Ecological tipping points are the<span> points where environmental problems reach threshold level causing irreversible shifts in the behavior of natural systems. These are also called thresholds where the biodiversity changes.</span>
I've had the same question, the answer is longitude.
Mass movement<span> is the </span>movement<span> of surface material, such as soil, rocks and debris, caused by gravity and other underlying conditions, such as water, wind, ice and human activity.</span>