Category Archives: High-Adventure Science

Transpire Locally, Cool Globally

As plants grow, they transpire, releasing water into the atmosphere.  During the summer in a city, trees help to cool the immediate surroundings through transpiration.

New research from Carnegie’s Global Ecology department, published last month in Environmental Research Letters, concludes that transpiration has a global effect as well.

How does this happen?  Water vapor is a greenhouse gas, so one might expect that more water vapor in the atmosphere would lead to higher temperatures.

But water vapor also condenses into clouds, which reflect sunlight, resulting in a cooling effect.  The increased transpiration from plants, combined with evaporation from bodies of water, results in lower-level clouds.  Lower clouds tend to reflect more sunlight, hence the cooling effect.

So you can plant trees locally, reap the cooling effect locally, and also help to cool globally!

Learn more about the relationship between clouds and climate in the High-Adventure Science climate investigation.

Pumice: Islands of Life?

Pumice, a type of volcanic rock, is so porous that it floats on water, as shown in the picture below.

Now researchers from Oxford University and the University of Western Australia are suggesting that life on Earth could have formed on floating rafts of pumice.

The researchers argue that pumice has a unique set of properties which would have made it an ideal habitat for the earliest organisms that emerged on Earth over 3.5 billion years ago.

‘Not only does pumice float as rafts but it has the highest surface-area-to-volume ratio of any type of rock, is exposed to a variety of conditions, and has the remarkable ability to adsorb metals, organics and phosphates as well as hosting organic catalysts, such as zeolites,’ said Professor Martin Brasier of Oxford University’s Department of Earth Sciences who led the work with David Wacey of the University of Western Australia. ‘Taken together these properties suggest that it could have made an ideal ‘floating laboratory’ for the development of the earliest micro-organisms.’

Floating pumice could have been exposed to lightning, oily residue and metals from hydrothermal vents, and ultraviolet light.  All of these conditions have the potential to generate the kinds of chemical reactions that scientists hypothesize created the first living cells.

The scientists plan to test their hypothesis by subjecting pumice rocks with cycles of heat and radiation to see if the process creates molecules associated with life.  They also plan to examine the early fossil record for evidence of fossils in pumice.

If scientists can determine how life on Earth began, they’ll be better prepared to search for evidence of life on other planets.

Learn about the search for extraterrestrial life in the High-Adventure Science space investigation.

Irrigation and Climate Change

What does irrigation have to do with climate change?  Possibly a lot.

According to a new study from the University of Wisconsin-Madison, irrigation has increased agricultural productivity by an amount roughly equivalent to the entire agricultural output of the United States.  That’s a lot of increased productivity!

All of those growing plants take up more carbon dioxide, which could lead to slowing global warming.  But without the extra water required for irrigation, not as much carbon dioxide would be taken up by plants–and that could lead to more warming.

The study also shows quantitatively that irrigation increases productivity in a nonlinear fashion — in other words, adding even a small amount of water to a dry area can have a bigger impact than a larger amount of water in a wetter region. “More irrigation doesn’t necessarily mean more productivity,” Ozdogan says. “There are diminishing returns.”

This was already known on the field scale, he says, but is true globally as well. Interestingly, he found that, on average, worldwide irrigation is currently conducted close to the optimal level that maximizes gains. While this may be good news for current farmers, it implies limited potential for irrigation to boost future productivity even as food demands increase.

So what does this mean for us?

Be mindful of the amount of water that we use so that we can continue to irrigate fields, grow food to feed ourselves, and, along the way, reduce the amount of carbon dioxide in the atmosphere.

Learn about fresh water availability and climate change in our High-Adventure Science investigations.

Good Science/Bad Science

How can you tell when a scientific claim is bad?

Look at the results.  Compare the results from the models with what happened in real life.

An August 2010 study published in Science claimed that drought induced a decline in global plant productivity during the past decade, posing a threat to global food security.  Zhao and Running, the authors of that study, set up their model based on their expectations that global plant productivity would continue to increase, as it had in the 1980s and 1990s.

A new study has found that Zhao and Running’s 2010 model was flawed.

… According to the new study, their model failed miserably when tested against comparable ground measurements collected in these forests. “The large (28%) disagreement between the model’s predictions and ground truth imbues very little confidence in Zhao and Running’s results,” said Marcos Costa, coauthor, Professor of Agricultural Engineering at the Federal University of Viçosa and Coordinator of Global Change Research at the Ministry of Science and Technology, Brazil.

What went wrong?

