tR SAMPLINGS: THE WARMING EARTH 



Losing Contact 



Agriculture, d«elopment, and logging are often blamed for 

 habitat fragmentation. Now we can blame global warming, too. 

 Worldwide, a combination of rising temperatures and fire sup- 

 pression by foresters is causing mountain tree lines to climb. The 

 trees are creeping into alpine meadows and carving them to piec- 

 es; along the way, animal populations are being carved up as well. 



Take Jumpingpouijd Ridge in the Rocky Mountains of Alberta. 

 There, trees now live some 650 feet higher up the mountainsides 

 than they did forty years ago. Each year from 1995 through 2005, 

 Jens Roland of the University of Alberta in Edmonton and Ste- 

 phen F. Matter of the; University of Cincinnati surveyed the num 

 ber of Apollo butterflies, Parnassius smintheus, living in a series 



Apollo butterfly 

 basks in a Rocky 

 Mountain meadow. 



of alpine meadows on the ridge. After counting each meadow's 

 butterflies for eleven summers and comparing the fluctuations in 

 their numbers, Roland and Matter discovered that the broader 

 the swath of forest between two adjacent meadows, the less in 

 synch were the ups and downs of the two butterfly populations. 

 In other words, populations divided by thick forest fall out of 

 touch and become increasingly independent. 



The encroaching forests, the ecologists conclude, prevent the 

 Apollos (and quite possibly other organisms) from dispersing and 

 thus mixing their genes. That could be bad news for the butter- 

 flies and other locals: isolated populations are more vulnerable to 



being wiped out than are connected populations. (PNAS) 



Bias or Balance? 



Scientific consensus that humans have caused 

 global warming coalesced in about 1995. Yet 

 for the next decade many Americans still 

 believed that humankind's role in the emerg- 

 ing crisis was a matter of great debate. A new 

 study lays some of the blame for that national 

 misconception on the nightly TV news shows. 

 To avoid the appearance of bias, they contin- 

 ued to air contrarian viewpoints long after the 

 scientific debate was settled. 



Maxwell T. Boykoff of the University of 

 Oxford analyzed 143 news segments about 

 climate change that were broadcast be- 

 tween 1995 and 2004 on programs ranging 

 from the CBS Evening News to CNN's Wolf 

 Blitzer Reports. Only 28 percent of the seg- 

 ments paralleled scientific opinion in por- 

 traying humans as the main cause of global 

 warming, Boykoff discovered. Just a handful 

 of segments went so far as to suggest that 

 humans had a negligible effect on Earth's 

 climate, but a full 70 percent gave roughly 

 equal play to both sides of the debate. 



Journalistic skepticism is useful, but 

 Boykoff thinks that in this case, overrepre- 

 sentation of minority opinions amplified 

 uncertainty in viewers' minds. Fortunately, he 

 notes, the accuracy of TV news — at least re- 

 garding humanity's role in global warming — 

 has improved since 2004. (Climatic Change) 



—B.B. 



naiuhai misiokv November 2007 



Change on the Range 



On rangelands around the world, grasses 

 are giving way to woody shrubs. Deer and 

 antelope still have room to play, but the 

 encroaching shrubbery worries ranchers, 

 who rely on grasses as forage for their 

 cattle. As has long been suspected, the 

 rising concentration of atmospheric carbon 

 dioxide (CO2) contributes to the prolifera- 

 tion of shrubs. 



In a five-year experiment on Colorado's 

 shortgrass steppe, Jack A. Morgan of the 

 U.S. Department of Agriculture in Fort Col- 

 lins, Colorado, and colleagues placed six 

 clear-sided, open-topped enclosures on 

 the ground before each growing season. 

 Air circulated continuously through all six 

 enclosures; three received natural air, and 



Cattle ponder grass futures 

 on the Colorado range. 



three received air with double the current 

 atmospheric concentration of CO2. 



Inside the enclosures with double-strength 

 CO2, fringed sage [Artemisia frigida) — a 

 small shrub unpalatable to cattle — flourished 

 dramatically, while almost all forage grasses 

 grew at their normal rates. Like many other 

 rangeland shrubs, fringed sage absorbs more 

 atmospheric carbon during photosynthesis 

 than most grasses do. Morgan's team expects 

 that shrubs worldwide are responding to 

 elevated CO2 in a similar fashion. Since at- 

 mospheric CO2 may well double by 2100, the 

 explosion of shrubbery in the experimental 

 enclosures could occur on many open range- 

 lands, with inestimable economic and ecolog- 

 ical consequences. (PNAS) — Harvey Leifert 



