1-when 考虑到，既然

All food generates greenhouse gases to reach our plates, but when nearly a third of it is thrown away or wasted, does that mean we could be doing more to protect the climate.

2-scraping

How much did you leave on your plates last time you ate?

A few scrapings?

3-finish off 完成，结束

Or perhaps a few mouthfuls you were too stuffed to finish off?

4-rot 腐烂

And when we throw it away, as it rots it releases yet more greenhouse gases into the atmosphere.

5-a drop in the ocean 沧海一粟，九牛一毛，微不足道

6-in isolation 孤立地，单独地

If your own contribution to seems like a drop in the ocean, don't think of your actions in isolation.