The great pacific garbage patch is rather overhyped. From what you hear and the way some people describe it you'd think it would be like a sargasso sea of garbage, but it's actually just an increased concentration of small bits of plastic just under the surface of the ocean. If you were looking right at the water in the densest part of the garbage patch you probably wouldn't even be able to tell that the water was unusual.
For example, here's a typical picture illustrating the garbage patch: http://myecoaction.com/wp-content/uploads/2009/08/great-paci... However, it's a fraud, it's actually a picture from Manila harbor. The fact that this isn't the deep ocean should be blatantly obvious by the fact that there is a person in a canoe in it, and canoes are not well known trans-pacific transportation vessels.
I'm not saying that the various oceanic gyre garbage patches aren't a problem, but they certainly will not form a legacy for humanity, as they are pretty much invisible.
For example, here's a typical picture illustrating the garbage patch: http://myecoaction.com/wp-content/uploads/2009/08/great-paci... However, it's a fraud, it's actually a picture from Manila harbor. The fact that this isn't the deep ocean should be blatantly obvious by the fact that there is a person in a canoe in it, and canoes are not well known trans-pacific transportation vessels.
I'm not saying that the various oceanic gyre garbage patches aren't a problem, but they certainly will not form a legacy for humanity, as they are pretty much invisible.