Researchers Warn of Dangers of Climate Engineering

Researchers have warned that climate engineering, or geoengineering, is increasingly discussed as an option to mitigate the impacts of global warming. However, new research suggests that such technology could disrupt the Earth’s climate system if applied without adequate understanding of its consequences. A study by the University of California, published in the journal Earth’s Future, found that each climate engineering method carries different consequences. Some approaches could trigger major changes in regional climate systems, whilst others have a much smaller impact. “We must be careful when implementing climate engineering proposals before we fully understand what is happening,” said lead author Chen Xing. Xing and his colleague Cali Pfleger examined the impact of climate engineering on marine ecosystems, focusing on the El Niño-Southern Oscillation (ENSO) phenomenon, a natural cycle of sea surface temperature changes in the Pacific Ocean that influences weather patterns across the globe. The team compared two approaches that both aim to reflect some sunlight back into space to lower the Earth’s temperature. The first approach is Marine Cloud Brightening (MCB), which involves spraying sea salt particles into the lower atmosphere to make clouds brighter so they reflect more sunlight. The second is Stratospheric Aerosol Injection (SAI), which disperses sulphate particles into the stratosphere for a more uniform cooling effect. Simulation results showed that applying MCB in the eastern Pacific Ocean could reduce ENSO strength by approximately 61 per cent. “It is very difficult to make ENSO change that much in such a short time,” said University of California Associate Professor Samantha Stevenson. According to the researchers, this change is triggered by sea surface cooling and reduced rainfall due to altered cloud characteristics. This then affects atmospheric circulation, strengthening equatorial winds and increasing the upwelling of cold seawater, which ultimately weakens ENSO. Xing said the findings indicate that the MCB approach in the eastern Pacific region could trigger unintended consequences for the global climate system. “Do not do MCB over the eastern Pacific because it could trigger a very strong chain reaction due to the loss of ENSO,” he said. In contrast, the SAI approach showed no significant influence on ENSO because the dispersed particles spread more evenly in the atmosphere, avoiding drastic changes to the regional climate balance. However, Stevenson stressed that the findings do not mean all MCB approaches should be abandoned. “We are not saying that all MCB will kill ENSO. We are just saying that this happens if you do it in this specific region,” she said. The study also cautioned that climate engineering could cause other impacts, including reduced sunlight intensity needed for photosynthesis. This could potentially affect agricultural productivity and marine ecosystems, which underpin the food chain and produce most of the Earth’s oxygen. “Two interventions could achieve the same global temperature reduction target but have remarkably different regional climate impacts. The most important question is, have we thought about all the possible consequences?” Stevenson said.