Ever been alarmed at tropical forests slowly disappearing? Or animal species dying off? Well, scientists are saying that these are natural processes as we are living in the midst of the ‘Sixth Mass Extinction’. However, unlike earlier waves of extinction, this one is being driven by human activities on the earth (anthropogenic impact).
Researchers had recently found that larger mammals experienced a greater risk of decline. However, greater variation in body size and litter size was associated with reduced risk of extinction. This suggests that species that maintain variability at the population level may be better able to adapt to changing environmental conditions.
Express spoke to ecologists in the city to find out what they thought about this. Uma Ramakrishnan, faculty of ecology and evolution at National Centre for Biological Sciences, Tata Institute of Fundamental Research, agreed that the current extinction event has been driven by human activities.
She noted that earlier such events were triggered by other factors, referring to the meteorite impact that caused the extinction of dinosaurs about 65 million years ago. Dust from this impact probably engulfed the atmosphere, blocking out sunlight. This killed off the dinosaurs that were cold-blooded animals, which needed sunlight to survive.
She explained that other such mass extinctions were caused by sudden increases in concentration of methane in the atmosphere.
“Several species have gone extinct in the last 200 years or are on the verge of extinction. Human impact (climate change, habitat destruction) are triggers for the current event. Any solutions that address these problems would slow down this process,” Uma added.
Prof Anindya Sinha of School of Natural Sciences and Engineering and dean of academic affairs at National Institute of Advanced Sciences, worried that the current extinction event was being driven by humans. He also referred to past extinction events, which had natural causes such as the Ice Age or volcanic eruptions. The ash from volcanoes blocked sunlight, resulting in the deaths of plants and animals.
“The increase in population in developing countries and lifestyle in developed ones are major factors coming in the way of growth of flora and fauna. Commercial interests like timber and hunting have also played a role. Silent forests have come up in Northeastern India where forests still survive but all animals have been killed by hunting,” he explained.