The Concord Consortium

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.

http://www.sciencedaily.com/releases/2011/08/110825152457.htm

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.

http://www.sciencedaily.com/releases/2011/08/110825141621.htm

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.

http://www.sciencedaily.com/releases/2011/09/110912143536.htm

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.

http://www.sciencedaily.com/releases/2011/08/110823115651.htm

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. http://en.wikipedia.org/wiki/File:BeaverDam_8409.jpg

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?”.

http://online.wsj.com/article/SB10001424053111904253204576512391087253596.html?mod=ITP_AHED#articleTabs%3Darticle

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.

http://www.sfexaminer.com/news/2011/08/irene-forecasts-track-not-speed-wind

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.

(Source:  http://xkcd.com/925/)

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.

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.

http://www.sciencedaily.com/releases/2011/08/110822124955.htm

Scientists have known for a long time that ocean currents affect climate.  The big unanswered question is how ocean currents change during the periods of greatest change–from ice ages to periods of global warming.

During the Eocene period, 38 million years ago, the Antarctic had a temperate climate.  What is now the midwest United States was covered in tropical jungles.  The temperature differential during that last warm period was much smaller than it is today, when Antarctica is a frozen tundra.

New research suggests that the Antarctic Circumpolar Current (ACC), an ocean current that surrounds Antarctica, played a major role in the Eocene climate shift and that ACC formation played a vital role in the formation of modern ocean structure.  During the Eocene, when temperature differences were not as large between the poles and the midlatitudes, ocean currents were weaker than they are today.  Today, the ACC is considered the most significant ocean current, thermally isolating Antarctica from the rest of the planet, keeping warm surface waters away from the frozen ice sheets.

“What we have found is that the evolution of the Antarctic Circumpolar Current influenced global ocean circulation much earlier than previous studies have shown,” said Katz, who is assistant professor of earth and environmental science at Rensselaer.  ”This finding is particularly significant because it places the impact of initial shallow ACC circulation in the same interval when the climate began its long-term shift to cooler temperatures.”

Just how did this shift in ocean currents happen?  That’s not yet understood.

Scientist Miriam Katz points out, “By reconstructing climates of the past, we can provide a science-based means to explore or predict possible system responses to the current climate change.”  As always, science requires more study to start filling in the blanks of the big unknowns!

http://www.sciencedaily.com/releases/2011/05/110526141406.htm

A new study has been published disproving the previous explanation for the end of the Marinoan ice age, also known as “Snowball Earth.”  That ice age ended abruptly about 600 million years ago.

The debunked explanation stated that methane bubbled up from the oceans and was consumed by microbes, which released carbon dioxide into the atmosphere, warming the Earth.  Earlier scientists had interpreted “bubbles” in the rocks as evidence of the ancient microbial activity.

A new study on those rocks showed that they were formed under very high temperatures–temperatures at which no microbes are known to survive.  In addition, better dating of the rocks showed that the “bubbles” were formed millions or tens of millions of years after the end of the ice age.

So scientists still don’t have an explanation for the end of “Snowball Earth.”  But they do know a couple of things that didn’t cause the end of the ice age.

As scientists come up with new explanations for the end of the ice age, those explanations will be tested by other scientists.  When explanations can be disproved with evidence, science moves forward.  We may never discover the true cause of the end of “Snowball Earth,” but one thing’s for sure–we’ll know a lot more about how the Earth works by trying to craft a good explanation.  That’s the way science works!

http://www.sciencedaily.com/releases/2011/05/110525141540.htm