Archive for the ‘Earth’ Category

Habitability, Taphonomy, and Curiosity’s Hunt for Organic Carbon

Tuesday, December 24th, 2013

By John Grotzinger
This blog entry from John Grotzinger, the project scientist for NASA’s Curiosity Mars rover, was originally prepared for use by the Planetary Society and explains the importance of some of the rover’s findings.

Curiosity Selfie

This self-portrait of NASA’s Mars rover Curiosity combines dozens of exposures taken by the rover’s Mars Hand Lens Imager (MAHLI) during the 177th Martian day, or sol, of Curiosity’s work on Mars (Feb. 3, 2013), plus three exposures taken during Sol 270 (May 10, 2013)
› Full image and caption

It was fun for me to catch up with Emily Lakdawalla of the Planetary Society at the American Geophysical Union meeting, and to discuss our new Curiosity mission results. They focus on the discovery of an ancient habitable environment; we are now transitioning to the focused search for organic carbon. What’s great about Emily’s blog is that with her strong science background she is able to take complex mission results and translate these into something that can reach a broader and more diverse audience. I’ll try to do the same here.

Since we first reported our results on March 12, 2013, from drilling in Yellowknife Bay it has been my experience that lots of people ask questions about how the Curiosity mission, and future missions, will forge ahead to begin with looking for evidence of past life on Mars. There is nothing simple or straightforward about looking for life, so I was pleased to have the chance to address some of the questions and challenges that we find ourselves most frequently discussing with friends and colleagues. The Planetary Society’s blog is an ideal place to take the time to delve into this.

I also need to state at the outset that what you’ll read below is my opinion, as Curiosity science team member and Earth geobiologist, and not necessarily as its Project Scientist. And I have only worked on Mars science for a decade. However, I can say that many other members of the Curiosity team share this opinion, generated from their own experiences similar to mine, and it was easy for us to adopt these ideas to apply to our future mission. To a large extent, this opinion is shaped by our experience of having spent decades trying to explore the early record of life on Earth. As veterans of the Mars Exploration Rover and Curiosity missions, we have learned that while Mars has significant differences from Earth, it also has some surprising similarities that could be important in the search for evidence of ancient Martian life - a “paleobiosphere,” if you will. The bottom line is that even for Earth, a planet that teems with life, the search for ancient life is always difficult and often frustrating. It takes a while to succeed. I’ll try to explain why later on.

So here goes….

The Dec. 9, 2013, publication of the Curiosity team’s six papers in Science provides the basis for understanding a potentially habitable environment on ancient Mars. The search for habitable environments motivated building the rover, and to that end the Curiosity mission has accomplished its principal objective. This naturally leads to the questions of what’s next, and how we go about exploring for organic carbon?

To better understand where we’re coming from, it helps to break down these questions and analyze them separately. With future advocacy of missions to Mars so uncertain, and with difficult-to-grasp mission objectives located between “the search for water” (everyone got that) and “the search for life” (everyone wants NASA to get on with it), the “search for habitability” and the “search for carbon” are important intermediate steps. By focusing on them scientists can identify specific materials to study with more sophisticated future missions and instruments, or to select for sample return, or to be the target of life detection experiments.

Note: You can get access to all six of these Science papers here or here. The latter site also has the papers we published back in September. Science has a policy that allows us to post a “referrer link” to our home websites. This redirects the query to AAAS, where the paper can be downloaded without cost.

Habitability

Let’s start with “habitability.” We reported the discovery of an ancient lake, and one that formed clay minerals. The presence of clays represents more benign environmental conditions than the acid sulfates found by Spirit and Opportunity. However, clays are not the only thing needed to demonstrate habitability. The bar is high: In brief, a mission needs to demonstrate the presence of water, key elements regarded as the building blocks of life (including carbon), and a source of energy. And you need to find them all together, and at the same instant in geologic time. In turn, each one of these must be characterized further to qualify an environment as having been habitable. Finally, it’s never black and white; understanding habitability is part of a broad continuum of environmental assessment, which is why orbiters and earlier rovers and landers are important assets in this process as well.

It is also important to define what group of organisms is being imagined to have inhabited the environments - their requirements will vary. Single-celled microorganisms are a great place to start based on our understanding of the early evolution of life on Earth, which was dominated by microbes for at least the first two billion years of the planet’s history. More specifically, the Curiosity team has been focusing on the conditions of habitability relevant to “chemolithotrophs,” a group of microbes that feeds on chemical energy available in rocks.

Water.

The water of a habitable environment should be relatively fresh, or at least not contain so much salt that the relative abundance of water is so low (what chemists call “water activity”) that the osmotic pressure on cells would cause them to collapse. My favorite analog here is honey. Yes, it’s an aqueous environment but no, it’s not habitable: The sugar content is so high that microbes can’t live in it. This is why honey doesn’t spoil when not refrigerated. Salt serves the same role as sugar; too much salt inhibits life. Acidity is also important, although microbes have been shown to tolerate an extraordinary range of pH, including the very lowest values encountered in natural environments on Earth. However, more moderate pH favors a greater diversity of microorganisms, and thus more options to explore for emerging life forms. Finally, the water needs to last a long time on the surface; the longer, the better. A flow of water emerging on the surface of Mars from an underground source and boiling off in the presence of Mars’ modern low atmospheric pressure is not a good scenario for life. A stable source, such as a very ancient lake, with associated streams, and water flowing through the ground beneath it, is much better. We envision for the lake/stream/groundwater system that Curiosity discovered at Yellowknife Bay that the water could have existed for millions of years potentially. But even shorter periods are viable - the qualitative point here is that the rocks at Yellowknife Bay record more than a one-time event.

Key building blocks of life.

A conventional list of key elements for life will include “CHNOPS” - carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Previous orbiter and landed missions have provided ample evidence for H, O, and S via observations of sulfate and clay minerals, and P was measured by earlier rovers and landers. Curiosity has done the same. The tricky stuff is N and C and, along with P, they must all be “bioavailable,” which means to say they cannot be bound tightly within mineral structures that water and microbial chemical processes could not unlock. Ideally, we are looking for concentrated nitrogen- and phosphorous-bearing sedimentary rocks that would prove these elements were actually dissolved in the past water at some point, and therefore could have been available to enable microorganism metabolism. But in the interim Curiosity has been able to measure N as a volatile compound via pyrolysis (heating up rock powder in the SAM instrument), and P is observed in APXS data. We feel confident that N was available in the ancient environment, however we must infer that P was as well. Two of the Science papers, Grotzinger et al. and Ming et al., discuss this further.

