Biodiversity hotspots most vulnerable

Polar and tropical regions that foster the planet’s richest biodiversity are the most vulnerable to future impacts of climate change, a study published in the journal Nature Climate Change has found.

Worryingly, those biodiversity hotspots have historically provided refuge for species during climatic upheavals, in turn enabling existing organisms to prosper and new lineages to spawn.

The accelerated impacts of human-driven climate change stand to uproot this protection, says senior author Damien Fordham from the University of Adelaide, Australia.

“More than 75% of the area of these climate safe havens will be lost in the near future due to 21st century warming, negatively affecting biodiversity – particularly in tropical regions and the world’s biodiversity hotspots,” he warns.

“A key mechanism for maintaining biodiversity during past glacial-interglacial cycles is likely to be lost.”

The researchers, comprising climate scientists and ecologists from Australia, Europe and the US, used state-of-the-art climate models to map global and regional patterns of unusually extreme climate change events since the Last Glacial Maximum.

They compared this with species richness of contemporary amphibians, mammals and birds, based on millions of species occurrence records, and patterns of 21st century climate change.

“Spatial projections of past climates were simulated at daily time steps for the entire Earth for the last 21,000 years,” says Fordham. “This very high temporal resolution is needed to appropriately capture biodiversity responses to past climate change.”

In the climate safe havens that are predicted to persist until the end of this century – just one lifetime away – the researchers found that temperatures are likely to exceed the adaptive capacity of many species, making the refuges temporary at best.

“The future is most ominous for species in tropical oceans. Severe negative impacts on the richness of coral species and marine life they support are expected in regions such as the Indo-Pacific,” says first author Stuart Brown.

“This is likely to cause human hardship for communities that depend on these resources for food, employment and income.”

What can be done?

Lower and sequester greenhouse gas emissions, says Fordham, for starters.

“Mitigate the impact of other harmful processes of global change that erode the ecological resilience and adaptive capacity of plants and animals in fragile hotspots, including habitat loss and degradation, exploitation and the spread and impact of invasive species.”