Physics notes for the broken balance of 4.5 billion years

The planet Earth is composed of living creatures as well as non-living elements like rocks, water, air, etc. All parts are connected and interact with each other. There are many ways of interaction, and many of these interactions are critical for survival. For example, one category of interaction is how organisms obtain their food. Some organisms can make their own food, while others need to eat other organisms to obtain their nutrients. Another interaction is symbiosis, which describes a close, long-term relationship between two organisms from different species. Sometimes, symbiosis can be mutually beneficial for both organisms.

One of the biggest and most complex ecosystems is coral reefs, which have become affected by subtle changes in seawater temperature and ocean acidification. In this article, I will try to explain the science behind this process.

Coral reefs

Approximately 25% of marine species use coral reefs as habitats. Scientists have observed that an increase of 1°C in the water for 4 weeks can trigger the bleaching process in coral reefs. The process occurs when coral polyps expel the algae that live inside their tissue. These algae provide up to 90% of the coral's energy. If coral dies, it will affect the whole ecosystem and the species that depend on it for shelter, food, habitat, etc.

Humans are also affected. Coral reefs bleaching socio-economic impact

Degraded coral reefs may not be able to provide shoreline protection for human communities.
Changes in fish communities will also affect the food supply and associated economic activities.
Coral reefs are a valuable source of important medicinal resources, including drugs to treat heart disease, cancer, and other illnesses.

On the Left a healthy coral and in the right a bleached coral.

DIOXIDE CARBON CO2

CO2 measurement began in March 1958 at Mauna Loa in Hawaii. Charles Keeling measured, for the first time, 313 ppm (particles per million). Since then, the Keeling curve is a daily record of global atmospheric carbon dioxide concentration. As of January 2022, the reading is 417.69 ppm, updated measure here. It may not seem like a big change over 64 years, but the perspective shifts when comparing CO2 data from 800,000 years ago. This has been possible by extracting air trapped between the ice layers at different depths in Antarctica.

There is an interesting correlation between the glacial periods - warmer periods and the variations of earth orbit around the sun. It worth to mention that the highest CO2 concentration: 300ppm was 350,000 years ago.

In the beginning, the Earth was covered by rocks and a dense atmosphere composed of carbon dioxide (CO2), hydrogen (H), and water vapor (H2O). The Earth's temperature decreased, and the water from vapor condensation and rain created the oceans. At this point, the predominant gas was CO2, and estimates indicate the atmosphere was 30 times denser than today. The CO2 balance, which made life possible, began when CO2 and water started interacting to produce carbonic acid.

Carbonic acid does not dissolve in water and sinks to the seabed. It then interacts with rocks to form carbonate, which is essentially a salt of carbonic acid (CO2-;3). Later, the carbonate interacts with other elements like calcium (Ca), magnesium (Mg), and iron (Fe). Eventually, tectonic plate movements bury the carbonate, transferring it to the continental crust. The carbonate is then released back into the atmosphere through magma pools and volcanoes.

For a single CO2 molecule, this process lasts one hundred million years. After billions of years, the planet found the right balance between atmospheric CO2 and carbonate in the ground, making life possible to evolve.

H2O + CO2 = H2CO3 (carbonic acid)

THE CO2 EQUILIBRIUM

The equilibrium value on planet Earth for carbonate is 600 gigatons (Gt) in the biosphere and 600 Gt in the atmosphere (1 Gt represents 1,000,000,000 tons). There are 1,800 Gt of carbonate in the ground and 1,000 Gt in the ocean surface in contact with the atmosphere. Finally, there are 37,000 Gt of carbonate in the seabed. The carbonate from CO2 is recycled: from the atmosphere, biosphere, ground, and ocean.

The red box on central park represents a gigaton. Central park is 4Km long and 0.8Km wide. A gigaton wild extend 341mt high.

In 1 Year...

The biosphere absorbs 120 Gt of carbonate: 60 Gt go to the ground, and 60 Gt are released into the atmosphere in the form of CO2.
90 Gt are exchanged between the atmosphere and the ocean surface.
35 Gt are added to the atmosphere each year by humans. In the last seventy years, human activity has contributed 400 Gt of carbon to the atmosphere, which is around two-thirds of the previously existing CO2 in the atmosphere over the last million years. If current emission levels continue, in 150 years, human activity will have added between 1,000 Gt and 4,000 Gt to the atmosphere.

