Author Archives: Sarah Pryputniewicz

What caused the Paleocene-Eocene Thermal Maximum?

What caused the Paleocene-Eocene Thermal Maximum (PETM)?

About 56 million years ago, Earth’s temperature was a lot warmer than it is today–as much as 21°F higher than today (see the graph).  Earth’s temperature is rising today, likely because of human emissions of greenhouse gases.  But 56 million years ago, there were no human emissions; there were no humans.  What caused the big increase in Earth’s temperature?  And could it happen again today?

Researchers at Rice University suggest that the temperature increase could well be due to releases of stored methane from the oceans.

Methane is a powerful greenhouse gas and a natural product of bacterial decomposition.  In the oceans, methane sinks into the sediments and freezes into a slushy gas hydrate, stabilized in a narrow band under the seafloor.

According to calculations done by the Rice University scientists, the warmer oceans resulted in more methane hydrate being stored.  At warmer temperatures, bacteria decompose organic materials faster, resulting in more methane in a shorter period of time.  They estimate that, just before the PETM, there was as much methane hydrate stored as there is today, in a smaller band than exists today.

If this band is disturbed, as by a meteor impact or earthquake, the methane can be rapidly released into the atmosphere.  More greenhouse gases in the atmosphere result in increased warming.  But there’s no evidence of there having been an impact.  So what happened to release the methane 56 million years ago?

Nobody really knows, but the significance is clear.

“I’ve always thought of (the hydrate layer) as being like a capacitor in a circuit. It charges slowly and can release fast — and warming is the trigger. It’s possible that’s happening right now,” said Gerald Dickens, a Rice professor of Earth science and an author of the study.

That makes it important to understand what occurred in the PETM, he said. “The amount of carbon released then is on the magnitude of what humans will add to the cycle by the end of, say, 2500. Compared to the geological timescale, that’s almost instant.”

“We run the risk of reproducing that big carbon-discharge event, but faster, by burning fossil fuel, and it may be severe if hydrate dissociation is triggered again,” Guangsheng Gu, lead author of the study, said, adding that methane hydrate also offers the potential to become a valuable source of clean energy, as burning methane emits much less carbon dioxide than other fossil fuels.

Learn more about the feedback loops involved in climate change in the High-Adventure Science climate investigation.

http://www.sciencedaily.com/releases/2011/11/111109111542.htm

When More Is More

In science, less isn’t more; more is more.

That basic premise is supported by a recent report from Lawrence Livermore National Laboratory: Separating signal and noise in climate warming.  Earth’s overall temperature is affected by natural processes, such as La Niña and El Niño, as well as by human factors.

From 1999 to 2008, Earth’s temperature was fairly steady, coming after the steady rise in temperature that occurred from the late 1980s.  What happened in that 10 year period?  Probably noise from natural phenomena, conclude scientists at LLNL.

“Looking at a single, noisy 10-year period is cherry picking, and does not provide reliable information about the presence or absence of human effects on climate,” said Benjamin Santer, a climate scientist and lead author on an article in the Nov. 17 online edition of the Journal of Geophysical Research (Atmospheres).

The solution?  Look at longer time periods to see past the natural noisy fluctuations in Earth’s temperature data.  After looking at all of the data, scientists concluded that temperature records must be at least 17 years long to see the human-caused warming amidst the natural fluctuations.  More data leads to more accurate conclusions.

Explore the hows of climate change in the High-Adventure Science climate investigation.

https://www.llnl.gov/news/newsreleases/2011/Nov/NR-11-11-03.html

Absolute Certainty Is Not Scientific

That’s the title of an editorial by Daniel Botkin, president of the Center for the Study of the Environment and professor emeritus at the University of California, in today’s Wall Street Journal.

With the ongoing polarization of science in today’s political environment, it’s more important than ever to remember that science is filled with uncertainty.  Everything that scientists know about how the world works has been discovered by observation and experimentation.  None of us were around at the very beginning, so we can never be absolutely certain about how the world works, though we can be very certain that we understand how it works.

You can’t prove anything to be true in science.  This seems unintuitive to many people, including many of my former students, who used to insist that they had proven their point because the data supported their hypotheses.  But since we will never be absolutely certain about how the world works, we can never prove that any particular hypothesis or theory is absolutely true.  That’s why good scientists design experiments to disprove their hypotheses.  While you can’t prove anything to be true, you can prove things to be false.

So good scientists are forever questioning their assumptions, looking for evidence that their hypotheses and theories are wrong, open to the idea that they may have misinterpreted the data.  It’s vitally important for science teachers to remind their students to have this kind of healthy skepticism; scientific progress cannot easily proceed if people entrench themselves into opposing camps without regard for the data.

This is something that the High-Adventure Science investigations aim to do–immerse students in the data about climate change, finding extraterrestrial life, and freshwater resources–without making all-or-nothing judgements about the current state of the science.

“If you think that science is certain–well that’s just an error on your part.” ~Richard Feynman

http://online.wsj.com/article/SB10001424052970204630904577058111041127168.html?mod=WSJ_Opinion_LEADTop#articleTabs%3Darticle

Finding Fossil Aquifers on Earth

NASA technology is being used to find fossil aquifers underneath Earth’s driest deserts.  This technology was developed to explore underneath the surface of Mars, to help determine if there might be water on the red planet.  Water is a sign that life might be possible.

Why are they using this technology on Earth?  We know that there is water on Earth; we know that there is life on Earth.

Firstly, it’s the only way that scientists can “see” underground structures.

“This demonstration is a critical first step that will hopefully lead to large-scale mapping of aquifers, not only improving our ability to quantify groundwater processes, but also helping water managers drill more accurately,” said Muhammad Al-Rashed, director of Kuwait Institute for Scientific Research’s Division of Water Resources.

We might have a lot of water on Earth, but it’s not distributed equally.  Knowing the availability of the water supply helps us to use it in a sustainable manner.

Secondly, it’s a good way to study the climactic history of these regions.

“This research will help scientists better understand Earth’s fossil aquifer systems, the approximate number, occurrence and distribution of which remain largely unknown,” said Essam Heggy, research scientist at NASA’s Jet Propulsion Laboratory. “Much of the evidence for climate change in Earth’s deserts lies beneath the surface and is reflected in its groundwater. By mapping desert aquifers with this technology, we can detect layers deposited by ancient geological processes and trace back paleoclimatic conditions that existed thousands of years ago, when many of today’s deserts were wet.”

Previously, climate research has focused on Earth’s polar regions and forests.  It is important to study those areas, but arid and semi-arid regions make up a big part of the planet, and they should be studied too.

This is a great story that shows how technology developed for one area of research can often be useful for several other fields of science–all of which are highlighted in our High-Adventure Science investigations!

Learn about searching for water on other planets in the High-Adventure Science space investigation, learn about aquifers and water sustainability in the High-Adventure Science water investigation, and learn about using geologic formations to reconstruct previous climates in the High-Adventure Science climate investigation.

http://www.sciencedaily.com/releases/2011/09/110915182850.htm

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.

http://www.sciencedaily.com/releases/2011/09/110914161729.htm

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.

http://www.sciencedaily.com/releases/2011/09/110903131404.htm

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.

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

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.

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

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.

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

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.

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