Biodegradable plastic sounds like a wonderful idea when you first hear about it. Most plastics are notorious for how long they stick around and how hard it is to break them down naturally, so to think that all those bits of plastics that end up scattered to the four winds could just melt away harmlessly sounds almost too good to be true. And well, once you read the fine print, it kind of is…A new report by the United Nations looks at these so-called biodegradable plastics and their impact on oceans, and compared to the theory, reality is a lot less rosy. The biodegradable plastics rarely actually degrade because they require long-term exposure to high-temperatures (around 122F, or 50C), like those found in large municipal composters, to actually break-down. Those conditions are not found very often in nature, and especially not in the oceans.