Explain why scientists are concerned about human activities that cause global warming if global warming is caused by the greenhouse effect and the greenhouse effect is a natural part of earth’s climate.

scientists are concerned because through deforestation, the cars we drive, and the burning of fossil fuels humas are omitting excess greenhouse gases into the environment which causes global warming to increase at a much faster rate

Explanation: use this.

the first phase of the government’s plan for settlement was building the transcontinental railroad. the railroad provided a way to bring settlers and manufactured goods west and ship their agricultural and mining produce east. the transcontinental railroad was an essential artery for rapid development of the frontier.

the second phase of the government’s plan was a liberal land distribution policy that made it possible for many people to homestead. with these two key elements—transportation and cheap land—the government rapidly achieved its goal of persuading people to move west, settle on farms, and push back the frontier.

answerthe above statement is correct(true)