As climate anxiety grows around the planet, there is a rising chorus of informed scientific voices asking the fatal question: Could climate change lead to biological extinction? A vital first strategy to avoid that outcome is global cooperation to protect the most vulnerable nations from extreme climate impacts.
A major extinction event is characterised by the loss of more than 75% of global biological species in a geologically short period of time. A major extinction event occurred 65 million years ago and it involved a large asteroid crashing into what is now called the Yucatan peninsula in Mexico. This event, which would have caused drastic changes in the Earth’s atmosphere and climate, extinguished about 75% of biological species on planet Earth. The mammals surviving that extinction event evolved over a long period into the primates and eventually into a series of ancestor species leading to modern humans. Homo sapiens or modern humans appeared only 0.2 million years ago in this long evolutionary journey.
Hence, modern humans did not exist during the most destructive extinction events that have occurred over the past 500 million years.
However, humans have certainly been involved in the ongoing extinction-type processes occurring during the industrial revolution over the past 150 years. Data suggests that recent extinction rates of biological species have been running tens to hundreds of times faster than in pre-human times.
The threats to human populations from climate events are becoming evident. The respected science journal Nature predicts that by 2100, 83 million people will die directly of physical effects of extreme heat beyond the thermal limits of the human body. However, this figure, which is roughly 10 times greater than total covid fatalities, understates the problem because it excludes human lives lost by non-physiological factors. These include deaths from flooding, inundation, wild fires, storms and conflicts over shrinking food resources necessary for survival.
The Earth has experienced a disastrous series of climate events in 2021 and 2022, including the most extreme heat wave in modern history, a record four weather disasters with a total economic impact of $80 billion, and the hottest month on record. China experienced the longest and most serious heat wave in its recorded history. Iran has had the hottest day globally (53C) in July this year. Extended exposure to temperatures higher than 46.5C is likely to be lethal for human beings. Such lethal temperatures may soon cause the equatorial belt of the planet, which is home to a substantial fraction of the global population and much of its poverty, to be uninhabitable for humans. A 2021 United Nations report projects 118 million poor people in Africa will be exposed to drought, floods and extreme heat by 2030. Loss of fragile food sources to climate change in sub-Saharan Africa has led the United Nations Development Program to project that by 2100 massive migration of climate refugees (86 million) will occur, driven by famine and poverty. Also, this year’s Pakistan flooding events from 3.4 metres in flood depth have impacted 33 million people and caused 1700 deaths, as well as $40 billion in damage.
This acceleration in the number of major climatic disasters and the associated loss of human lives is being felt disproportionately in impoverished developing communities. As a first step in reducing the risk of extinction, the recent COP27 meeting agreed to the establishment of an historic Loss and Damage Fund, which will help vulnerable nations adapt to major climate impacts.