It is enlightening to read in your pages that Govindasamy Bala and his colleagues from the Lawrence Livermore National Laboratory in California have built a climate model that shows that chopping down the world’s forests would help fight global warming (“A New Tree Line,” April 14, 2007). Although trees swap carbon dioxide for oxygen, which is a good thing, they absorb more heat and release more water vapor into the atmosphere than cleared land. On balance, trees are not good for the planet. So far, so good. Surely, though, Bala’s model can be used to advocate even more radical measures to fight global warming. Culling down the world’s animals is the case in point, for they swap oxygen for carbon dioxide, which is a bad thing, while their heat absorption and vapor release are negligible. And there is one plentiful animal species, which should remain nameless at this juncture, whose culling would do wonders in this regard. No-one, of course, would consider culling down all the world’s animals, but the model could be used to gauge the extend of the culling, as well as the trade-off between culling and chopping.