A new study published in the Scientific Reports journal suggests that between the years 2000 through 2100, environmental shifts has contributed to novel global ocean surface temperatures. Researchers of the study believe that the occurrence of novel marine climates (and the disappearance of preexisting marine climates) is being spurred by anthropogenic climate change. Carbon introduced from human activities are likely to be a sufficient cause of extreme changes in sea surface temperature, but how can researchers (Katie E. Lotterhos, Áki J. Láruson & Li-Qing Jiang) be sure that novel temperatures are appearing?
Representative Concentrations Pathway (RCP)
To predict how climates will change due to greenhouse gas fluctuations, researchers implemented Representative Concentrations Pathway (RCP). The RCP establishes pathway trajectories of climate change for the near future (until the year 2100). Each pathway has a unique concentration of greenhouse gases and therefore, a unique set of possible consequences. The worst-case scenarios are those pathways which have the highest estimated future greenhouse gas emissions.
RCP 4.5 & RCP 8.5
Lotterhos and her colleagues used pathways RCP 4.5 and RCP 8.5. RCP 4.5 is a future in which human beings curb their greenhouse gas emissions and moderate our warming trajectories. RCP 8.5, sometimes considered the ‘business as usual scenario’, is a future pathway in which humans do not limit their emissions statistics, while greenhouse gas emissions continue to rise throughout the 21st century. For this reason, RCP 8.5 has the highest global mean temperature increases of all pathway scenarios.
The sea water near and along the ocean’s surface regularly interacts with atmospheric gases. Airborne gases may pierce depths hundreds of feet down below the ocean’s surface as gases like carbon dioxide are absorbed by the water. The sea, as you know, is a renown carbon sink. The buildup of atmospheric greenhouse gases inevitably increases the amount of carbon dioxide stored in sea water and contribute to ocean acidification in the future.
Researchers used the RCP models to quantify ocean surface climates. Ocean climates are defined by temperature, pH acidity and carbonate chemistry. The temperature and chemistry models the years between 1800, and project out to the year 2100. Of the climates that were analyzed, no novel extremes of global ocean surface temperature were judged to have occurred until the year 2000. In the RCP 4.5 scenario, 35.6 percent of sea surface climates may be lost by 2100. On the other hand, the RCP 8.5 scenario is projected to lose 95 percent of surface level climates.
Lotterhos and colleagues concluded that aquatic lifeforms may survive climatological changes by “dispersing” themselves. ‘Dispersal’ is the process by which organisms relocate. Organisms that do not disperse into a suitable area or adapt in some other way, face nonexistence. As carbon dioxide increases, the number of suitable climates for these organisms decreases. The loss of these climate zones effectively contributes to the loss of marine biodiversity.