Margaret Atwood's novel, The Year of the Flood, is a continuation of her earlier novel, Oryx and Crake. In that novel, we learn of the first example of environmental terrorism: the Crake released a plague to kill humans in order to allow the introduction and survival of "a new race of genetic hybrids called 'Crakers.'” The effect of such a move has a devastating effect on the environment and its ability to sustain the lives of the survivors.
There are other forms of "environmental terrorism."
One of the animals that has been genetically-altered are pigs, called "pigoons;" they are very smart and destructive to gardens which are necessary for the survival of those still alive, as well as those who are preparing for the next "apocalyptic pandemic, which they call the 'Waterless Flood,'" by "prepar[ing] 'Ararats' that contain food and supplies" for survival after the flood.
One of the surviving groups is called the Gardeners, that is something of a religious cult. Their wish is to live peacefully, honoring those who have died and what has been lost, rather than taking steps to stop further degradation of their world.
...our role in respect to the Creatures is to bear witness...and to guard the memories and genomes of the departed.
However, one of its members, Zeb, creates a new group called "MaddAddam." He wants to stop the extinction of countless species, occurring at an alarming rate. This is another example of environmental terrorism:
There’s at least a hundred new extinct species since this time last month.
This is caused, in some part, by a restaurant called Rarities, "which serves endangered species."
One of the new members of MaddAddam is Crake (introduced in the first novel). He is supportive of the group's desire to halt the destruction of their world, however his idea in doing so comes in the form of a pandemic plague that he releases. One of the major characters, Toby, reflects that this is...
not an ordinary pandemic: it wouldn’t be contained after a few hundred thousand deaths.
This then, becomes the "Waterless Flood" that the characters of the book have feared, another act of environmental terrorism for which so many have been storing food and supplies in hope of surviving its destructive power.