Question 1

The Milankovitch cycles in association with other natural factors explain how glaciers may advance and retreat over periods of hundreds of millions of years.

Accepted Answer

Milankovitch cycles explain variations in Earth's climate and ice cover over tens to hundreds of thousands of years, not hundreds of millions of years. These cycles are due to changes in Earth's orbit and tilt, affecting solar radiation distribution.

Question 2

What is meant by the term "positive feedback?" What role could positive feedback play in the atmospheric greenhouse effect? Would this enhance or reduce global warming? Can you think of any "negative feedback" mechanisms?

Accepted Answer

The answer of What is meant by the term "positive...

Question 3

During the Little Ice Age,the climatic optimum occurred.

Accepted Answer

The Little Ice Age was a period of cooling that occurred from the 16th to the mid-19th century, while the climatic optimum was a period of warming that occurred during the Holocene epoch, between 9,000 and 5,000 years ago. These two periods were not concurrent.

Question 4

Explain how analysis of glacial and polar ice cores provide important clues about past climate.

Accepted Answer

The answer of Explain how analysis of glacial and polar...

Question 5

What are meant by the terms positive and negative feedback mechanisms? Give an example of a process that would be considered a positive feedback mechanism during a period of warming on the earth.Can you think of a negative feedback mechanism?

Accepted Answer

The answer of What are meant by the terms positive...

Question 6

During the Pleistocene epoch,continental glaciers alternately advanced and retreated over large portions of North America and Europe.

Accepted Answer

The Pleistocene epoch, which began about 2.6 million years ago and ended about 11,700 years ago, was characterized by multiple glaciations that caused the advance and retreat of continental glaciers over large parts of North America and Europe. This led to the formation of various landforms, such as moraines, glacial lakes, and outwash plains, that still exist today.

Question 7

The most recent warming trend experienced over the Northern Hemisphere could be the result of increasing volcanic eruptions.

Accepted Answer

While volcanic eruptions can temporarily cool the Earth's climate by releasing ash and sulfur dioxide into the atmosphere, causing a short-term cooling effect, they do not provide a plausible explanation for the recent warming trend observed over the Northern Hemisphere. The primary drivers of the current warming trend are human activities, such as burning of fossil fuels and deforestation, which release greenhouse gases into the atmosphere and trap heat.

Question 8

The much-studied temperature record of the past 140 years is derived from land-based observations only.

Accepted Answer

The temperature record of the past 140 years includes both land-based observations and ocean surface temperatures, providing a comprehensive view of global temperature changes.

Question 9

Presently glaciers cover less than 1% of the earth's surface.

Accepted Answer

Glaciers currently cover about 10% of the Earth's surface, primarily in polar regions and high mountain areas.

Question 10

Studies reveal that during colder glacial periods,CO₂ levels were lower than during warmer interglacial periods.

Accepted Answer

Studies suggest that during the colder glacial periods, the levels of CO₂ were lower than during warmer interglacial periods.

Question 11

During the climatic optimum,alpine glaciers began to advance down river valleys.

Accepted Answer

During the climatic optimum, which occurred around 6,000 to 8,000 years ago, alpine glaciers actually retreated and shrank in size. This warming trend was caused by changes in the Earth's orbit and axis tilt, and led to the growth of forests and expansion of agricultural land in many areas. It wasn't until the Little Ice Age, which occurred from the 16th to 19th centuries, that alpine glaciers began to advance again.

Question 12

The earth has been in a warming trend for

Accepted Answer

The earth has been in a warming trend for more than 100 years, with the average global temperature increasing by about 1.1°C since the late 19th century. This increase is primarily due to human activities, such as the burning of fossil fuels and deforestation, which release greenhouse gases into the atmosphere and trap heat from the sun.

Question 13

Asia and the North American continent have been connected by a land bridge at various times during the past.When was the Bering land bridge most recently exposed? Did this coincide with a warm or cool climatic period?

Accepted Answer

The answer of Asia and the North American continent have...

Question 14

The Milankovitch Theory proposes that climatic changes are due to particles suspended in the earth's atmosphere.

Accepted Answer

The Milankovitch Theory proposes that climatic changes are due to variations in the earth's orbit and tilt, and not particles suspended in the earth's atmosphere.

Question 15

In a warmer world,higher latitudes would have a __________ growing season.

Accepted Answer

Warmer temperatures would result in longer growing seasons as plants would have more time to grow and mature before the onset of winter.

Question 16

Precession of the equinox refers to the wobble of the earth on its axis.

Accepted Answer

The precession of the equinox is the gradual shift in the direction of Earth's axis, which causes the position of the equinoxes to move along the ecliptic over time. This is often referred to as a wobble, which is caused by a combination of the gravitational forces of the sun, moon, and other celestial bodies on Earth's equatorial bulge.

Question 17

Lowering of sea levels is not one of the possible consequences of global warming predicted by climate models.

Accepted Answer

Climate models predict that global warming will lead to rising sea levels due to the melting of ice caps and glaciers and the thermal expansion of seawater, not the lowering of sea levels.

Question 18

The higher the ratio of oxygen 18 to oxygen 16 in the shells of organisms that lived in the sea during the geologic past,the colder the climate at that time.

Accepted Answer

This statement is true. The ratio of oxygen isotopes in the shells of marine organisms is a well-established proxy for past climate conditions, with higher ratios of oxygen 18 to oxygen 16 indicating colder temperatures.

Question 19

Describe some of the techniques used to infer past climates.About how far into the past are these different methods able to reconstruct past climatic conditions?

Accepted Answer

The answer of Describe some of the techniques used to...

Question 20

Ice cores record both the record of past temperatures,and also the causes of climate change.

Accepted Answer

Ice cores have trapped air bubbles within them that contain information about the past atmospheric composition, which can help scientists determine the causes of climate change. Additionally, ice cores provide a physical record of past temperatures through the layers of ice that accumulate over time.

Quiz 15: The Earths Changing Climate