President Trump leaves the G-7 Leaders Summit in La Malbaie, Quebec, on June 9 with White House Chief of Staff John F. Kelly, left, and national security adviser John Bolton. (Sean Kilpatrick/Canadian Press via AP)

There was a quiet detail in a report on this weekend’s disastrous Group of 7 summit in Canada that didn’t receive much notice. It’s known that there was a variety of issues on which President Trump and the U.S. delegation disagreed with its allies in drafting a statement meant as a capstone to the brief meeting, but the Toronto Star lifted up something unexpected: plastics.

From its report:

“The Americans didn’t want to agree to a declaration on climate change that referenced the Paris accord, nor did they want to sign on an oceans charter, which contained targets on plastics, with similar language. … No one expected Trump would sign on the climate change piece, but they’d hoped the U.S. would agree to take joint action to tackle plastic pollution in the world’s oceans.”

“In the end, it didn’t.”

This is an interesting thing on which to dig in one’s heels. Although Trump’s attitude toward climate change is well understood and predictable — the Paris accord, as you may remember, was a voluntary global effort to address warming — opposition to curtailing plastics pollution is a new one, at least to me. Climate change has been heavily laced with politics and a deliberate effort to mask or question the science linking greenhouse gas emissions to a warming climate. The amount of plastic in the world’s oceans, though, is both directly measurable and obvious in its origins.

Two of the largest measured collections of plastic in the ocean are in the Pacific and Atlantic oceans near the United States.

Particle count (a) and particle mass (b) of plastic samples collected from 11,854 surface-towing plankton net trawls. (source)

All of that plastic isn’t from the United States, though. As plastic waste enters the ocean, it travels with currents as it breaks down into smaller particles. The collection points on the map above are a function of those currents, not of their points of origin.

That said, there has been analysis aimed at determining the origin point of plastics that end up in the ocean. The heaviest contributor, 2015 research found, was China, which makes up about 28 percent of the mismanaged plastic waste in the world. A number of developing countries compose the top 20 most significant contributors — but the United States comes in in the 20th slot.

The challenge is that, although the United States is much better at preventing plastic waste from escaping the refuse collection process, we generate so much more waste that it contributes a lot to the problem. As the researchers put it, “even a relatively low mismanaged rate results in a large mass of mismanaged plastic waste because of large coastal populations and, especially in the United States, high per capita waste generation.” A small percentage of a large number can be as big as a large percentage of a small number.

That 2015 estimate is a range of annual plastic debris that enters the ocean each year. Researchers figured that the upper end of the U.S. estimate was about 0.11 million metric tons of debris — or about 73 percent of the mass of gold that has ever been mined (according to Wolfram Alpha). The low end, 0.04 million metric tons, is the equivalent of three-quarters of the mass of the Titanic.

In other words, the problem of plastic pollution in the ocean — which is a problem, including because of the negative health effects on sea life — is more a function of the United States than any of the other member nations of the G-7. That, too, is a function of scale, but it doesn’t really matter. Like climate change, the United States contributes more than other major developed economies.

The American objection to action on climate change often takes the form of preserving economic competitiveness of American industry. If we were to apply limits or demand certain technologies to reduce greenhouse gas emissions, the argument goes, overseas companies that ignored those restrictions would gain a competitive advantage.

The agreed-upon communique released following the summit includes language particular to the issue of plastics pollution, endorsing a charter that would reduce certain uses for plastic and move toward using only recyclable plastic. The mention of plastics makes up the second part of the second-to-last of 28 points of agreement.

“We endorse the Charlevoix Blueprint for Healthy Oceans, Seas and Resilient Coastal Communities, and will improve oceans knowledge, promote sustainable oceans and fisheries, support resilient coasts and coastal communities and address ocean plastic waste and marine litter. Recognizing that plastics play an important role in our economy and daily lives but that the current approach to producing, using, managing and disposing of plastics and poses a significant threat to the marine environment, to livelihoods and potentially to human health, we the Leaders of Canada, France, Germany, Italy, the United Kingdom, and the European Union endorse the G-7 Ocean Plastics Charter.”

Notice the absence of the United States and Japan from that list.

America’s exclusion ended up not mattering anyway. Shortly after leaving the summit, incensed at Canadian Prime Minister Justin Trudeau, Trump backed out of the communique entirely.