Global warming increases risk of 'extinction domino effect', warns EU study

Predictions that fail to take into account the 'extinction domino effect' may underestimate the scale of mass extinctions by up to 10 times

The risk of an "extinction domino effect" that could wipe out human life are being dramatically increased by climate change, according to a new research led by the European Commission Joint Research Centre (JRC).

The study also claims that predictions about the impact of global warming that fail to take into account this domino effect underestimate the scale of mass extinctions by up to 10 times.

A domino effect - also known as ripple effect or secondary extinction - occurs when an extinction or sudden major population reduction directly leads to a similar effect in another species.

This could happen as a result of climate change should it cause a major disruption to farming, for example, with a sudden and rapid decline in food output.

An example of domino effect is extinction of native flora and butterfly species in Singapore.

Whenever a species leaves our planet, we lose much more than a name on a list

When Singapore was turning into a developed country, it experienced a 90 per cent decrease in forest cover. Cutting down trees to accommodate a burgeoning human population led to the extinction of 208 plant species in the country, which further caused the extinction of 56 butterfly species that had depended on those plants.

So far, very few studies have attempted to explain the drivers of species extinction that go beyond the direct impact of environmental change.

In the current study, which was led by JRC scientist Giovanni Strona, and also included Professor Corey Bradshaw from Flinders University in Australia, scientists created 2,000 "virtual-Earths" and populated them with thousands of species of plants and animals. All these species were organised into a well-connected system of food-webs.

The virtual-Earths were then exposed to extreme environmental changes, either a "global warming" or a "nuclear winter".

In global warming conditions, the virtual-Earths experienced a linear, monotonic rise in temperature. In contrast, a "nuclear winter" subjected virtual-Earths to progressive cooling, which usually follows an asteroid impact or multiple nuclear detonations.

They then analysed how a loss of species diversity will occur in two different scenarios. In the first scenario, they considered only those extinctions that occurred when the temperature of the virtual-Earth went beyond toleration limits of the species.

In the second scenario, they also simulated the cascading effects of co-extinctions of species.

The findings suggested that failing to consider the interdependencies between species could result in the underestimation of the scale of mass extinctions activated by climate change by up to 10 times.

"Whenever a species leaves our planet, we lose much more than a name on a list," said Professor Giovanni Strona.

The results also showed that between five and six degrees centigrade of warming would destroy most of the life on the virtual Earths created by the scientists.

Although Earth is not likely to become 5-6°C warmer in the near future, global temperatures may continue to rise, thereby putting more pressures on biodiversity. Co-extinctions of species will add to that impact, according to scientists.

The findings of the study are published in journal Nature.