Study: A third of living beings on Earth may go extinct by 2100

A new study has shown that nearly one-third of living organisms around the world are at risk of extinction by the end of the century.
The study found that if global temperatures rise by 1.5 degrees Celsius (2.7 degrees Fahrenheit) above the pre-industrial average, exceeding the Paris Agreement target, extinction will accelerate significantly, especially for amphibians and species living in mountainous, island, and freshwater ecosystems.

The Earth’s temperature has already risen by about 1 degree Celsius (1.8 degrees Fahrenheit) since the Industrial Revolution.

Climate change has affected temperatures and rainfall patterns, thereby altering habitats and species interactions. For example, warmer temperatures have caused a mismatch between the migration of the monarch butterfly and the blooming of the plants it pollinates. Many animals and plants are moving to higher latitudes or elevations to follow more suitable temperatures.

While some living species may adapt or migrate in response to environmental changes, others cannot survive due to these drastic environmental changes, leading to a decline in their numbers and sometimes extinction.

Global assessments have predicted an increase in extinction risks for over a million species, but scientists have not clearly understood how these rising risks are linked to climate change.

The new study, published on December 5 in the journal Science, analyzed over 30 years of biodiversity and climate change research, covering more than 450 studies on known living species.

And if greenhouse gas emissions are managed according to the Paris Agreement, nearly 1 in every 50 living species worldwide (about 180,000 species) will be threatened with extinction by 2100. And when the climate model temperature is raised to 2.7 degrees Celsius, which is expected under current international emission commitments, 1 in every 20 species will be threatened with extinction worldwide.

The number of living species threatened with extinction sharply increases when the temperature exceeds this threshold, as 14.9% of living species will be threatened with extinction in the case of a temperature rise of 4.3 degrees Celsius, which is a scenario assuming high greenhouse gas emissions.

Under a scenario of a 5.4-degree Celsius temperature rise, which is a high estimate but possible with current emission trends, 29.7% of all living species will be threatened with extinction.

Mark Urban, a biologist at the University of Connecticut and one of the study’s authors, told Live Science: “If we keep global warming below 1.5 degrees Celsius, according to the Paris Agreement, the risk of extinction from today to 1.5 degrees Celsius is not a significant increase.” But a temperature rise to 2.7 degrees Celsius accelerates the path.

Living species in South America, Australia, and New Zealand face the greatest threats. Amphibians are the most threatened because their life cycle heavily depends on the weather, and they are very sensitive to changes in rainfall and drought patterns, Urban added. Mountainous, island, and freshwater ecosystems also contain the most threatened species. It is likely that these isolated environments are surrounded by habitats unsuitable for living species, making it difficult or impossible for them to migrate to more suitable climatic areas.