Carbon is the elephant in the room. We’ll discuss organic carbon further below, but here it’s important to make one very important point: Organic carbon in rocks is not a hard-line requirement for habitability, since chemoautotrophs can make the organics they need to build cellular structures from metabolizing carbon dioxide (CO2). These organisms take up inorganic carbon as CO2 dissolved in water to build cellular structures. Organic carbon could serve as fuel if it was first oxidized to CO2, or could be used directly for biomass, or could be part of waste products. As applied to Mars it is therefore attractive to appeal directly to CO2, presumed to have been abundant in its early atmosphere. Curiosity does indeed see substantial carbon generated from the ancient lake deposits we drilled. The CO2 that was measured is consistent with some small amount of mineral carbon present in those lake mudstones. These minerals would represent CO2 in the ancient aqueous environment. Furthermore, it is possible that Martian organic sources have been mixed with inorganic sources of carbon in the mudstone; however, any organic contributions from the mudstone would be mixed with Earth-derived sources during analysis (see Ming et al. paper).

Energy.

All organisms also require fuel to live and reproduce. Here it is essential to know which kind of microorganism we’re talking about, since there are myriad ways for them to harvest energy from the environment. Chemolithotrophs derive energy from chemical reactions, for example by oxidizing reduced chemical species like hydrogen sulfide or ferrous iron. That’s why Curiosity’s discovery of pyrite, pyrrhotite, and magnetite are so important (see Vaniman et al. and Ming et al. papers). They are all more chemically reduced than their counterparts discovered during earlier missions to Mars (for example, sulfate and hematite). Chemolithotrophic microbes, if they had been present on Mars at the time of this ancient environment, would have been able to tap the energy in these reduced chemicals (such as hydrogen sulfide, or reduced iron) to fuel their metabolism. If you are interested in more detail regarding these kinds of microbial processes I can strongly recommend Nealson and Conrad (2000) for a very readable summary of the subject.

The next section describes where I think we’re headed in the future. We’ll continue to explore for aqueous, habitable environments at Mt. Sharp, and along the way to Mt. Sharp. And if we discover any, they will serve as the starting point for seeing if any organic carbon is preserved and, if so, how it became preserved.

Taphonomy

Now there’s a ten-dollar word. Taphonomy is the term paleontologists use to describe how organisms become fossilized. It deals with the processes of preservation. Investigations of organic compounds fit neatly in that category. We do not have to presume that organic compounds are of biologic origin. In fact, in studies of the Earth’s early record of life, we must also presume that any organic materials we find may be of inorganic origin - they may have nothing to do with biology. Scientific research will aim to demonstrate as conclusively as possible that the materials of interest were biogenic in origin. For Earth rocks that are billions of years old, it’s rare to find a truly compelling claim of ancient biogenic carbon. Here’s why.

On a planet that teems with life, one would presume these discoveries would be ordinary. But they aren’t, and that’s why fossils of almost any type, including organic compounds (so-called “chemofossils”), are so cool - it’s because they are rare. That’s also why taphonomy emerged as an important field of study. We need to understand how biologic materials become recorded in Earth’s rock record. It’s important in understanding modes of organism decomposition, to interpret ancient environmental conditions, and in reconstructing ancient ecosystems. But there also is one other reason that is particularly relevant for early Earth, and even more so for Mars: If you want to find something significant, you have to know where to look.

To explore for organics on Mars, three things have to go right. First, you need to have an enrichment of organics in the primary environment where organic molecules accumulate, which is large enough so that your instrument could detect them. Second, the organics have to survive the degrading effects associated with the conversion of sediment to rock. Third, they must survive further degradation caused by exposure of rock to cosmic radiation at Mars’ surface. Even if organics were once present in Martian sediment, conversion to rock and exposure to cosmic radiation may degrade the organics to the point where they can’t be detected.

Organics degrade in two main ways. The first is that during the conversion of sediment to rock, organics may be chemically altered. This generally happens when layers of sediment are deposited one on top of the other, burying earlier-deposited layers. As this happens, the buried sediment is exposed to fluids that drive lithification - the process that converts sediment to rock. Sediments get turned into rocks when water circulates through their pores, precipitating minerals along the linings of the pores. After a while the sediment will no longer feel squishy and it becomes rigid - lithified.

During the process of lithification, a large amount of water may circulate through the rock. It can amount to hundreds, if not thousands, of times the volume of the pore space within the rock. With so much water passing through, often carrying other chemicals with it, any organics that come into contact with the water may be broken down. Chemically, this occurs because organics are reduced substances and many chemicals dissolved in water are oxidizing. Those two chemical states don’t sit well together, and this tends to drive chemical reactions. Simply put, organics could be broken down to the point where the originally organic carbon is converted into inorganic carbon dioxide, a gas that can easily escape the lithifying sediment. Water on Mars may be a good thing for habitability but it can, paradoxically, negatively affect the preservation of organics.

Now, if any organics manage to escape this first step in degradation, then they are still subject to further degradation when the rock is exhumed and exposed to the surface of Mars. There it will be bombarded by cosmic radiation. I won’t go into the details here, but that is also bad news for organics because the radiation tends to break apart organic molecules through a process called ionization. The upper few meters of a rock unit is the most susceptible; below that the radiation effect rapidly dies away. Given enough time the organics could be significantly degraded.

The Hassler et al. paper just published in Science reports that the surface radiation dose measured by Curiosity could, in 650 million years, reduce the concentration of small organic molecules, such as amino acids, by a factor of 1000, all other factors being equal. That’s a big effect - and that’s why we were so excited as a team when we figured out how to measure the cosmogenic exposure age of rocks we drilled (see Emily’s blog and the Farley et al. paper). This gives us a dependable way to preferentially explore for those rocks that have been exposed for the shortest period of time. Furthermore, it is unlikely that organics would be completely eliminated due to radiation effects and the proof of this is that a certain class of meteorites - the carbonaceous chondrites - have been exposed to radiation in space for billions of years and yet still retain complex organics. This provides hope that at least some types of organics should be preserved on Mars.

Being able to account for the radiation history of rocks that Curiosity might drill is a very big step forward for us in the search for organic molecules. It is a big step forward in learning how to explore for past life on Mars (if it ever existed there). Now we have the right tools to guide the search for rocks that might make the best targets for drilling. Coupled with our other instruments that measure the chemistry and mineralogy of the rocks, to help select those that might have seen the least alteration of organics during burial, we have a pretty good sense of what we need to do next. That’s because we have been through this before on Earth.

Magic Minerals

Over the years Emily has written many blogs dedicated to the discovery of interesting minerals on Mars. There are many reasons for this, but I’ll suggest one more that may grow in importance in years to come.

Believe it or not, the story starts with none other than Charles Darwin. In pondering the seemingly instantaneous appearance of fossils representing complex and highly differentiated organisms in Cambrian-age rocks (about 500 million years ago), Darwin recognized this as a major challenge to his view of evolution. He explained the sudden appearance of fossils in the record by postulating that Cambrian organisms with no known antecedents could be explained by “record failure” - for some unknown reason, older rocks simply didn’t record the emergence and evolution of life’s beginning. Conditions weren’t suitable to preserve organisms as fossils.