The authors of the original study included poor quality data and did not test trends for statistical significance.  They also didn’t test their assumptions against real-life.  There was a 28% disagreement between the model’s results and real-life results–far too much to make for a useful model!

So what’s the lesson from all this?  Don’t trust scientists?  Don’t trust models?

No.  The lesson is that scientific progress is made when scientists question their own and each others’ assumptions about what they think should happen.

Could all of this have been avoided?  Yes, if Zhao and Running had better tested their model against real-life to remove, as much as possible, their biases from their work.

Scientists, like all other humans, make errors.  Question the basic assumptions of each claim, and see how the models hold up to a real-life test.  That’s how you’ll know when you’re dealing with good science.

Learn some good science in the High-Adventure Science investigations on climate, water, and space.

Harvesting Planets

On September 12, 2011, a team of scientists announced that the HARPS telescope has identified more than 50 new planets; this is the largest number of planets ever announced at once.

The HARPS telescope works by detecting the movement of stars.  A star with an orbiting planet will be pulled towards the planet as it orbits.  If the star moves toward and away from Earth, this movement can be detected and planets can be discovered.

Astronomers have pointed HARPS at 376 Sun-like stars, and over the past eight years, they have discovered more than 150 new planets.  At least one of the newly-discovered planets is potentially habitable; HD85512b is estimated to be only 3.6 times the mass of Earth and it orbits its star within a zone in which liquid water could exist.

The increasing precision of the new HARPS survey now allows the detection of planets under two Earth masses. HARPS is now so sensitive that it can detect radial velocity amplitudes of significantly less than 4 km/hour– less than walking speed.

“The detection of HD 85512 b is far from the limit of HARPS and demonstrates the possibility of discovering other super-Earths in the habitable zones around stars similar to the Sun,” adds Michel Mayor, of the University of Geneva, Switzerland.

This is just the beginning for finding Earth-like planets around other stars!

Learn more about planet hunting in the High-Adventure Science space investigation.

Digging into Permafrost

Permafrost, the thick layer of soil that remains frozen throughout the year, currently holds a large amount of carbon.  If the permafrost thaws, it will release the stored carbon, which could contribute to further warming.  This is not new news.

What is new is the idea that high latitude areas will become a carbon source rather than a carbon sink.  The 2007 assessment report from the Intergovernmental Panel on Climate Change suggested that the thawed permafrost would allow for greater vegetation in polar regions, leading to carbon uptake.  But a recent study published in the Proceedings of the National Academy of Sciences contradicts that assertion.

The authors of that study–Charles Koven, of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and a team of scientists from France, Canada, and the United Kingdom–used a model that took into account how carbon behaves in different layers of the ground.

But unlike earlier models, the new model includes detailed processes of how carbon accumulates in high-latitude soil over millennia, and how it’s released as permafrost thaws. Because it includes these processes, the model begins with much more carbon in the soil than previous models. It also better represents the carbon’s vulnerability to decomposition as the soil warms.

New models lead to updated forecasts on what is likely to happen to Earth’s climate.  But this isn’t the final word.  Even the latest and greatest models can be refined to make ever-better forecasts of the future.

Koven adds that there are large uncertainties in the model that need to be addressed, such as the role of nitrogen feedbacks, which affect plant growth. And he says that more research is needed to better understand the processes that cause carbon to be released in permanently frozen, seasonally frozen, and thawed soil layers.

The quest to forecast the future continues.

To learn about how carbon dioxide affects Earth’s climate, try out the High-Adventure Science climate investigation.

Raising the water table the natural way

Today’s Wall Street Journal ran a story about using beavers to raise the water table and rehabilitate natural areas.  Beavers?  How can beavers do this?

Photo by Walter Siegmund Beaver dam of Hat Lake and Hat Creek in foreground.  Bridge over Hat Creek on highway 89, Lassen Volcanic National Park.

Beavers are rodents that live in and along streams and rivers.  They gnaw down trees and build dams, which back up the rivers and streams.  The standing water behind the dam can percolate into the ground, recharging the groundwater and raising the water table.  The dams minimize flooding during the wet season and keep water from drying up during the dry season.

It’s especially important to recharge the groundwater in areas that don’t have precipitation throughout the year.  As we draw water out of the ground for our own uses, the water table falls, so much so that natural watering holes dry up.  One solution is for us to simply use less water during the dry seasons.  Another solution for humans to build dams.  Using less water is a good start (for as much as that is possible during the dry season), but we can also turn to natural sources–such as beavers–to recharge the water supply AND restore natural habitats.

“We can spend $200,000 putting wood into a stream, cabling down logs. Sometimes it works and sometimes it doesn’t.  Put in a colony of beavers and it always works.”

