If we don’t reduce our carbon emissions and instead allow global temperatures to rise from 4.5˚C, up to half the animals and plants in a few of the world’s most biodiverse regions can go extinct by 2100, according to a new analysis. Another study found that local extinctions (when a species goes extinct in a special area, but still exists elsewhere) are already occurring in 47 percent of the 976 species analyzed, in every kind of habitat and climatic zone.
With temperatures climbing, precipitation patterns changing, along the weather getting less predictable and more intense, a 2016 study decided that climate change is already significantly disrupting organisms and ecosystems on land and in water. Animals aren’t merely altering their range and changing the time of crucial life span — they’re also exhibiting differences in their gender boosters, tolerance to heat, and in their own bodies. Some of the changes can enable a species to adapt, while others could speed its death.
Transfer, Adapt or Die
Animals can react to climate change in only three ways: They could proceed, adapt or die.
Many creatures are moving to higher elevations and latitudes to escape warming temperatures, but climate change may be happening too fast for most species to outrun it. In any case, moving isn’t necessarily a simple alternative –entering new territory could mean limiting more competition for food, or even interacting with unfamiliar species. Some animals, like the hamster-like American pika, are at the farthest extent of the scope. Pikas need the cool moist conditions of the alpine Sierra Nevadas and Western Rockies, but the rocky habitat they require is getting hotter, drier, and less snowy. Because they live so high in the hills, if their terrain becomes inhabitable, there’s nowhere left to move. Other creatures attempting to move to cooler climes may be hemmed in by highways or other manmade structures.
Additionally, a few impacts of rising temperatures can’t be outrun. Monarch butterflies take their cues from day temperature and length to fly south from Canada into overwintering in Mexico. The butterflies’ southern migration was recently postponed to six weeks since warmer than normal temperatures don’t cue them to fly south. Scientists also discovered that the onset of cooler temperatures in Mexico arouses the butterflies to return northward to lay their eggs in the spring.
As temperatures warm, their migrations could fall out of sync with all the bloom period of the nectar-producing plants they rely on for food. Logging where they overwinter in Mexico and the dwindling of the milkweed habitat, in which they breed and their larvae feed, as a result of drought, heat, and herbicides are added aspects in the monarch’s reduction. Its numbers have decreased by 95 percent in the previous two decades.
As temperatures increase in the Arctic and sea ice melts, polar bears are also losing their food source; they are often unable to come across the sea ice they use to search seals from, and rest and breed on. Puffins in the Gulf of Maine normally eat white hake and herring, but as oceans warm, those fish are moving further north. The puffins are trying to feed their young on butterfish rather, but baby puffins are not able to swallow the larger fish, so many are starving to death.
Many Species are Adapting
Some animals, however, seem to be adapting to changing requirements. As spring arrives sooner, insects emerge earlier. Some migrating birds have been laying their eggs earlier to match pest accessibility so their young will have meals. Over the past 65 years, the date when female butterflies in southern Australia emerge from their cocoons has shifted 1.6 days earlier per decade since temperatures there have warmed 0.14˚C per decade.
Coral reefs, which are actually colonies of human animals called polyps, have experienced extensive bleaching as the oceans warm–when overheated, they expel the vibrant symbiotic algae that live within them. Scientists studying corals around American Samoa found that lots of corals in pools of warmer water had not been breached.
When they subjected these corals to even higher temperatures in the laboratory, they discovered that just 20 percent of them expelled their algae, whereas 55 percent of corals from cooler pools were also exposed to the high heat. When corals from a cool pool have been transferred into a popular pool for a year, their warmth tolerance improved–only 32.5 percent now ejected their algae. They adapted with no genetic shift.
This coral research illustrates the difference between development through natural selection over the course of several generations, and adaptation through phenotypic plasticity–the ability of an organism to change its own developmental, behavioral and physical attributes during its life in response to changes in the environment. (“Plasticity” here signifies flexible or malleable. It has nothing to do with all the hydrocarbon-based products which are clogging our landfills and oceans.) The corals living in the hot pools had evolved over many generations as natural selection favored the survival of their very heat-tolerant corals and enabled them to reproduce. But the corals in the pool exposed to the hotter water were also able to accommodate because they had phenotypic plasticity.