By Henry Workman
Marine Science Today Writer
Today, the body of evidence that points towards the climate change driven melting of the polar ice caps is substantial, and continues to grow. The environmental implications of this process have been consistently shown to be severe, and the problems associated with the subsequent rise in sea levels are becoming understood with increasing clarity. However, conclusive evidence regarding the means of halting or reversing this melting is harder to come by, and this area of our knowledge is often the subject of debate.
Previous studies done on climate fluctuations raised concerns about potential hysteresis (irreversibility) in the ice’s melting and reforming patterns, with a “tipping point” in the breakdown of the polar ice caps. This hypothesis held that after a certain stage in the process, the return of cooler temperatures wouldn’t be enough to facilitate corresponding reestablishment of ice. It would follow that the trend of rising summer temperatures observed in the Arctic region could lead to permanent damage. The temperature at which this point would be reached, as well as how many years it would take to occur, were never clear.
New research from the University of Washington aimed to evaluate the reasoning behind this environmental concern. Scientists used a state-of-the-art computer-based climate model to predict how change is likely to occur in the polar regions, starting with today’s conditions and factoring in estimates of future greenhouse gas levels and temperatures.
The model demonstrated a high level of sensitivity of Arctic sea ice to steadily increasing summer temperatures, with a complete loss of ice during the month of September projected for less than 50 years from now. However, for the same loss to occur during the winter months, the global temperature had to be raised by 6 degrees Celsius, which would take an estimated 230 years to occur. When the situation was reversed, and the model had levels of atmospheric CO2 then fall at the same rate, the amount of sea ice was indicated to make an eventual return to its previous state.
The findings alleviate a specific worry that threatened to complicate the issue of the ice caps’ peril. In a larger sense, though, we are left with many other areas of concern about the devastating effects of rising greenhouse gas levels and climate change. For starters, the model of this study operated on the condition that carbon dioxide levels fall at the same rate at which they rose, whereas these levels would not likely drop so steeply, even with greatly reduced use of fossil fuels. In addition, species that depend on a stable climate for survival, such as polar bears, would not return even if the ice did.
Copyright © 2011 by Marine Science Today, a publication of OceanLines LLC