Exam 2 (critical thinking questions - chapter 15) Flashcards
Differentiate between climate variability and climate change.
Climate variability means changes in climate that occur within smaller time frames, such as a month, a season or a year. Whereas climate change - are the changes that occur over a longer period of time, typically over decades or longer.
Describe the Maunder minimum and its possible connection to the climate of the Little Ice Age. Why do scientists search for mechanisms that amplify the effect of changes in solar activity, such as those that occurred during the Maunder minimum.
The Maunder minimum (MM) was a period of extremely low solar activity from approximately AD 1650 to 1715. In the solar physics literature, the MM is sometimes associated with a period of cooler global temperatures, referred to as the Little Ice Age (LIA), and thus taken as compelling evidence of a large, direct solar influence on climate. While the MM occurred within the much longer LIA period, the timing of the features are not suggestive of causation and should not, in isolation, be used as evidence of significant solar forcing of climate. Climate model simulations suggest multiple factors, particularly volcanic activity, were crucial for causing the cooler temperatures in the northern hemisphere during the LIA. A reduction in total solar irradiance likely contributed to the LIA at a level comparable to changing land use.
Define feedback in terms of Earth’s climate system and differentiate between positive and negative feedback.
A feedback that increases an initial warming is called “positive feedback.” A feedback that reduces an initial warming is a “negative feedback.” Clouds. Clouds have an enormous impact on Earth’s climate, reflecting about one-third of the total amount of sunlight that hits the Earth’s atmosphere back into space.
Why does an extensive winter snow cover tend to be self-sustaining?
A winter snow cover can feed back on its environment by reflecting away solar radiation. Fresh-fallen snow typically reflects 80% or more of incident solar radiation, substantially reducing the amount of solar heating and lowering the daily maximum air temperature. Snow is also an effective emitter of infrared radiation, so infrared radiation is efficiently emitted to space, especially on nights when the sky is clear. Moreover, persistent snow cover may be further enhanced by tracks of extratropical cyclones that have a higher likelihood of following the margins of a regional snow cover, where horizontal air temperature gradients are relatively sharp. This places snow-covered regions on the cold, snowy side of migrating winter storms, thereby adding to the snow cover and reinforcing the chilled air.
Explain how the ice-albedo feedback affects the extent of Arctic sea-ice cover.
Ice-albedo feedback is a key aspect of global climate change. In the polar region, a decrease of snow and ice area results in a decrease of surface albedo, and the intensified solar heating further decreases the snow and ice area. The change in albedo acts to reinforce the initial alteration in the ice area leading to more warming. Warming tends to decrease ice cover and hence decrease the albedo, increasing the amount of solar energy absorbed and leading to more warming. The capacity of the Arctic to reflect heat is determined by something known as the albedo effect. Thus, darker surfaces tend to absorb more heat. As the albedo effect in the Arctic is reduced, there is a positive feedback effect because, as the region warms, more and more ice and snow cover is lost.
Why are current warming trends expected to continue throughout the 21st century even if greenhouse gas emissions stabilize?
(IPCC) Report, released today. Many of the changes observed in the climate are unprecedented in thousands, if not hundreds of thousands of years, and some of the changes already set in motion - such as continued sea level rise - are irreversible over hundreds to thousands of years. However, strong and sustained reductions in emissions of carbon dioxide (CO2) and other greenhouse gasses would limit climate change. While benefits for air quality would come quickly, it could take 20-30 years to see global temperatures stabilize.
Summarize how current global climate change trends stress agriculture.
Agriculture contributes a significant share of the greenhouse gas (GHG) emissions that are causing climate change - 17% directly through agricultural activities and an additional 7-14% through changes in land use. … Both of these gases have a significantly higher global warming potential than carbon dioxide. Agriculture is a major source of GHGs which contribute to the greenhouse effect and climate change. However, the changing climate is having far reaching impacts on agricultural production, which are likely to challenge food security in the future. Climate change is likely to contribute substantially to food insecurity in the future, by increasing food prices, and reducing food production. Food may become more expensive as climate change mitigation efforts increase energy prices. Water required for food production may become more scarce due to increased crop water use and drought. Competition for land may increase as certain areas become climatically unsuitable for production. In addition, extreme weather events, associated with climate change may cause sudden reductions in agricultural productivity, leading to rapid price increases. For example, heat waves in the summer of 2010 led to yield losses in key production areas including: Russia, Ukraine and Kazakhstan, and contributed to a dramatic increase in the price of staple foods. These rising prices forced growing numbers of local people into poverty, providing a sobering demonstration of how the influence of climate change can result in food insecurity.
