There is much concern over Earth’s changing climate and the role humans may have played in these changes, especially since the
Industrial Revolution in the mid-1800’s, which began an ever-increasing trend of burning fossil fuels for energy (coal, oil, gas).
Combustion of fossil fuels releases extra carbon dioxide (CO2) into the atmosphere, which is expected to increase/intensify Earth’s natural greenhouse effect. The question is an important scientific one, but because the answers can have economic and political
consequences, the issue of climate change has become very contentious. The issues are complex. My advice is to keep an open,
but critical mind.
One issue that could potentially affect Florida especially is the prospect of sea level rise due to warming, melting ice, or other factors (see textbook, page 344). According to long-term tidal records, sea level is indeed rising. But the causes are not fully understood.
This discussion forum is a simple question about sea level rise, and only requires a bit of critical thinking. Answers to this question
may differ. I have attached 2 sea level diagrams: one is called Quaternary Sea Level Changes, and the other is called Holocene
Transgression. The QSLC chart shows fluctuating sea levels throughout the last half of the Pleistocene Epoch, the so-called “Great
Ice Age.” The cyclical rise and fall of sea level during this ~one-million-year time is thought to be related to variations in Earth’s orbit, called Milankovitch Cycles (described on pages 320-322 in your textbook). During these glacial-interglacial cycles, a glacial was a
time of large glaciers, and an Interglacial was when glaciers would melt back-but not completely-and sea level would rise. On the
chart look to the far right. The last interglacial time was called the Sangamon Interglacial. Note that sea level then was higher than
sea level is today (the zero point on the chart is modern sea level). Some say sea level was up to 10 meters (~30 feet) higher than
today!
Now look at the Holocene Transgression chart. The Holocene Transgression is a time of enormous sea level rise that occurred
between about 18,000 and 6,000 years ago, a time of global warming after the great Wisconsin Glacial (see text page 322, Figure 12.13 to see how extensive the glacier was over North America). Sea level rose as much as 400 feet during this time, up to its present level. Geologists say we are presently in the Holocene Interglacial time. We still have larger glaciers (over Greenland and Antarctica), but they are not so large as during the Wisconsin Glacial time.
DISCUSSION QUESTION: During the Sangamon Interglacial, when sea level was up to 30 feet higher than today, atmospheric carbon dioxide levels were at about 300 ppm (parts per million; based on ice core data). First, what is the current level of atmosphere CO2
in the atmosphere (see text page 336)? Second, what do you think this might mean for the prospects (for? against?) sea level rise in the near future. Remember: CO2 controls greenhouse warming, Earth is presently warming, but sea level was much higher during
the Sangamon Interglacial when CO2 was only about 300 ppm. Short paragraph answer should be fine.
