a.Briefly explain the different effects of losing ice from the Greenland ice she
ID: 284893 • Letter: A
Question
a.Briefly explain the different effects of losing ice from the Greenland ice sheet and from Arctic sea ice on sea level, and why this is. You do not need to give any numerical values in this answer, only descriptions.
b.Ice cores and satellites are both used to measure changes in the polar regions. What are the differences between them in terms of space and time when sampling data?
c.Some measurements from these ice core samples may provide direct data on past conditions, while others are proxy variables. Explain the difference between these two types of data.
d.List one item of direct data and one item of proxy data that can be measured from ice core samples. For each item, state what is measured and what aspect of past climatic conditions it relates to, as well as whether it is an example of direct or proxy data.
e.The data from ice core samples has enabled us to infer the behaviours of surface temperature and atmospheric CO2 levels for the past 800 000 years, these two quantities are said to ‘appear to be positively and very closely correlated’. Explain in a sentence or two what the term ‘correlated’ means.
Explanation / Answer
a. The albedo is a measure of how well the surface of earth is reflecting the solar radiation. Since ice has a higher albedo and reflects about 85% of solar radiation. With lesser ice, lesser heat is reflected and thus more heat will be absorbed by the planet. This could lead to rise in global warming. As a result of global warming more ice will melt which raise the level of the sea. This could lead to inunduations of the low lying areas and disastrous floods.
b. With the help of ice core we can continuously reconstruct the past climate of about 800,000 years. On looking at the past concentrations of greenhouse gases in layers of ice we can compare the modern concentration of greenhouse gases like methane and carbon dioxide with them and calculate the temperature in the past.
Since ice cover in the polar regions is changing and this is detected by the satellite data. We can measure the mass balance of glaciers and can also measure the distance between the modern glacier terminus and its maximum position during the little ice age around 1850 in the northern hemisphere. Also we can revisit the same glacier over a period of 10 years and can visually see the recession of its snout. So the satellite data are very useful in observing the change in the modern glaciers.
c. Since we cannot directly observe the climatic conditions of the past. eg temperature. For the study of past climates scientists use proxy data to reconstructs the climatic conditions that existed in the past. These proxy data are the natural recorder of the climatic variability in the past. Examples of proxy data are tree rings, pollen, ice cores etc. Scientists drill the ice cores which have distinct layers in them. These layers contain air bubbles, dust, isotopes of oxygen which differ from year to year based on the surrounding environment. These ice cores can be used to interpret the past climatic conditions like temperature, precipitation, volcanic activity, atmospheric composition and wind patterns.
The direct measurements from the ice core are the concentration of green houses like methane and carbon dioxide present in the different layers of ice core which can be used to directly infer the atmospheric composition of the past and on the basis of the concentration of greenhouse gases present in the ice layers we can infer the temperature in the past so temperature is the proxy data and atmospheric composition is the direct data.
d. The concentration of greenhouse gases present in the different layers of ice cores can be used to directly infer the geochemistry or the atmospheric composition of the past. Whereas on the basis of greenhouse gases present in the ice core layers we can reconstruct the temperature in the past. So temperature calculated is the proxy data and the geochemistry and atmospheric composition measured in the ice cores is the direct data.
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