GEOL 101 Climate Change
GEOL 101 Climate Change GEOL 101
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This 3 page Class Notes was uploaded by Victoria Williams on Wednesday May 4, 2016. The Class Notes belongs to GEOL 101 at George Mason University taught by Mark Uhen in Fall 2016. Since its upload, it has received 12 views. For similar materials see Introductory Geology in Geology at George Mason University.
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Date Created: 05/04/16
Global Climate Change The last time Earth had no permanent ice was 40 million years ago Climate – the long term pattern of weather o The climate system includes the atmosphere, hydrosphere, geosphere, biosphere, and cryosphere Detecting Climate Change o Proxy data such as sea floor sediments, glacial ice, fossil pollen, and treegrowth rings can indicate changes in past climate. The study of past climate is paleoclimatology. o Historical Records – After looking back in time, we can see that there was a warm period during the medieval. And moving towards the recent we see a rise in temperature steadily. Today we are way above historical levels that we know of. Sea Floor Sediment – mostly formed from the skeletons of single cell organisms. Calcium carbonate skeletons. Scientists can put tubes down into the floor and collect samples of fossils from deeper down. Oxygen isotope analysis – O (lighter) and O (heavier) o Sea water evaporates, the lighter oxygen isotope will evaporate easier. The water will rain on land and then run back to the ocean. o However, when ice forms some of that water doesn’t return to the ocean. During times when there’s ice on the planet, the sea is abundant in the heavy oxygen isotope. We can see the climate at the time and whether there was ice or not if we look at skeletons made of CaCO3 to see if the oxygen is lighter or heavier. Ice Core Analysis o In old ice, gas bubbles are trapped and are a direct sample of the air at the time. Tree Ring Analysis: Dendrochronology o Ring width is based on temperature and precipitation o Ring size is based on the climate at the time (enough water, not too hot, not too cold) Fossil Pollen o Certain trees grow in certain areas with certain climates. o If you take a sample of earth deep down, you can see patterns in pollen so you can see the climate influences. Humans also play a role in what pollen shows up. Coral Skeletons o Banding can be seen in coral that might be kinds of growth rings. You can analyze the rings and the oxygen within it to see the climate. Atmospheric Composition o Mostly nitrogen, lots of oxygen, other trace elements, a little bit of carbon dioxide. o Water vapor can make up 04% of the atmosphere by volume o The atmosphere can also contain aerosols, which are tiny particles of solids or drops of liquid o Aerosols can block out light rays and disrupt growth Solar Energy o Electromagnetic spectrum Incoming Solar Energy o Most solar radiation is absorbed by land or sea (50%) o About 20% is absorbed into the atmosphere, like in clouds o The rest gets reflected by the sea, atmosphere, and clouds Albedo Effect o Light objects have high albedo (more likely to reflect) o Dark objects have low albedo (more likely to absorb) o The fraction of the total radiation that is reflected by a surface is called its albedo. Greenhouse effect o Short wave radiation absorbed by land and sea o Long Wave radiation reradiated and absorbed by greenhouse gasses. The CO in 2 the atmosphere in the atmosphere absorbs the warmth. o Greenhouse gases reradiate longwave radiation and warm the atmosphere. The heat keeps transferring. o This isn’t a bad thing, but the problem is that humans have put a lot of carbon dioxide into the atmosphere which has enhanced the greenhouse effect Volcanic activity o Particulate matter blocks solar radiation and cools the atmosphere o Ex. El Chichon and Pinatubo eruptions blocked out a lot of sun. Solar Variability o The sun is pretty steady o The number of sunspots varies on an 11 year cycle Human Impacts on Climate o Carbon dioxide concentration in the atmosphere changes over time. o We are well over what we have measured is the ‘normal’ concentration of carbon dioxide o The atmosphere’s response is that it keeps getting warmer. o Mean annual temperature of the planet has changed dramatically over the past 50 70 years. Climate Feedback Mechanisms o Decline in the perennial ice > Reduced Reflectivity > Increased absorption of solar radiation > Warmer Ocean > Longer Melt Period > Decline… (repeats) o Stops when there is no more ice to melt Consequences: Sea Level Rise o When the sea rises, the east coast has a gentle slope so it will flood o The west coast has a steeper slope so flooding won’t injure them as badly Consequences: Ice Melt o Ice shelves decoupling, habitats for polar animals disappear, etc.
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