[Report File] Climate change is more fatal to the deep ocean than the ocean surface

Due to global warming, the temperature of the earth continues to rise. This rise in temperature goes beyond just the hot weather we feel on our skin and affects the entire Earth system. Advanced'[Report File] North Korean Fruit, Changing Korean Peninsula… What is the future climate in 2100?' As already explained in the article, global warming has caused fruit to noticeably north, and terrestrial organisms are also changing habitat. In this [Interview File], I would like to introduce a paper on marine life. The paper used the concept of climate velocity to explain the impact of climate change on the marine biosphere. It was created in 2009 when applied to land creatures, and is a concept in nature. Climate speed is a concept that quantifies how much a creature moves in search of a suitable environment when there is climate change. For example, if the plantation of apples has been northward from Wonju to Daegu for 10 years due to climate change, the climate velocity of apples is 150 km/10 years. The larger the value of climate velocity, the more sensitive it is to climate change. In this paper, the concept of climate speed was extended from land to marine life.

● Warming Deeper and more fatal global warming As global

temperatures rise, the effects of climate change are also appearing in the oceans. The global average surface temperature of the ocean continues to rise in 10-year increments from 1971 to 2010. (See picture)

Overseas researchers have analyzed the consequences of climate change on the ocean, and it has been interesting. The researchers first classified the oceans into four categories according to their depth. The surface layer (0~200m), the middle layer ocean (200~1,000m), the lunch layer (1,000~4,000m), and the deep sea water layer (4,000m or less). The results show that climate change has a greater impact on the deep sea side than on the top surface, which is most affected by sunlight and the atmosphere. It is concluded that deep sea below 200m is a place where temperature change is small because sunlight does not reach, and it is most affected by climate change. First, the researchers found that deep oceans below 1,000 m deeper than the surface were more affected by climate change in past 1955 to 2005 ocean temperature changes. Future predictions using climate change scenarios also show that deep water below 200m is more affected by climate change than the surface. The climate change scenario used the Representative Concentration Pathways (RCP) scenario that reflected greenhouse gas emissions and concentrations. We calculated from the scenario RCP 2.6 with a lot of abatement to 4.5 at the intermediate stage and 8.5, when little abatement was achieved. (See table below)

Even in the RCP 2.6 scenario, which strictly enforces greenhouse gas reduction, the impact of the middle-class marine layer (200-1,000 m) due to climate change was seven times faster than it is today. In the 8.5 scenario, where there is little reduction, the impact has increased by more than 20 times. In addition, if the impact of climate change between 1955 and 2005 was greater in the surface layer than in the middle and deep ocean layers of 200 to 1,000 m, it was analyzed that in all future scenarios, the depth of the water below 200 m was more affected than the surface layer.

However, it is analyzed that the impact of climate change, which is not absolute, is greater in the deep sea. As can be seen from the previous table, the impact index (climate speed) reflecting the concept came out larger in the deep sea. Deep sea is a place where there is little temperature change, so creatures that are concentrated in the deep sea are sensitive to even small temperature changes. It is much more sensitive to temperature changes than the surface organisms. In addition, deep sea species that feel a change in temperature must travel much more distances than seawater species in the surface layer to find and move to an appropriate temperature. In deep water to the surface layer because many car global temperature deepwater basically become even move only 100m, to be moved to 1km or more than 2km. (Climate concept of rate of climate velocity)

the concept of climate rates used in this paper, Only considered the horizontal movement of the creatures. Of course, marine creatures can also move vertically in the same place to prepare for temperature changes, unlike land creatures. However, considering the water pressure and the marine environment, it is unlikely that the concept of climatic velocity could be applied to the marine ecosystem, as the possibility of vertical movement of marine organisms is low.

● What if the deep sea ecosystem is broken?

Marine species in the middle ocean (200-1,000 m) play a very important role in marine ecosystems. Of course, there are more creatures and populations on the surface. However, in order to maintain the marine ecosystem, the role of the creatures of the middle-sea marine is essential. Middle-class marine species show a cycle of going up and down the surface and the middle layer for one day. It goes up to the surface during the day and usually goes down to the middle during the night, which serves as a prey for predators such as tuna, sharks and whales. Because of this, climate change will cause changes in the surface food chain if living creatures in the middle-sea are moved to other regions. Eventually, it could affect the entire marine ecosystem.

In addition to maintaining the marine ecosystem, the middle-tier marine species also serve as a link to the carbon cycle. When seaweed or phytoplankton synthesizes organic substances in the surface layer through photosynthesis, these organic substances are transferred to the middle-tier ocean through the food chain. If it stays on the carbon surface, carbon will escape through the air again through breathing, but if it goes to the middle layer in the form of organic matter, it will be stored in the ocean. The carbon delivered to the middle-tier marine layer enters deeper waters in the form of various excrements, and organic matter in the form of excrements often feeds the creatures in deeper waters.

As shown in the table above, if the greenhouse gas reduction is sufficiently reduced, the impact of the ocean surface layer can be reduced to the current level. However, it is not easy to reduce the damage that the deep sea will suffer because the heat energy already accumulated in the ocean will be increased to the deep sea even through continuous efforts. However, it cannot be put down. Climate forecasts basically show trends for the future and serve as indicators for us to set policies and goals. According to the current scenario and results, we need to minimize the impact of marine ecosystems that will deteriorate through greenhouse gas reduction.

<References>
Isaac Brito-Morales, David S. Schoeman, Jorge García Molinos, Michael T. Burrows, Carissa J. Klein, Nur Arafeh-Dalmau, Kristin Kaschner, Cristina Garilao, Kathleen Kesner-Reyes and Anthony J. Richardson, " Climate velocity reveals increasing exposure of deep-ocean biodiversity to future warmin", nature climate change, 10, 576–581 (2020), doi.org/10.5281/zenodo.3596584.