Radically redesigning the planet using geoengineering may seem like a great, albeit somewhat sci-fi sounding solution to fixing the problem of global warming. However, some experts disagree with the current proposals.

Researchers from the Helmholtz Centre for Ocean Research have published a new study that indicates that five currently proposed geoengineering projects aimed at halting or slowing down global warming could do more harm than good. Put simply, geoengineering entails the use of a wide variety of sciences, technologies and disciplines to reshape the world we live in. The results of the study were published in the online journal Nature.

The scientists who conducted the study zeroed in on five particular proposals. These proposals include the greening of the North African and Australian deserts, bringing up nutrient rich cold water from the ocean depths, mass distribution of lime to help the oceans absorb more carbon dioxide, seeding oceans with iron to promote algal blooming and lastly, decreasing the amount of solar radiation entering the atmosphere.

"However, the long-term consequences and side effects of these methods have not been adequately studied," says Dr. David Keller from the GEOMAR Helmholtz Centre for Ocean Research.

The researchers have also predicted that even if these projects are put in motion four to five years from now, the results would only show marginal reductions in carbon dioxide levels and global temperatures. Due to the sheer complexity of the living Earth, recklessly tampering with processes that affect the entire planet could also lead to unforeseen problems.

"The problem with previous research was that in most cases the methods were studied with different models using different assumptions and different sets of earth system components, making it difficult to compare the effects and side effects of different methods," says Dr. Keller. "We wanted to simulate different climate engineering methods using the same basic assumptions and Earth system model".

Dr. Keller and his colleagues conducted simulations to show how these geoengineering projects could affect the planet. The team found that even under ideal conditions, the proposed projects could only bring about marginal results. In fact, the proposal that involved the greening of the North African and Australian deserts could actually result in speeding up global warming.

"The forests removed carbon dioxide from the atmosphere, but at the same time the earth's surface became darker and could store more heat," Dr. Keller explains of this phenomenon. 

Considering the scale of these geoengineering proposals, they could easily fall prey to political and economic problems. The researchers say that it the projects are initiated but are halted for one reason or another in the future, the results could be very problematic.

"For several methods we saw a rapid change in the simulated climate when climate engineering ended," says Dr. Keller. "For example, if after 50 years the sun's rays were no longer partially blocked, the Earth warmed by several degrees within a few decades. This change would be much faster than the current rate of climate change, with potentially even more catastrophic consequences."