17. What is the highest historical CO2 level? What is the current CO2 level?
18. How much have CO2 levels increased since January of 2005?
19. What is the warmest year on record?
20. Between 2002 and 2014, how much did arctic sea ice decrease?
21. Why do you think global warming has reduced arctic sea ice?
22. How many planet Earths would it take to support your lifestyle?
23. List three ways you can reduce your ecological footprint. (2)