[Editorial] Evidence with a quiet voice

Important aspects of this moment in history are typified by two developments during the last week of September. On the one hand an annual report from the Potsdam Institute for Climate Impact Research released during New York Climate Week revealed, for the first time, that a seventh planetary boundary - related to ocean acidification - has now been breached. That is seven out of nine planetary boundaries exceeded. Planetary boundaries are scientifically defined guardrails intended to establish a safe operating space for humans that ensure the Earth's health, so such sweeping exceedances are very serious.