Rav Aharon Lichtenstein, "By His Light," Chapter One:

When seeking to shape our personalities according to Torah values, we must relate to at least three levels of expectation and responsibility. These can be regarded as concentric circles, moving from the broader to the more specific:

1. The universal demands placed upon one simply as a human being;

2. The demands of a Jew;

3. The responsibilities of a ben-Torah, one who makes Torah study essential part of his life and embodies its values.

I wish to deal now with the first level. What are the basic, cardinal, universal values for which every person should strive?
... God placed Man (Adam) in the Garden,"le-ovdah u-leshomrah," to work or cultivate the Garden and to grow it. Here we have two distinct tasks. One, "leshomrah, is largely conservative aimed at preserving nature. It means to guard the world, to watch it...

On a basic human level, like Rav Lichtenstein explains, how can we guard the world and take care of it?