Team member Stiv reporting here. I will start by saying I'm not an oceanographer, but I am an investigative journalist by trade and I've spent the better part of four years researching plastic pollution issues from science to policy. What I've learned is that the problem of plastic pollution has very little to do with pure oceanography, and much more to do with waste management infrastructure, global economics/markets, polymer chemistry, watershed hydrology, and countless other disciplines-- in short, any solution, to truly be informed, needs to be derived from a multidisciplinary approach.
However, understanding how gyres work is of utmost important, and there are very, very few experts out there who can speak credibly to their movements. I've spoken with almost all the experts on how the gyres work (most notably Curtis Ebbesmeyer and Nicolai Maximenko advises the 5 Gyres science team), what factors affect how they behave, and what I've learned is that gyres are very difficult to read.
What I've also learned is that the solutions being proposed and applied to the marine plastic epidemic are often, anything but scientific. As an activist, I can get downright angry about the notion of gyre cleanup, and when I see stories in the media about it, it often elicits a visceral response from me. Obviously, this is not a helpful vantage in the grand scheme of things, but the motivation for my response is simple: selling the idea of gyre cleanup to the public actually makes the problem worse. If a barge full of plastic comes back from the gyre, and helicopters take pictures of it, and newspaper headlines read, 'gyre cleanup group's first mission to clean plastic from the gyre is successful,' the ocean is in for a world of hurt.
In the coming weeks, I will state my case in parts on the 5 Gyres blog, talking about some of the nuances associated with the notion of cleanup. We'll look at the issue from scale to politics, and we'll attempt to bring some transparency as to which groups are funded (at least partially) by a plastics industry that fights us tooth and nail on ANY policy which would reduce plastic consumption, and what that may or may not mean in with regard to how these groups message to the public.
We'll also share some good news: you don't need to go out to the ocean to clean up plastic as the gyres themselves upon each full rotation spit plastic out. The North Pacific Gyre, for example, takes three years to complete an orbit and dumps roughly 50% of it's contents (Curtis Ebbesmeyer, Flotasmetrics). This flotsam will either wash up on land or go into another gyre. All you need to do to clean the gyres is pick what washes up off the beach, and stop it from being thrown in, in the first place.
PART ONE: THE SCALE OF GLOBAL PLASTIC POLLUTION
If you haven't sailed to a garbage patch, it's very difficult to understand what they look like and how big they actually are. Contrary to popular media, they are not a floating island the size of Texas. They're incredibly diffuse and plastic pollution is everywhere in the ocean, not just in the gyres. Gyres simply concentrates it. Sailing across the North Atlantic taught me something that all oceanographers know, but don't necessarily say: the ocean is BIG, and running the numbers on how much garbage is out there is an extremely difficult task because the scale itself is hard to noodle on.
According to one of SEA's leading researchers, Giora Proskurowski, plastic is extremely diffuse and calculating its density is very difficult. If we were to attempt to quantify how much is out there, we need to do some big math. Giora's data states that concentration in The Atlantic gyre is about 50,000 .1g pieces per square kilometer on the surface. If we apply big math to that simply for the sake of getting an idea of scale, we get: 5 kilograms per square kilometer or roughly 11 pounds per square kilometer on the surface. There are 316 million square kilometers of ocean surface. This makes for about 3.5 billion pounds of degraded plastic fragments fewer than 5mm in length on the surface of the ocean worldwide. Again, this is an extremely conservative estimate, extrapolating from a local data set to show the scale in the world. Giora's work, for example, shows that plastic doesn't just exist on the surface, it gets stratified within the water column, close to 90 feet down (not to mention all the types of plastic that sink, too, which is about half of the types manufactured). This estimate doesn't include all the big pieces you find in various garbage patches within the gyres, but we'll leave that weight out for now.
So, for the purposes of argument, let's say that for each of those 90 feet of stratification, there is roughly the same weight per foot. Now we're up to 315 billion pounds in the ocean. For comparison, The Gulf Spill is spewing roughly 2.5 million pounds of oil per day.
COST OF CLEANUP, HYPOTHETICAL
A supertanker's dead weight (amount of weight it can carry) is 500 million pounds. That would mean that to clean the ocean, you'd need to fill 630 oil supertankers to the brim at a cost of about $56,000 per each a day to charter (United Nations Conference on Trade and Development). So, to cleanup the gyres (assuming there is actually technology out there to do it which, as of today, nothing has been proven to work), we're looking at a cost of at least about $35 million a day or roughly $13 billion a year, and about 17% of all the oil tankers in service in the world would have to be full time devoted to cleaning it up.
Again, these numbers here are as conservative as I can get across all spectrums.
SCALE OF A WASTE STREAM
Now let's talk about the scale of waste. As of 1992, the world (5.5 billion people, which today has grown to 7 billion) dumped 14 billion pounds of garbage in the ocean each year, over half (at least) is synthetics (if we apply this statistic over 40 years-- the plastics era in the limelight-- we get a very similar number to the 315 billion pound number stated before of overall plastics in the ocean). Worldwide, we're looking at 1-3% recycling rates on plastic, a number based on an industry that is governed by supply and demand. The plastics industry produces 250 billion pounds of virgin raw plastic pellets per year. Okay, so now we at least have an 'some idea' of what we're dealing with.
One American's 'garbage in the ocean' footprint is about 600 (as of 1992) pounds annually (if you want to know precisely what your plastics in the ocean footprint is do a simple experiment: throw all your waste in the same bin for a week. Separate organic materials and synthetics. Determine the percentage of synthetics and apply that percentage to that 600 pound number, and you'll know roughly how much damage your lifestyle causes on the ocean in terms of weight.)
CONCLUSIONS
Yes, it's bad, and it's overwhelming and it's getting worse, fast. Just to stop how much we contribute as a world annually, we'd need 14 full time oil tankers operating everyday, at a cost of roughly $286 million annually-- ouch. Scale, yes it's a a crazy amount to even comprehend, and even if the problem was 1/10th of what we stated here, we're still dealing with degrees of scale much larger than cleanup technology allows. In short, the plastic needs to stop going into the ocean in the first place, and that's where gyre cleanup efforts should be focused if well intentioned people are meaning to take meaningful action.
Stay tuned to the blog, as I'll investigate this issue more deeply throughout the next few weeks.
on the National Geographic Channel tomorrow night, July 3, @ 7-10pm ET, to watch Mississippi River Quest, a journey down the Mississippi River from the beginning at Lake Itasca, Minnesota 2,300 miles to the Gulf of Mexico. 
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