Strong evidence exists supporting the theory that the warming of the Earth’s atmosphere is due to human activity. Other theories for global warming exist such as sunspot activity, changes in ocean currents, volcanic activity, sea floor spreading, and natural variation in the Earth’s energy balance due to long-term cycles of glaciation and de-glaciation. The phenomenon of warming is irrefutable; what we don’t know is why, how long it will last or what control we have over it.
Scientists have speculated since the early 1970s that the greenhouse effect could be intensified by human activities, such as industrial emissions and deforestation, causing global warming over and above any natural variations in climate. What is important is that we are already existing in a naturally warm period of earth’s climate (measured in millions of years) and may be warming the climate beyond the previous warmest periods.
In 1990, Glacier National Park (The U. S. portion of Waterton-Glacier International Peace Park) and the surrounding area was selected as one of several centers for the study of global warming. Scientists in and around the park are studying various aspects of Earth’s climate system and feeding the resulting data to a computer program which will generate a regional climate model. This computerized climate model is a tool designed to assist the scientists in their attempt to predict the long and short term effects of any changes to the Earth’s climate. The emphasis of nearly all National Park Service and Parks Canada global change programs is to research possible effects of global warming on park resources, and to help establish whether warming is continuing.
Some of the most interesting data comes from W-GIPP studies on the shrinkage of glaciers. They respond slowly and steadily to large and long-term changes, so they are perfect for the study of climate change (as opposed to short-term weather). Glaciers have melted much faster in the last 20 years than they have in the past 5000 years. At the present rate of glacial shrinkage, there will be no glaciers in W-GIPP in 30 years!
This unit on global climate change investigates the issues of global warming and the procedures that scientists are using to further our understanding of the global climate system. Background information and activity suggestions are included. Teachers are encouraged to incorporate these activities into daily classroom study and then take a field trip to W-GIPP.
Global Warming and the Greenhouse Effect
The Earth’s climate system is a complex and dynamic tapestry woven of physical processes and many individual components. These components may be gaseous (atmosphere), fluid (oceans), or solid (land, ice and snow, terrestrial, and marine life-forms) and they may interact with each other on many different time scales (20,000 years for a sheet of ice to sculpt a mountain range or 1 week for a hurricane to cruise up the East Coast). One of the key components of Earth’s climate system is the Greenhouse Effect--the thermostat.
Life on earth exists because temperatures favored the creative process. Interestingly enough, these favorable temperatures have been perpetuated by…life on Earth. The planet is warmed by sunlight and radiates the resultant heat in the form of infrared energy. If all of this radiated heat were to escape into space, the planet’s temperature would be too cold to support life. Luckily, some of the radiated heat is trapped in the atmosphere by the gas carbon dioxide. This trapped heat warms the planet’s surface, allowing life-forms to thrive and grow--hence the name greenhouse gas. Where do the greenhouse gases in the atmosphere come from? From the life-forms growing on the surface!
Life on Earth is described as carbon based -- utilizing carbon as the central element in its molecular structure. Carbon is fixed or stored in living tissue during the growth process and it is released into the atmosphere during the process of decomposition. When the planet grows too cool, more living forms die, decompose, and release carbon dioxide into the atmosphere. This in turn increases infrared energy absorption which then raises the temperature of the planet and promotes the growth of life-forms. So the temperature of the planet is continually fluctuating up and down within a favorable range and at a rate that is determined by the growth and decomposition cycles of the life-forms. This very neat system for regulating Earth’s temperature works relatively smoothly as long as the parameters of the equation remain the same. They haven’t.
Human activity on the planet has grown to the point where it has changed the balance of the greenhouse effect by rapidly increasing the amounts of greenhouse gases released into the atmosphere. In our energy consumptive lifestyles, we burn vast amounts of fossil fuels and wood, thereby releasing carbon dioxide, nitrous oxide, and tropospheric ozone into the atmosphere. Our beef and rice industries have increased the release of methane and we have also generated a new batch of greenhouse gases, chloro-fluorocarbons, which are used as cooling agents, foam blowers, circuit cleaners, and aerosol propellants. This all adds up to an excess of greenhouse gases in the atmosphere, trapping more infrared energy and warming the planet at an accelerated rate.
Trees and ocean plankton would normally absorb the excess carbon dioxide out of the atmosphere, but as a result of deforestation and ocean pollution, they are losing their ability to maintain a balance. Scientists are predicting that the effect will be a global temperature rise of between 4 and 9 degrees Fahrenheit (F) by the middle of the next century. This accelerated warming trend will, according to preliminary predictions, cause major changes in Earth’s climate. Precipitation will decline in some areas, leading to crop failures and expanding deserts. Elsewhere, rainfall will increase causing flooding and erosion. Temperature changes will force plants and animals to evolve rapidly to new conditions or face extinction. And sea levels will rise, flooding coastal areas and causing salt water intrusion into freshwater ecosystems.
These preliminary predictions are non-specific, and most government officials do not feel confident about basing legislation on them, so policy makers have asked scientists to provide them with more specific details on the consequences of the global warming trend. But even as scientists move to find out more about the global climate system’s intricacies, the imbalance grows greater as we continue in our energy consumptive lifestyle. That is why many groups of concerned citizens, scientists, and law makers are not waiting for more data. They are urging everyone to take action immediately by banning the production of chloro-fluorocarbons, stopping deforestation, changing over to renewable energy sources like solar, wind, and geothermal, and most important of all, becoming more efficient at recycling and energy conservation so that fossil fuel consumption is reduced.