Since the early 1900s, there has been a steady increase in the earth’s atmospheric temperature, resulting in a phenomenon called “Global Warming.” While the steady temperature change has been well documented, the cause of global warming remains controversial.

Scientist 1

Scientist 1 believes that “external forcings” are the cause of increased temperature over the past century. “External forcings” can direct the change in temperature over thousands of years. One example of an external force is variation in the earth’s orbit around the sun. The earth orbital cycle lasts 26,000 years and causes general trends in warming and cooling.

Scientist 2

Scientist 2 believes that global warming is a man-made phenomenon due to an increase in greenhouse gases such as carbon dioxide or methane. Greenhouse gases have a natural warming effect, however, an increase in the amount of atmospheric greenhouse gases many enhance that effect. Since 1750, the concentration of carbon dioxide has increased 36 percent while the amount of atmospheric methane has increased 148 percent.

What data supports Scientist 2's theory?

Since the early 1900s, there has been a steady increase in the earth’s atmospheric temperature, resulting in a phenomenon called “Global Warming.” While the steady temperature change has been well documented, the cause of global warming remains controversial.

Scientist 1

Scientist 1 believes that “external forcings” are the cause of increased temperature over the past century. “External forcings” can direct the change in temperature over thousands of years. One example of an external force is variation in the earth’s orbit around the sun. The earth orbital cycle lasts 26,000 years and causes general trends in warming and cooling.

Scientist 2

Scientist 2 believes that global warming is a man-made phenomenon due to an increase in greenhouse gases such as carbon dioxide or methane. Greenhouse gases have a natural warming effect, however, an increase in the amount of atmospheric greenhouse gases many enhance that effect. Since 1750, the concentration of carbon dioxide has increased 36 percent while the amount of atmospheric methane has increased 148 percent.

What is a potential cause for an increase in greenhouse gases since 1750?

Since the early 1900s, there has been a steady increase in the earth’s atmospheric temperature, resulting in a phenomenon called “Global Warming.” While the steady temperature change has been well documented, the cause of global warming remains controversial.

Scientist 1

Scientist 1 believes that “external forcings” are the cause of increased temperature over the past century. “External forcings” can direct the change in temperature over thousands of years. One example of an external force is variation in the earth’s orbit around the sun. The earth orbital cycle lasts 26,000 years and causes general trends in warming and cooling.

Scientist 2

Scientist 2 believes that global warming is a man-made phenomenon due to an increase in greenhouse gases such as carbon dioxide or methane. Greenhouse gases have a natural warming effect, however, an increase in the amount of atmospheric greenhouse gases many enhance that effect. Since 1750, the concentration of carbon dioxide has increased 36 percent while the amount of atmospheric methane has increased 148 percent.

In the year 2438 another ice age occurs, supporting which scientists' theory?

Since the early 1900s, there has been a steady increase in the earth’s atmospheric temperature, resulting in a phenomenon called “Global Warming.” While the steady temperature change has been well documented, the cause of global warming remains controversial.

Scientist 1

Scientist 1 believes that “external forcings” are the cause of increased temperature over the past century. “External forcings” can direct the change in temperature over thousands of years. One example of an external force is variation in the earth’s orbit around the sun. The earth orbital cycle lasts 26,000 years and causes general trends in warming and cooling.

Scientist 2

Scientist 2 believes that global warming is a man-made phenomenon due to an increase in greenhouse gases such as carbon dioxide or methane. Greenhouse gases have a natural warming effect, however, an increase in the amount of atmospheric greenhouse gases many enhance that effect. Since 1750, the concentration of carbon dioxide has increased 36 percent while the amount of atmospheric methane has increased 148 percent.

In the year 2150, the United Nations institutes a global limit on the production of greenhouse gases. The average atmospheric temperature continues to increase, although the rate of increase is less than it was before 2150. Does this invalidate the theory proposed by Scientist 2? Why or why not?

The results of this experiment show that ________.

Global warming is defined as the slow increase in the temperature of the earth’s atmosphere and is caused by pollutants and carbon dioxide (CO₂). While the gradual increase in temperature cannot be refuted, scientists argue over the cause.

 Scientist 1:

Global warming is caused by increases in atmospheric CO₂, which is directly created by humans and their consumption of fossil fuels. The natural CO₂ released from carbon sinks has a different isotopic ratio from the CO₂ released from fossil fuels. Current measurements of the radioactive isotopes of CO₂ show that it is from human activity, not from nature. The Earth’s carbon sinks cannot absorb these large amounts of unnatural CO₂ emissions. About fifty percent of the CO₂ produced by mankind remains in the atmosphere, unable to be absorbed.

Scientist 2:

The rise in atmospheric CO₂ levels are a result of global warming, not the cause of it. When the temperature increases, the CO₂ in carbon sinks is released. While humans do cause release of CO₂, the carbon sinks absorb it. The activity of the carbon sinks increases to allow for higher levels of CO₂ absorption. Proponents for human causation of global warming point to the warming and cooling of the stratosphere, however, these temperature fluctuations are caused by changes in the sun’s heat. These proponents also look at the acidity of the ocean as evidence of human causation, however, the rise in ocean acidity is within the normal range of fluctuations over the past ten thousand years.

Which of the following best outlines the evidence provided by Scientist 2 to make his argument?

A scientist observes the motion of stars, planets, and other objects in deep space through a high-powered telescope. She observes that these objects all appear to be moving away from the Earth and graphs her results comparing their velocities, in kilometers per second, and their proper distance, in megaparsecs.

A new planet is discovered 11 megaparsecs (MPSC) away from the Earth. Which of the following is its likely velocity?

A scientist observes the motion of stars, planets, and other objects in deep space through a high-powered telescope. She observes that these objects all appear to be moving away from the Earth and graphs her results comparing their velocities, in kilometers per second, and their proper distance, in megaparsecs.

Two planets, one with mass , the other with mass , are the same distance away from Earth. What will their relationship be in terms of their velocity, ?

A scientist observes the motion of stars, planets, and other objects in deep space through a high-powered telescope. She observes that these objects all appear to be moving away from the Earth and graphs her results comparing their velocities, in kilometers per second, and their proper distance, in megaparsecs.

What is the acceleration on these bodies?

A scientist observes the motion of stars, planets, and other objects in deep space through a high-powered telescope. She observes that these objects all appear to be moving away from the Earth and graphs her results comparing their velocities, in kilometers per second, and their proper distance, in megaparsecs.

Which of the following, if true, would contradict the findings of this experiment?