With 30 countries from Kenya to Indonesia and from Canada to Brazil now involved in the world campaign to beat pollution by countering the torrents of plastic trash that are degrading oceans and endangering the life they sustain, the UN has strengthened its massive efforts to clean up the seas, which are the Earth’s main buffer against climate change.

They work for years to bolster the economies of two countries. For one, the United States, they provide labour and taxes; for the other, Mexico, they send remittances that support tens of thousands of families and communities. Then they are deported, and neither government takes into account their special needs.