32000000,
    "1970": 35000000,
    "1971": 38000000,
    "1972": 44000000,
    "1973": 51000000,
    "1974": 52000000,
    "1975": 46000000,
    "1976": 54000000,
    "1977": 59000000,
    "1978": 64000000,
    "1979": 71000000,
    "1980": 70000000,
    "1981": 72000000,
    "1982": 73000000,
    "1983": 80000000,
    "1984": 86000000,
    "1985": 90000000,
    "1986": 96000000,
    "1987": 104000000,
    "1988": 110000000,
    "1989": 114000000,
    "1990": 120000000,
    "1991": 124000000,
    "1992": 132000000,
    "1993": 137000000,
    "1994": 151000000,
    "1995": 156000000,
    "1996": 168000000,
    "1997": 180000000,
    "1998": 188000000,
    "1999": 202000000,
    "2000": 213000000,
    "2001": 218000000,
    "2002": 231000000,
    "2003": 241000000,
    "2004": 256000000,
    "2005": 263000000,
    "2006": 280000000,
    "2007": 295000000,
    "2008": 281000000,
    "2009": 288000000,
    "2010": 313000000,
    "2011": 325000000,
    "2012": 338000000,
    "2013": 352000000,
    "2014": 367000000,
    "2015": 381000000
  },
  "historical_production_source": "Geyer, Jambeck & Law (2017), Production, use, and fate of all plastics ever made, Science Advances",
  "reference_masses_tonnes": {
    "ocean_cleanup_cumulative_to_2025": 53000,
    "great_pacific_garbage_patch_floating": 100000,
    "estimated_ocean_stock_2015": 150000000,
    "marine_pool_2015_kaandorp": 263000000,
    "combined_body_mass_all_adults_2005": 287000000,
    "oecd_projected_river_and_ocean_stock_2060": 493000000,
    "all_plastic_ever_made_all_compartments": 8000000000
  },
  "reference_mass_sources": {
    "combined_body_mass_all_adults_2005": "Walpole et al., BMC Public Health (2012)",
    "all_plastic_ever_made_all_compartments": "Elhacham et al., Nature (2020)",
    "oecd_projected_river_and_ocean_stock_2060": "OECD, Global Plastics Outlook (2022)"
  },
  "per_capita_basis": {
    "world_population": 8200000000,
    "bottle_mass_kg": 0.035,
    "bottle_description": "1.5 litre PET bottle, used as a unit of mass visualisation only; implies nothing about the product type of the plastic"
  },
  "scenarios": [
    {
      "name": "default",
      "description": "Opening state of the tool: every parameter on its cited reference value.",
      "parameters": {
        "start": "wef",
        "growth": 2.4,
        "peak": 2045,
        "removal": 25119,
        "half": 450
      },
      "results": {
        "stock_2050_t": 523911108,
        "stock_2100_t": 1194040945,
        "stock_2200_t": 2388961984,
        "stock_2300_t": 3413300855
      }
    },
    {
      "name": "oecd_consistent",
      "description": "Both the starting stock and the leakage rate set to the OECD's position.",
      "parameters": {
        "start": "oecd",
        "growth": 2.4,
        "peak": 2045,
        "leak": 1.5,
        "removal": 25119,
        "half": 450
      },
      "results": {
        "stock_2050_t": 410003950,
        "stock_2100_t": 939066738,
        "stock_2200_t": 1882448486,
        "stock_2300_t": 2691156814
      }
    },
    {
      "name": "no_peak",
      "description": "Production growth continues indefinitely.",
      "parameters": {
        "start": "wef",
        "growth": 2.4,
        "peak": 2101,
        "removal": 25119,
        "half": 450
      },
      "results": {
        "stock_2050_t": 529381588,
        "stock_2100_t": 2051644435,
        "stock_2200_t": 6918106260,
        "stock_2300_t": 11089851377
      }
    },
    {
      "name": "removal_100x",
      "description": "Global removal capacity scaled to 100 times The Ocean Cleanup's best year.",
      "parameters": {
        "start": "wef",
        "growth": 2.4,
        "peak": 2045,
        "removal": 2511900,
        "half": 450
      },
      "results": {
        "stock_2050_t": 446203664,
        "stock_2100_t": 1002329827,
        "stock_2200_t": 1993968786,
        "stock_2300_t": 2844045317
      }
    },
    {
      "name": "leakage_eliminated_2026",
      "description": "All further leakage stopped from 2026. Shows how slowly the existing stock declines.",
      "parameters": {
        "start": "wef",
        "growth": 2.4,
        "peak": 2045,
        "leak": 0,
        "removal": 25119,
        "half": 450
      },
      "results": {
        "stock_2050_t": 217729998,
        "stock_2100_t": 200380964,
        "stock_2200_t": 169445578,
        "stock_2300_t": 142926404
      }
    },
    {
      "name": "optimistic_degradation",
      "description": "Degradation half-life cut from 450 years to 20.",
      "parameters": {
        "start": "wef",
        "growth": 2.4,
        "peak": 2045,
        "removal": 25119,
        "half": 20
      },
      "results": {
        "stock_2050_t": 277829883,
        "stock_2100_t": 404878717,
        "stock_2200_t": 431308266,
        "stock_2300_t": 432134189
      }
    }
  ],
  "url_parameters": {
    "description": "Any scenario can be linked directly by query string.",
    "example": "?start=oecd&growth=2.4&peak=2045&leak=1.5&primary=23&histprimary=15&removal=25119&removefrom=2026&half=450&to=2100",
    "keys": {
      "start": "oecd | wef | sciadv",
      "growth": "percent, -3 to 6",
      "peak": "year, or 'none'",
      "leak": "percent, 0 to 5",
      "removal": "tonnes per year",
      "half": "years",
      "to": "2100 | 2200 | 2300",
      "scale": "log (optional)",
      "primary": "percent of leakage entering as microplastic, 0 to 45",
      "removefrom": "year removal begins, 2026 to 2100",
      "histprimary": "historical microplastic share endpoint, percent, 0 to 31"
    }
  },
  "charts": {
    "cost_of_waiting": {
      "plots": "microplastic at the horizon in excess of the value obtained by beginning removal in 2026, against the year removal begins",
      "note": "A difference, not a level. The curve rises with removal capacity because a larger capacity forgoes more by waiting. In the main model, raising removal capacity lowers the absolute microplastic stock, since removed macro plastic is no longer available to fragment."
    }
  }
}