A Lesson in Earth Science

And Climate Change

Sometimes you can’t keep ahead of the news. Especially in science.  As I was working on the climate change exhibits for California Academy of Sciences earlier this year, I’d keep tabs on research and discoveries in Earth sciences, particularly Earth’s atmosphere and oceans. And, as fast as I’d write up something from peer-reviewed science, there’d be more information and discoveries coming in.  Which is great, but when it comes to climate change, it seems like it might be chronicling drastic change that we neither need nor want.  But, that’s the nature of science research — it reports on what’s happening and tries to find out why it’s happening.If we’re smart, we heed what we see and take action.

Tomorrow there’s a peer-reviewed science paper coming out that I wish had come out earlier, since it would make a striking addition to the exhibits. It states that as Earth’s oceans absorb more carbon dioxide generated by human consumption of fossil fuels and other activities (which warms up oceans and causes them to become more acidic), sounds will travel farther underwater. What’s the big deal, you might ask.  Well, noisier oceans affect marine mammal, for one thing. And, there are likely other effects that reverberate throughout the ocean environment.

Image credit: (c) 2008 MBARI (Base image courtesy of David Fierstein). This illustration shows how increasing carbon dioxide in the atmosphere leads to an increase in the acidity of seawater, which in turn allows sounds (such as whale calls) to travel farther underwater.

Image credit: © 2008 MBARI (Base image courtesy of David Fierstein). This illustration shows how increasing carbon dioxide in the atmosphere leads to an increase in the acidity of seawater, which in turn allows sounds (such as whale calls) to travel farther underwater.

This projected impact on ocean sound is the result of calculations by Keith Hester and his colleagues at the Monterey Bay Aquarium Research Institute (MBARI) in Moss Landing, Calif. Their paper is coming out in tomorrow’s (October 1, 2008) issue of  Geophysical Research Letters, a journal of the American Geophysical Union (AGU).

So, what does it mean? Ocean chemists know that as seawater chemistry changes, its ability to absorb sound changes. As sound moves through seawater, it causes groups of atoms to vibrate, absorbing sounds at specific frequencies. This involves a variety of chemical interactions that are not completely understood.

The overall effect is strongly controlled by the acidity of the seawater. The bottom line is this: the more acidic the seawater, the less low- and mid-frequency sound it absorbs.

As the oceans become more acidic, sounds will travel farther underwater and the level of underwater noise will rise. This change in chemistry will have the greatest effect on sounds below about 3,000 cycles per second (two and one half octaves above “middle C” on a piano).

This range of sound includes many of the underwater noises generated by industrial and military activity, as well as by boats and ships. Such human-generated underwater noise has increased dramatically over the last 50 years, as human activities in the ocean have increased. For marine mammals that also use this range of sounds to communicate, it’s like having your neighborhood go from one of relative quiet to one where the neighbors are blasting their stereos and revving their engines all the time.

The MBARI researchers say that sound already may be traveling 10 percent farther in the oceans than it did a few hundred years ago. However, they predict that by the year 2050, under conservative projections of ocean acidification, sounds could travel as much as 70 percent farther in some ocean areas (particularly in the Atlantic Ocean). This could dramatically improve the ability of marine mammals to communicate over long distances, but, on the down side, it could also increase the amount of background noise that they have to live with.

There are no long-term records of sound absorption over large ocean areas. However, the researchers cite a study off the coast of California which showed an increase in ocean noise between 1960 and 2000 that was not directly attributable to known factors such as ocean winds or ships.

Hester’s research shows how human activities are affecting the Earth in far-reaching and unexpected ways. As the researchers put it in their paper, “The waters in the upper ocean are now undergoing an extraordinary transition in their fundamental chemical state at a rate not seen on Earth for millions of years, and the effects are being felt not only in biological impacts but also on basic geophysical properties, including ocean acoustics.”


Hubble Loses Side A

Control System Failure Cuts Off Science

and May Affect Servicing Mission

Hubble on Orbit

Hubble on Orbit

Well this is bad news. NASA Spaceflight.com is reporting that science operations on Hubble Space Telescope have been shut down by the failure of the “Side A” control system. The telescope is in safe mode but is without any way to run the science instruments. HST’s technical handlers are working to transfer control of science operations to a Side B backup system, but this will take some time.  Side B has never been used on orbit, but is assumed to be in working condition. If it works, then science can resume.

However, from what I’m able to glean from several websites, this may affect the servicing mission scheduled for an October 14 launch.  If Side B can be activated and used, then the mission may well go on as scheduled.  If Side B is not working, the mission could be delayed into 2009 in order to figure out a repair strategy.  This is still a developing situation, so stay tuned.

Update: the upcoming repair mission for HST has been delayed until 2009, and the telescope’s handlers will work to bring up Side B to use until the astronauts have been trained on replacing the parts for Side A (and those parts can be put together).  For an in-depth look at the issues, check out Phil Plait’s Bad Astronomy Blog.


In other news: I was on travel last week and didn’t get a chance to blog about the Chinese space mission until now. I think it’s very cool and wish their agency the best of luck!  In a way it was like watching the U.S.’s own first steps in space in the late 50s and early 60s.  Congrats to the Chinese taikonauts!