Most of that story goes on in the direction of evolutionary biology, and we’ll skip that, rather focusing instead on learning more about taphonomy. What is important for Mars was the discovery of minerals that could preserve evidence of early microorganisms on Earth. (For a good read on Precambrian paleobiology, try Andy Knoll’s “Life on a Young Planet: The First Three Billion Years of Evolution on Earth.”)

We now know that pre-Cambrian time represents about 4 billion years of Earth’s history, compared to the 540 million years represented by Cambrian and younger rocks that Darwin had studied. (See Emily’s blog on the Geologic time scale.) We also know now that the oldest fossil microbes on Earth are about 3.5 billion years old, and that in between there is a compelling, but very sparse record of the fossil organisms that Darwin had anticipated. However, what’s even more remarkable is that it took 100 years to prove this. And this was with hundreds, maybe thousands, of geologists scouring the far corners of the Earth looking for evidence.

The big breakthrough came in 1954 with the discovery of the “Gunflint microbiota” along the shores of Lake Superior in southern Canada. A University of Wisconsin economic geologist, Stanley Tyler, discovered microscopic threads of what we now understand to be fossil bacteria in a kind of rock called “chert”. Chert is a microcrystalline material formed of the mineral quartz, or silicon dioxide, which precipitates very early in waters that contain microbial colonies. It forms so early that it turns the sediment almost instantly into rock, and any microbes become entombed in a mineral so stable it resists all subsequent exposure to water, and the oxidizing chemicals dissolved in water, for billions of years.

As it turned out, this was the Rosetta stone that helped decipher the code to the field of pre-Cambrian paleontology. It took almost 10 years for the discovery to be fully appreciated (the initial report in Science was viewed with much skepticism), but once it was confirmed, in the mid-1960s, the field exploded. Once geologists and paleontologists knew what to search for, they were off to the races. Since that initial discovery, other magic minerals have been found that preserve ancient microbes, sometimes with spectacular fidelity. But chert is still the mineral of choice, and I never pass by it in the field without collecting some.

We don’t know yet what magic minerals exist on Mars that could have trapped and preserved organics. Clays and sulfates hold promise, and that’s why we’re so interested in them. Silica, perhaps similar to terrestrial chert, has been observed from orbit at a few places on Mars, and in Spirit rover data from Gusev crater. The great thing about Gale crater as a landing site is that we have so many choices in this trial-and-error game of locating a mineral that can preserve organic carbon.

The figure below provides some sense of the impact of this discovery. It is modified from a similar figure published in a very nice summary by Bill Schopf, a Professor of Paleontology at UCLA. Bill also was a very early participant in this race for discovery and has made a number of very significant contributions to the field.

chart

In studying Mars, the importance of this lesson in the search for life preserved in the ancient rock record of Earth cannot be overstated. Curiosity’s discovery of a very Earth-like ancient habitable environment underscores this point. With only one or two rovers every decade, we need to have a search paradigm: something to guide our exploration, something to explain our inevitable failures. If life ever evolved on Mars, we need to have a strategy to find it. That strategy begins with the search for organics, and regardless of their origin - abiotic or biotic, indigenous to Mars or not - they are important tracers for something more significant. Curiosity cannot see microfossils, but it can detect organic compounds. And just as with microfossils on Earth, we first have to learn where organics on Mars might be preserved. So that’s what we’re going to try and do.


Science Fact, Not Fiction: Isaac Asimov on the Greenhouse Effect

Monday, January 10th, 2011

By Amber Jenkins

I stumbled upon this video earlier today. It’s Isaac Asimov, famous science fiction writer and biochemist, talking about global warming — back in January 1989. If you change the coloring of the video, the facial hair style, and switch out Asimov for someone else, the video could pretty much have been made today.

Asimov was giving the keynote address at the first annual meeting of The Humanist Institute. “They wanted me to pick out the most important scientific event of 1988. And I really thought that the most important scientific event of 1988 will only be recognized sometime in the future when you get a little perspective.”

What he was talking about was the greenhouse effect, which, he goes on to explain, is “the story everyone started talking about [in 1988], just because there was a hot summer and a drought.” (Sound familiar, letting individual weather events drive talk of whether the Earth’s long-term climate is heating up or cooling down??)

The greenhouse effect explains how certain heat-trapping (a.k.a. “greenhouse”) gases in our atmosphere keep our planet warm, by trapping infrared rays that Earth would otherwise reflect back out into space. The natural greenhouse effect makes Earth habitable — without our atmosphere acting like an electric blanket, the surface of the earth would be about 30 degrees Celsius cooler than it is now.

The problem comes in when humans tinker with this natural state of affairs. Our burning of fossil fuels (coal, oil and gas) constantly pumps out carbon dioxide — a heat-trapping gas — into the atmosphere. Our cutting down of forests reduces the number of trees there are to soak up some of this extra carbon dioxide. All in all, our atmosphere and planet heats up, (by about 0.6 degrees Celsius since the Industrial Revolution) with the electric blanket getting gradually thicker around us.

“I have been talking about the greenhouse effect for 20 years at least,” says Asimov in the video. “And there are other people who have talked about it before I did. I didn’t invent it.” As we’ve stressed here recently, global warming, and the idea that humans can change the climate, is not new.

As one blogger notes, Asimov’s words are as relevant today as they were in 1989. “It’s almost like nothing has happened in all this time.” Except that Isaac Asimov has come and gone, and the climate change he spoke of is continuing.

Asimov’s full speech can be seen here.

This post was written for “My Big Fat Planet,” a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.


Unchained Goddess: Frank Capra Knew

Monday, December 6th, 2010

By Amber Jenkins

a screen grab from The Unchained Goddess

You might think from the amount of “climate science debate” that is given airtime in the U.S. media that it’s undiscovered territory. But it’s not. The science is very well established and goes back a long way. Global warming is not a new concept.

The Victorians knew about it. John Tyndall (born 1820) knew about it. So did Svante August Arrhenius. In April 1896, Arrhenius published a paper in the London, Edinburgh and Dublin Philosophical Magazine and Journal of Science entitled “On the influence of carbonic acid in the air upon the temperature of the ground.” (Arrhenius referred to carbon dioxide as “carbonic acid” in accordance with the convention of the time.)

Arrhenius’ paper was the first to quantify how carbon dioxide contributed to the greenhouse effect — carbon dioxide warms up the Earth by trapping heat near the surface, a bit like swaddling the planet in an extra blanket. Arrhenius was also the first to speculate about whether changes in the amount of carbon dioxide in the atmosphere have contributed to long-term variations in Earth’s climate. He later made the link between burning fossil fuels and global warming.

Another person who “knew” some time ago was Frank Capra. Graduating from Caltech in 1918, he went on to become a famous filmmaker responsible for “It’s a Wonderful Life” and other movies. But one that stands out, at least for nerds like me or people with an interest in climate change is “Meteora: The Unchained Goddess”, released in 1958:

Made for Bell Labs, this most awesome educational film speaks of “extremely dangerous questions”:

Dr. Frank C. Baxter: “Because with our present knowledge we have no idea what would happen. Even now, man may be unwittingly changing the world’s climate through the waste products of his civilization. Due to our release through factories and automobiles every year of more than six billion tons of carbon dioxide, which helps air absorb heat from the sun, our atmosphere seems to be getting warmer.”