-Celeste Coulter, stewardship director at the North Coast Land Conservancy, a Seaside, Oregon, group that urges developers to set aside land for beavers

Learn about the science behind groundwater recharge and the water table in the High-Adventure Science investigation, “Will there be enough fresh water?”.

What makes scientists more certain?

For the past five days, Hurricane Irene affected the weather for residents on the East Coast.  For the Northeastern United States, the forecasts of the storm’s intensity turned out to be wrong; the storm weakened more than meteorologists had expected.
At the same time, the prediction of where the storm would go was very good.  Why was there such a difference between the two forecasts?
“People see that and assume we can predict everything,” National Hurricane Center senior forecaster Richard Pasch said.
“It’s frustrating when people take our forecasts verbatim and say, ‘This is where it’s going to be at this time and this is how strong it’s going to be,'” Pasch said. “Because even though the track is good it’s not certain.”
What will improve the forecasts?  More data.
The computer models that did so well as predicting the path that Irene would take use large-scale data.  “The keys to intensity changes are usually too small for big computer models,” said Georgia Tech meteorology professor Judith Curry.
Retired hurricane center director Max Mayfield says what’s needed is better real-time, small-scale information, like Doppler radar. NOAA used old propeller planes to take Doppler radar data inside Irene, but the information will be used to design better intensity forecasts in the future, he said.
With more data, meteorologists are able to make better models, which will more accurately predict the intensity of future storms.  This is applicable across all fields of science: more data leads to better models, leading to more accurate predictions of the future.

Learn about how scientists use new data to make better models of Earth’s future climate and fresh water availability with High-Adventure Science investigations.

Causality: How to Interpret Graphs

Graphs are often used to show data; they provide a very powerful way to show numerical trends.  But graphs can also be done poorly and be misinterpreted.


In the comic, the man in the hat has made a graph that shows the incidence of cancer in the United States with the number of cell phone users.  The incidence of cancer has been fairly steady over the past 30 years while the number of cell phone users has increased.

This means that cancer causes cell phones, right?  The graph shows that there are increases in cell phone users just as the cancer incidences start to plateau, so that conclusion makes sense, or does it?

Is there another–better–way to interpret this graph?  What does that graph really show?

Explore how good scientists draw conclusions from data in our High-Adventure Science investigations in climate, space, and water.

A Red “Snow White”

Astronomers at the California Institute of Technology have discovered that “Snow White,” a dwarf planet officially named 2007 OR10, is actually red.  Time to come up with another name!  But why was it called Snow White to begin with?

It was originally called Snow White because Mike Brown, a professor of planetary astronomy at Caltech, had guessed that it was an icy body formed by a breakup of another dwarf planet.  Since he thought the planet would be icy and water ice appears to be white, the name fit.

Dr. Brown and his team have discovered that the little planet known as Snow White is actually red.  And it is covered with water ice, which is usually white.  So what makes this little planet red?

The explanation is probably in Snow White’s disappearing atmosphere.  In 2002, Dr. Brown helped to discover a similar dwarf planet, Quaoar.

Quaoar was covered with volcanoes that spewed an icy slush.  Quaoar was too small to hold on to its atmosphere, so it has slowly drifted away into space. What was left behind was some methane, the heaviest gas thought to have been in its atmosphere.  The methane, after being exposed to space radiation, combined into long hydrocarbon chains.  The hydrocarbon chains rest on the icy surface, giving Quaoar a rosy hue.

The spectrum of “Snow White” looks similar to the spectrum of Quaoar, an indication that the planets’ atmospheric compositions may be the same.

“That combination — red and water — says to me, ‘methane,'” Brown explains. “We’re basically looking at the last gasp of Snow White. For four and a half billion years, Snow White has been sitting out there, slowly losing its atmosphere, and now there’s just a little bit left.”

Mike Brown doesn’t yet know that Snow White has methane; there’s no evidence, other than the comparison with Quaoar.  It will take more investigation, with a larger telescope, to determine that for sure.

And now that the astronomy community has determined that Snow White is an interesting object to study, it needs a real name.

Before the discovery of water ice and the possibility of methane, “2007 OR10” might have sufficed for the astronomy community, since it didn’t seem noteworthy enough to warrant an official name. “We didn’t know Snow White was interesting,” Brown says. “Now we know it’s worth studying.”

That’s science–there’s always more to discover, even when it seems like all of the interesting discoveries have already been made.

Stay tuned to see what they re-name “Snow White.”

Explore how spectroscopy is used to determine the atmospheric composition of distant planets in our space investigation.