For the second time, the Kayapo people of Brazil are fighting to stop their homes being flooded for the construction of a hydro-electric dam.
Thousands of them will be displaced if this government-backed project goes ahead. Rainforest will be destroyed, fisheries and other wildlife, on which indiginous people depend, will disappear for good.
The dam is being promoted as a clean energy scheme but those against it say its environmental and social costs are too high.
News of their protest came on the day the Welsh government urged conservationists to see sense and back construction of a £15 billion barrage across the Severn Estuary. The similarities between the two proposals are striking.
The point of a barrage, stretching 10 miles from Cardiff to Weston-super-Mare, is to harness the power of the Severn’s tides. Its tidal range is 45 foot, the second largest in the world. Potentially, it is a source of huge amounts of clean energy.
The estuary is protected by UK and European law and listed under the Ramsar convention which means it is recognised as an internationally important wetland – one of a network across the globe on which wild birds depend. It is not possible for a site to have stronger safeguards.
This does not rule out development, however, which, under certain conditions, can go ahead. Two of those conditions are that no alternative is available and that new and equally valuable wildlife habitat can be created elsewhere.
These conditions were met when the Shellhaven (London Gateway) port was given the go-ahead recently. The new sites being created in compensation for this Thames Estuary development may turn out to be even better than the original.
The chances of this if the Severn is developed are slim - land is in short supply and the estuary is huge.
And too little thought has been given to other, cheaper ways of using the Severn’s tidal power, which could generate equal amounts of electricity and take less time to build.
Rhodri Morgan, the Welsh Assembly’s First Minister, suggests the global environmental need – tackling climate change – outweighs the need to protect the local environment – the estuary - and that the massive potential of the Severn is too great a prize to ignore.
It is a great prize but there may be other ways of winning it.
Those backing the Kayapo believe the sacrifices they will have to make are not justified by the benefits of building a huge dam.
The UK government will need to decide if extensive damage to the Severn Estuary is a sacrifice worth making for construction of a hugely expensive barrage across the Severn.