Richard Carlson: “This is bad?”

Dr. Frank C. Baxter: “Well, it’s been calculated a few degrees rise in the Earth’s temperature would melt the polar ice caps. And if this happens, an inland sea would fill a good portion of the Mississippi valley. Tourists in glass bottom boats would be viewing the drowned towers of Miami through 150 feet of tropical water. For in weather, we’re not only dealing with forces of a far greater variety than even the atomic physicist encounters, but with life itself.”

In 1958, they knew about the effects of heating up the planet. In the 1800s they knew about it. Today, the biggest challenge facing climate scientists lies in predicting how much our climate will change in the future. It’s not a trivial task, given how complicated the climate system is — we can barely predict in detail more than a week’s worth of weather. We’re not viewing Miami through bottomed-glass boats yet, but we’re already beginning to see some of the predictions of global warming — melting sea and land ice, sea level rise, more extreme weather events, changes in rainfall and effects on plants and animals — be borne out.

Thanks to OSS and Discovery News for the tip.

This post was written for “My Big Fat Planet,” a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.


Pulling for the Deniers — Place Your Bets

Friday, November 12th, 2010

By Ed Begley Jr.

Ed Begley Jr.
A guest blog written for My Big Fat Planet by Ed Begley Jr.

 

I visit the NASA website and review the data. CO2: Up. Ocean and land temperature: Up. Sea level: Up. Polar ice: Down.

Oops.

But, as bizarre as this sounds … I find myself pulling for the climate change deniers. Wouldn’t it be swell if they were right? We could all just relax and ride around in huge cars, and life would be good again.

Like it was in 1970 when I showed up at the first Earth Day. Oh, wait. The smog kind of sucked back then. That might not be the best example.

But, what about the main reason the deniers give not to address climate change?: The cost.

As it turns out, a great example can be found back in smoggy Los Angeles in 1970. Many of us wanted to do something about the horrible choking smog of that era. But, we were told we couldn’t afford it.

“We’d love to do something too, Ed, but … the cost!” Fortunately, we didn’t listen to them. Fortunately we also weighed healthcare costs and lost productivity into the equation, and realized the cost of doing nothing was much greater.

And, now, even though we have millions more people in L.A., and four times the cars … we have far less smog. And, there were many jobs and tremendous wealth created by doing the things that addressed the problem.

Making catalytic converters, combined cycle gas turbines, spray paint booths, and a myriad of other clean technologies of that day - they all created new industries, and brought growth with them.

We have that same choice today. Do we want to accept the costs of doing nothing, and hope that the problem goes away?

So, please, do as I do, and direct everyone you know to reputable sources of climate data, such as NASA’s Global Climate Change website. At every talk I give, I make sure that everyone is aware that this information if available. The clock is ticking, and to ignore the science on this one is the worst bet we have ever placed.

Ed Begley Jr. is an Emmy-nominated actor who is active in the environmental community and turns up to Hollywood events on his bicycle. He currently lives near Los Angeles in a self-sufficient home powered by solar energy.


Taking On Water Resource Issues

Friday, October 15th, 2010

By Stephanie Granger

water resources

Worldwide today, it is estimated that nearly 1.1 billion people live without access to adequate water supplies and about 2.6 billion people lack adequate water sanitation. Improved understanding of water processes at global and regional scales is essential for sustainability.

Researchers at JPL recently launched the Western Water Resource Solutions website to highlight activities that apply NASA expertise and data to water resource issues in the western United States.

One focus area for this new site is the hydrologic cycle and using global satellite observations of the Earth to improve our understanding of water processes on a regional and local level. The western United States is expected to bear the brunt of impacts to water resource availability because of changing precipitation patterns, increasing temperatures, and a growing population. California is already starting to feel the impacts and is taking action to develop new adaptive management practices to ensure a safe and reliable water supply, while maintaining healthy ecosystems throughout the state.

NASA researchers at Ames Research Center, the Jet Propulsion Laboratory, and Marshall Space Flight Center are currently working with water managers to apply NASA expertise and data to water resource issues in California. The project partners with universities, agencies and other stakeholders, to utilize information from a number of sources, including existing ground observations and models.

This project is only one of several NASA initiatives aimed at providing actionable scientific information on water quality and the water balance worldwide. These other projects include development of better estimates of snow pack, groundwater monitoring, soil moisture and evapotranspiration, water quality, and monitoring fragile levee systems.

In addition to raising awareness about current water resource challenges, the new website highlights NASA’s capability to use satellite and airborne data to help solve some of these challenges.

Learn more about the Western Water Resource Solution Group at: http://water.jpl.nasa.gov/


Written as part of Blog Action Day 2010


2012 - A Scientific Reality Check

Tuesday, November 10th, 2009
Donald Yeomans
Donald Yeomans

There apparently is a great deal of interest in celestial bodies, and their locations and trajectories at the end of the calendar year 2012. Now, I for one love a good book or movie as much as the next guy. But the stuff flying around through cyberspace, TV and the movies is not based on science. There is even a fake NASA news release out there… So here is the scientific reality on the celestial happenings in the year 2012.

Nibiru, a purported large object headed toward Earth, simply put - does not exist. There is no credible evidence - telescopic or otherwise - for this object’s existence. There is also no evidence of any kind for its gravitational effects upon bodies in our solar system.

I do however like the name Nibiru. If I ever get a pet goldflish (and I just may do that sometime in early 2013), Nibiru will be at the top of my list.

The Mayan calendar does not end in December 2012. Just as the calendar you have on your kitchen wall does not cease to exist after December 31, the Mayan calendar does not cease to exist on December 21, 2012. This date is the end of the Mayan long-count period, but then – just as your calendar begins again on January 1 - another long-count period begins for the Mayan calendar.

The Galileo spacecraft's view of the Moon and Earth
On December 16, 1992, 8 days after its encounter with Earth, the Galileo spacecraft looked back from a distance of about 6.2 million kilometers (3.9 million miles) to capture this remarkable view of the Moon in orbit about Earth. Image credit: NASA/JPL
› Full image and caption

There are no credible predictions for worrisome astronomical events in 2012. The activity of the sun is cyclical with a period of roughly 11 years and the time of the next solar maximum is predicted to occur about May 2013. However, the Earth routinely experiences these periods of increased solar activity – for eons - without worrisome effects. The Earth’s magnetic field, which deflects charged particles from the sun, does reverse polarity on time scales of about 400,000 years but there is no evidence that a reversal, which takes thousands of years to occur, will begin in 2012. Even if this several thousand year-long magnetic field reversal were to begin, that would not affect the Earth’s rotation nor would it affect the direction of the Earth’s rotation axis… only Superman can do that.

