School Email Exchange

Based on your expedition, how big is the “Pacific Plastic Patch”?

Posted on November 10 2012

Question submitted by Trinity-Pawling School

Our cruise track transected a small fraction of the vast North Pacific subtropical gyre, so we really cannot answer this question from our data.  Although we did collect plastic debris in every net tow in the gyre, areas of extremely high concentrations were not consistently in a single location (see previous question), making it difficult to determine the boundaries of any high concentration region.  For this reason, the concept of a "garbage patch" is a bit misleading.

To determine the size of the region in which floating plastics accumulate, one would have to survey great swaths of the North Pacific subtropical ocean to look for the "boundaries" where plastic concentrations change rapidly and consistently over a short distance.  This is further complicated by the fact the the ocean is a dynamic place, constantly moving, so you would have to do massive surveys repeatedly over time to give a reasonable estimate from ocean data.

Another approach is to use numerical models of ocean circulation, such as the one developed by Nikolai Maximenko and Jan Hafner at University of Hawaii,  to predict where floating debris will accumulate if carried by ocean currents (as opposed to also being blown by the wind).  Such models give a nice hypothesis about the size of these accumulation zones, but must be ground-truthed with ocean data to determine their accuracy.  Oceanographers typically use data and models together to try to answer questions such as this one.