Global warming caused by anthropogenic intervention could have a serious impact on terrestrial organisms, especially for those living in the tropics, due to a greater biological and physiological sensitivity of these organisms to climate change, scientists reported in a study published on Monday and available on http://www.pnas.org.

A team of researchers, led by Curtis A. Deutsch, assistant professor of atmospheric and oceanic sciences at the University of California, Los Angeles and Joshua J. Tewksbury, assistant professor of biology at the University of Washington, concluded that the warming process in the tropics is likely to have severe consequences on insects, which are most sensitive to temperature changes.

The study, called “Impact of climate warming on terrestrial ectotherms across latitude,” draws attention that “in the absence of ameliorating factors such as migration and adaptation, the greatest extinction risks from global warming may be in the tropics, where biological diversity is also greatest.”

The impact of human intervention on natural systems will affect species depending on geographic variations, in other words, species at higher latitudes have greater thermal resistance and a warmer climate would pose no challenge to their capability of adaptation.

On the other hand, insects (which constitute the vast majority of terrestrial organisms) are the most vulnerable to temperature changes: the environmental temperature at the tropics is considered ideal for them as it is now.

The insects’ population growth rates are likely to change due to global warming as follows: mid- to high-latitude insect populations will increase, as the environment gets warmer (reaching the ideal temperature for them); in the tropics, the growth rates are expected to decrease by 20% as temperatures reach a thermal maximum.

The thermal performance curve unveiled that the ability of insects to perform functions such as locomotion, growth, and reproduction is highly influenced by environmental temperature, rising gradually from the minimum critical temperature to an optimum temperature, and rapidly dropping to a critical thermal maximum.

Tropical species of insects generally have a low ability to acclimate. The scientists concluded that the species with the greatest risk of extinction due to a rapid climate change are those with low tolerance for warming, limited acclimation ability, and reduced dispersal, and the organisms best described by these factors are tropical.

The study draws attention on the fact that the regions most exposed to climate change and less capable of adaptation are also the places where biodiversity is greatest. Insects are in fact just a small part of the terrestrial organisms that are likely to be affected by these changes. The question is: how many of them will survive?