It announced a substantial cut in production from its Hunter mines, in response to a thermal coal price that had more or less halved from its 2010 peak of $US130.

Glencore had begun job cuts in late 2014. Prices kept falling throughout 2015, but they hit bottom in January 2016 at about $US49 a tonne.

They peaked again in August 2018 at about $US120 a tonne, and have fallen since to 2015 levels, or perhaps lower.

ROLLER COALSTER

With global coal markets in surplus, Glencore is doing the economically rational thing by reducing production with the aim of tightening supply, and in turn lifting prices.

At this stage, it appears to believe it can cut production without major job losses.

As one of the world's major mining and commodity trading companies, Glencore has a power to move markets - or at least to boast about it - that few companies ever have.

Usually, the really big players in a given market rarely talk about such power publicly, for fear of being branded market manipulators.

But Glencore - publicly listed on the London and Johannesburg stock exchanges but very much under the control of its billionaire chief executive and largest individual shareholder, Ivan Glasenberg - is no ordinary company.

Glasenberg joined Glencore in 1984 and spent much of his time in the coal side of its businesses before assuming the top job in 2002.

Now 63, he has publicly flagged his intention to retire in the next few years.

But he was adamant on Thursday, when presenting the company's half-year results, that Glencore had no intention of being pushed by institutional investors into getting out of thermal coal.

This is good news for Glencore mineworkers here in the Hunter, more broadly in NSW, and across the Queensland coalfields.

But even Glencore's market-moving power has its limits.

Once renewable energy has the storage side fixed, that's pretty much it for thermal coal.

Batteries and the other contender, "super capacitors", are not there yet, but human ingenuity suggests they'll get there soon enough.

In the meantime, Glencore intends to mine less for a little while, to allow it to dig more later.

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