THE GREENHOUSE

Carbon dioxide (CO2) molecules in the atmosphere vibrate when hit by infrared radiation from the sun. This vibration produces energy, and since molecules are constantly moving and colliding, the energy is transferred during collisions. This is why CO2 molecules absorb infrared radiation and raise the temperature of gases in the atmosphere. The temperature of a gas is measured by the speed of the molecules in it; the faster they vibrate, the higher the temperature.

Earth's atmosphere is composed mainly of oxygen (O2) and nitrogen (N2), which are simple molecules not affected by infrared radiation. However, CO2 molecules vibrate in ways that nitrogen and oxygen cannot. Other significant greenhouse gases include water vapor (H2O), methane (CH4), nitrous oxide (N2O), and ozone (O3).

In the above image you can see the molcule structure of green gases is more complex than oxigen and nitrogen. The vibration of green gases molecules is slower than others, and is affected by low frequencies like infrarred radiation.

THE WATER LEVEL

Without greenhouse gases and the greenhouse effect, Earth's temperature would be -18°C. However, current models calculate an increase of the average surface temperature by 1.3°C since the year 1900, considering only the CO2 factor, from 300 ppm to 417.69 ppm. Global warming is a direct consequence of the increased CO2 level and other greenhouse gases. One effect is the current temperature increase in the Arctic and, in the long term, the rise of temperatures in Antarctica. These two regions hold about 90% of Earth's freshwater. Predicting the future of Greenland and Antarctica is critical to understanding the impact and potential consequences of continued temperature increases.

Thermal expansion of water is the main factor in sea level rise, and this expansion will continue because of the heat stored in the oceans. The second cause is glacier shrinkage in Greenland. For many years, this effect was secondary, but new data shows the opposite.

The diagram on the left shows the ice mass reduction from 1992 to 2018. the difference is a reduction of 4,040 Gt. The diagram on the right shows the increment of sea level in mm from the same range of years, total of 11.22mm.

The latest models predict a near-certain temperature increase of 2°C before the end of this century. Greenland ice melt will contribute to a 5 cm rise in sea level. However, the ice sheet melt rate has doubled, and current models suggest a contribution of 10 cm to 16 cm to the sea level by Greenland ice melt alone. Antarctica will contribute 12 cm by the same year.

Contribution	Sea Level in meters
Sea water dilatation	~ 0,23 ± 0,09 meters
Other Glaciers	~ 0,37 ± 0,02 meters
Greenland ice melt (current ice melt speed)	~ 0,16 meters
Antarctic ice melt (current ice melt speed)	~ 0,12 meters
TOTAL :	~ 0,88 ± 0,12 meters

Cummulative sea level increase by the year 2,100 (in 78 years).

The pictures in the left, Antarctica, is the difference of ice between 10 days in the past January. This area is called Larsen B. The diagram on the right, shows how the icebergs are separated from the ice shelf. The grounding line is the point where the ice and the ground are in contact.

THE ACID OCEAN

For millions of years, Earth's ecosystem maintained a fragile balance between atmospheric CO2 and the production of carbonic acid (H2CO3). Oceanographic measurements have shown a consistent reduction in seawater pH over the past decade. The process of carbonate concentration in the ocean is called ocean acidification (OA). Current models estimate that by 2100, ocean surface water could become 150% more acidic, reaching a pH level not seen for more than 20 million years.

Calcium carbonate minerals are essential for the skeletons of many marine organisms. Continued acidification reduces these minerals in the ocean, impacting reef-building corals, oysters, and mollusks' ability to form their skeletons.

Based on the keeling curve from 1958 (red), there is a clear correlation between the amount of CO2 in the atmosphere and ocean acidification.

Shells exposed to the predictive acid levels by the year 2100.

THE EMERGENT SYSTEM (Conclusions)

A simple entity like a neuron, a CO2 molecule, or a human interacting with others creates complex and unpredictable behaviors. The interaction rules are quite simple; for example, a CO2 molecule vibrates when hit by infrared photons, generating heat. Complexity emerges when all entities in the system continuously influence one another.

Predicting all the consequences of climate change in the short term is difficult because Earth is a complex system. However, current models suggest drastic changes to the planet by 2100 if CO2 emissions continue. These models have also been able to accurately predict temperatures from 400,000 years ago, providing strong evidence that their predictions are correct. Additionally, similar conclusions are reached by different studies.

I hope these notes encourage you to rethink your relationship with climate change. We are the only entities in this ecosystem capable of altering our actions, and we have the responsibility to do so. CO2 molecules will continue to vibrate and produce heat when hit by infrared photons.