TransCanada, the same company behind the controversial Keystone XL, is abandoning its proposed Energy East pipeline and Eastern Mainline projects.

President and CEO Russ Girling said Thursday morning in Calgary that the company will inform Canada's pipeline regulator, the National Energy Board (or NEB), and Quebec's Environment Department that "we will no longer be proceeding" with the projects.

The decision is expected to cost the pipeline giant C$1 billion (US$801 million).

"TransCanada was forced to make the difficult decision to abandon its project, following years of hard work and millions of dollars in investment," the Canadian Energy Pipeline Association, an industry group, said in a statement to Bloomberg. "The loss of this major project means the loss of thousands of jobs and billions of dollars for Canada, and will significantly impact our country's ability to access markets for our oil and gas."

The shuttering of the Energy East pipeline, however, is a major victory for environmental groups, who have long fought against the so-called Keystone XL on steroids.

According to the Natural Resources Defense Council, the US$15.7-billion pipeline would have transported 1.1 million barrels per day of mostly tar sands oil from Alberta to St. John and would bring a significant increase in carbon pollution—equivalent to the annual emissions of as many as 54 million passenger vehicles—and lock in high-carbon infrastructure expected to operate for at least 50 years.

Oil Change International estimated that the pipeline's construction would have created up to an additional 236 million tons of carbon pollution each year, multiplied over decades of operation.

The decision comes a month after TransCanada said it might suspend or even abandon the Energy East and Eastern Mainline projects after the NEB issued tough, new climate standards that widened the scope of its risks assessment to consider upstream and downstream, or indirect, greenhouse gas emissions.

As 350.org founder Bill McKibben quipped then via tweet, "Transcanada may abandon its #energyeast pipeline because it doesn't want to confront the climate implications."

Adam Scott, senior advisor at Oil Change International, celebrated today's news.

“This is an important day in the fight against climate change in Canada. Realizing that Energy East would never be allowed if its full climate impact was accounted for, TransCanada has walked away from the project," he said. “Energy East was a disaster waiting to happen."

"The fossil fuel era is ending. Energy East is just the latest in a growing list of projects that will never see the light of day," he continued. "Movements will continue to stand up to projects that we know are not in the best interests of our communities, our climate, and our children. But our governments must also step up to ensure that our transition off of fossil fuels to the safe and renewable energy future is just and managed."