4.3 Study Guide Flashcards
Explain how the greenhouse effect works. Give 3 examples of greenhouse gases.
The greenhouse effect is the process by which certain gaseous compounds trap heat from the sun within Earth’s atmosphere, heating the planet. The greenhouse gases include: Carbon Dioxide, Methane, Water Vapour, Nitrous Oxide, various Chlorofluorocarbons, various Hydrofluorocarbons, Sulfur Hexafluoride, and more.
Explain the difference between positive and negative feedback loops. Which type generally keeps things balanced in Earth’s ecosystems?
In positive feedback loops, one occurrence increases another occurrence, which in turn increases the first occurrence and creates a loop of amplification. In negative feedback loops, one occurrence still increases another occurrence, but the second decreases the first instead of increasing it, creating a loop of amplification and reduction. In most cases, negative feedback loops are the ones that keep various factors in Earth’s ecosystems balanced, as positive feedback loops often produce uncontrolled growth if unnaturally instigated.
Explain why the greenhouse effect, when working at a natural level, is vital for life on Earth.
Without anything to trap heat from the sun within Earth’s atmosphere, all the heat would reflect back into space, and the planet’s surface would be too cold to support most life. The presence of greenhouse gases to perform the greenhouse effect is what keeps Earth at a habitable temperature.
Explain how various human activities are affecting the greenhouse effect and making it harmful to the planet.
Many current human activities are releasing excess greenhouse gases into the atmosphere. The most notable is the burning of fossil fuels for energy, which steals high amounts of stored carbon dioxide from the long-term carbon cycle and releases them unnaturally. Additionally, activities like deforestation both release carbon dioxide stored in trees and render large areas of forest unable to sequester any excess carbon dioxide from the air. The consequences of these activities are swiftly and drastically amplifying the greenhouse effect to a level that is causing the planet to overheat, and, unfortunately, they only compound themselves the more intense they become.
What have collected ice cores told scientists about the correlation between atmospheric CO2 levels and temperature over the years? What have they shown us about current levels compared to historic peaks?
From information collected from polar ice cores, scientists have observed that atmospheric CO2 levels and global temperature have historically had a very close direct relationship, marked by their rising and falling together. Additionally, scientists have found that present-day levels of CO2 and temperature are much higher than anything seen in the last 800,000 years and that the recent increase has occurred drastically swifter than what has been observed to be natural.
Based on the various feedback loops regarding carbon dioxide, water vapor, methane, albedo, and the like, why might the effects of global climate change be difficult to reverse once initiated?
The feedback loops regarding carbon dioxide, water vapor, methane, and albedo all stem from increased temperature caused by excess greenhouse gas emissions, and all are positive feedback loops that compound temperature increases. Because of this, even a relatively slight increase in temperature could activate all 4 loops at once, all of which compound temperature on their own and all of which compound each other’s temperature increases. This relationship between the loops would make it so that even if the original excess greenhouse gases were later removed from the atmosphere, the damage would already be done and the global temperature would still be rising uncontrollably.
Using the various diagrams of climate feedback loops, explain how the recent outbreaks of the mountain pine beetle caused by the effects of global climate change indirectly lead to the release of carbon dioxide and other greenhouse gases from different locations.
The main climatic consequences of the mountain pine beetle outbreaks stem from the beetles’ widespread killing of trees and creating conditions for wildfires, both of which release stored carbon dioxide into the atmosphere and render large patches of trees unable to sequester excess carbon dioxide. This release of carbon dioxide increases the global temperature through the greenhouse effect, which then instigates the climate feedback loops of other areas. For example, increased temperatures lead to both the thawing of thousands-of-years-old permafrost layers and the instability of methane clathrate hydrates underwater, which release methane and other greenhouse gases into the atmosphere. As well as this, the increased temperatures caused by the now three loops also instigate increased evaporation and melting of polar ice, which increases atmospheric water vapor and decreases Earth’s average albedo respectively, causing an even higher increase in temperature. Now, there are 5 positive feedback loops working together to increase the planet’s temperature to an unnatural level all because of a single species of beetle.
