A group of scientists from the Oregon State University found that the ocean temperatures in the last interglaciation process were as warm as the present measures. However, in that opportunity, the level of the sea was 20 or 30 feet below when comparing to the current levels.
The last interglaciation process took place between 126,000 and 116,000 years ago, and the recent findings show the direct influence the human activity has had regarding the climate changes that affect sea temperature and levels. The study was published in the January issue of the journal Science.
Historically, the Earth goes through cooling and warming processes that have been present since million and billions of years. When the Earth undergoes a cooling period, this translates into the freezing of the ocean and the progressive augment of glaciers, to the diminishment of the sea levels at the time.
On the other hand, when the Earth is passing through a warming period, as it is right now, the sea levels tend to rise as the ice formations start to diminish. For these conclusions, the scientific community has to observe the clues that are hidden in ancient rock and ice formations that can explain the Earth conditions in each process.
What the ancient times can teach us
According to the lead author of the study, and doctoral student from the Oregon State University, Jeremy Hoffman, the last interglaciation process is quite intriguing concerning the Earth’s recent history, as it shows some similarities when comparing with the planet’s current conditions and the possible consequences.
“The last interglacial is extremely interesting because it’s the last time period in recent Earth history when global temperatures were a little bit higher and global sea level was about 6 to 9 meters higher — but carbon dioxide in the atmosphere was roughly at what it was during the pre-industrial era,” Hoffman stated. “So it’s a really interesting scientific question: What is it about the last interglacial that’s so unique, that gave rise to higher sea levels?”
One of the principal problems, said the investigators, is that scientists often assume that the historical climate change present on Earth’s several periods, happened at the same time, all at once. This leads to the conclusion that if a particular area gets chilly, all the other areas were cooler, and if a zone got warm, all the planet also registered that high temperature.
According to Hoffman, who is also a paleoclimatologist at the Science Museum of Virginia, that assumption is clearly a mistake. He explains that even when the overall temperature of the Earth is considerably high, that doesn’t mean automatically that a cooling of certain areas could not be registered.
Therefore, the generalization regarding the planet’s actual temperatures in ancient times could mislead investigations that try to explain the phenomena at the moment and interfere in the estimations that the scientific community often provides. To Hoffman, there must be a better understanding and interpretation of past events that occurred on the planet to get valid conclusions.
Human activity and its consequences
The investigation team has found a way to portrait more accurate estimations regarding what happened in ancient times and the relation that conditions have with the current Earth state.
The research team was able to conduct a study in which all the information from ice formations and marine sediments at the bottom of the oceans serves to have a better estimation of the temperature of the planet at specific zones and specific periods of time.
For the publication of this study, the team analyzed over 104 sets of data concerning sea surface temperature records in the last interglacial process – about 120,000 years ago. The team compared this information with the data from other two periods. One that goes from 1870 to 1889, and other that goes from 1995 to 2004.
This investigation showed that the temperature levels registered at the very beginning of the interglacial process were similar that the one recorded for the 1870-1889 period. However, that temperature rose about one degree Fahrenheit over the course of 4,000 years, reaching the levels recorded during the 1995-2004 period.
The scientific team explained that the temperature change that took the Earth thousands of years to carry out happened in over a century when the human activity started being an influence on the climate. The rates of carbon dioxide and other greenhouses are currently at high levels, a condition that was not present in the last interglacial process.
“The fact of the matter is that we are putting heat-trapping gasses into the atmosphere faster than the Earth was able to do by itself for 66 million years. So it just continues to really highlight the unique role that humans are playing in the climate system now,” Hoffman said when presenting the study.
These findings complement independent analyses conducted by both NASA and NOAA, that shows how 2016 broke heat records and for the third year in a row. According to those studies, the El Niño phenomenon explains the steady rise in Earth’s temperature over the last years.
Source: Oregon State University