D - an increase in tree cover in the tundra.
That Energy comes from SUNLIGHT.....
Answer:
Mar 4, 2011 — Past changes in Earth's temperature happened very slowly, over ... Human activities contribute to global warming by increasing the greenhouse effect. ... Emissions of carbon dioxide, the most important greenhouse gas, ... Even slight rises in average global temperatures can have huge effects. ... 100 years.
Explanation:
There were no options but I would assume something around the lines of..
It allows for procreation