The only important gravitational tugs experienced by the Earth are due to the moon and sun. There are no planetary alignments in the next few decades, Earth will not cross the galactic plane in 2012, and even if these alignments were to occur, their effects on the Earth would be negligible. Each December the Earth and Sun align with the approximate center of the Milky Way Galaxy but that is an annual event of no consequence.

The predictions of doomsday or dramatic changes on December 21, 2012 are all false. Incorrect doomsday predictions have taken place several times in each of the past several centuries. Readers should bear in mind what Carl Sagan noted several years ago; “extraordinary claims require extraordinary evidence.”

For any claims of disaster or dramatic changes in 2012, the burden of proof is on the people making these claims. Where is the science? Where is the evidence? There is none, and all the passionate, persistent and profitable assertions, whether they are made in books, movies, documentaries or over the Internet, cannot change that simple fact. There is no credible evidence for any of the assertions made in support of unusual events taking place in December 2012.

For more information on the silliness surrounding December 2012, see:


Tackling Clouds for Improved Predictions of Future Climate

Thursday, October 15th, 2009

Blog Action Day

Today, JPL Earth scientist Hui Su joins thousands of other bloggers in more than 130 countries around the world for the Blog Action Day ‘09 Climate Change.

Blog Action Day is an annual event that unites the world’s bloggers in posting about the same issue on the same day, with the aim of sparking discussion around an issue of global importance. The theme of this year’s event, climate change, affects us all and will be the topic of international climate negotiations taking place in Copenhagen, Denmark, this December.

As a world leader in studying Earth’s climate, NASA researchers play a vital role in shaping our understanding of global change. In today’s post, Su discusses the critical role clouds play in climate, and why learning more about them is a key to predicting how our climate will change in the future.

For more information on Blog Action Day, visit: http://www.blogactionday.org .


Hui Su
Hui Su

Clouds are among the most fascinating natural phenomena and have inspired countless works of literature and art. Their ever-changing forms make them a great challenge to atmospheric scientists working to predict how our climate will change in the future in response to increasing greenhouse gases such as carbon dioxide.

Clouds occur at many different heights in our atmosphere and take many different forms. There are three main types of clouds: stratus, cumulus and cirrus. Stratus clouds are low clouds, usually within 2 kilometers (7,000 feet) above the surface. They look like a gray blanket, extending thousands of kilometers across the sky. Cumulus clouds look like puffy cotton balls and extend vertically for large distances. The third type is wispy and feathery-looking cirrus. Cirrus clouds are usually high in the sky, about 7 kilometers (23,000 feet) above the surface. These three types of clouds have different impacts on Earth’s climate due to their unique abilities to reflect sunlight and trap heat radiated from Earth’s surface.

Artist's concept of NASA's CloudSat spacecraft
Artist’s concept of NASA’s CloudSat spacecraft, which is providing the first global survey of cloud properties to better understand their effects on both weather and climate. Image credit: NASA/JPL

cirrus cloud diagram
Su et al. (2008, Journal of Geophysical Research) suggested that cirrus clouds increase as sea surface temperature becomes warmer, further enhancing surface warming. Image credit: NASA/JPL/Caltech
› Full image

Stratus clouds can effectively block sunlight from reaching the surface; therefore, they act as an umbrella that cools Earth. Cirrus clouds are relatively transparent to sunlight but can trap terrestrial radiation, JUST AS carbon dioxide does, so they have a net warming effect on Earth. Cumulus clouds can block sunlight and also trap terrestrial radiation. Their net effect varies greatly depending on their actual heights and thicknesses.

Climate scientists have long struggled to quantify how different types of clouds change when global warming occurs. For example, an increase in stratus clouds may cool Earth’s surface, compensating for global warming; while an increase in cirrus clouds may further warm Earth’s surface, exacerbating global warming. Up to now, scientists have not been able to come to a consensus as to whether stratus, cumulus or cirrus clouds will increase or decrease as global temperatures increase.

A key advancement in cloud studies in recent years has been the availability of global satellite observations of clouds, especially the measurements of clouds at different heights provided by NASA satellites like CloudSat, managed by NASA’s Jet Propulsion Laboratory (JPL). These observations are allowing scientists to better simulate clouds in climate models, which are the primary tools climate scientists use to predict future climate change. Up till now, the dynamic nature of clouds has made them very difficult to simulate in current climate models. But by applying space data, we at JPL are working closely with modelers to improve cloud simulations and thereby improve predictions of future climate change.

To learn more about JPL’s research in this field and the CloudSat mission, visit:
http://cloudsat.atmos.colostate.edu/home .


Five Things About Hurricanes

Wednesday, July 1st, 2009
Bjorn Lambrigtsen
Bjorn Lambrigtsen

JPL scientist Bjorn Lambrigtsen goes on hurricane watch every June. He is part of a large effort to track hurricanes and understand what powers them. Lambrigtsen specializes in the field of microwave instruments, which fly aboard research planes and spacecraft, penetrating through thick clouds to see the heart of a hurricane.

While scientists are adept at predicting where these powerful storms will hit land, there are crucial aspects they still need to wrench from these potentially killer storms.

Here are thoughts and factoids from Lambrigtsen in the field of hurricane research.

1. Pinpointing the moment of birth

Hurricane Gustav
Hurricane Gustav moved along the southern side of Jamaica on Aug. 29, 2008. Image credit: NASA MODIS Rapid Response

Most Atlantic hurricanes start as a collection of thunderstorms off the coast of Africa. These storm clusters move across the Atlantic, ending up in the Caribbean, Gulf of Mexico or Central America. While only one in 10 of these clusters evolve into hurricanes, scientists do not yet know what triggers this powerful transformation.

Pinpointing a hurricane’s origin will be a major goal of a joint field campaign in 2010 between NASA and the National Oceanic and Atmospheric Administration (NOAA).

2. Predicting intensity

Another focus of next year’s research campaign will be learning how to better predict a storm’s intensity. It is difficult for emergency personnel and the public to gauge storm preparations when they don’t know if the storm will be mild or one with tremendous force. NASA’s uncrewed Global Hawk will be added to the 2010 research armada. This drone airplane, which can fly for 30 straight hours, will provide an unprecedented long-duration view of hurricanes in action, giving a window into what fuels storm intensity.

3. Deadly force raining down

Think about a hurricane. You imagine high, gusting winds and pounding waves. However, one of the deadliest hurricanes in recent history was one that parked itself over Central America in October 1998 and dumped torrential rain. Even with diminished winds, rain from Hurricane Mitch reached a rate of more than 4 inches per hour. This caused catastrophic floods and landslides throughout the region.

4. Replenishing “spring”

Even though hurricanes can wreak havoc, they also carry out the important task of replenishing the freshwater supply along the Florida and southeastern U.S. coast and Gulf of Mexico. The freshwater deposited is good for the fish and the ecological environment.

