Exam 2 (critical thinking questions - chapter 3) Flashcards
What is the significance of the Stefan-Boltzmann law when applied to the Sun versus the Earth-atmosphere system?
The Stefan-Boltzmann law shows that small changes in the temperature of a black body result in a much greater change in radiational energy. The Sun’s temperature is much higher than that of Earth therefore its energy output is 190,000 times that of Earth’s.
Speculate on some means whereby Earth’s planetary albedo might increase. What would be the climate implications?
Earth’s planetary albedo would increase in correspondence with significant increases in types of surfaces with high reflectivity values. Examples include a large-scale increase in sea ice, glacial ice, and snow cover, and a significant increase in high cloud cover. An increase in albedo would, on average, decrease Earth’s surface temperatures.
The concentration of methane in the atmosphere is so low that it must be measured in parts per billion (ppb). Why then is methane considered an important greenhouse gas?
Methane is a very efficient absorber of infrared radiation (about 21 times more effective in trapping heat than carbon dioxide). Although it has fluctuated over the past 400,000 years, it is now at its greatest concentration. Its concentration is on the rise due to rice cultivation, cattle, landfills, termites, coal mining, wastewater treatment, and petroleum systems.
Provide a convincing argument that water vapor is the principal greenhouse gas.
Water vapor is the principle greenhouse gas because it causes the greatest amount of warming at Earth’s surface. For example, in areas with very little water vapor in the air, infrared radiation readily escapes to space, causing lowered temperatures than would otherwise occur at Earth’s surface. In areas with a great amount of cloud cover or high tropospheric water vapor content, water vapor strongly absorbs infrared radiation emitted by Earth and emits some IR back to Earth’s surface, having the effect of warming Earth’s surface.
Identify the two main factors in global sea level rise and compare their relative performance.
Global sea level rise is caused by ocean thermal expansion of seawater, as well as glacial melt. The IPCC states that there is high confidence of these factors accounting for about 75% of the observed sea level rise. From IPCC reporting and the NCA4, ocean thermal expansion has been the dominant factor accounting for 30-55% of 21st century global mean sea-level rise, while glaciers account for 15-35%.
