While insects are generally out of sight and mind, ignoring the impact of climate change on the global insect population could have dire consequences for delicately balanced ecosystems.
Climate change and global warming are easily two of the most discussed topics in the world today. From living room conversations to global conferences, the phrases and their consequences have been dissected time and time again. Unfortunate as the situation seems, new consequences of the man-made phenomenon crop up every few years, sparking fresh conversation and a quest for new methods of mitigation, or at the very least, adaptation.
One such consequence that is now claiming its stake in all recent conversations is that of insects. If you look at the causes, or actions leading up to global warming and climate change, such as the use of pesticides, air pollution and rapid deforestation, the fact that it would affect the smallest members of the animal kingdom seems a little more obvious.
While we may not realise it due to their small size and the relatively few interactions we have with insects, they play a highly influential role in our lives. They form the bedrock of natural ecosystems, are pollinators who recycle nutrients, and serve as food for animals above them in the food chain.
Habitat loss, the lack of clean air, pesticide-laced food, frequently occurring climate hazards and the harsh winters and summers of today, have all done their bit to make life much more difficult for the insect population of the world, driving their numbers down.
A group of scientists from 19 countries conducted research on the health of insects around the world and found that for decades, climate change alone may have been posing a number of risks to those populations of insects that are endangered or at a declining stage. While we may not realise it due to their small size and the relatively few interactions we have with insects, they play a highly influential role in our lives. They form the bedrock of natural ecosystems, are pollinators who recycle nutrients, and serve as food for animals above them in the food chain. They are also, unfortunately, very sensitive to temperature fluctuations.
As global warming drastically alters the climate conditions that many species require to thrive, the insect communities often have no choice but to migrate. The mass migration of insects from one area to another has its own set of consequences. Most pests are generalists, being able to survive on a number of different plants. Needless to say, these are the least negatively impacted by climate change. However, the same cannot be said for the problems they ignite in places where they migrate. They may become pervasive, destroy crops and bear new diseases in areas not previously dominated by them. The unfamiliar territory may be as harmful to insects as to other animals and humans they interact with.
Unlike mammals, insects are ectotherms; unable to regulate their own body temperatures. Their dependence on the external environment makes them more vulnerable to global warming and climate change effects.
Just as some insects migrate to cooler, less familiar regions, others who stay in known territories are also subjected to adverse effects such as infertility. Their entire life cycle and interactions with other species must change, leading to dramatic disruptions in the ecosystem, and, consequently, in human life.
Unlike mammals, insects are ectotherms; unable to regulate their own body temperatures. Their dependence on the external environment makes them more vulnerable to global warming and climate change effects. The rate at which the world is heating up is alarming and it will invariably affect more and more insects as it climbs. If the planet, for instance, were to heat up by 3.2 degrees Celsius, the heat could very well wipe out the range of nearly half the insect species around the world, by at least 50%. If the heat could be contained within 1.5 degrees Celsius, as urged by the Paris Agreement, it would affect only about 6% of the world’s insect range.
The loss of biodiversity is among one of the most worrying effects of climate change and global warming, considering that it may lead to a complete breakdown of ecological communities, and negatively affect critical ecosystem functions. Across the earth, lead causes of changes and/or a decline in biodiversity remain habitat alteration in the form of deforestation, the changing of river courses, and salinisation of water bodies, biological invasion, and anthropogenic climate change caused by an almost unchecked acceleration of global warming.
Scientists say that climatic changes not only have the potential to lead to the extinction of certain species of insects, but can also cause changes in their population, compositions, and the ways in which they interact with other species. Insects are vital components for both aboveground and belowground biodiversity, which is why a growing body of empirical research showing a decline in the populations of insects across the earth has started to make scientists fairly uneasy. This unease is multiplied a few times over, especially as media, and even some experts play up the phenomenon by terming it the ‘insect apocalypse.’
It is worth noting that the effects of global warming on insect populations are higher in certain regions and lower in others. Charlotte Outhwaite, a scientist at University College London, feels that insects of the tropical region are more at risk than those of other areas. In all likelihood, this is because tropical insects are less hardy – they have lower temperature tolerance and are more specialised than insects in other areas of the world. The same study that came to the above conclusion has also found a mysterious rise in the population of insects in certain temperate climates, indicative of migration. They also have reason to believe that many cold-tolerant insects that had lived in these climates may already have disappeared by the time these studies were conducted. While one limitation of this study is that it only provides a snapshot in time it does adequately demonstrate that insects fare worse in the tropics due to climate change.
With climate change, the world seems to have gone beyond the tipping point some months ago. Therefore, as quoted by researcher Ganguly, even if greenhouse gas emissions stopped today, the environmental impact on insect populations would not be completely wiped out.
An exploratory research paper that studied temperature variability led by Northeastern doctoral student Kate Duffy, however, has found the opposite to be true. She feels it is the temperate region that is more straining for the insects, as the temperature swings may be larger in temperate zones. Her research simulation also finds that out of 38 species studied, nearly all were at risk of going extinct between 2050 and 2100.
Upon further research, however, it was found that climate change alone could not be held responsible for the substantial drop in insect populations around the world. While accounting for half the problem, the issue was seen to be exacerbated when detrimental agricultural practices were added to the melting pot of wrong environmental choices as a whole. Insects in areas with more intense agricultural practices, where overexploitation of natural resources has taken place, such as areas affected by land degradation, higher chemical fertiliser usage, more livestock, and less plant diversity, fared much worse than those inhabiting less intensely farmed land, especially as climate change amplified the situation manifold.
Even if the insect population has been declining for decades and scientists know it as one of the most severe consequences of global warming, the research surrounding the full impact of the issue is still murky. Cited above, these studies are nothing more than a starting point for more extensive work that must happen before scientists can be sure what the actual consequences of an ecosystem collapse, brought upon by insect population declines would look like, or how quickly the phenomenon could take place.
Charlotte Outhwaite urged urgent actions from environmentalists and world leaders to “preserve natural habitats, slow the expansion of high-intensity agriculture, and cut emissions to mitigate climate change.” Similarly, Anahi Espíndola, an assistant professor of entomology at the University of Maryland, urges humans to be more considerate in their actions. “We need to realize, as humans, that we are one species out of millions of species, and there’s no reason for us to assume that we’re never going to go extinct. These changes to insects can affect our species in pretty drastic ways,” she says.
With climate change, the world seems to have gone beyond the tipping point some months ago. Therefore, as quoted by researcher Ganguly, even if greenhouse gas emissions stopped today, the environmental impact on insect populations would not be completely wiped out. However, even as he acknowledges the risks, he is not pessimistic. “Ecosystems managers can explore ways to preserve and enhance biodiversity, perhaps by introducing certain species to new environments,” Ganguly says.
Anahi Espíndola’s research paper on the same topic offered suggestions on how individuals can help manage public, private and urban gardens and green spaces in a more environmentally mindful way. This could be as simple as adding more native plants to the mix of shrubbery one chooses for their garden, using organic gardening techniques, and avoiding making drastic changes in the usage of land wherever possible. Espíndola emphasised how important collective action is, for this situation and encouraged people to involve their friends, neighbours and families to take similar ecologically viable steps to amplify the impact on the environment. “It is true that these small actions are very powerful,” Espíndola said. “They are even more powerful when they are not isolated.”
