How global warming is effecting the wild kingdom.

The planet is warming, humans are mostly to blame and plants and animals are going to dramatic lengths to cope. That's the consensus of a number of recent studies that used wildlife to gauge the extent of global warming and its effects.

While the topic of climate change is contentious -- including whether the planet is actually heating up -- a growing number of documented shifts in traits and behaviors in the wild kingdom is leading many scientists to conclude the world is changing in unnatural ways.

Among the changes [see full list]:

• Marmots end their hibernations about three weeks earlier now compared to 30 years ago.

• Polar bears today are thinner and less healthy than those of 20 years ago.

• Many fish species are moving northward in search of cooler waters.

• A fruitfly gene normally associated with hot, dry conditions has spread to populations living in traditionally cooler southern regions.

While we argue ...

Over the past century, Earth's average temperature has risen by about 1 degree Fahrenheit and many scientists believe greenhouse gases and carbon dioxide emissions from human activities are to blame. Left unattended, they warn, temperatures may rise by an additional 2-10 degrees by the end of the century. In the leading computer models, it follows that polar ice will melt and seas would rise drastically, threatening coastal communities around the globe.