The Worldwide Phenomenon That's Shrinking Animals

Repetitive mammalian dwarfing during ancient greenhouse warming events 
"Abrupt perturbations of the global carbon cycle during the early Eocene are associated with rapid global warming events, which are analogous in many ways to present greenhouse warming. Mammal dwarfing has been observed, along with other changes in community structure, during the largest of these ancient global warming events, known as the Paleocene-Eocene Thermal Maximum"

As the planet gets hotter, some mammals may get smaller 
"Abigail D'Ambrosia, a graduate student at the University of New Hampshire, is interested in what happens to living things when the global temperature jumps. Do they go extinct? Do they adapt? Do they change? Her research, published Wednesday in the journal Science Advances, shows that at least in the case of some mammals, they shrink."

Mountain Goats Are Shrinking-A Lot-Because of Global Warming 
"Although global warming is known to be driving changes in body size in a number of animals, this result was more dramatic than researchers expected and suggests that a changing climate may have significant impacts on natural systems in the near term, in ways that are only beginning to be understood."