In his poem "Earth Hour," how does David Malouf explore universal themes? What quotes from his poem demonstrate this, and with what techniques?

The concept of an "earth hour" was conceived to celebrate an annual, worldwide movement that involves switching off all lights for an hour, as a way of minimizing humanity's environmental impact on the planet.
David Malouf, in his poem, "Earth Hour," uses this very concept to touch on universal themes of life and death. He intimates how these lie buried to penetrate us all, even as we live through a distracting maze of man-made modernity. Ironically, that same modernity includes the very concept of having to come up with an "earth hour" to remind ourselves to care for life on earth.
He begins his poem with an immediate call to action. He makes the reader realize, almost admonishingly, that it is not necessary to remind ourselves of this, because all raw life is within us every minute, every hour:

It is on our hands, it is in our mouths at every breath, how notremember?

He then takes us right back to a primal sense of humanity, a time when all that mattered were the basic elements of life. He does this by conjuring images of fire, wildlife, cows, moonlight. These paint a scene of warm, calm freedom—something that the modern-day "earth hour" tries to achieve in switching off all lights.
However, Malouf is quick to depict a rather different scenario. It mirrors the quiet, though not quite. He does this by juxtaposing a cold darkness achieved instead by present-day, urban conditions:

glass in our McMansions, coolmillions at rehearsal . . .

Such a use of the image of "McMansions" makes the contrast even sharper. McMansion is a derogatory term used to describe an immensely showy and spacious house built with substandard materials and designed in rather poor taste. It is a striking metaphor for the growing popularity of overzealous materialism. And Malouf makes use of this to underscore the sham of having to "rendezvous each with his own earth hour."
Malouf, in criticizing the shortcomings of "earth hour," goes on to remind us whom we are and where we all come down to in the end, in the final hour, regardless of the heft of our habitats:

Schatzkammer and midden, our green accommodating tomb.