Evidence has been accumulating for some time that increases in global temperatures are due, at least in part, to human-released gases such as carbon dioxide. The evidence has reached the level where even many politicians long in denial are conceding that this is the case. The most general assumption has been that, overall, increased temperatures will harm plants and animals. On the other hand, some researchers have speculated that increased levels of carbon dioxide will offset the damage done by higher temperatures by increasing the growth rate of crops. The reasoning behind this is that carbon dioxide is a critical raw material for plant photosynthesis.
Recent studies, however, tend to go in the other direction; not because
carbon dioxide doesn't increase crop yield in at least some cases, but because
important, destructive invasive weeds seem to be helped much more than are crops. There
also now is evidence that increased levels of carbon dioxide may decrease the nutritive
value of some grasslands. All in all, it's looking more and more like hot times are
not good times.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.