MORE PLASTIC THAN FISH BY 2050?

Media Fact-Checks on the More Plastic than Fish by 2050 Claim

Most news sites blindly repeated the claim without ever fact-checking it, but some news sites published investigations. For example, the BBC had this to say after conducting their investigation:

“So how much plastic is there in the ocean, and how much will there be in 2050? We don’t know, but probably a lot. How many fish? We don’t really know but certainly a lot. And when will one overtake the other? We definitely do not know.”

The BBC interviewed the authors of the studies that the Ellen MacArthur foundation had based their calculations on and those scientists were not at all supportive of the conclusions drawn by the Foundation.

Jenna Jambeck, the scientist who estimated the amount of plastic expected to be in the ocean by 2025 did not support the Foundation decision to extrapolate the amount out to 2050. She was not convinced that such an extrapolation was valid.

Jennings who authored the study estimating the amount of fish had this to say:

“We’re not absolutely confident in our methods to determine what proportion of this is fish at the moment…it’s a very uncertain number to predict.”

The CBC/Radio Canada conducted their own investigative and few years later, in 2019 and the journalist concluded:

“What can be said with certainty is that there is already far too much plastic in the world’s oceans. But comparing the weight of the garbage to the marine life is, at best, fishy business.”

Summary of Media Fact-Checks on “More Plastic than Fish”

As we have just seen, the BBC investigated the story in 2016 and found that it did not stand up to scrutiny. They found the there is no evidence to support the claim and that the authors of the scientific articles that the Ellen MacArthur Foundation cited were not convinced either.

Then, again in 2019, the CBC conducted their own fact-check. Just as the BBC found, the CBC concluded that there was no evidence to support the claim.

As the story is not supported by evidence and as the story has been debunked twice we might ask why so-called “environmental” groups continue to promote it on their websites. Why have they not removed the story in the many years since it was debunked not once but twice?

Both fact-checks concluded that there’s probably a huge amount of plastic in the oceans, so we might wonder whether it makes any difference whether there’s more plastic than fish. As a scientist, I would argue that it does make a difference and the reasons will become clear when we re-examine the story in light of new evidence.

A New Examination of the “more plastic than fish in the sea by 2050” Story

The Ellen MacArthur Foundation’s report makes several claims and assumptions, so let us examine each one in turn. If even one of these points is unsubstantiated or false, then the “more plastic than fish in the ocean by 2050” claim is dispelled once and for all.

I am impressed that some journalists looked into this, but they were not able to show us the whole picture in part because they were not scientists or experts in the field and secondly because new information has come to light in the interim.

Let us now take a fresh, independent look at the statement from the Ellen MacArthur Foundation report:

“Each year, at least 8 million tonnes of plastics leak into the ocean — which is equivalent to dumping the contents of one garbage truck into the ocean every minute. If no action is taken, this is expected to increase to two per minute by 2030 and four per minute by 2050. Estimates suggest that plastic packaging represents the major share of this leakage. The best research currently available estimates that there are over 150 million tonnes of plastics in the ocean today. In a business-as-usual scenario, the ocean is expected to contain 1 tonne of plastic for every 3 tonnes of fish by 2025, and by 2050, more plastics than fish (by weight).”

That is pure guesswork, not solid science. In the next section addressing point 2, we will show that the 8 million tons number is now known to be a gross overestimate.

Ellen MacArthur Foundation cites this study for the 150 million tons of plastic already in the oceans – Ocean Conservancy and McKinsey Center for Business and Environment, Stemming the Tide: Land-based strategies for a plastic-free ocean (2015).

There is no scientific basis for the 150 million tons claim

Point Two – 8 million tons added per year

The Ellen MacArthur Foundation claimed that there over 8 million tons of plastic will enter the oceans per year. Again, the number was based on the work of Jambeck who assumed that a proportion of all plastic within 30 miles (50km) of the coast will somehow end up in the ocean. In contrast, a new peer-reviewed scientific study found that number to be false due to a serious mistake in the calculations. The best estimate for microplastics entering the oceans from rivers is now down from 8-12 million tons per year to just ~6000 tons per year. Whereas 8-12 million tons a year would be an emergency. The figure of 6000 tons still leaves room for improvement, but it does not constitute an emergency.

