Question

question 40 (2 points) why do estimates of future temperature increases due to global warming vary so much? 1) the amount of greenhouse gases in the atmosphere is unknown 2) past evidence of warming contained in such things as tree rings and fossilized pollen is unreliable 3) the role of clouds and oceans is still little understood 4) all of the above

Explanation:

The amount of greenhouse - gases is difficult to precisely quantify. Past climate evidence from tree rings and fossilized pollen has some uncertainties. Also, the complex interactions and roles of clouds and oceans in the climate system are not fully understood, all contributing to the variability in future temperature increase estimates due to global warming.

Answer:

1. All of the above