Increases in Greenhouse Gases

What is the primary cause of current climate change?

• Natural variations in Earth's orbit.

• Increased solar activity.

• Human activities releasing greenhouse gases.

• Volcanic eruptions.

Humans have caused the greenhouse gas Carbon Dioxide [CO2] to increase _______ since 1790. 

• increased

• decreased

In addition, we see warming happening primarily in the _______ layers of the atmosphere, where we just so happen to have more and more greenhouse gases!

• lower

• upper

• middle

By what percentage has carbon dioxide (CO2) concentration increased in the atmosphere since the Industrial Revolution (1790)?

• 10%

• 25%

• 40%

• 60%

How has the relationship between global temperature and solar activity changed since the 1970s?

• They have moved in the same direction.

• They have moved in opposite directions.

• Solar activity has remained constant while temperature increased.

• Temperature has remained constant while solar activity increased.

How much faster is Earth currently warming compared to the end of an ice age?

• Twice as fast.

• Five times faster.

• Ten times faster.

• Fifty times faster.

Through studying ________, we have determined that CO₂ levels are the highest they have been in nearly 1 million years. 

• plant life

• ice cores

• tree rings

• the atmosphere

How do we know the excess CO₂ in the atmosphere (which is causing the warming) is from humans? Well, burning fossil fuels releases a special isotope _____, which is a lighter version of Carbon, and that is the isotope that we have seen increasing in the atmosphere. 

• Carbon - 10

• Carbon-12

• Carbon-13

• Carbon-14

Eliminating carbon _____ has led to a dramatic increase in CO₂. If humans weren't cutting down trees and burning fossil fuels, they would be working to naturally balance the CO₂ levels in the atmosphere. 

• sinks

• sources

Oceans are particularly vulnerable to climate change because they absorb nearly ______ of the heat added to the planet. 

• 50%

• 65%

• 90%

• 75%