Is This a Climate Change Solution So Crazy it Just Might Work?Takepart.com
By Padma Nagappan | 49 minutes ago
It’s one of those ideas that seemed to have sprung from the mind of a mad scientist: Deploy a fleet of 1,500 ships across the globe to blast seawater into the sky to make clouds brighter so they reflect more sunlight into space. Why? The deflected radiation would slow global warming. In theory.
Called “marine cloud brightening,” the geo-engineering scheme proposed by scientists Stephen Salter and John Latham has been bandied about academic journals for the past 15 years. But it seemed impossible to put into practice as it would cost more than $3 billion to just to build the ships. Plus shooting salt particles into the clouds would consume far too much energy to be practical.
Now atmospheric scientists at the University of Manchester in the United Kingdom think they’ve found an energy-efficient way to brighten clouds. In a paper published in the journal Philosophical Transactions of the Royal Society A, lead author Paul Connolly describes how a technology called the Rayleigh jet would be the most effective way to spray seawater into the sky.
A century ago, Lord Rayleigh, an English baron, explained how a stream of liquid would break down into tiny droplets when sprayed in the atmosphere, leaving a residue of salt particles.
Salter had proposed using silicon wafers to create the tiny nozzles to spray seawater. Connolly’s team focused on calculating how much energy would be needed to create the pressure to pump the water through the nozzles.
Their calculations show that the ships would need 13 megawatts of power on board to power the Raleigh jets—which is far more energy efficient than the other techniques.
“This method of powering the ships will cost about $50 million, which is separate from the cost of building and outfitting the ships,” Connolly said.
“By the end of this century, we think cloud brightening can offset whatever increase in temperature there would be, if we were to carry on as we were with no changes,” said Connolly.
But Connolly acknowledged that just because geo-engineering schemes like cloud brightening could feasibly be done, doesn’t mean they should be carried out.
“I’m not saying we should do this, because we don’t know if seeding clouds is going to create other problems,” he said. “What this research is doing is just looking into the possibilities—just in case.”
For instance, one great unknown is whether cloud brightening would change global wind and rain patterns.
“We wouldn’t want to do this and find we might cut off the Indian or Australian monsoon, because then we could affect millions of people who depend on the monsoon as a source of water,” Connolly said.
Like other atmospheric scientists, Connolly thinks that a massive investment in cloud brightening is worth it, but mostly as a stopgap measure to slow climate change.
There’s one big catch: The ships would need to keep spraying continually or the benefits would disappear, since the salt particles only last about two to three days.
“It would be a huge undertaking,” Connolly said. “But it doesn’t do much about the carbon dioxide in the atmosphere, so what we really need to do is move to a low carbon society.”
http://news.yahoo.com/climate-change-solution-crazy-just-might-210039396.html
