THE LAST CAST

THE LAST CAST • JOHN NICKUM What if There is No Cold water?

Q

The Planet Earth has experienced changes in average temperatures many times in its past history, such as the Little Ice Age, a five century episode starting around 1300; and the Medieval Warming period in the four to five centuries prior to those cold centuries. Is the degradation caused by our present climate change different from these previous events? What can we learn from past history that can help us deal with current problems?

A

I like this question. We have to learn from history, or we are doomed to repeat the mistakes of the past. I must emphasize that we cannot assume that the future will follow exactly the patterns of the past. There are lessons from the past that may be applicable, but there are also critical differences. The “Industrial Revolution” and the enormous increase in human population are major differences that must be considered as we deal with 21st century climate issues. Maintaining productive and stable fish populations are but one of the challenges facing us as we move into 2022 and beyond. If we are to enjoy angling based on clean waters and healthy trout populations in the coming decades, we must learn from the past and adapt to the future.

I have just finished reading a book, The Great Warming, written by Brian Fagan in 2008. The author discusses the effects of substantially warmer climate on ecological, social, cultural, and economic conditions in locations around our entire planet. The period of time that is the basis for Fagan’s discussions is approximately AD 950 to 1250; although some climatologists expand the warming time to four centuries, AD 900 to 1300. Although most summaries of the Medieval Warming Period focus on the northern hemisphere, especially examining effects in Europe and North America, historical records and evidence derived from such sources as changes in tree growth rings and the mineral composition of coral reefs show that Africa, Asia, Australia, and Oceana were subject to unusual patterns during the Warming Period. Fagan’s studies cover the entire planet except Antarctica and the Arctic.

Although temperature increases and their direct effects on human activities are the primary focus of most studies dealing with the medieval warming period, there were other changes that may have had even greater effects on ecosystems, human activities, and human cultures. Severe droughts occurred throughout the world as changes in ocean temperatures produced changes in currents and caused phenomena, such as El Ninos and La Ninas. Century after century, droughts persisted and productive lands were turned into wastelands. Crops failed and starvation caused millions of deaths, both humans and their domesticated animals. Wildlife was also affected, especially “residential” species which lacked the ability to relocate themselves to more favorable conditions.

As we evaluate our present warming situation, can we expect the same changes and patterns that developed and persisted in the past? The most probable answer is, “yes, but…” There will be widespread warming, ice caps will melt, sea levels will rise, weather will be more erratic and extreme conditions, especially drought will become more common. But we can expect warming to be more extreme and the effects of that warming to be different from the past.

Two major environmental factors that did not exist in the past exacerbate the effects of warming far beyond conditions in the past. The human population is much larger today than it was a thousand years ago. Also, human activities have changed drastically in the last 250 years because of the industrial revolution and its dependence on fossil fuels. Coal and petroleum fuels were not primary energy sources in AD 1000, or even in AD 1750. At the time of medieval warming, wood and animal wastes were used for heating, cooking, and other fuel-based activities. The environmental effects of deforestation were probably the worst problems related to human activities. Air pollution from burning fossil fuels was unheard of prior to the industrial revolution.

We can look back, shrug our shoulders, and say, “Well, trout have survived the ups and down of climate for thousands of years. Things have been more or less the same in western North America ever since the end of the last ice age, 10,000 years ago. Why worry now?” That approach is a non-starter, a loser, because the combination of a human population beyond the planet’s carrying capacity and extensive pollution caused by modern industrial systems makes a “business as usual” approach unsustainable. For the sake of trout - and human - survival, we must change how we do business.

Trout fishing in the future requires survival of “fishable populations” of trout, aquatic environments that support trout, and human populations that place value on recreational fishing. Sustaining environmentally-conscious human populations is a topic too large to cover in a brief article, but suggestions for clean waters are within the domain of short, environmentally focused writing. Given the problems related to present day climate change that are caused by burning fossil fuels; the first step is shifting to sustainable energy supplies, such as solar and wind. The second step is careful, but intense monitoring of the quantity and quality of water in our streams. Stopping deforestation, whether caused by logging or by wildfires, is essential to maintaining adequate stream flows. We can have quality trout fishing in the future, but to do so will require hard work and major changes in the way we do business. About The Author John Nickum, is a retired PhD. fishery biologist whose career has included positions as professor at research universities including Iowa State and Cornell University, director of the Fish and Wildlife Service’s fisheries research facility in Bozeman, MT, and science officer for the Fish and Wildlife Service’s Mountain-Prairie Region. He was inducted into the National Fish Culture Hall of Fame in 2008.