1. Our growing human population numbers have to be taken into account when trying to formulate a sustainability plan. There are some who think that, although sustainability is a good goal, it is too late to prevent many of the anticipated environmental consequences of our polluting past and present. Engelmen, Assadourian, and Prugh (2013) state " science fiction writer Kim Stanley Robinson says the real question is not 'is it too late?' but 'how much will we save?'" Is it too late to prevent future environmental consequences by changing our habits now? is this alarmist, or do presents valid concerns for our future?

2. Population growth might differ between developed and undeveloped countries. In fact, "Almost all of the additional 3.7 billion people from now to 2100 will enlarge the population of developing countries, which is projected to rise from 5.9 billion in 2013 to 8.2 billion in 2050 and to 9.6 billion in 2100.("Linking Poverty, Population, and Development", 2013). To all: If we want to control population growth, should we focus our efforts on the high-growth regions? What action can we take?

3. Humans can be inconsistent and biased. However, when a scientific study is done again and again by different groups of scientists, it adds credibility to the results when they are the same as the original study. Let's look at a scenario. Suppose that a group of scientists find that a new medication is successful in causing mice to lose weight. They publish their results, and another team of scientists repeats the study. They find that the medication does not cause the mice to lose weight. What does this say about the original study? What do the scientists in the original study should do now?