That's an interesting article and it seems to make sense. Another that was read seems to come to a similar conclusion, that it is not grass fed cows that pose an environmental problem because they are eating what is naturally produced, the grass which growing is right there where the cattle are.
Unfortunately, grass-fed cows amounts to only 3% of production (according to the article) - the remaining 97% being grain-fed (mostly using corn in the feed, that has to first be grown, watered, fertilized, harvested, transported).
How Much Carbon is That?
To put this in perspective, “a medium growth coniferous tree, planted in an urban setting and allowed to grow for 10 years, sequesters 23.3lbs of carbon.” (Environmental Protection Agency, 2011). To offset only the feedlot feed of this “best-case” animal, you need to plant nine trees that live for at least ten years.33.5 million head of cattle were harvested in the US in 2011 (National Cattlemen’s Beef Association). Grass-fed beef may represent 3% or less of all U.S. beef sales (Cross, 2011). If 32,495,000 of those cattle were fed corn according to the “best case” example above, we’d need to plant at least 292,455,000 trees (living 10 years) to offset the feedlot corn from one year’s worth American grain-fed beef.
That therefore seems to show that the issue is not cows, it's that the demand has grown to much too high levels.
(It could possibly be explained by addictive substances that are said to be formed during the curing phase of meat. Hypoxanthine is said to form and increase during the curing phase. It is said to be addictive due to having a stimulating effect, similar to caffeine. -
https://childhoodobesitynews.com/2013/05/14/burger-addiction-why-consumers-eat/
Is Meat Addictive? – Nutrient Rich )
Having to grow, harvest and then transporting lots of corn to be able to feed 97% of the cows, that are then used to feed humans, it seems is what creates a lot of emissions. And cutting down rainforests in order to open up more farmland to be able to produce more cannot be a seen as being a solution either.
A move back towards natural, grass-fed pasturing of cows and other cattle seems like the obvious solution. But, if the numbers in the above article is factually correct, then natural grass fed cattle has only been able to satisfy 3% of the current demand for beef in the US, the rest being made up of grain-fed cattle, which is (it seems) what is said to be causing environmental issues.