The effects that climate change has on polar ice sheets, particularly Greenland in this study, are important for many reasons. The two most important reasons that are discussed in this article involve rising sea levels and decreased planetary albedo as the globe’s ice sheets melt. Solar radiation management has been suggested to reduce the warming of the globe and buy some time while engineers and scientists address the larger problem of removing CO2 from the atmosphere. The installation of a solar “sunshade” or the injection of sulfate aerosols into the clouds are the two most promising methods of geoengineering. Previous studies have shown that a world exposed to climate engineering would experience warming at the poles, cooling in the tropics, and a decreased precipitation rate, which may have certain effects on the Greenland ice sheet (Irvine et al.). In this study, the melting of the Greenland ice sheet was prevented at levels of partial climate manipulation, which suggests that the geoengineering required to cool the planet and reduce the impacts of greenhouse warming may not be as thorough as geoengineers originally believed. Ellie Pickrell
Irvine, Peter J., Lunt, Daniel J., Stone, Emma J., Ridgwell, Andy, 2009. The Fate of the Greenland Ice Sheet in a Geoengineered, High CO2 World. Environmental Research Letters, 4.
Irvine et al. conducted twelve 400-year simulations on a climate model. The first model was control simulation that modeled a climate similar to that of a pre-industrial world, and wasn’t exposed to climate engineering. The second has atmospheric CO2 concentrations of 1120 ppmv, which is four times the pre-industrial amount, and 0% climate manipulation. The last ten simulations have the same CO2 concentrations and range from 10% to 100% climate engineering by intervals of 10%. At each simulation, Irvine et al. measured the temperature and precipitation anomalies in comparison to the control simulation. The results were then combined with an observed climatology to create an ice-sheet model—Glimmer. Glimmer is a three-dimensional ice sheet model representing the Greenland region, and provided results showing the impact of solar radiation management on the ice sheet.
In the simulation with 0% climate engineering, the center of the Greenland ice sheet had an annual temperature increase of 8°C, and an average summer temperature that increased by 6°C when compared to the pre-industrial simulation. This 0% geoengineering simulation also showed an increase in annual precipitation of over 6 meters a year, which would increase the amount of annual snowfall, which could potentially cause the ice sheet to grow.
For simulations experiencing 100% engineering, the annual average surface air temperature was significantly lower than simulations with lower climate manipulation, although Greenland remained warmer than it was in the pre-industrial period. The island showed an increase of at least 0.5°C, with its northern and southern coasts undergoing an increase of 0.75°C, and a 1°C increase at the southern tip. For simulations experiencing 50% engineering, the model predicted a warming of 3°C across the majority of Greenland. Both 100% and 50% simulations showed an increase in precipitation rates, although it was lower than the 0% engineering simulation. A 100% simulation resulted in a precipitation rate of 21 mm per year.
The results from the Glimmer test were then used to predict the change in sea level of the Greenland region. In the pre-industrial control simulation, the sea levels were at 8.6 m. In the 0% simulation, only 12.8% of the original ice sheet remained, which could result in a sea level rise of 6.4 m. The remaining 12.8% of the ice sheet is located at the high altitude regions on the southern tip and on the eastern coastline. In the 100% simulation, there was a sea level increase of 0.1 cm. These results show that as the climate engineering percentage came closer to 100%, the volume of the ice sheet increased.
The Glimmer test also showed that there was no linear relationship, rather a step-like behavior, between an increase in climate engineering and an increase in height and coverage of the ice sheet. The 20% simulation showed an ice sheet that was slightly larger than the 0% simulation, but the remaining ice sheet was more inter-connected. The 30% and 40% simulations show slight increases from the previous simulation, with a partial ice sheet in the north that wasn’t present in the 20% simulation. The ice sheet at the 60% simulation was at full height and coverage, and the pre-industrial ice sheet was maintained.
For all of the simulations that include geoengineering, Greenland experiences a warmer and wetter climate in comparison to the pre-industrial period. On average, the temperature and precipitation rates of Greenland decrease relatively linearly with increases in the level of climate manipulation.