Global Climate Change 



Overview 



Scientists have long rec- 

 ognized climate, especial- 

 ly temperature and precipitation, as one of the 

 major ecological forces affecting the abun- 

 dance, location, and ecological health of living 

 organisms. This relationship is so strong that in 

 many cases, if biologists know what plants and 

 animals are present in an area, they can approx- 

 imate the climate of the area. Quantifying these 

 relationships will allow scientists to predict the 

 ecological consequences of global climate 

 change. 



Recently the scientific community reached a 

 remarkable consensus on the likelihood and 

 magnitude of global climate change, describing 

 a likely scenario of a 3°C (5.4°F) average glob- 

 al warming, significant changes in the patterns 

 and abundance of precipitation, and 0.6-m ( 1 .9- 

 ft) sea-level rise in the next 60 years (Houghton 

 et al. 1990; LaRoe 1991). These changes will 

 occur faster than previous change in geologic 

 history and are therefore expected to have 

 greater ecological impact. 



Because of the strong relation between cli- 

 mate and ecosystem health and distribution, the 

 U.S. Global Change Research Program has as a 

 major component the monitoring of plants and 

 animals to detect, understand, and ultimately 

 predict the effects of global climate change on 



living resources (CEES 1990). The National 

 Biological Service's research includes several 

 projects to monitor the effects of climate change 

 on animal and plant populations and ecosys- 

 tems. Not only will the results of these projects 

 allow a better understanding of the ecological 

 effects of climate change, but they will also give 

 an early, clear indication of the onset and mag- 

 nitude of climate change because living 

 resources may be sensitive indicators of global 

 change. 



Determining if long-term change in a 

 species' population abundance or distribution 

 was caused by specific climate changes is an 

 extremely difficult scientific problem for two 

 reasons: first, both climate and biological fac- 

 tors vary greatly from year to year, and these 

 annual variations often mask long-term trends, 

 making them difficult to detect. Second, several 

 factors such as habitat loss, hunting pressure, 

 competition with other native species and non- 

 native species, and contaminants are simultane- 

 ously affecting species" population size and dis- 

 tribution along with climate change so that it is 

 difficult to determine definitively the effect of 

 any one cause. 



Some species of plants and animals already 

 may be affected by one type of global climate 

 change: global warming. Much of the evidence 



Edward T. LaRoe 



Senior Science Editor 



National Biological 



Service 



