These days you don't hear much concern over the size of Earth's ballooning human population, even as it reaches nearly 7 billion people - nearly twice the population of 1970.

Yet the topic has popped up again, this time in the context of climate change. In a paper to be published in the Proceedings of the National Academy of Sciences, researchers led by the National Center for Atmospheric Research found that adding another three billion people by mid-century (considered a conservative population estimate) could reverse many of the gains won in greenhouse gas emissions reductions.

A 16 to 29 percent reduction in emissions - deemed necessary to stem the serious consequences of rising global temperatures - would be offset by the additional carbon produced by the extra people.

Of course, the problem would be helped by lowering the world's birth rate.

"A slowing of population growth in developing countries today will have a large impact on future global population size. However, slower population growth in developed countries will matter to emissions, too, because of higher per capita energy use," said Shonali Pachauri, a researcher at the International Institute for Applied Systems Analysis in a UCAR press release.

The researchers went on to analyze which subsets of the population would add the most emissions. Surprisingly to smart growth advocates, a growth in the urban population could lead to a 25 percent rise in emissions in some developing countries - particularly China and India - because city living tends to lead to economic growth and higher rates of consumption. An aging population reduces emissions because of lower productivity.

Population growth is a condition not typically considered in climate scenarios, but arguably should be, since it's surely not going to remain stagnant.

Commerical space travel could threaten the climate
Commercial spaceflight could open up all kinds of new opportunities that would expand the limitations of Earth. Mining asteroids for heavy metals, energy generation through solar power satellites, and space tourism are all ideas that are being explored as companies seek ways to make business out of the Final Frontier.

With companies like Spaceport America opening the world's first commercial spaceport in Las Cruces, New Mexico earlier this month and Virgin Galactic now booking $200,000 space tours, it seems the future of space travel could be right around the bend.

Congress is investing $1.6 billion in private space-flight investments through NASA to kick-start the fledgling industry, particularly in the outsourcing of astronaut and cargo transport.

Not to put a damper on all the hype, but it seems there's been one overlooked aspect of expanding travel into space. As you can imagine knowing the kind of damage that landlubbing and ocean-spewing vehicles wreak on the climate, spacebound vehicles will also contribute to global warming.

A paper published in a recent journal of the Geophysical Research Letters indicates that emissions from 1,000 private rocket launches a year could increase the surface temperatures at the poles by 1.8 degrees Fahrenheit and reduce polar sea ice between 5-15 percent.

The author, Martin Ross, an atmospheric scientist at the Aerospace Corporation in Los Angeles, came up with the estimate using global atmospheric models that took into account the emissions of 600 tons of black carbon a year above Las Cruces.

The results showed a soot layer persisted within 10 degrees latitude in the stratosphere the spaceport, while some 80 percent of it spread to 25-45 degrees. This caused a cooling effect in the tropics and subtropics, while the poles got warmer. Ozone was also reduced in the tropics, while increasing at the poles.

The scientists believe the results show that private rocket launches could alter circulation in the atmosphere and the distribution of ozone - surprisingly even with emissions that occur at one point (the spaceport).

The big problem with dumping emissions into the stratosphere is that, unlike the atmosphere near the Earth's surface, rain and weather never wash them away. Maybe it's wise for the nascent space travel to go green with low-emissions vehicles right from initial take off.

del.icio.us	Digg	Reddit
YahooMyWeb	Google	Facebook

Memory Foam Mattress Review

SPACE MEDIA NETWORK PROMOTIONS Solar Energy Solutions Tempur-Pedic Mattress Comparison ... Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News