There are some very dedicated and hardy souls who will travel into areas that are not safe or comfortable at all in order to examine and monitor the health, migration and location of all types of plants and animals. In the course of the past few years, there have been many indications that global warming is causing species of all types to die out, move out and move on to cooler or warmer habitats, mostly in the direction of the Earth's poles.
As supportive plants die out from increased temperatures, less moisture, or other overall changes to the environment, the supported animals and other lifeforms will move on to more supportive grounds.
"Subsequent analyses conducted with colleagues such as David Easterling of the National Climatic Data Center in Asheville, N.C., and Gary Yohe of Wesleyan University uncovered evidence of climate change nearly everywhere they looked. For instance, plants and animals have shifted their ranges by about six kilometers per decade toward the poles during the past quarter of a century." 1
There are also pathogens that are on the move. From funguses to infection bearing mosquitoes, the movement of the bad guys is going along with the inability of life forms to defend themselves against invasive and relatively alien species. When the native life forms are weakened from starvation or changes to normal seasonal weather patterns, the invasive pathogens and migrating alien predators are a hazard, indeed.
As an example of the sensitivity of animals to rises in temperature, the white lemuroid possum of Australia, now believed to be extincted, lived at a particular altitude and could not live for more than a few hours in temperatures in excess of 30 degree Celsius or 86 degree Fahrenheit. It is estimated that 15 to 37 percent of Earth's species could be extincted by 2050, should temperatures rise and stay at intolerable levels.
There are, of course, no clear or actual predictions that can be made, but life becomes acclimated and adapted to certain temperatures, seasonal activity and supporting elements of habitat. Migration is often not the solution, as more tolerable aspects are replaced by overpopulation, migration is blocked by natural and man made barriers, and defenses of weakened migrating animals are poor against new predators. Only the most hardy can survive migration and may decimate not only competition, but food in the new location.
In the case of resurgence, there are mosquitoes reappearing in areas of the world that have reached warmer average temperatures that support their living and reproducing. This is increasing the threat of mosquito borne diseases, such as malaria, dengue fever,encephalitis, and West Nile. These diseases are the biggest killers and debilitating issues of humans, but mostly in areas that do not cause as much alarm. When they reach Europe and the United States, there will be far more alarm.
Add in lyme disease, plague, avian flu, SARS and other deadly diseases that migrate along with their hosts, and the issue becomes more critical.
Then, there are the fungus and other microbes that affect plants and animals that humans need in order to thrive. These will migrate to areas that are now more temperate and hospitable.
Living things become used to and dependent upon a certain sequence of weather and seasonal events. Seasonal changes. where temperatures are supposed to change and settle into a specific range for a specific length of time might be disrupted to the point where metabolism, reproduction and thriving might be disrupted.
Relatively small and incremental changes in moisture, weather, the ability of food and habitat to stay at viable levels, and change in a host of other environmental factors will wipe out the most sensitive, while the more hardy will migrate into areas that present new challenges. Those challenges might be for the native species or for the migrating species.
Finally, species that were in small numbers, or living on the edge of survival might bloom in the incremental changes toward temperature, moisture and habitat that benefit them, and not all of these resurgences are good for other living things. Fungus, insects, microbial, viral and other species will migrate to, or bloom in, environments where other living things have no natural defenses.
1. David Appell, "Can "Assisted Migration" Save Species from Global Warming?", Scientific American, March 2009.
Christine Dell'Amore, "'Deadly Dozen' Diseases Could Stem From Global Warming", National Geographic, 7 October 2008