It may be better / cheaper to do some other form of geoengineering.

Dig a really big hole in the middle of a desert, cover it with a highly reflective geodesic dome / tent and use canals to funnel "surplus" seawater into it. Use solar power to refrigerate the inside of the tent and harvest the (slightly) desalinated water for something useful.

Cover all the deserts with solar panels... cheaper.

Launch a big venetian blind in the earth sun lagrange point to reduce insolation by a percent or two.

We may need that water at some point, throwing it away seems silly.