Here is an example summary of this reading selection:

Jensen defines the concept of “declining baselines,” the gradual adjustment to diminishment, with several examples from his own observation, including environmental changes around his home in contrast with his grandmother’s childhood recollections. After comparing those observations to large-scale environmental changes, he then extends the concept of declining baseline to other fields, leading to his thesis that, once people become used to injustice as the new normal, they can no longer see injustice and so cannot address the problem. Jensen urges readers to pay attention to what is around them physically and politically so they can stay aware of injustice in its many forms.

Your summary will differ from this one in the way it is written, but it should include roughly the same information.