Page 3 of the letter [1] has 13 examples of steps to take, including habitat conservation, re-wilding, reducing food waste, eating a mostly plant-based diet, and "massively adopting renewable energy sources". Nothing we haven't heard and mostly ignored many time before.

1. http://scientists.forestry.oregonstate.edu/sites/sw/files/Ri...

> Nothing we haven't heard and mostly ignored many time before.

except for embarking on habitat conservation, programmes of re-wilding, reducing food waste, more people than ever eating a mostly plant-based diet, and "massively adopting renewable energy sources".

Isn't that evident from the article?

Stop pushing Earth's ecosystems to their breaking point. Find some sustainable way to achieve human existence and prosperity without just gobbling up all the world's natural resources. Stop poisoning our environment. Stop the runaway growth in human population and consumption, before nature steps in and does it for us.

to stir controversy... war is the best form of population control?

Disease and famine were also good controls on population growth that are now obsolete.

"Over the past century humankind has managed to do the impossible and rein in famine, plague, and war. This may seem hard to accept, but, as Harari explains in his trademark style—thorough, yet riveting—famine, plague and war have been transformed from incomprehensible and uncontrollable forces of nature into manageable challenges. For the first time ever, more people die from eating too much than from eating too little; more people die from old age than from infectious diseases; and more people commit suicide than are killed by soldiers, terrorists and criminals put together."

https://www.amazon.com/Homo-Deus-Brief-History-Tomorrow/dp/1...

That's not exactly controversial, it is a fairly well established fact that historically humanity got rid of excess young males by waging war.