by Whit Gibbons

October 16, 2005

I recently read that one of the problems we face today about accepting and solving global climate change problems is political denial. The point was that some politicians have ignored scientific evidence and proceeded as if no problem existed. Consequently, no government controls, regulations, or meaningful appeals for conservation have been instituted to reduce carbon dioxide emissions through moderation in energy consumption.

On the other side are those, including a few respected scientists, who remain unconvinced that global climate change, based on the geological record, is any more dramatic than has occurred in former eras. In other words, the world’s climates have changed at other times before people were involved, and the U.S. culture of overconsumption is not affecting global climate change.

Regardless of whether humans are affecting the world’s weather, the scientific evidence indubitably supports that the climate has changed. For example, in a study of red grouse, the climate had changed enough in a century--not a long time on a geological timescale--for scientists to test two hypotheses that depended on climate change. Red grouse are a common game bird for which long-term records were available. Records of red grouse in northern England taken since the 1800s were used to reveal how climate change can influence population levels of grouse and other forms of wildlife.

In a study to explain why all grouse populations in a particular year either increased or decreased, even though they were from five distinct regions, I. M. Cattadori and P. J. Hudson of Pennsylvania State University teamed with D. T. Haydon of the University of Glasgow to examine a century-old data set. One hypothesis was that what determined fluctuations in grouse population size were direct effects of the climate on the breeding success and survival of grouse chicks. The alternative hypothesis was that the climate affected the interaction between the host (grouse) and a parasitic worm that reduced fecundity in the grouse. A parasite that lowers reproductive capacity could be a driving force affecting the abundance of the bird populations.

The investigators used elaborate statistical models and detailed weather data for each of the five regions to verify that environmental conditions favorable for the spread of parasite infection led to widespread population declines in grouse. Years that were unfavorable for the parasite infection resulted in increases in grouse survival. The findings are important in their applicability to the management of grouse populations. But they are also another example of how regional changes in climate can result in local changes in ecological factors, in this case parasite burdens, that can lead to significant changes in animal population sizes and ultimately biodiversity patterns in a region.

Previous evidence that the world is warming also came from British scientists who determined that flowers of nearly 400 species of plants for which records were available are now blooming more than 4 days earlier than they did half a century ago and more than a month earlier than they did a century ago. Likewise in North America, a comparison of blooming dates of plants in the Arnold Arboretum in Boston during the last 20 years revealed that they have flowered on average more than a week earlier than they did in the early 1900s.

Gas prices themselves may solve the overconsumption problem. But Americans need to be aware that by some reports the United States is the major industrial country unwilling to cut back on the use of oil and coal for fuel that leads to greenhouse emissions that cause global warming. Understandably, such an unyielding position in the face of what the rest of the world views as overwhelming evidence has led some to wonder if U.S. political connections with the fossil fuel industry are so strong that even decisions in the best interest of the nation and the world are brushed aside.

The question of whether politicians in power are using their influence to continue a dependence on the oil industry for personal profit will probably remain unresolved for many more years. But the fact that climate change is occurring and that it is affecting plants and animals on a global scale seems incontestable.

If you have an environmental question or comment, email

(Back to Ecoviews)