For some years now we have been talking, more or less correctly, about the “insect apocalypse”, that is, the fact that climate change and human activities are leading to a decline in global insect populations. A factor that could lead to the extinction of many species. The problem is that it is not easy to quantify this decline, for an obvious reason: it is not easy to count them.
Now a study published on Global Change Biology proposes a new counting method that uses weather radar to have a precise estimate of the quantity of insects flying every day in the skies of the United States (and also the rest of the world, potentially).
Radar containsetti. As mentioned, the problem of counting insects is not trivial: we know that the populations of certain species are reducing or even heading towards collapse thanks to studies conducted at a local level, which show trends that are then applied on a larger scale. The international team that published the study therefore proposes to exploit tools that are used for something completely different, but which can help in counting insects: meteorological radars.
Dual use. These are radars (or networks of radars that work “in groups”) that monitor and measure precipitation: they record clouds, rain and snow, but they can be modified to also sense anything else flying in the atmosphere – including insects.
The data from US weather radars, then, are collected by NOAA and are available to anyone: using them, the team managed to produce the first estimate ever made of the global number of flying insects in the United States (and only them: the limitation of radars is that they cannot be used for those that do not fly).
Climate change and decline. The figure is obviously impressive: we are talking about 100 trillion insects, that is, one hundred billion billion, or if you prefer 1014. What is most impressive, however, is that the data was calculated over a ten-year period, between 2012 and 2021: the general count in this period remained stable, but with large fluctuations in the areas that are normally colder, and which are warming quickly due to climate change. In these areas, insect populations have shown a steady decline over the past decade.
Data not recent enough. The main limitation of this method is that the NOAA data stops at the beginning of the 1990s, and according to the authors of the study the real great decline of flying insects occurred between the 1970s and the 1990s, and was therefore not documented by radar.
Then there is the problem of identification: radars can count insects, but cannot distinguish them by species, and the data obtained by NOAA must therefore be integrated with other types of observations to get a more precise picture. The system is nevertheless effective, and could also be applied to other areas of the world.
