Chat with AIExam 10: Ancient Climate and Environment
The warmer waters of El Niño brought weather that decimated a staple of both the Peruvian coastal diet and highland trade during the reign of the Moche. What food source was drastically reduced?
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What do ice cores tell us about climate change for the past 10,000 years or so?
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Answered by Examlex AI CopilotIce cores are cylindrical samples of ice drilled from ice sheets and glaciers. They are one of the most valuable tools for studying past climate change because they contain a wealth of information about the Earth's climate history. By analyzing ice cores, scientists can infer climate conditions over the past 10,000 years or more. Here's what ice cores can tell us about climate change during this period:
1. **Atmospheric Composition**: Ice cores trap tiny bubbles of air that provide samples of the Earth's past atmosphere. By measuring the concentration of greenhouse gases, such as carbon dioxide (CO2) and methane (CH4), scientists can determine how the composition of the atmosphere has changed over time. This data has shown that current levels of CO2 are higher than at any point in the past 800,000 years, indicating a significant human impact on the atmosphere.
2. **Temperature Records**: The isotopic composition of the water molecules in ice (the ratio of heavy to light oxygen and hydrogen isotopes) can be used to infer past temperatures. This is because the isotopic composition of precipitation changes with temperature. These records have shown periods of warming and cooling, such as the Medieval Warm Period and the Little Ice Age.
3. **Precipitation Patterns**: Variations in the layers of ice cores can indicate changes in precipitation. Thicker layers may suggest wetter periods, while thinner layers can indicate drier times. This helps scientists understand how climate change has affected water availability in different regions.
4. **Volcanic Activity**: Ice cores can contain layers of volcanic ash or sulfate deposits from historic eruptions. These layers can be precisely dated and are used to correlate ice core records with other climate proxies. Volcanic eruptions can have a short-term cooling effect on the climate, which can be seen in the ice core records.
5. **Solar Variability**: The presence of certain isotopes, such as beryllium-10, can indicate changes in solar activity. Periods of high solar activity correspond to warmer climates, while low solar activity is associated with cooler climates.
6. **Sea Ice and Ocean Circulation**: By examining the presence of certain ions and isotopes, scientists can infer changes in sea ice extent and ocean circulation patterns. These changes can have significant impacts on global climate systems.
7. **Biological Activity**: Ice cores can contain remnants of biological material, such as pollen, that can be used to infer changes in vegetation and the movement of ecosystems in response to climate change.
8. **Chronology of Events**: Ice cores provide a high-resolution timeline of past climate events, allowing scientists to understand the sequence and duration of climate changes and to correlate these changes with other geological and historical data.
Overall, ice cores have revealed that the climate over the past 10,000 years has been relatively stable until the recent past. The rapid increase in greenhouse gases and the corresponding rise in global temperatures over the last century is unprecedented in the context of this long-term ice core record. This evidence supports the conclusion that human activities are significantly altering the Earth's climate system.
Dendrochronologies for the Ancestral Pueblo give us the most precise time scale for any early human society anywhere, because they are now accurate to within
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Ice core samples preserve records of annual snowfall in a format much like
(43) Which is the study of archaeology using the methods and concepts of the earth sciences, which plays a major role in reconstructing ancient environments and landscapes?
(37) Britain was joined to the European continent in the area of the English Channel and the southern North Sea
(39) Since the beginning of the Middle Pleistocene, there have been a number of cold (glacial) and warm (interglacial) cycles, with the last cycle ending about 12,000 years ago. How many cycles are known to have occurred during this time?
(36) Our knowledge of ancient climatic shifts is being revolutionized in particular by information obtained through
(35) The last prolonged Ice Age glaciation ended when North American and European ice sheets retreated and the world entered a period of pronounced global warming. This occurred about
(36) Through palynology, botanists can use pollen data to work out a series of vegetational time zones. They can determine a relative date for a site by comparing
(30) The catastrophic drought that came with the Younger Dryas period may have been a major factor in the start of animal domestication and
(42) Why are El Niño events of such interest to archaeologists, especially since they represent only short-term climate change?
(36) Lower Pleistocene times lasted from the beginning of the Ice Age until about
(41) Although no humans lived very close to the great ice sheets that covered so much of the Northern Hemisphere during the Great Ice Age, they did live in areas that were affected by geological phenomena associated with the ice sheets. These areas might be any of the following EXCEPT
(30) What happened climatologically and botanically to Europe and southwest Asia during the Younger Dryas? What were the apparent results for human societies in these areas?
(35) About 1.8 million years ago, global cooling marked the beginning of this epoch, more popularly called the Great Ice Age or the
(44) Write an essay on some of the changes in climate that occurred during the Holocene, and relate these changes to agriculture. You may focus on any period you like (e.g., the Little Ice Age).
(37) Which was named after a river in the Alps, this glaciation lasted until about 15,000 years ago, when there was a rapid return to more temperate conditions?
(36) What is the relationship between more-recent (last 15,000 years) fluctuations in ice sheet coverage and sea levels? How did this affect human settlement patterns?
(35) Some scientists calculate that in about 23,000 years' time, Earth will see the return of
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