The other inconvenient truth is that it will be hard to feed people in the near future. Conservation advocates like me have to face the truth that our treasured places will suffer if people need more food. We can't control fishing if people are catching fish to avoid starvation. Most of us would probably eat the last fish if we were truly hungry.
We need to produce food more efficiently, and that has many aspects. More food production with a lower ecological footprint is key. Not just more food per area used, but more food per resources consumed.
And...as Jon Foley points out in Time,
we need to alter our diets.
Much of the grain grown in developed nations goes to feed not human beings but domesticated animals, and inefficiently too — one filet mignon requires 32 lbs. of corn, and converts that grain into calories at just 3% efficiency. Globally we'll likely need to eat less meat — if only to give parts of the growing developing world space to eat a little meat — and, at least in much of the unhealthily overfed West, eat fewer calories overall. That might help reduce global food waste — one out of every three calories produced globally are never eaten, which isn't just a waste of food but of water, land and energy.
Eating meat and ocean predators like tuna is a resource-costly way to feed ourselves, and we need to get started in cutting back on resource use in eating.