Introduction

With global warming becoming more of a concern to society, as well as entire ecosystems, it is important to address proposed methods to alleviate its negative impacts. The Arctic is seeing more changes than anywhere else in the world, and endangered species, such as polar bears, may become extinct as they continue to lose their habitat. Geoengineering is one possible way to cool that climate, and in this situation is characterized by injecting sulfur aerosols into the stratosphere. The goal of this experiment is to see if it is possible to modify the climate using geoengineering to save Arctic ice without jeopardizing other locations throughout the world including the monsoon regions of India and Africa.

Experimental Design

In order to complete this experiment many model runs were required. There are two control runs, one that maintains constant conditions from the year 1999, and the other with constant conditions from the year 2007. In addition to the control runs, the geoengineering runs were also compared to the A1B scenario as indicated by the IPCC (2007). There were three different geoengineering runs, each with three ensemble members. Each run injects the sulfur aerosol at a rate of 3 MT per year, however one continuously injects the sulfur throughout the entire, the second during the months of April, May, and June, and the last injects the same quantity as the second run, however only during the month of April. Since changes were made to the model in between the initiation of the year-round and spring geoengineering , a “pseudo A1B” run was created to make all of the output comparable.

Results

Figure 1a shows that geoengineering is doing what is expected during the year-round scenario. The sulfur is only affected the temperature above 60 degrees north is latitude, with the majority of the Arctic seeing a decrease in temperature of at least 0.6 degrees Celsius on an annual average. Figure 1b confirms the preliminary experiments that the Indian and African monsoon will fail, by the large decrease in precipitation, which turns out to be statistically significant when divided by the standard deviation.

Conclusions

The spring geoengineering scenarios proved to be just as effective as the year-round scenario. If geoengineering were to be exercised to replenish Arctic ice, it would be more efficient. Scientists have the knowledge to modify the Earth’s climate but there are many political boundaries that most be crossed in order to do so. In addition, geoengineering could only be used as a temporary solution, and these scenarios are not capable of reversing all of the negative impacts of global warming, spanning the entire Earth.

Acknowledgements

I would like to thank Ben Kravitz and Dr. Alan Robock for their support and guidance in completing this research as well as NSF Grant ATM-0730452.References

IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: Impacts, Adaption and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 7-22.

Robock, Alan, Luke Oman, and Georgiy L. Stenchikov, 2008: Regional climate responses to geoengineering with tropical and Arctic SO2 injections, Journal of Geophysical Research, 113, D16101, doi:10.1029/2008JD010050.

Geoengineering: Designing a Strategy to Save Arctic Ice from Global Warming with

Stratospheric Sulfate AerosolsAllison Marquardt

Department of Environmental Sciences, Rutgers University, New Brunswick, NJ

Figure 1: 3MT per year injection compared to the A1B ensemble averaged over years 10 to 19. (a) Surface Air Temperature flux (b) Precipitation flux (Robock et al. 2007)

Not only does a 3MT injection decrease the surface air temperature, but it also contributes to replenishing the Arctic Sea ice, including during the month of September when the peak ice melt usually occurs. With a 3MT injection per year, the ocean ice thickness will increase by 8%, while the snow and ice coverage within each grid will increase by 6% in the Greenland and Norwegian Seas on an annual average when compared to the A1B scenario. In addition, the ice over northern Europe and Asia will even increase by over 25 kg/m2. As shown in figure 2, the two spring scenarios showed a very similar increase in the sea ice in the Arctic.

Figure 2: Total earth ice flux compared to the A1B ensemble averaged over years 10-19. (a) 3MT/year (b) 0.75MT/April

Figure 3: Precipitation flux compared to the A1B ensemble averaged over years 10-19. (a) 0.75MT/Spring (b) 0.75MT/April

As seen in figure 3, the spring injection scenarios do not indicate that the monsoon has failed in India or Africa, although there are fluxes in precipitation over the oceans.