Climate Change’s Impact On The Seven Seas

By: Alexander Heredia

Climate change is one of the biggest problems mankind is facing. Our Earth has had a fluctuating climate for eons. From the Big Bang to now, climate is not, and will never be a constant. 

Earth’s Climate History

Following the collision that spawned the Moon, the planet was estimated to have been around 2,300 Kelvin (3,680°F) [1]. After these periods of extreme heat; drastic change occurred. Millennia of frigid temperatures—engulfing the planet. Oxygen levels rose; freezing the planet over—in its cryogenic rampage—oxygen breathing life bloomed. Brutal cold struck again during a stretch of Earth’s history known as the Cryogenian Period. At least twice between 750 and 600 million years ago, Earth fell into a deep freeze. Because the Cryogenian Period events occurred during a longer geologic era known as the Neoproterozoic Era, the deep freezes are sometimes referred to as the Neoproterozoic Snowball Earths [2]. Here we are, millions of years later—faced with a problem that is killing our planet—global warming. Evidence of global warming can come in many forms; Rising sea levels, melting glaciers, warming glaciers, catastrophic events are more common,  shrinking ice sheets, etc. Today, we can observe three major pieces of evidence. Firstly, rising sea levels. 

The Evidence Behind Sea Level Rise

Sea level rise, as the name implies, is an increase in the total volume of ocean water. It results from the addition of melting glaciers and polar ice sheets, as well as the natural expansion of water as it warms—both consequences of climate change, which is driven by the burning of fossil fuels [3].

Global mean sea level has risen about 8–9 inches (21–24 centimeters) since 1880. The rising water level is mostly due to a combination of meltwater from glaciers and ice sheets and thermal expansion of seawater as it warms. In 2022, global mean sea level was 101.2 millimeters (4 inches) above 1993 levels, making it the highest annual average in the satellite record (1993-present). The global mean water level in the ocean rose by 0.14 inches (3.6 millimeters) per year from 2006–2015, which was 2.5 times the average rate of 0.06 inches (1.4 millimeters) per year throughout most of the twentieth century. By the end of the century, global mean sea level is likely to rise at least one foot (0.3 meters) above 2000 levels, even if greenhouse gas emissions follow a relatively low pathway in coming decades. In some ocean basins, sea level has risen as much as 6-8 inches (15-20 centimeters) since the start of the satellite record. Regional differences exist because of natural variability in the strength of winds and ocean currents, which influence how much and where the deeper layers of the ocean store heat [4].

The Problem Of Melting Glaciers

The second piece of evidence we’re looking at in the modern world are melting glaciers. Glacial ice is very important to polar habitats and their inhabitants. Today, about 10% of land area on Earth is covered with glacial ice. Almost 90% is in Antarctica, while the remaining 10% is in the Greenland ice cap. Rapid glacial melt in Antarctica and Greenland also influences ocean currents, as massive amounts of very cold glacial-melt water entering warmer ocean waters is slowing ocean currents. And as ice on land melts, sea levels will continue to rise [5].

"This glacier used to be closer," Fagre declares as we crest a steep section, his glasses fogged from exertion. He's only half joking. A trailside sign notes that since 1901, Sperry Glacier has shrunk from more than 800 acres (320 hectares) to 300 acres (120 hectares). "That's out of date," Fagre says, stopping to catch his breath. "It's now less than 250 acres (100 hectares)." 

Everywhere on Earth ice is changing. The famed snows of Kilimanjaro have melted more than 80 percent since 1912. Glaciers in the Garhwal Himalaya in India are retreating so fast that researchers believe that most central and eastern Himalayan glaciers could virtually disappear by 2035. Arctic sea ice has thinned significantly over the past half century, and its extent has declined by about 10 percent in the past 30 years. NASA's repeated laser altimeter readings show the edges of Greenland's ice sheet shrinking. Spring freshwater ice breakup in the Northern Hemisphere now occurs nine days earlier than it did 150 years ago, and autumn freeze-up ten days later. Thawing permafrost has caused the ground to subside more than 15 feet (4.6 meters) in parts of Alaska. From the Arctic to Peru, from Switzerland to the equatorial glaciers of Man Jaya in Indonesia, massive ice fields, monstrous glaciers, and sea ice are disappearing, fast [6].

The Greenhouse Gasses Behind Our Warming Oceans

Our third and last piece of evidence on global warming are warming oceans. Increasing ocean heat is closely linked to increases in atmospheric greenhouse gas concentrations, making the ocean an excellent indicator of how much Earth is warming. Since 1971, the ocean has absorbed 90 percent of the excess energy added to Earth's climate by burning fossil fuels and other human activities [7].

Greenhouse gasses are gasses in the Earth’s atmosphere that trap heat and raise the surface temperature. This is caused by heat that the earth produces after being warmed by the sun. This is known as the greenhouse effect. Without greenhouse gasses, such as Carbon Dioxide (CO2), the planet's surface temperature would be around -18°C or 0.4°F. 

We have greenhouse gasses to thank for making this planet suitable for life. However, greenhouse gasses must be made in moderation over significant periods of time. Excessive greenhouse gas concentrations can easily tear down the ozone layer, which protects us humans from the harmful ultraviolet (UV) rays that the sun emits. The more the ozone layer deteriorates, the more our planet is exposed to global warming and excessive heat events, such as heat waves. We must strive to protect our home from changes in climate, reduce emissions, and greenhouse gasses. Bringing awareness to climate changes and environmental science is essential for the future success of our planet.

---------------------------------------------------------------------------------------------------------------

Author Alexander Heredia is an 9th grader from the Southern United States, specializing in earth science and climate-based research topics.

Works Cited

1. “What’s The Hottest The Earth’s Ever Been?” (https://www.climate.gov/news-features/climate-qa/whats-hottest-earths-ever-been) 

2. “What’s The Coldest The Earth’s Ever Been?” (https://www.climate.gov/news-features/climate-qa/whats-coldest-earths-ever-been#:~:text=At%20least%20twice%20between%20750,as%20the%20Neoproterozoic%20Snowball%20Earths.) 

3. “Sea Level Rise 101” (https://www.nrdc.org/stories/sea-level-rise-101) 

4. “Climate Change: Global Sea Levels” (https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level) 

5. “Why are Glaciers and Sea Ice Melting?” (https://www.worldwildlife.org/pages/why-are-glaciers-and-sea-ice-melting) 

6. “The Big Thaw” (https://www.nationalgeographic.com/environment/article/big-thaw) 

7. “Ocean Warming” (https://www.whoi.edu/know-your-ocean/ocean-topics/climate-weather/ocean-warming/#:~:text=Increasing%20ocean%20heat%20is%20closely,fuels%20and%20other%20human%20activities)