howdy today we will be discussing the biosphere in some of the ways in which humans are driving change in these natural systems by the end of this module you have gained an understanding in what the biosphere is and how biosphere biomes are interconnected we will also examine a few of the ways that humans have impacted the biosphere what is the biosphere well it's the layer of all life systems on earth the biosphere is a very complex set of interconnected systems what is a biome well a biome is a geographic area that is defined by a specific environmental factor we have terrestrial biomes and aquatic biomes on land vegetation can appear on a scale from brown which is low vegetation to dark green which is lots of vegetation some variables that can affect location of biomes include precipitation and temperature so what happens is that you see similar to rest real biomes within shared latitudes here are a few examples of terrestrial biomes that you're probably familiar with we have tropical rainforests savannas tropical deserts chaparral temperate grasslands temperate forests boreal forests and Arctic tundra aquatic biomes are divided up into two main regions we have freshwater regions ponds and lakes streams and rivers wetlands and marine regions which include oceans coral reefs and estuaries as we have already learned humans have become profound drivers of change in these natural systems in this slide I've included just a few examples of how humans are impacting different biomes in rainforests we have deforestation biodiversity loss oceans we have to combat plastic pollutions and overfishing rangelands we have over grazing and habitat loss savannas we have major land use and land cover changes wetlands are often destroyed for commercial development and deltas are overloaded with nutrients and pollute from fertilizers again these are just a few examples of how humans can impact natural biomes biogeochemical cycles are the systems that help scientists understand the extraordinarily complex ways in which nutrients move between different life systems you've probably heard of most of these but just in case you haven't we have the carbon cycle the water cycle the nitrogen cycle sulfur cycle oxygen cycle and phosphorous cycle we'll be talking a little bit more about these next week as an example human activities can have a variety of different impacts on different geochemical cycles acid rain is a good example of a way in which humans are impacting other natural biomes sulfur dioxide and nitrogen oxide are created by burning fossil fuels when these pollutants interact with water and oxygen in the atmosphere they are transformed into acid particles that migrate through the environment acid particles fall to earth with precipitation and can have drastic impacts on forests soils rivers lakes and oceans while a small proportion of sulfur dioxide and nitrogen oxides come from volcanoes most come from burning of fossil fuels the cycling of elements is a major aspect of how ecosystems function most of our major environmental problems of today involve perturbations of critical element cycles such as water nitrogen or carbon acid rain is produced by the interactions of nitrogen and sulfur oxides that are put into the atmosphere from burning fossil fuels in industrial pollution and the impacts of acid rain are controlled by many other element cycles on land and in water so as you can see here humans are burning fossil fuels which impacts the water and oxygen cycle the nitrogen cycle the sulfur cycle and the carbon cycle because when the acid rain falls to earth it can erode bicarbonate found riverbeds on the slide will you'll find a few different examples of specifically how acid rain can impact terrestrial and aquatic biomes so in aquatic systems nutrient pollution depletes oxygen which can lead to eutrophication and decline in various species of fish it can also make the water more toxic and further decrease aquatic species populations in terrestrial systems like forests acid rain can have a negative impact on trees and plants because it robs the soil of nutrients it further adds stress to forest growth by impacting reproduction ability again to learn more please go to your book and read the in-depth description of how acid rain impacts these natural systems luckily the Clean Air Act was passed in 1990 and a targeted acid rain by putting limits on emissions and since then we've seen a reduction of eighty eight percent of sulfur dioxide emissions between 1990 and 2011 teen and additional air quality standards have driven a 50% reduction in nitrogen oxides the result is that emissions have fallen rainfall and surface waters are less acidic however recovery will take time because of how these nutrients get locked into things like soils and stream macroinvertebrates and trees for next week's homework please choose a type of biosphere change that most interests you this can be a really wide variety of topics I've listed just a few here just as examples to help get you thinking about what you can write about and I really want students to write a 1 to 3 page position essay on the biosphere change of your choice I want you to entertain ideas of how power and authority and oppression have played a role in changing these natural systems please also consider how might those who have suffered directly from these biosphere changes have a different or an alternative view of how power authority and oppression impacts decision making and policy change in the biosphere here are a few weekly podcasts to consider one is from NPR it's on River rivers on Rolaids and talks a little bit more about how acid rain is changing waterways and then there's another by science Friday that talks about fire five populations blinking out