Way back in 1968, Paul Ehrlich asserted in The Population Bomb:
The battle to feed all of humanity is over. In the 1970s and 1980s* hundreds of millions of people will starve to death in spite of any crash programs embarked upon now.
How did that work out for you Paul? Oh, yes, that pesky Green Revolution came along and ruined the prophecy.
But this time Ehrlich's got it right, because he's got a Consensus Statement to back him up over at the Millennium Alliance for Humanity and the Biosphere. It forthrightly declares:
Earth is rapidly approaching a tipping point. Human impacts are causing alarming levels of harm to our planet. As scientists who study the interaction of people with the rest of the biosphere using a wide range of approaches, we agree that the evidence that humans are damaging their ecological life-support systems is overwhelming.
The Five Horsepersons of the Ecological Apocalypse are:
Climate disruption—more, faster climate change than since humans first became a species.
Extinctions—not since the dinosaurs went extinct have so many species and populations died out so fast, both on land and in the oceans.
Wholesale loss of diverse ecosystems—we have plowed, paved, or otherwise transformed more than 40% of Earth's ice-free land, and no place on land or in the sea is free of our direct or indirect influences.
Pollution—environmental contaminants in the air, water and land are at record levels and increasing, seriously harming people and wildlife in unforeseen ways.
Human population growth and consumption patterns—seven billion people alive today will likely grow to 9.5 billion by 2050, and the pressures of heavy material consumption among the middle class and wealthy may well intensify.
Never mind that estimates of climate sensitivity and thus the pace and severity of future man-made climate change are trending down; that humanity has reached peak farmland which will have big follow-on benefits with regard to species extinctions (which have been exaggerated in any case) and the restoration of more land for nature; that pollution levels in modern countries have been falling for decades and there is every prospect that they will do so for developing countries as they become wealthier; and finally, economic growth and wealth creation is increasingly decoupled from material resource use.
It just so happens that I am working on a new book, The End of Doom, showing that the balance of the scientific and economic evidence, well, contradicts this "consensus."
*Actually he added the "1980s" to the 1973 edition. In 1968, massive famines were definitely going to happen in the 1970s.