INTRODUCTION

The year is 1884, and the Swedish Academy of Sciences stands before a young university student named Svante Arrhenius, who is defending his doctoral thesis. His research focuses on the logarithmic relationship between the temperature at which a chemical reaction occurs and the duration or rate of the reaction. If you, like me, find this concept difficult to grasp, you are not alone—the jury members also struggled to comprehend it, awarding Arrhenius the lowest possible passing grade. Yet, merely 19 years later, the same Academy of Sciences would bestow upon him the Nobel Prize for the groundbreaking work that formed the foundation of his thesis.

Arrhenius does not fall into complacency; instead, he pioneers a principle that will only be fully appreciated years later: "If the amount of carbon dioxide in the atmosphere doubles, the air temperature could increase by 5 to 6 degrees Celsius." However, the brilliant chemist makes one miscalculation—he predicts that this doubling will take approximately three thousand years. Today, even the most advanced supercomputers confirm Arrhenius' projected rate of temperature rise, with one crucial difference: this phenomenon is not expected to unfold over millennia but rather within the current century. What we now refer to as the greenhouse effect was termed "hothouse" by Arrhenius. The most unambiguous indication that the planet is heating lies in the atmospheric carbon dioxide concentration, which has risen from 280 parts per million in the 1850s to 420 parts per million today.

Among those who fail to grasp the severity of the issue is Donald Trump, who withdrew his country from the Paris Climate Agreement, stating, "I don’t believe in human-induced climate change. Some days the weather gets warmer, some days it gets colder—that’s called weather."

Regarding our topic, carbon dioxide is the fundamental raw material for photosynthesis. It is not only terrestrial plants that absorb and utilize CO₂ from the atmosphere but also microscopic organisms known as phytoplankton, which are concentrated in the upper 100 meters of oceans and lakes. Recognizing the need to quantify how much carbon dioxide phytoplankton remove from the atmosphere through photosynthesis, the U.S. Institute of Marine Sciences assigned a young assistant professor, Charles Keeling, to this research.

In 1958, Keeling began measuring atmospheric carbon dioxide levels at the Mauna Loa Observatory in Hawaii, a location chosen for its remoteness from industrial pollution. These measurements have continued uninterrupted, forming the longest-running dataset on atmospheric CO₂ concentrations. The findings from these studies provided irrefutable evidence that the rise in atmospheric carbon dioxide is directly linked to industrial activity. In recognition of his groundbreaking work, Charles Keeling was awarded the U.S. National Medal of Science in 2002, personally presented to him at the White House by President George W. Bush.

I am genuinely curious—could Charles Keeling’s Medal of Honor, awarded for his groundbreaking climate research, be revoked by climate change denier Donald Trump with the words, “We made a mistake, may God forgive us”? I am certain that Keeling, from wherever he is, is looking down on these times with a knowing smile.

WHAT IS CLIMATE?

To understand climate change, we first need to understand “what climate is”,

We call climate the expectations we formulate based on averages of measurements over many years.

We call the phenomenon we accept as constantly changing weather and the one we think does not change climate.

The period we call the Holocene started 18 thousand years ago, and we accept that it continues. The characteristic of this period was that the climate did not change.

Three things determine climate; the first is the amount of energy coming to the Earth from the Sun, the distance of the Earth from the Sun.

The second main factor is the distribution of land and seas on Earth and the color of the objects covering these surfaces.

The last main factor is the structure of the atmosphere. The proportion of gases in the atmosphere determines how much of the Sun's light the Earth traps and how much it scatters into space. 

If there were no atmosphere on Earth, the surface temperature would be -18 degrees Celsius, while the Earth's average surface temperature is +16 degrees Celsius due to the trapping of some of the heat in the atmosphere. The difference is entirely due to the presence of the atmosphere.

The Paris Climate Agreement was signed by 197 countries at the 21st COP meeting in 2015 and entered into force in 2016. According to this agreement, the goal is to limit the increase in global surface temperature to 2 degrees and, if possible, to keep it below 1.5 degrees.

 

The atmosphere comprises 78% nitrogen, 21% oxygen, and 1% other gases. Whatever happens is caused by carbon dioxide, methane, and two nitrogen monoxide gases in this 1%. Namely, after the rays coming from the sun hit our planet, they turn into infrared rays and are reflected. When the reflected light hits our atmosphere, the following situation occurs: diatomic gases (oxygen and nitrogen) allow the light to scatter into space, but when it hits gases with three or more atoms (carbon dioxide, methane, two nitrogen monoxides), the light does not know what to do, half of it scatters into space, while the other half returns to our world and heats our planet.

We call the gases that trap heat in the Earth's atmosphere “greenhouse gases”.

These gases are carbon dioxide, methane, two nitrogen monoxide and ozone.

Combustion is when carbon combines with oxygen to form carbon dioxide. In other words, if fossil fuels are used for the movement of ships, carbon dioxide is produced as a result of combustion.

ALTERNATIVE SHIP FUELS

Ships emit 800 million tons of carbon dioxide into the atmosphere in a year. Now we come to our main topic; the European Union has introduced an application called FuelEU Maritime for all ships over 5000 gross tons arriving at its ports to be implemented from the beginning of this year to reduce the well-to-wake greenhouse gas intensity by 80% by 2050.

 This means; based on the well-to-wake carbon emission intensity of 91.16 gr CO2 per megajoule equivalent in 2020, they will reduce it by 2% in 2025/2029, 6% in 2030/2034, 14.5% in 2035/2040, 31% in 2040/2045, 62% in 2045/2049 and 80% in 2050.

For the time being, IMO will take a decision similar to this decision taken by the European Union or under more aggravated conditions within this year and will probably put it into practice as of 2026. This means that severe penalties will be imposed on greenhouse gas emissions in the world seas beyond IMO's determined rate.

The shipowners of the world, who are aware of this, have been looking for solutions to minimize the penalties and have turned to green fuels (mainly hydrogen, methanol, and ammonia), but liquefied natural gas (LNG) has become the preferred fuel for today due to the difficulty and expense of obtaining these fuels.

Sources Utilized:

• Sargun Tont - Climate Change
• Levent Kurnaz - Before the Last Glacier Melts
• Drewry Shipping Consultants - Alternative Ship Fuels Data and Tables