The core message of the Global Warming crowd is ultimately (although rarely admitted) that mankind is a cancer on the planet.  At least in this story, the participant is honest and so is her husband.  And hints of the religious nature of the movement is also revealed:

At the age of 27 this young woman at the height of her reproductive years was sterilised to “protect the planet”.
Incredibly, instead of mourning the loss of a family that never was, her boyfriend (now husband) presented her with a congratulations card.
While some might think it strange to celebrate the reversal of nature and denial of motherhood, Toni relishes her decision with an almost religious zeal.
“Having children is selfish. It’s all about maintaining your genetic line at the expense of the planet,” says Toni, 35.
“Every person who is born uses more food, more water, more land, more fossil fuels, more trees and produces more rubbish, more pollution, more greenhouse gases, and adds to the problem of over-population.”
While most parents view their children as the ultimate miracle of nature, Toni seems to see them as a sinister threat to the future. 

It is indeed sad when mankind ceases to see their offspring as hope and starts to see them as simply a “genetic line at the expense of the planet.”  Having no children of my own, if I were so fortunate as to have them, I would aspire for them to be an attribute to the planet and not a “sinister threat.”