5. One size doesn’t fit all

Hurricanes come in a huge a variety of sizes. Massive ones can cover the entire Gulf of Mexico (about 1,000 miles across), while others are just as deadly at only 100 miles across. This is a mystery scientists are still trying to unravel.

NASA and NOAA conduct joint field campaigns to study hurricanes. The agencies use research planes to fly through and above hurricanes, and scientists collect data from NASA spacecraft that fly overhead. NOAA, along with its National Hurricane Center, is the U.S. government agency tasked with hurricane forecasting.

For more information on how NASA and JPL study hurricanes, go to www.nasa.gov/hurricane and http://tropicalcyclone.jpl.nasa.gov


Good and Bad Ozone

Thursday, April 23rd, 2009
Chris Boxe
by Chris Boxe
Scientist and Engineer

Oxygen, or O2 on the table of chemical elements, is a vital component for life on Earth. It is the second most abundant gas in Earth’s atmosphere, making up about 21 percent of its volume. On the other hand, its cousin ozone (O3) makes up less than 0.00001 percent. In fact, if all the ozone in Earth’s atmosphere were brought down to the surface, air pressure and temperature conditions would compress ozone into a layer just three millimeters thick, equivalent to two pennies stacked one on top of the other. ! Despite its tiny amount, ozone is also a vital ingredient for life on Earth.

Ozone in fact is vital for life on Earth, but it also has a “bad” side as well - that is, there is both good and bad ozone out there. Good ozone, which accounts for about 91 percent of the ozone in Earth’s atmosphere, is present in the stratosphere, the middle layer in Earth’s atmosphere. This portion of ozone is commonly referred to as the “ozone layer.” The ozone layer absorbs more than 90 percent of the sun’s high-frequency ultraviolet light, which is potentially damaging to life on Earth. Without the ozone layer, this radiation would not be filtered as it reaches the surface of Earth, resulting in detrimental health effects for life on Earth. Among the health effects humans could experience as a result of overexposure to ultraviolet radiation are skin cancers, premature aging of the skin and other skin problems, cataracts and other forms of eye damage, and suppression of our bodies’ immune systems and our skin’s natural defenses.

The troposphere, the part of the atmosphere closest to Earth, contains both good and bad ozone. In the lower troposphere, ozone may serve as an air pollutant since it is a major component of photochemical smog. In the middle troposphere, ozone acts as an atmospheric cleanser, and in the upper troposphere, ozone is a greenhouse gas, which could be bad if concentrations get too high.

artist concept of NASA's Aura spacecraft
The Tropospheric Emission Spectrometer flies aboard NASA’s Aura spacecraft. Image credit: NASA JPL

The Tropospheric Emission Spectrometer, a science instrument onboard NASA’s Aura satellite, is improving our understanding of the good and bad ozone in the troposphere. The spectrometer, which was launched in 2004, provides the first global view of tropospheric ozone and vertical concentrations of ozone, as well as temperature and other important tropospheric features, including carbon monoxide (CO), methane (CH4), water vapor and ammonia (NH3). The instrument has studied the origin and distribution of tropospheric ozone. It has also shed light on how the increasing ozone abundance in the troposphere is affecting air quality on a global scale, as well as ozone’s role in chemical reactions that “clean” the atmosphere, and climate change.

These data are used by scientists to determine the degree to which natural sources, like lightning and plant growth, and human-produced sources, like automobiles, industrial pollution, and biomass burning, contribute to ozone production and chemistry. For example, during summertime in the upper troposphere, where ozone acts as a greenhouse gas, lightning generates much greater amounts of ozone than do human activities, thereby having a big impact on regional pollution. Over the last few years, the spectrometer has obtained global data on ozone and chemicals that participate in ozone formation. The fact that the instrument is able to quantify vertical profiles of ozone improves our understanding of how various reactions taking place at specified heights contribute to ozone chemistry. Similar to ozone, chemicals that participate in its production also exist in tiny amounts. Still, this enables scientists to better understand long-term variations in the quantity, distribution and mixing of many tropospheric gases that have a large impact on climate and air quality.

My role with the instrument is to validate the quality of the most recent ozone measurements, which are taken in a special observation mode, called “stare.” This mode is used to monitor biomass burning events and volcanic activity. I compare measurements taken by an ozonesdone (a lightweight, balloon-borne instrument that measures ozone, air pressure, temperature and humidity as it ascends through the atmosphere) with measurements from the tropospheric spectrometer. We do this so we can demonstrate the accuracy and precision of the instrument’s readings. I am also participating in projects that use the instrument data to better understand the chemistry and transport of pollutants coming from wildfires, such as those that occurred in Australia in December 2006. For the future, I am interested in using the tropospheric spectrometer satellite data for ozone and methane to better quantify the degree to which they contribute to global warming and climate change.


Oceans Up Close - From Space

Thursday, April 2nd, 2009
Jorge Vazquez
by Jorge Vazquez
Oceanographer

Not all oceanographers spend their time out on the seas. As a project scientist for the Physical Oceanography Distributed Active Archive Center here at JPL , I study the world’s ocean from my computer, using data from a series of NASA satellites that orbit Earth. These data measure everything from how the ocean changes during an El Nino to how such climatic changes affect local regions like California’s coast.

This kind of precise data was impossible 100 years ago. In fact, scientific and technological advances over the last century have revolutionized the field of oceanography. Today, we gather data both from instruments in the ocean and from satellites in space. These satellite data measure changes in sea surface topography (the ocean surface has changes in elevation, just like the land), ocean surface winds, sea surface temperature and water pressure at the bottom of the ocean. The satellites view the ocean from 700 to 1,300 kilometers (440 to 800 miles) above Earth. Current advanced technologies allow scientists to combine data from different satellites to view ocean conditions in near-real time, only 6 to 12 hours from when the satellite acquires the data. This information can then be sent to researchers and decision makers for use in improving forecasts for hurricanes to the regional and local impacts of ocean phenomena like El Nino and La Nina.

The image shows temperatures off the coast of California in September of 1997 (El Nino).
Image above: Sea surface temperatures in 1997 during El Nino and in 2008, when the waters had returned to more normal conditions.Image credit: NOAA

Examples of satellite data can be seen in these images. The view on the left shows temperatures off the coast of California in September of 1997 (El Nino). On the right, sea surface temperatures from September of 2008 (normal conditions). Notice the warmer temperatures (seen in red) resulting from the 1997-1998 El Nino event. Such temperature changes have direct impacts on local climate and fisheries. These data are leading to a new understanding of how hurricanes get their energy from the ocean. These satellite data also help forecast regional ocean temperatures, which affect local weather.

As technology improves, along with the availability of these data in real time, new opportunities will continue to expand to better understand our planet and its impacts on our lives.


