Oh Noes! Kitchen Scraps Cause Global Warming!!

So I'm looking up leeks online, trying to learn a little more about ways to prepare them, when I come upon an "article" about the fact that you can use the dark green parts of the vegetable.  Toward the end, we get a list of reasons to do so, winding up with this:

"Finally, putting this valuable food stock to your benefit means it doesn’t end up in landfills where it becomes a contributor to global warming. "

...What?  
Am I missing something here?  

...How on earth could putting part of a vegetable into the garbage-- and by extension in a landfill-- contribute to global warming?  Does this writer think that (the very natural process of) vegetable matter decaying in/on the earth leads to global warming?  Quick!  Someone gather up all the fallen leaves and withered plants from all the gardens and parks and forests of the world!  Do... something with them, before they start to decay and contribute to global warming!! 

It is possible that s/he meant the gas used to transport the leek trimmings to the landfill would contribute to blah blah blah blah, but that's not what s/he said-- and even so, how much extra gas will a few measly leaves require of the garbage truck?  

I wonder if tossing them on the compost pile causes global warming...

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Merry Christmas and Happy New Year!  ;o)