Producers in Alberta’s tar sands/oil sands celebrated 50 years of commercial activity at the end of last month, but they still haven’t “addressed many of the largest environmental impacts” their operations generate, the Pembina Institute notes in a multi-part assessment of the anniversary.

“After 50 years of production, the oilsands remain among the world’s most carbon-intensive large-scale crude oil operations,” Pembina asserts. “Studies continue to back this up.” The Carnegie Endowment’s Oil-Climate Index, for one, “suggests most oilsands crude is associated with 31% more emissions than the average North American crude, from the point of extraction through its life cycle to the point of end use.”

Moreover, the emissions just from extracting tarry bitumen and upgrading it into heavy synthetic crude show “little improvement over time,” Pembina states. Indeed, after some “one-off advances nearly 20 years ago,” producing a barrel of diluted bitumen in 2015 actually released 9% more greenhouse gas than it did in 2004.

Earlier this year, InsideClimate News reported the U.S. State Department had assessed the carbon footprint of a litre of synthetic crude to be more than 23% greater than previously estimated.

“This trend will certainly continue,” Pembina notes, “as producers access deeper, lower-quality bitumen, and the distance from mines to processing facilities increases.”

‘In situ’ operations produce 58% more greenhouse gas emissions than do surface mines, its report notes, and have become the dominant development form for the industry, in part to avoid the massive surface disturbances that surface mines cause.

But little of that disfigurement has been repaired, the think tank finds in a separate report. Over the last half-century, open pit tar sands/oil sands mines have produced enough toxic ponds of tailings—the water-borne sand left over after the bitumen has been steamed out—to crater or flood some 940 square kilometres of northeastern Alberta. Just one of those sites has so far been “reclaimed and returned to the province,” Pembina reports, representing “0.1% of overall oilsands mining development.”