An interesting area for discussion is to define what is being impacted by humans and what is just occuring during the time of humans. The scientific consensus is that climate change is exacerbated human activity. More often this is defined as anthropogenic climate change, showing the direct link between human activity and destructive climate change. Beyond its use as referring to climate change, it is often still difficult to define exactly when the anthropocene began. This is often debated not as exactly when homo sapiens arrived as a distinct species, but instead caused a real impact on the earth itself through habits and practices. Certainly structures and tools have left an impact on earth, as many are still around for modern humans to observe today. But scientists have often looked to more ephemeral markers to make this definition. Endeavors to measure prehistoric levels of carbon dioxide in the atmosphere have been used to make a measurement of the impact caused by humans. Agrarian practices changed the atmospheric concentration of certain compounds as high concentration of plants and animals in smaller and smaller areas naturally increase in these circumstances. As the author notes, there is great possibility that the greatest and deepest impacts of the anthropocene as still yet to come. Many policymakers have become more future-thinking, asking what actions today will cause impacts way into the future for other humans to deal with in the efforts to maintain habitable landscapes for the most number of individuals.