The article is a complete pile of bio-waste.
The motivation of the iron dump was to geo-engineer a “solution” to (the non-problem of) global warming. Among the possible consequences — the triggering of a new ice age. Opposition is not “antihuman” — quite the opposite.
As I read the article, the primary motivation was to stimulate plankton growth which would benefit salmon populations. The carbon sequestering was a possible side effect, not a primary motivator.