Natural resources

- [Instructor] Humans are an amazingly adaptable species. Not only can we survive almost anywhere, we also find ways to thrive even in the most inhospitable environments. Our clever brains allow us to look the world around us and figure out how to find food and water, build safe and comfortable shelters, and design useful tools. All of this is possible because of the natural resources that surround us wherever we go. A natural resource is anything found in nature that can be used by people. Natural resources can be renewable, meaning they can be replenished over a human lifetime, or non-renewable, meaning they can take far longer to be replaced. Both kinds of resources are unevenly distributed across Earth. This makes sense for non-renewable resources, right? These resources are formed by geologic processes, such as plate tectonics that take place in specific locations on Earth. As a result, non-renewable resources like soil, minerals, and fossil fuels are often concentrated in the places where they first formed. Let's take a look at one type of non-renewable resource, metal ore. Metal ores are rocks that contain valuable metals that people can extract, and they're often found in large accumulations called deposits. For example, most copper ore is found in what are called porphyry copper deposits. Porphyry just means that the rock that makes up these deposits contains a mix of large and small crystals, like in this image here. Porphyry copper deposits form in subduction zones along convergent tectonic plate boundaries. Today, most subduction zones are found along Pacific coastlines, so you can expect to find a lot of porphyry copper mines in these places. However, we also find many of these ore deposits throughout Eurasia and Australia. Why? Turns out many of these places were subduction zones in the ancient past. The geologic processes that form non-renewable resources are always happening, even if they occur over thousands or millions of years. This means that non-renewable resources are not always found where they first formed. Porphyry copper deposits follow the same, slow life cycle as many other metal ores, forming in magma chambers below the crust, then uplifting towards the surface through tectonic activity. Once exposed to the elements, the deposits can experience weathering and erosion, which allows them to gradually recycle back into the earth, unless people find and mine them first. How can renewable natural resources be unevenly distributed across Earth though? Doesn't everywhere have things like sunlight and wind? Well, yes, but Earth's tilt means that some places experience more direct sunlight throughout the year than others. And geography and other factors mean that some places are windier than others. For example, take a look at this map of average annual wind speeds across the contiguous United States. These purple, red, and orange places typically experience higher wind speeds, while these green and yellow places typically experience lower wind speeds. As a result, this central part of the country here has a much higher capacity for producing wind energy, so more people have invested in wind turbine technologies in these places. We can see that in this second map, which shows the distribution of wind power plants across the same area. Notice how most of the country's wind power plants are concentrated around the places where people recorded the highest wind speeds. The distribution of certain natural resources can also be impacted by human activities. After all, we typically need to harvest and move natural resources to use them. Think about fossil fuels, like coal and oil. Humans extract these raw materials from Earth's crust using mining or drilling wells and then transport them all over the world to refine into usable products. Once fossil fuels are removed from the ground, it can take millions of years for Earth to replace them. So every time we use these non-renewable resources, we have less available for future use. People can seek out new deposits, but they run the risk of finding lower-quality materials or sites that are more challenging to extract resources from. Even renewable resources can be affected by human actions. Take fresh water, for example. People may redistribute fresh water on the surface by building dams across rivers or other waterways. Dams store water for communities to use, and some even act as renewable hydropower generators, converting the kinetic energy of running water into electricity. However, by changing the natural flow of the water, dams can reduce the amount of water available to communities and ecosystems further downstream. People may also redistribute freshwater by pumping it up from underground. Groundwater can consistently provide freshwater in places where other sources are scarce, but if communities draw that groundwater up faster than the water cycle can replenish it, it can dry up. Naturally, unequal distribution of resources already makes life difficult for some places. And without careful management, human activities can make these disparities even worse. However, if we work together to avoid overexploiting the resources our planet naturally provides, whether they can renew themselves or not, we can all continue to thrive no matter where we live.