A new paper in the journal Science finds that climate change is now set to occur at a pace "orders of magnitude more rapid" than at any other time in the last 65 million years. That breakneck speed may mean extinction for species that cannot keep up.
For example, the paper's authors Noah S. Diffenbaugh and Christopher B. Field of Stanford write, consider the global cooling that took place beginning some 52 million years ago. That change was of a greater magnitude than even the worst-case global-warming projections for the 21st century.
But that transition occurred over a period lasting 18 million years, not a matter of decades. Similarly, the Paleocene-Eocene Thermal Maximum, thought one of the more rapid climatic shifts, was 100-fold slower than the most dramatic 21st century scenarios, and 10-fold slower than the best-case ones.