Weiss et al., The missing ocean plastic sink: Gone with the rivers, Science, 373 (6550), pp 107-111, 2021

A layperson’s explanation from the scientists can be found free of charge in the article and video interview here:

The ocean plastic sink that went away with the rivers

A new study estimates the amount of plastic coming from the fishing industry is much higher than that coming from land, which highlights why it is so important to make policy based on accurate data. We now know that ocean plastic coming from land is just 14%, compared to 86% coming from fishing activities, so the latter is is where we must focus our attention.

“We estimate that industrial trawl, purse-seine and pelagic longline fisheries operated 2.1 Mt of plastic gear over 2018 to obtain 49.7 Mt of retained and discarded catch, representing 74% of industrial marine capture globally. The median estimate for plastic gear lost during the use of these gear types was 48.4 kt (95% confidence interval: 28.4–99.5 kt). This estimate excludes abandoned and discarded gear.”

B. Kuczenski et al., Plastic gear loss estimates from remote observation of industrial fishing activity, Fish & Fisheries, 23 (1), 22-33, 2022

“Once a global map was produced from the “corrected” model observations, the total amount of plastic was aggregated. Between three model input scenarios, the mass of plastic floating on the ocean surface was estimated to be between 93 300 and 236 000 tonnes. However, the most conservative estimate for plastic emissions in 2010 was 4.8 million tonnes – two orders of magnitude higher. Errors may explain the difference between these two estimates.”

McAdam, Plastic in the ocean: How much is out there?, significancemagazine.com, October 2017

Claim 2 is incorrect and is too high by a factor of ~100-1000 times

Point Three – amount in the ocean increasing exponentially

The Ellen MacArthur report assumed that the amount of plastic entering the ocean would increase exponentially as the amount of plastic produced increased over time. Eight peer-reviewed studies show no increase in ocean microplastic for five decades despite production continuing to grow. It has been scientifically proven that the amount of plastic entering the oceans does not increase simply because the amount of plastic manufactured increases. Instead, the amount entering the oceans depends on how well or how badly we manage the waste we create. Note that the Galgani citation below reviews 8 separate scientific publications all showing no change in ocean plastic amounts for decades.

Richard C. Thompson et al., Lost at Sea: Where Is All the Plastic?, Science, 304 (5672), p838, 2004

F. Galgani et al., Are litter, plastic and microplastic quantities increasing in the ocean?, Microplastics and Nanoplastics, 1 (2), 2021

Claim three is incorrect

Point Four – plastic is only added and never degrades

The report assumed that all of the plastic ever entering the oceans would remain there forever and accumulate. In fact, there are thousands of scientific, peer-reviewed publications spanning decades all showing that plastics degrade and rather rapidly. This occurs even in the sea. The global market for additives to prevent plastics degrading is in the billions of dollars per year. No-one would be spending billions of dollars on stabilizers for plastics if they were stable. There is a page dedicated to dispelling the myth that plastics do not degrade here.

Point four has been disproven

Point Five – amount of fish is ~900 million tons

The report claimed that the amount of fish in the oceans is 800-900 million tons. The source they cited was:

Jennings et al., Global-scale predictions of community and ecosystem properties from simple ecological theory, Proceedings of the Royal Society B., 275, 1375–1383, 2008

The publication took a wild guess at the amount of fish, not by measuring fish but by estimating the amount of phytoplankton i.e. fish food there is from satellite data. There is no direct evidence that the amount of fish in the oceans is 800-900 million tons. In fact, the author Jennings, now believes that the number is far greater. This study says that the actual amount of fish is at least 10 times higher than the older estimate.

“With a current estimate of ~1,000 million tons, mesopelagic fishes likely dominate the world total fishes biomass. However, recent acoustic observations show that mesopelagic fishes biomass could be significantly larger than the current estimate. Here we combine modelling and a sensitivity analysis of the acoustic observations from the Malaspina 2010 Circumnavigation Expedition to show that the previous estimate needs to be revised to at least one order of magnitude higher.”

Point five is found to be in error

“you can be for the environment, or against plastics, but not both”.