When the world's average temperature changes, some places shift a lot more than others. Those that have been most stable in recent times tend to be those teeming with the greatest biological richness. They're also generally the ones in greatest danger from human-induced rising temperatures, a new study reports.
Despite a few exceptions, global temperatures are rising much more rapidly near the poles than at the equator, and this is expected to continue. Consequently, we worry more about the effect of rising temperatures on polar bears and penguins than rainforest dwellers, who are assumed to be more affected by deforestation.
However, Adelaide University's Dr Damien Fordham told IFLScience this ignores the fact animals and plants living at the poles have faced relatively abrupt climate shifts, or at least their recent ancestors have. Twenty-first century temperature rise is likely to be faster than anything for millions of years, but the flexibility that comes from surviving smaller climatic shifts offers species and ecosystems at least some protection.
When Fordham and colleagues divided the world into more than 10,000 cells and charted temperatures around the planet over the last 21,000 years for each, however, they found 58 percent of tropical cells have been stable. “We've been able to show this stability of climate is a driving force for diversity,” Fordham said. “It allows more species to build up,” although other factors also contribute to this biological wealth.
Without the experience of sharp changes, these areas are exceptionally vulnerable to even small changes in temperature if they happen quickly, Fordham reports in Nature Climate Change.
“Disturbingly, our research shows that more than 75 percent of the area of these climate safe havens will be lost in the near future due to 21st century warming,” first author Dr Stuart Brown said in a statement.
“The future is most ominous for species in tropical oceans,” Brown said. Coral reefs worldwide are suffering from many threats, and higher temperatures in the Indo-Pacific region will hit them hard. “This is likely to cause human hardship for communities that depend on these resources for food, employment and income."
Fordham told IFLScience the team's analysis only went back 21,000 years because this is the period for which they could model changes “at fine temporal scales”, rather than blurring longer periods together. However, he doubts any earlier climatic instability will provide a legacy of resilience regions can draw on today.
Potentially the worst part of this is that many of these so-called “climate refugia” store large amounts of carbon that could be released if their ecosystems are destroyed. However, Fordham told IFLScience it was outside his expertise to discuss the scale of this threat.
Some scientists warning of climate change-related threats to ecosystems suggest ways impacts can be softened at a local level, but Fordham has only one solution. “We need action on climate change,” he said.