Jamail: To provide perspective on how far along we are regarding runaway ACD, another recent study shows that the planet’s wildlife population is less than half the size it was four decades ago. The culprits are both ACD and unsustainable human consumption, coupling to destroy habitats faster than previously thought, as biodiversity loss has now reached “critical levels,” according to the report. More than half of the vertebrate population on the planet has been annihilated in just four decades.