Warming Enhances Plant Growth

Lin et al. (2010) conducted a meta-analysis of 127 studies that evaluated the effects of warming on plant growth, where the studies were selected across as wide a range of latitudes as possible. Standard meta-analysis statistical tests were employed, with change in biomass being the response variable. Across all studies, the biomass response was positive for all seed plants, with trees showing the greatest response (+34%); then came shrubs, and then grasses. The response of forbs was positive, although not statistically significant, perhaps because of the inherently limited growth form of forbs. Spore-producing plants were negatively affected, presumably because of soil drying, to which they are sensitive, and/or competition from faster growing seed-producing plants. The effect of mean annual precipitation on the growth response was slightly positive, but not statistically significant.

When examined in terms of either latitude or mean annual temperature, the effect was quadratic, with a positive response at all latitudes/temperatures except the very warmest. And since climate models forecast little warming in the tropics over the next hundred years, these results suggest that the greatest growth responses will occur at mid-latitudes, and that they will be strongly positive to neutral almost everywhere.