PLEASE HELP 4. The current carbon emissions are 9.8 gigatons, or 9.8 billion tons. Complete all three scenarios to find out what happens to the global temperature if these emissions stay the same, decrease, or increase over the next century. Follow the instructions in the Data section of this report.

If you answer this with out a link thank you SO much.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

the answer is option a.

alchemy hadn't scientific methods of study, appeal to mysticism and fantasy, the knowledge of chemistry and physics were modest at that time.

alchemy was - but as new rules were discovered it either changed into chemistry or it became "unscientific".