 One of the fundamental understandings as part of the Earth systems model that we use to characterise the atmosphere, biosphere, hydrosphere and geosphere or the interaction of those systems, one of the fundamental concepts that lies behind that is that if you make a change in one of those spheres that it's likely to impact at least another one of those spheres and it can impact all of them in fact. One example might be that if you had a water contamination issue then that might have a direct flow on effect. So if you've got water that's polluted or toxic that might have a flow on effect to the local biota so that automatically affects the so the hydrosphere is affecting the biosphere and then let's say for example that causes some of the vegetation to die back and so it's less able to photosynthesise and hence it's not putting gases into the atmosphere as it was previously so let's say a forest dies back in that way then that directly impacts the atmosphere and let's say this toxic water is also filtering down through the soil and contaminating groundwater or just making the soil too toxic for life to continue in that area then clearly it's impacted the geosphere as well and so that's one example of how different the different spheres or a change in one of the spheres can impinge on the others. Now if we think about this from an energy system let's say for instance think about the thermal transfer of energy from the sun to the earth's oceans the way that that works is that we have some bodies of water that are warmer with respect to others and this starts causing movement of water in the oceans it's also affected by the rotation of the earth so that's a natural process and those ocean currents work in certain ways but one of the aspects of this is that nutrient rich cold bottom waters sometimes make their way up to the ocean surface and so that creates a food supply for small organisms which eventually are predated on by a bit larger organisms and so on and so forth so there's already an impact on the biosphere in that way so that transfer of energy through the system influences where we have these upwellings and where those organisms can consume the nutrients and then you might have various trophic levels so if we get back to biology food chains where larger things predate smaller things and so on up through the food chain and so there's that transfer of energy through the biosphere in that way so one of the main sources of energy to the surface of the planet is the sun but there is also another source of energy which is from within the earth so it's associated with radioactive decay and we see that probably manifesting in a mechanism that we understand or that we see fairly regularly is the extraction of minerals like uranium that have radioactive decay and we can utilise that for example in nuclear power plants so uranium plutonium those sorts of things and what tends to happen is they utilise the heat energy or the thermal energy from the breakdown of those or the chemical reactions of those minerals and use that to heat water and flash it to steam, drive a turbine and in that way generate electricity so thereby converting the radioactive energy or the chemical energy to electrical energy and then of course we can use that electricity in a multitude of different appliances that might then say your electric stove that will convert that electrical energy into heat and light energy and so on