A variety of species, from frogs to flowering plants, have demonstrated changed behavior in response to increasing world temperatures over the last few decades. According to the results of two studies published today in the journal Nature, these changes are not isolated events, but instead represent a worldwide pattern, or "fingerprint," of global warming.

Camille Parmesan of the University of Texas at Austin and Gary Yohe of Wesleyan University examined data on 1,700 species of plants and animals to assess the global biological impacts of climate change. They determined that there have been significant overall species range shifts of 6.1 kilometers a decade, on average, toward the planet's poles. Meanwhile, spring events such as egg laying and migration are occurring 2.3 days earlier each decade. The authors conclude that, according to the Intergovernmental Panel on Climate Change's guidelines, there is "'very high confidence' that climate change is already affecting living systems."

In the second report, Terry L. Root of Stanford University and her colleagues analyzed data from 143 previously published scientific studies that included information on 1,473 species. The team found that a consistent temperature-related shift, noting that "the balance of evidence from these studies strongly suggests that a significant impact of global warming is already discernible in animal and plant populations." Species that live at higher latitudes are particularly affected because temperature increases in these regions have been more pronounced than those at lower latitudes, according to the report. The authors posit that their findings may only hint at what is to come. Says Root: "Clearly, if such ecological changes are now being detected when the globe has warmed by an estimated average of only one degree Fahrenheit over the past 100 years, then many more far-reaching effect on species and ecosystems will probably occur by 2100, when temperatures could increase as much as 11 degrees Fahrenheit."

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