Major reversal in ocean circulation detected in the Southern Ocean

Can someone explain in simple terms what this means? Like what is happening (like am 5) and what are the consequences of this.

You get unreliable weather patterns . monsoon in dry places, and monsoon dependent countries falling dry..

And thus unreliable investment, a house or factory might be flood prone in a dessert valley, a dam with power stations might fail to provide.

So you have uninsureable riches, that might aswell no longer be there.

And as a consequence, massive migration from inhabitable regions. Hard to imagine the implication when there are billions of people affected

Not important, but I want to briefly point out as a Grammar Nazi that you mean uninhabitable regions. Inhabitable and habitable mean the same and their opposites are uninhabitable and not habitable. This is one of those bizarre oddities of the English language.

Just for kicks:

    English       | French
    --------------+------------
        habitable |   habitable
      inhabitable |   habitable
    uninhabitable | inhabitable