As good a place to start as any is a basic environmental policy glossary.
It's dull - but read the entry for the millenium ecosystem assessment.
"The bottom line is that human actions are depleting Earth's natural capital
putting such strain on the environment...
...that the ability of the planet's ecosystems to sustain future generations can no longer be taken for granted."
"... the assessment shows that with appropriate actions it is possible to reverse the degradation of many ecosystem services over the next 50 years, but the changes ...required are substantial ...and not currently underway."
Looks a bit serious, dunnit?
But people don't become concerned about something just because they read some stuffy report - there is always something personal going on.