Thoughts After Launch

Tuesday, February 24th, 2009
Randy Pollock
by Randy Pollock
Lead Instrument Systems Engineer

A few hours ago I had the privilege to watch the Orbiting Carbon Observatory launch from Vandenberg Air Force Base. The creativity, effort and dedication of many, many people were sitting on the launch pad. Many of the people who had worked so hard to get the mission to the pad were in attendance with family and friends there to share in the excitement. The weather was perfect. Cold enough to make the stars seems to be just out of reach, still enough to be pleasant to stand outside waiting for the main event. As it got closer, hundreds of voices followed along the magic of the countdown - “10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 - Liftoff!”. The rocket cleared the pad - rising on a column of intense white light. At our distance, it seemed to rise forever before the roar finally reached us. In the dark, clear sky we could watch the various stages burn out, fall back and be replaced by the ignition of the next state. Everything seemed to be going perfectly.

We got on the buses to leave the viewing area, excited by what we witnessed and excited by the mission to come. Both feelings did not last long. Soon text messages and phone calls started to disturb the darkened buses. Within a few minutes, it was clear that the launch had not gone as well as we thought. By the time we got off the buses, it looked grim. In the next couple of hours, it became clear that the rocket failed and we never achieved orbit.

Oddly, hearing that the spacecraft hit the ocean near Antarctica made it worse. I had this vision of the system orbiting the Earth - dead and mute - like a modern day Flying Dutchman. Knowing that the hardware I helped design and build had been destroyed on impact made the loss real.

Artist concept of Orbiting Carbon Observatory
Artist concept of Orbiting Carbon Observatory. Image credit: NASA/JPL.

Almost 10 years ago, I was working with a scientist who was also supporting the Mars lander that was lost in 1999. The day after it failed, she told me to always try to enjoy the intellectual challenge of designing a mission and the hardware to make it possible. At the end of the day, that might be all you get. Since then, she has been involved in the incredibly successful Mars Exploration Rovers and the Phoenix lander. She is working to prepare the Mars Science Laboratory for its 2011 launch.

I hope that her past is my prologue. I hope that the next 10 years bring a productive series of missions to advance our understanding of the carbon cycle - much as the recent Mars missions have advanced our understanding of our solar system’s history.


Counting Carbon

Friday, February 20th, 2009
Randy Pollock
by Randy Pollock
Lead Instrument Systems Engineer

Imagine if you could scoop exactly one million molecules out of the air in front of you (while being careful not to grab any water vapor). Now, start sorting these molecules into different piles. Start with the two most common molecules and you’ve sorted 99 percent of your sample — the nitrogen pile will have about 780,000 molecules, and oxygen pile will have about 210,000 molecules. Working on the third most common molecule, argon, gets you a new pile with about 9,000 molecules. Congratulations, you’ve sorted 99.9 percent of the molecules into just three piles. The remaining 1,000 molecules are called “trace gases.” The most famous and the most common trace gas is carbon dioxide, or CO2. Out of the million you had at the beginning, you’ll count about 385 CO2 molecules.

Now, imagine repeating this experiment 12 times per second while flying over Earth at more than 16,000 miles per hour. Each of those counts needs to be accurate enough to note the addition or subtraction of one molecule of CO2 per one million of air. This is the experiment that a group of scientists and engineers at NASA’s Jet Propulsion Laboratory conceived almost 10 years ago. We call it the Orbiting Carbon Observatory, and it is now at the launch pad waiting for its ride into space.

The heart of the mission is a very accurate instrument — called a “spectrometer” — tuned to sense the presence of CO2. A spectrometer is a type of camera that splits incoming light into hundreds of different colors and then measures the amount of light in each of these colors. In the case of this mission, the spectrometer measures sunlight that has passed through the atmosphere twice: once on the way down to the surface, and then again on the way up to the orbiting spacecraft. When the light passes through air containing CO2, certain colors are absorbed. The spectrometer creates an image with dark bands where the sunlight is partially or completely missing. This image looks similar to a barcode. Encoded in that barcode is the information to infer how many CO2 molecules the sunlight encountered on its way to the spacecraft.

Artist concept of Orbiting Carbon Observatory
Artist concept of Orbiting Carbon Observatory. Image credit: NASA/JPL.

I joined the project in early 2001 as the lead engineer for the spectrometer. In the eight years that have followed, we’ve gone from an idea to a fully built and tested system sitting on top of a rocket, ready for launch. Along the way, a group of talented people has put in countless hours designing, building, and testing the system. When doing something for the first time, there are always issues that come up — some of which look insurmountable at the time. It’s been a challenge, but the hard work and creativity of our team saw us through all of them.

Now we are waiting for the payoff — the first data from space. We’ve done everything we can to be ready. Now, launch awaits …


Sizing Up Near-Earth Asteroids

Wednesday, November 12th, 2008
author
by Amy Mainzer
Scientist and Engineer

Asteroids. The word conjures images of pitted rocks zooming through space, the cratered surfaces of planets and moons, and for some, memories of a primitive video game. Just how hazardous are these nearest neighbors of ours? We think that one contributed to the extinction of the dinosaurs, giving rise to the age of mammals. How likely is this to happen again?

The Wide-field Infrared Explorer (WISE) mission, an infrared telescope launching in about a year, will observe hundreds of near-Earth asteroids, offering unique insights into this question. The risk posed by hazardous asteroids is critically dependent on how many there are of different sizes. We know that there are more small asteroids than large ones, but how many more, and what are they made of?

Asteroids reflect sunlight (about half of which is the visible light that humans see), but the sun also warms them up, making them glow brightly in infrared light. The problem with observing asteroids in visible light alone is that it is difficult to distinguish between asteroids that are small and highly reflective, or large and dark. Both types of objects, when seen as distant points of light, can appear equally bright in visible light. However, by using infrared light to observe asteroids, we obtain a much more accurate measurement of their size. This is because the infrared light given off by most asteroids doesn’t depend strongly on reflectivity.

asteroid
This image of near-Earth asteroid 433 Eros reveals that its ancient surface has been scarred by numerous collisions with other small objects. Image credit: NASA/JPL/JHUAPL

WISE will give us a much more accurate understanding of how many near-Earth asteroids there are of different sizes, allowing astronomers to better assess the hazard posed by asteroids. The danger posed by a near-Earth asteroid depends not only on its size, but also on its composition. An asteroid made of dense metals is more dangerous than one of the same size made mostly of less dense silicates. By combining infrared and visible measurements, we can determine how reflective the asteroids are, which gives us some indication of their composition.

 

 

 


Shakeout for Southern California

Wednesday, October 22nd, 2008
author
by Maggi Glasscoe
Geophysicist

For those of us living in southern California, the risk of earthquakes is a constant fact of life. In fact, small earthquakes occur daily, we simply may not notice them. It’s the larger, more damaging earthquakes that are cause for concern. The infamous San Andreas fault twists its way through much of California, posing significant risk to southern and northern California both-- and as many scientists have said, it’s not a question of if, it’s a question of when, a large earthquake will occur.

Even though the risk of earthquakes is always present, I am sure most people are not thinking about this on the way to work, or as they are watching TV at night, or just generally going about their daily lives. Establishing an earthquake preparedness plan probably doesn’t even come to mind, except possibly when there is a major earthquake elsewhere, or a minor earthquake nearby.

