Justin Rowlatt for BBC News:  Whatever happened to all the talk of international co-operation to tackle climate change that we heard during the climate conference in Paris just a few months ago?

That is what many environmentalists are asking after the United States delivered a damaging blow to India's ambitious solar power programme this week.

In response to a US complaint, a World Trade Organization (WTO) panel has ruled that India's National Solar Mission breaches trade rules.

It judged that India's policies on buying locally made solar power equipment discriminates against imports.

"The ink is barely dry on the UN Paris Climate Agreement, but clearly trade still trumps real action on climate change," Sam Cossar-Gilbert of Friends of the Earth International said in a statement.

But is the decision really as damaging as many commentators seem to think?

Let's start at the beginning.  Cont'd...