Understanding how the Earth system works | Chroniclers


Earth is a complex, multi-system wonder! Just as the human body is made up of several systems that all work in tandem to support human life, the earth system is made up of several systems that support a large number and variety of life forms.

These subsystems are: the lithosphere, also called the geosphere (rocks, soils, molten rocks, fossil fuels), the hydrosphere (oceans, rivers, lakes, water tables, etc.), the atmosphere (tropo-, strato -, meso-, thermo-, magneto- and exo-sphere), the biosphere (oceanic and terrestrial plants and animals) and certain climatological conventions separate the cryosphere (ice and snow).

To understand how the Earth system works, we need to understand “systems thinking”. It helps break down the Earth into “stocks” (nouns) and “flows” (verbs). A stock / tank is any entity that can be filled or depleted, such as filling or emptying a tub. We have just listed the stocks of the Earth System: the lithosphere, the hydrosphere, the biosphere, the atmosphere and the cryosphere. We are interested in how materials and energy flow through the system, that is, how water, nitrogen, carbon, phosphorus and other elements of key interest move. in the different spheres. This means that flows / flows are actions or processes by which materials can move from one sphere to another.

Most of us confidently understand the hydrologic cycle. Evaporation is the flow that moves water from the hydrosphere and lithosphere (in the form of soil moisture) to the atmosphere. Precipitation is the flow that brings water back from the atmosphere to the hydrosphere and lithosphere. Condensation is another flow / process in the hydrological cycle, but in this example it does not transfer water from one sphere to another, but only occurs in the atmosphere.

Systems thinking also requires us to understand residence times and time lags, nonlinear relationships, as well as feedback loops. Residence times refer to the length of time an item remains in inventory. Sticking to our hydrologic cycle example, refer to the residence times table below, describing how long a water molecule stays, on average, in a given stock (from www.spokaneaquifer.org / the-aquifer / what-is-an- aquifer / time-of-residence-of-groundwater /).

For each of the cycles that we will cover (rock, carbon, nitrogen, etc.), there will be different residence times for the material of interest. I cannot stress enough the importance of considering the residence time of a given material. For some cycles, the residence time is several hundred million years!

The offset that we know each day is the daytime (daily) temperature offset. We get the most sun at noon, but daytime temperature peaks occur several hours after noon. This is because the air heats up (and cools!) Faster than water, dirt, and rock. The earth continues to radiate heat long after noon, maintaining warm temperatures. Another example is seasonal ocean temperatures: the oceans in the northern hemisphere tend to reach their hottest temperature in August and September, 2-3 months after the summer solstice! (www.seatemperature.org/atlantic-ocean). This is due to the enormous heat capacity of water: it takes 4,184 joules to heat 1 kilogram of water by 1 ° C (in comparison, it takes 385 joules to heat 1 kilogram of copper by 1 ° C) ( www.usgs.gov/ special-topic / water-science-school / science / specific-heat-capacity-and-water? qt-science_center_objects = 0 # qt-science_center_objects). Thus, the ocean continues to warm well beyond the longest day of the year.

Exponential growth is the most crucial nonlinear relationship to understand in the Earth system. The human population is one example: it took about 12,000 years to reach 1 billion people (in 1800), then it only took 120 years to reach 7.9 billion (https: //ugc.berkeley. edu / background-content / population growth /).

Finally: feedback loops. Positive feedback loops amplify or increase the effect of a forcing, negative feedback loops attenuate or decrease the effect of a forcing. Positive feedback: As the pack ice melts, the dark water of the ocean is revealed. Dark ocean water absorbs sunlight (as opposed to reflective white ice and snow), and thus absorbs more heat, which melts more ice over and over again. Currently, Arctic permafrost melts and releases methane, a greenhouse gas 30 times more potent than CO2 but with 1 / 10th of the atmospheric residence time (https://royalsocietypublishing.org/doi/10.1098/ rsta.2014.0423). This heats up the planet, which melts more permafrost, which releases more methane, etc. Ditto for forest fires: combustion moves carbon from the biosphere to the atmosphere, and the train flees.

Canary in the coal mine? Or the arctic tern on the burning permafrost graveyard…?

Many congratulations and a “Thank you!” grateful! to John P. who wrote to me with this well-articulated correction and clarification:

“I found one of your points misleading. The equator is hotter not because it is ‘physically closest to the sun’; the earth is millions of miles closer to the sun in January than it is. July The reason the equator is warmer is that at the equinoxes, the surface of the equator is 90 degrees from the sun, thus receiving twice the energy from the same area at latitude 60. At all other times, the thermal equator is north or south of the equator, causing pressure to change and sway northerly or southerly winds. For this reason, Trinity County enjoys a desert climate for six months and a Pacific Northwest climate. ”

Thank you, John, for deepening the geometry of the spheres and for sharing with us the knowledge of perihelion and aehlion: At perihelion, the Earth is 91,399,454 miles from the Sun; at aphelion it is 94,510,886 miles from the Sun. Is this good? Thank you also for explaining the pressure changes resulting in rainy and dry seasons.

I would also like to praise an unsung hero: thank you, Clarence, for your dedication to keeping Main Street in Weaverville garbage-free. You are a shining example of having a direct, immediate and positive impact on the community and I know you have inspired others to pick up the garbage collector and get down to business. You are appreciated, sir!

About Lucille Thompson

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