If any cause is worth being concerned about, it is the future well-being of the planet.
If any matter is deserving of determined protests, it is the environment, which our children and grandchildren and future generations will inherit.
Selfish or reckless stewardship of that environment is a very bad, even evil thing.
Taken to extremes over many centuries, it could conceivably result in an Earth in which it is difficult for humans to live.
There is big debate among scientists as to the extent of climate change, but there is overwhelming agreement among experts that human emissions are to a significant extent responsible for changes.
The Extinction Rebellion activists have been allowed to demonstrate aggressively in London, the capital of the United Kingdom and one of the most important and vibrant cities in the world.
Rightly, however, as the Easter weekend drew to a close, police cleared key demonstration sites.
Protest always has to co-exist with the right of other people to move around cities and countryside, and to conduct their business.
But there is a question that the more thoughtful among the hardline environmental protestors do need to answer, if they are to have any credibility.
These protests, and similar protests like it, are very much a feature of the first world. Yet it is the developed, rich and invariably democratic world that is making the greatest strides in combatting harmful emissions. As voices such as Boris Johnson (opposite) and others have pointed out, China is contemptuous of environmental concerns.
It is building coal plants, which are extremely harmful to the environment, while the west has closed most of its plants.
When is the protest moving to Beijing? Might the delay be due to the fact that China, unlike Europe and America, is not very accepting when it comes to democracy and protest?