Basic Earth Science
I’ve been a climate activist since 2019 and wanted to have a better understanding of how climate and Earth systems work. I pulled together a study guide of basic science and thought I’d share it as a resource for anyone interested. I’ll be adding more info over time. If you catch any misinformation, feel free to let me know!
Carbon Dioxide
Carbon is the chemical backbone of life on Earth. Carbon compounds regulate the Earth's temperature and are a key ingredient in the food that we eat. Most of Earth's carbon is stored in rocks and sediments. The rest is located in the ocean, atmosphere, and in living organisms.
Atmospheric carbon is absorbed by plants for photosynthesis. These plants are then consumed by animals with plant carbon bioaccumulating in their bodies. These animals and plants eventually die, and upon decomposing, carbon is released back into the atmosphere.
What is the carbon cycle?
From the Energy of Science, “The carbon cycle describes how carbon moves between the atmosphere, soils, living creatures, the ocean, and human sources. The carbon cycle is the process that moves carbon between plants, animals, and microbes; minerals in the earth; and the atmosphere. Carbon is the fourth most abundant element in the universe.”
Carbon Sink vs Carbon Source
A carbon sink absorbs carbon dioxide from the atmosphere. The ocean, soil, and forests are the world’s largest carbon sinks.
A carbon source releases carbon dioxide into the atmosphere. Examples of carbon sources include the burning of fossil fuels like gas, coal and oil, deforestation, and volcanic eruptions.
Climate Change
Increased human activity is upsetting the carbon balance. We’re releasing more carbon into the atmosphere than the Earth’s natural carbon sinks can absorb. Our continued reliance on fossil fuels creates billions of tonnes of carbon every year.
Carbon is an important compound for life, but needs to stay below a certain level in the atmosphere (350 parts per million) for earth’s climate system to remain stable. If we stop burning oil, coal, natural gas, & biomass and protect carbon sinks we still have time to drop carbon levels below 350ppm, considered the safe and habitable zone. We are currently at around 421ppm.
What is the difference between global warming and climate change? - U.S. Geological Survey
Oceans
70% of earth surface.
Generates Oxygen, Carbon sink, marine food, provides medicine, stabilizes climate.
Stabilizing force of climate system.
Generates 50 percent of the oxygen we need.
Absorbs 25 percent of all carbon dioxide emissions.
Ocean holds 90% of excessive heat from burning of fossil fuels and the resulting greenhouse effect.
Ocean absorb more sunlight and store more heat than land and retain that heat for longer.
The ocean takes up carbon dioxide through photosynthesis by plant-like organisms (phytoplankton). Carbon dioxide also dissolves in water. It reacts with seawater, creating carbonic acid.
The ocean stores 50 times more carbon than the atmosphere, and 20 times more than land plants and soil combined.
Once oceans begin to release heat, it goes into the atmosphere and increases global temperatures.
A warmer, more acidic ocean makes it increasingly uninhabitable for marine life and is less effective at storing carbon.
Thermal expansion- as water warms it swells and leads to sea-level rise.
Warmer waters carry less oxygen – leading to death of marine life by depriving them of oxygen.
Warmer water increases toxic algae blooms that can also kill marine life.
Fish and other seafood products provide vital nutrients for more than three billion people around the globe and supply an income for 10 to 12 percent of the world's population.
If we stay on the same path, oceans will increasingly become a carbon source. As oceans warm, oceans become less efficient at absording carbon dioxide, and releases carbon more rapidly.
Sea surface temperature (SST)
Because the oceans continuously interact with the atmosphere, sea surface temperature can have profound effects on global climate and weather.
Increases in sea surface temperature have led to an increase in the amount of atmospheric water vapor over the oceans.
SST data are especially useful for identifying the onset of El Niño and La Niña cycles.
Ocean Circulation System
The ocean circulation system, often called the global conveyor, follows a regular path through the Earth’s oceans and stirs ocean waters from top to bottom.
It starts with water plunging from the surface and disappearing to the depths. From there, it travels the world and does not surface for centuries.
By capturing heat and carbon dioxide from the atmosphere, and burying both deep in the ocean, it moderates global warming.
Warming oceans and melting glaciers and ice sheets effects circulation and can create stronger heat waves and storms.
Protecting Oceans
Stop burning fossil fuels; end oil spills
Ban underwater soundwaves
Ban deep sea mining
End dumping plastics and waste into oceans
Land
30% of earth surface.
The different types of land are known as biomes. The five major types of biomes include aquatic, grassland, forest, desert, and tundra.
Drylands
Includes deserts, tundra, grasslands, forests.
Drylands cover about 47% or global land area, home to 3 billion people.
Desertification in dryland areas is increasing, leading to loss of vegetation.
Without efforts to restore and protect the land, an extra 70 gigatonnes of carbon will be emitted by 2050 due to land use change and soil degradation.
The Earth’s soil absorbs roughly a quarter of all human emissions each year, with a large portion of this stored in peatland or permafrost.
Wetlands
Wetlands provide freshwater and includes marshes, swamps, bogs, and fens.
Wetlands act as a carbon sink. Peatlands store twice as much carbon as all of the world’s forests.
Protecting Land
Forests: Stop burning fossil fuels, to reduce warming and reduce rate of wildfires. Afforestation. Protect and conserve forests, prevent industry from cutting trees.
Stop the use of chemical fertilizers, pesticides, and herbicides.
