The recent editorials by Edward Stevenson and Andrew Kirk on global warming (Sept. 10’s “Is global warming hot air?”) present two polarized views that unfortunately suggest there is a lack of scientific understanding regarding climate change (a phrase we prefer over global warming), and that we either have nothing to be concerned about or are facing dire consequences.
We want to take this opportunity to identify the scientific knowns and unknowns and illustrate why society should, indeed, be concerned about climate change and not simply “chill out.”
There is no evidence to support the idea of a constant and unvarying climate. Every piece of paleoclimatic data, from glacial cores to ocean sediments to packrat middens to tree rings, illustrates that the only constant in climate is that it does change, sometimes abruptly. Glacier cores show that about 12,000 years ago Greenland underwent a massive climate shift, warming about 25 degrees Fahrenheit in one decade.
Even religious scholars know that the climate of the Middle East is substantially different today from how it was in biblical times.
Although climate change can be a global phenomenon, regional climate change and variability can occur even if global temperatures do not change appreciably. In fact, there are already well-documented examples of regional climate variability and human adaptation to it.
In the Sierra Nevada and Cascade Mountains, spring runoff today occurs about 25 days earlier than it was 40-50 years ago. The runoff occurs over a longer period without as abrupt of a spring peak. As a result, water resource managers have had to alter their water storage and power generation strategies.
Identification and adaptation to this example of regional climate change occurred despite the fact that it is unclear if it was caused by natural variability or greenhouse-gas induced warming.
There is also no doubt that the earth has warmed in the last 100 years, that the warming has accelerated in the last decade, and that the changes are most pronounced in the polar regions.
In fact, some areas in the high northern latitudes have warmed by about 1.5 degrees Fahrenheit per decade over the past 30 years. There are many well-documented examples of significant changes to polar ecosystems due to this warming.
Debunking global warming, Stevenson invoked the opinion of Dr. Richard Lindzen. Dr. Lindzen is a well-respected member of the atmospheric science community who has published seminal papers in the area of atmospheric dynamics.
Nevertheless, he, and the two or three other scientists mentioned by Stevenson, represent the very few remaining dissenting voices among thousands of scientists who believe humans are having a significant influence on climate.
The Intergovernmental Panel on Climate Change (www.ipcc.ch) produces the most comprehensive evaluation of climate change and its potential impacts. In its third assessment report, published in 2001, it concluded, “emissions of greenhouse gasses and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate.”
One might also add land surface change to that list because it also contributes to both regional and local climate change. There is no doubt that we now deal with a human-modified climate system influenced by both natural and anthropogenic components.
The debate around global warming has unfortunately distracted us from accepting the fact that society will need to adapt to the inevitable variability that exists within our human-modified climate system.
Even the Bush administration recognizes this fact and noted in a recent report to the United Nations that the climate of the United States will change dramatically in the coming decades (the same report also places most of the blame for recent climate change on greenhouse gas emissions).
Although we were disappointed that the Bush administration did not ratify the Kyoto agreement, we must admit that all the evidence suggests that the proposed cuts in emissions were so minor that they would have had virtually no impact on decreasing the rate of warming.
Reductions in greenhouse gas emissions are a worthwhile goal, but we must also recognize that such reductions can only slow down the rate at which greenhouse gas concentrations increase. They are not a solution because they can only buy us time to research possible technological solutions for energy alternatives and climate change mitigation and adaptation strategies. As a wise man once said, “prediction is very hard, especially with respect to the future.”
There are many uncertainties in climate prediction, but there is no doubt that society will be facing significant challenges due to climate change and variability in the future.
The young people of today must face these challenges and develop the technologies and adaptation strategies to both mitigate and take advantage of our ever-changing climate.