We here at JPL are working on ways to extend our ability to forecast earthquakes. We are combining the state of the art in high performance computing resources and modeling software with satellite observations made from space of small scale motion on Earth. This will enhance our understanding of the fundamental earthquake processes. With projects like NASA/JPL’s QuakeSim, which aims to improve our ability to forecast earthquakes, much as we do the weather, we will also be able to help prepare ourselves for the inevitable.

san andreas
This is a portion of the 1,200-kilometer (800-mile) San Andreas fault, the longest fault in California. Image credit: NASA/JPL

Unfortunately, should a large earthquake catch us unprepared-- and remember, it’s not a question of if, it’s a question of when-- this could have disastrous consequences. According to FEMA, the annualized loss due to earthquakes is $5.3 billion per year, with 66% ($3.5 billion) concentrated in the state of California alone. A moderate-sized earthquake in the metropolitan Los Angeles region could lead to loss of vital infrastructure-- water via the aqueduct, freeways, possibly even the ports or the airports, rendering us isolated and without resources for not days, but possibly months.

We are told to be prepared in case of an earthquake with 72 hours’ worth of water and food and other necessary emergency provisions. That will certainly see us through the first few days, but if the vital infrastructural resources like our water distribution, sewers, freeways, and other pipelines are taken out, we could be looking at much more than 72 hours without proper services, especially water and power. Are you prepared for such a circumstance?

On November 13, 2008, the United States Geological Survey will lead a disaster preparedness scenario called “The Great Southern California Shakeout.” It will be based on a magnitude 7.8 earthquake along the southern San Andreas fault. Shaking from an earthquake of this size is projected to last up to two minutes, and the modeling that they have done has predicted that sediments in the various basins around the Los Angeles area will trap and magnify seismic waves, amplifying ground motions, much like what occurred in the Northridge earthquake. (To learn more about the “Great Shakeout,” please visit: www.shakeout.org)

This earthquake scenario will also be the basis for the statewide emergency response exercise, Golden Guardian 2008. These complementary exercises are meant to demonstrate our ability to deal with an earthquake scenario in which there would be 1800 deaths, 50,000 injuries, and $200 billion in damage. An earthquake of this magnitude could produce destruction on the scale of the recent Gulf Coast hurricanes or worse.

One thing to keep in mind, though, is that we need to be proactive, rather than simply reactive. That way, when the inevitable moderate to large earthquake does hit, we will be as ready as we can be to deal with it. Exercises like the ShakeOut certainly help to keep the community more aware of the ever-present risk of earthquakes, but we as individuals also need to take the time to make sure that we are disaster prepared as well. That way we can be not only prepared, but resilient.


The Chemistry of Snow - by Christoper Boxe

Thursday, August 21st, 2008

snow
This graphic illustrates the path of ozone-damaging molecules at Earth’s poles. Image credit: NASA-JPL

Remember the warning to beware of yellow snow? Well, what’s true in your backyard is true on a much larger scale too. (For those from warmer climates, yellow-tinted snow is a sign that a dog or other animal has recently “paid a visit.”)

Snow at Earth’s north and south poles can also be tainted. Certain molecules — ones that can eventually damage our protective ozone layer in the stratosphere, affect the air down in the troposphere where we live, and possibly contribute to climate change — are being deposited into the snow.

Just how is this happening? Start with the fact that air at lower latitudes circulates toward the poles. This air carries ozone-damaging molecules picked up in industrial, highly populated areas. Once over the poles, some of these molecules are deposited onto the snowpack, where they migrate to thin liquid films in snow. Once sunlight hits the snow, the light energy breaks down these molecules, which are then released back into the atmosphere, giving the area over the poles a double hit of ozone-damaging molecules.

Scientists are finding that snow has unique properties that make these chemical reactions happen much faster than we used to believe. We don’t fully understand why this is happening, but we know that the mixture of sun (an energy source) and snow bring about the release of these ozone-damaging molecules into the atmosphere much faster than in areas without snow.

Many of the polluting molecules that remain in the snow eventually get incorporated in the polar food chain. When the snow melts into the sea, the molecules may be ingested by sea creatures. Not all of them are unhealthy, but some of them are.

Why care about reactions going on in distant, frozen expanses at Earth’s poles? Those regions are a beacon of climate change, where we see chemical processes that may play a large role in the planet’s future.


It’s a Sure Bet - by Josh Willis

Wednesday, August 13th, 2008

Chips

My wife likes to gamble. She’s no high roller or anything, but give her a hundred dollars, a spare weekend and a room full of slot machines and she’s happy.

Not me, though. Somewhere along the way, I guess I took one too many math classes and betting against the house just isn’t much fun anymore.

But I understand why she likes it. It’s the ups and downs of gambling that are fun. You lose, lose, lose and then every once in a while you win a great big jackpot. Maybe you even win enough to make up for the last 30 or 40 bets you lost. But like any game in the casino, the odds are stacked against you. If you play long enough, you will eventually lose.

Global warming and climate change work in much the same way. Wait long enough and odds are, the Earth will be warmer. But will tomorrow be warmer than today? Who knows! There are plenty of things about the atmosphere and ocean that can’t be predicted. Over a period of days or weeks, we call these unpredictable changes “the weather.”

No one can predict the weather more than a few days in advance, any more than they can predict which slot the roulette ball will land in before the croupier spins it. Weather, like roulette, is essentially random.

But a little randomness doesn’t stop casino owners from taking your bet at the roulette table. They know the odds, and they know if enough bets are laid they will eventually come out ahead. Climate scientists know that, too.

Random events happen in the atmosphere and oceans all the time. Not just the weather, but things like El Nino, La Nina and huge volcanic eruptions can make the planet warm up or cool down for years at time. There could even be a few others that we haven’t discovered yet.

Still, for all its short-term ups and downs Earth’s average temperature has risen dramatically over the last one hundred years. That’s no accident. Like the house edge at the roulette table, human-made greenhouse gasses have tilted the odds in favor of a warming planet.

Graph
This graph shows Earth’s global temperature has been in an upward swing overall for more than 100 years. Image credit: Goddard Institue for Space Studies

Sometimes it’s easy to forget that fact when new science results come out. Like the recreational gambler, we often find it more fun to focus on the ups and downs: a short-term cooling period, a warm year during a big El Nino.

But for climate change and casino owners, it’s important to remember the big picture. The roulette player might win three or four bets in a row, but that doesn’t change the odds. Eventually the casino will win. Likewise, as long as humans continue to add carbon dioxide to the atmosphere, the planet will continue to warm.

So whenever people ask me about the latest warming or cooling in the climate record, I’m always reminded of my wife and her slot machines. By the end of the weekend her hundred dollars is almost always gone, but the thrill of the ups and downs kept her entertained for the entire time. “Did you win?” people ask. She always flashes her sly smile and says, “Sometimes!”