At a recent talk in Hamilton sponsored by the Bitterroot Climate Action Group, retired fisheries biologist Chris Clancy discussed the scientific evidence concerning climate change. Being a scientist himself, he decided to look to the scientific community for an answer to two simple questions: Is it happening? What is causing it? The answer to both questions, according to Clancy, is clear. The earth is warming at an unprecedented rate and the change is being brought on by human activities.
“It’s now more certain than ever, based on many lines of evidence, that humans are changing our climate. This is not from some advocacy group, this is from the Royal Academy of Scientists and National Academy of Scientists, and other scientific academies around the world,” said Clancy.
Clancy said scientists started measuring carbon dioxide (CO2) in the atmosphere 120 years ago and recognized what is called the greenhouse effect, the trapping of heat in the atmosphere by a “blanket” of CO2. “This is not new science,” said Clancy, “this is well established and well accepted science.”
According to Clancy, a number of studies have been done comparing available data on global warming which found that 97% of scientists from academies all over the world are in agreement that the recent changes in the earth’s climate are primarily human caused. He noted that the 3% in disagreement are not necessarily wackos. He said there are some pre-immanent scientists that have problems with certain aspects of human caused climate change.
“Scientists are trained skeptics. They are arguing all the time,” said Clancy. To find them 97% in agreement over this is a big deal.” He said the most published scientists are the ones most in agreement.
The earth’s temperature has been tracked by scientists since 1850 and shows a rapid climb beginning at the start of the industrial revolution and the massive contribution of CO2 by burning fossil fuels. Since the 1990s the average temperature of the earth has gone up basically about .75 degree centigrade and 2019 was recorded as the third warmest year on record.
According to Clancy, there is a very strong correlation between atmospheric temperature and the amount of CO2 in the air and graphs of the CO2 concentration show the same dramatic upward jump in modern history as we see in the historic temperature trends.
The highest concentration of CO2 in the past 800,000 years related to warm interglacial periods was 300 parts per million. In the last 100 years that concentration has jumped to over 400 ppm.
The US Global Carbon Project (GCP) is an organization that seeks to quantify global greenhouse gas emissions and their causes. Established in 2001, its projects include global budgets for three dominant greenhouse gases — carbon dioxide, methane, and nitrous oxide — and complementary efforts in urban, regional, cumulative, and negative emissions. The project has brought together emissions experts, earth scientists, and economists to tackle the problem of rising concentrations of greenhouse gases.
What they have documented, according to Clancy, is the incredibly huge and unprecedented amount of CO2 being contributed to the atmosphere by burning fossil fuels. It has raised the concentration of CO2 in the atmosphere to unprecedented proportions and is pushing global temperatures higher than any time in the earth’s history.
Burning of fossil fuels has increased CO2 in the atmosphere by 40% since the industrial revolution. If not for this human activity, climate would have cooled slightly over the past 50 years. All of our government agencies are in agreement on this, according to Clancy, including Departments of State, Commerce, Transportation, Defense, USGS, NASA and others.
Clancy said that, using proportional units of measurement, it was found that the biosphere (forests and other vegetation) absorbs -2 units of CO2 from the atmosphere and the oceans absorb another -3 units, basically removing a total of -5 units from the atmosphere. Meanwhile, deforestation is adding +1 unit of CO2 into the atmosphere and burning of fossil fuels contributing another +8 units. In other words, humans are adding enough CO2 to the atmosphere to overwhelm the earth’s natural cleansing actions.
A chemical analysis of the CO2 building up in the atmosphere yields a “fingerprint” consistent with that produced by the burning of fossil fuels.
Clancy cautioned that people often confuse climate change with the weather. He showed a series of pictures of the globe flattened out with relatively cool average temperatures shown in shades of blue and relatively warm areas shown in shades of brown. The series exhibited a steady warming of the whole earth. Starting with lots of blue and cool with islands of brown, then turning gradually brown, with only a few isolated islands of cool blue.
Data indicates that Montana is following along with these global trends.
Average temperatures in every sector of our state measured from 1950 through 2015 show a similar upward trend
According to Bruce Maxwell, one of the lead authors of the Montana Climate Assessment, these rising temperatures are going to lead to reduced snow pack at higher elevations and an earlier snowmelt. Peak runoff in the rivers and streams will come earlier and late summer flows will be lower and for longer periods of time.
With the average air temperature rising as it is, it is not surprising to discover that most every stream and the river itself in the Bitterroot valley are also gradually warming. Montana FWP has documented the rising temperatures of the Bitterroot watershed from 1993 to 2019 and found that all the tributaries are gradually warming.
It’s not the end of the world, according to Clancy, but it does mean big changes for the different species of fish that currently occupy the waters. Trout love cold water. Some more than others. The difference of just a few degrees in water temperature can mean a lot. Bull trout, for instance will begin looking for colder waters when the water temperature gets above 59 degrees F. Brown trout, on the other hand, find water in the low 60’s quite comfortable.
As a result, as a stream warms up, like Sleeping Child Creek, it has been documented that the Bull trout are moving farther and farther upstream in search of colder water and the Brown trout are moving in to fill the area left behind. What we find is that Brown trout range is increasing as Bull trout range is decreasing.
“It’s not a rush upstream by these non-native warm water species,” said Clancy, “but it is a slow steady movement.”
These rising temperatures are especially hard on the native species like Cutthroat trout which also prefer cooler water, though they do better than Bull trout in higher temperatures.
Clancy doesn’t believe that we will necessarily lose our cold water fisheries, but they will be shorter stretches found at higher elevations.
Clancy said that in the years ahead it was going to become more important than ever for irrigators and recreationists in the valley to get together and work together to preserve and share our water resources.