Glaciers and Ice Sheets
Albedo effect, cools Earth by reflecting sunlight back into space.
Ice sheets contain about 99% of the freshwater on Earth.
Freshwater
Only about three percent of Earth's water is freshwater. Of that, only about 1.2 percent can be used as drinking water.
Your drinking water comes from natural sources that are either groundwater or surface water. Groundwater comes from rain and snow that seeps into the ground. The water gets stored in open spaces and pores or in layers of sand and gravel known as aquifers. We use water wells or springs to harvest this groundwater.
Atmosphere and Rising temperatures
Climate vs Weather
Climate is the average trajectory of weather and temperature over a long period of time. Weather is temperature and precipitation over short periods of time, and can vary greatly.
Greenhouse Effect
The greenhouse effect is the way in which heat is trapped close to Earth's surface by greenhouse gases. These heat-trapping gases keep Earth warmer than it would be without them.
Mainly caused from water vapor (H 2O), carbon dioxide (CO 2), methane ( CH 4), nitrous oxide ( N 2O), and ozone (O3).
El Nino and La Nina
During El Niño, temperatures in the Pacific near the equator are warmer than normal. During La Niña, the same area experiences colder than normal ocean temperatures. These cycles are caused by multi-year shifts in pressure and wind speeds, and affect ocean circulation, global weather patterns, and marine ecosystems.
Jet Steam
A narrow variable band of strong, mostly westerly air currents circling the globe. Jet streams are several miles above Earth. There are normally two or three jet streams in the northern and southern hemispheres.
Small temperature contrasts near Earth's surface can lead to big changes in the upper atmosphere. Now scientists report that such ripple effects are causing the atmosphere's jet streams to become more meandering, increasing the likelihood of extreme weather at some latitudes.
Aerosols
Greenhouse gases trap heat from the sun but they also produce aerosols that block the sun's heat. As we phase out fossil fuels, which we need to do to stop heating, we lose the aerosols' cooling effect. Aerosols only stay in the atmosphere for a few years, while heat trapping gases like carbon linger for hundreds of years, continuing to heat the planet.
Wet-bulb temperature
Wet-bulb temperature is the combination of dry air temperature and humidity. Wet-bulb temperatures above 35 celsius (95F) are deadly to humans within only 6 hours of exposure. 80% of our cooling occurs through sweat, but high humidity levels in the air prevents sweat from evaporating.
Earth’s Energy Imbalance
The difference between the amount of solar energy arriving at Earth vs. the amount of energy going back into space. The more energy that remains trapped within Earth’s atmosphere, the faster global warming occurs.
Radiative Forcing
Radiative forcing (or climate forcing) is the external driver that forces Earth's energy balance to rise to dangerous levels , drop to dangerous levels, or stay within the safe zone for sustaining life. External drivers of radiative forcing levels includes greenhouse gases, clouds, ice & the albedo effect, sea surface temperatures, aerosols, land use, and other forces that either warm or cool the planet. Radiative forcing is measured in watts per square meter (W/m2) and provides a way to quantify any disturbance in Earth's energy balance.
Climate Sensitivity
Climate sensitivity is the term used by scientists to communicate how human-created carbon dioxide (CO2) emissions affect global temperature.
From MIT News: “Specifically, the term is defined as how much the average global surface temperature will increase if there is a doubling of greenhouse gases (expressed as carbon dioxide equivalents) in the air, once the planet has had a chance to settle into a new equilibrium after the increase occurs. In other words, it’s a direct measure of how the Earth’s climate will respond to that doubling.
That value, according to the most recent IPCC report, is 3 degrees Celsius, with a range of uncertainty from 2 to 4.5 degrees.”
Tipping Points
Tipping points occur has human caused warming from burning fossil fuels triggers earths positive feedback loops.
Examples of tipping points include glacial and sea ice melting. As the ice melts, it no longer reflects sunlight back into the atmosphere. It exposes darker waters below which then absorbs more heat into the oceans. At some point oceans can no longer hold heat, acidify, killing coral and marine life. Land then has to absorb more heat which leads to desertification, which causes more wildfires, which releases more carbon, increasing warming further etc.
Why global warming creates floods, stronger storms, droughts, wildfires, heat waves, sea level rise, & intensifies the Sixth Mass Extinction.
Floods and storms
Earth's lower atmosphere is becoming warmer and holding more moisture as a result of fossil fuel emissions. This creates the conditions for more energy for floods, storms, and extreme weather events.
Drought
Warmer temperatures enhance evaporation, which reduces surface water and dries out soils and vegetation. Changes in the jet stream are also reducing rainfall in certain areas.
Wildfires
With worsening droughts, trees and underbrush are drying out and creating conditions that make wildfires easier to start, spread, and harder to contain.
Heatwaves
Climate change is leading to more frequent, longer, and intense heat waves. It has increased the size of stalled high-pressure weather systems called "blocking events” which can produce deadly and long lasting heat waves.
Sea level rise
Warming temperatures from burning fossil fuels is causing glaciers and ice sheets to melt, break apart, with the danger of completely collapsing and rising sea levels enough to destroy and displace island and coastal communities, including major cities like Miami.
Sixth Mass Extinction
We have been using more of earth’s resources to create goods and provide for a growing global population. Land use,…. Has caused the sixth mass extinction, the first mass extinction caused by human behavior. This mass extinction includes plant and animal life, and is threatening entire ecosystems, like coral reef, marine life, and the Amazon rainforest.
More reading & resources