Due to increasing carbon dioxide in the atmosphere, more carbon is dissolved in the ocean. As the ocean continues to absorb more CO₂, the pH decreases. This event is called:

An ecological footprint is the measure of the _____ made by humans on global _____.

Species_____ refers to the total number of species in a community, whereas species ____ refers to the total number of individuals within each species.

Which of the following statements about species extinction is correct?

"_________" is a key threshold in climate science that, when crossed, causes significant and frequently irreversible changes in the climate system.