Climate scientists have used sea levels past and present to help predict those of the future. Temperature affects land ice; increased land ice will lower sea levels while the melting of this ice will raise these levels. Thus increased sea levels (secondary to ice melting) reflect a warmer global temperature. The scientific debate about what is actually happening to our climate has become super heated by politics, much of the warmth coming from scientists themselves.
To know the direction towards which the earth’s temperature is headed we have to know what it was in the past. Let’s pick 81,000 years ago. I picked this time for reasons that will be obvious as we progress. The temperature in the past is fixed and immutable though our ability to read it is always subject to amendment. To say as some do that there’s a consensus about climate change that is not debatable is to have no understanding whatsoever about how science works. Any consensus can be upended by new data or a new insight into existing data. Scientific disputes are not resolvable by a vote, their resolution depends on facts. Scientists are human, worse I can say about no man, thus they frequently get carried away with their beliefs and depart from scientific rigor just like anyone else.
Back to 81,000 years ago. According to commonplace wisdom, the earth should have been cooler then, it was well into the last glacial period, and the sea level supposedly 15 to 20 meters below today’s level. A paper in the February 12, 2010 issue of Science by geoscientists Dorale, et al challenges this view. “A speleothem that has been intermittently submerged in a cave on the island of Mallorca was dated to show that, historically, sea level was more than a meter above its present height. This data implies that temperatures were as high as or higher than now, even though the concentration of CO2 in the atmosphere was much lower.” Quotation from Science page 757.
An accompanying perspective piece by geologist R Lawrence Edwards from the University of Minnesota shows that estimating what the climate was 81,000 years ago is not a simple issue. “Dorale et al. provide evidence for high sea level at ~81,000 years ago, in the middle of the most recent 100,000-year cycle. This result challenges the observational basis for much of the discussion over recent decades… Dorale et al. dated layers of the mineral calcite, which were deposited like bathtub rings from pools of water in Mallorca caves, in the western Mediterranean. Because the pools are connected to the sea through underground passages, the layers record sea level at the time they formed. Using this approach, Dorale et al. inferred sea levels similar to modern values ~81,000 years ago. They estimated maximum rates of sea level rise of ~2 m per century. This rate is high, but not unprecedented in the geologic record. It exceeds by several times those predicted for the next century… A number of previous studies have estimated sea level ~81,000 years ago. Some of these estimates appear to agree with Dorale et al.’s findings, whereas others appear to disagree… Regardless of the ultimate verdict on sea level ~81,000 years ago, Dorale et al’s findings will stimulate ideas, discussion, and new studies of ice age history and causes.”
Note the conclusion by Edwards that new studies are needed. In assessing the current debate about climate change several questions must be answered as best we can. If the planet is warming is it doing so at historically unprecedented rates? Do we know why the change is occurring? If so, can we do anything about it? If we can, is the result worth the cost? The answers to all these questions are still uncertain.
The lay press and our politicians have failed miserably in informing the public of the facts and uncertainties of climate change. The subject is difficult and not close to being definitively settled. People who are skeptical of man made global warning have been vilified. They have even been compared to holocaust deniers. Scientific disagreements are not resolved by ad hominem attacks. Likening global warming skeptics to holocaust deniers is itself so anti-scientific as to be like holocaust denial. The proper response to this subject is to gather more information before changing the entire world’s economy in an effort to save the planet – a task that may prove unnecessary or impossible.