Posts Tagged ‘climate’

Two “Global Experiments” about Climate Change

September 10th, 2014 by Andy Zucker

In an earlier post on this blog I wrote about the need to increase our knowledge of how people think about climate change and then apply that knowledge to expedite policy changes. Subsequently I discovered that there is an active community of psychologists, experts in communications and other researchers who conduct valuable inquiries in this field.

Some of their findings are sobering, such as data from April 2014 showing that only one in three Americans discusses global warming with family and friends even occasionally. One of the many reasons this is true is that for more than five years, with little variation from year to year, only about one in three Americans have believed people in the U.S. are being harmed “right now” by global warming—despite Superstorm Sandy, Hurricane Katrina, extreme drought in the West and other once-rare climate events. One does not wish for more droughts, extreme heat waves, superstorms or wildfires; however, those are the kinds of events that may, slowly, change opinions about climate change.

People who realize how threatening climate change is believe that we are conducting a risky “experiment” with the sensitivity of Earth systems to increasing levels of carbon dioxide and other heat-trapping gases. For example, we still don’t understand climate “tipping points” well; however, our global experiment is already teaching us about tipping points, like it or not.

Professor Richard Somerville of the Scripps Institution of Oceanography at UC San Diego—who was Coordinating Lead Author of the Intergovernmental Panel on Climate Change’s fourth assessment report (2007)—wrote, in his 2006 paper called “Medical metaphors for climate change,”

“What is still not obvious to many is that all of us are now engaged in a second global experiment [emphasis added], this time an educational and geopolitical one. We are going to find out whether humanity is going to take climate science seriously enough to act meaningfully, rather than just procrastinating until nature ultimately proves that our climate predictions were right.”

This educational experiment—where education is broadly defined and includes more than what is taught in schools—could hardly be more important. It will take a concerted effort, over many years, by formal and informal institutions, political leaders and organizations, TV stations, museums, churches and others, to increase knowledge and a sense of urgency among policymakers and the public. The Concord Consortium’s High Adventure Science (HAS) project is one element in this long-term effort.

The Next Generation Science Standards include climate change as an important topic for instruction, which is significant because more people need some understanding of the science behind climate change. But the “educational experiment” the world is conducting requires policymakers and the public to learn far more than science. Better understanding the economics, political, regulatory, governance, diplomatic and technology issues needed to address climate change will be vital, as will an emphasis on ethics and values. It would be interesting to know how, and how often, climate change is a topic of study in other subjects taught in schools, colleges and universities (including social science classes, like Psychology), or whether it is addressed almost exclusively in “hard science” courses.

Using Dynamic Models to Discover the Past (and the Future?)

December 16th, 2011 by Sarah Pryputniewicz

What was Earth like 2.8 billion years ago?  The first life was emerging on the planet.  The Sun was weaker than it is today, but geologic evidence shows that the climate was as warm (or warmer) than it is today.  Was Earth colder because of the weak Sun, or warmer, as geologic evidence suggests?  How did this affect how life arose?

A new 3-D model of early Earth suggests that the planet underwent significant changes–from very warm to very cold.  Past models were one-dimensional–holding constant the amount of cloud cover or sea ice–to make the calculations easier.  But with more advanced computing, researchers at the University of Colorado Boulder were able to make better models of the planet’s climate.

“The inclusion of dynamic sea ice makes it harder to keep the early Earth warm in our 3-D model,” Eric Wolf, doctoral student at CU-Boulder’s atmospheric and oceanic sciences department, said. “Stable, global mean temperatures below 55 degrees Fahrenheit are not possible, as the system will slowly succumb to expanding sea ice and cooling temperatures. As sea ice expands, the planet surface becomes highly reflective and less solar energy is absorbed, temperatures cool, and sea ice continues to expand.”

The scientists’ model shows that Earth was periodically covered by glaciers, but the geologic evidence suggests that it was much warmer than that.  The calculations show that an atmosphere that contained 6% carbon dioxide would have kept the temperature high enough for life to thrive, but the soil samples show that the carbon dioxide concentration was not that high. So what’s the warming mechanism?  Eric Wolf and Brain Toon are still searching for it.

Since the 3-D model takes so much computing time (up to three months for a single calculation), we’ll be waiting a while for the answer.

“The ultimate point of this study is to determine what Earth was like around the time that life arose and during the first half of the planet’s history,” said Toon. “It would have been shrouded by a reddish haze that would have been difficult to see through, and the ocean probably was a greenish color caused by dissolved iron in the oceans. It wasn’t a blue planet by any means.” By the end of the Archean Eon some 2.5 billion year ago, oxygen levels rose quickly, creating an explosion of new life on the planet, he said.

And along the way, better models of Earth’s climate will come out of this study, enhancing scientists’ ability to predict what Earth’s future might look like, and scientists will learn more about the conditions of early Earth, which could help in assessing the habitability potential of other planets.

Explore the interactions of greenhouse gases and ice sheets in the High-Adventure Science climate investigation, and explore the search for extraterrestrial life in the High-Adventure Science space investigation.

http://www.sciencedaily.com/releases/2011/12/111205140521.htm

The Great Antarctic Glaciation

December 14th, 2011 by Sarah Pryputniewicz

About 33 million years ago, the Earth abruptly went from being warm and wet to having Antarctic ice cover.  Only 23 million years after the Paleocene-Eocene Thermal Maximum, a time of some of the warmest temperatures on Earth, ice covered the surface.  What happened?

According to a recent study by scientists at Yale and Purdue universities, the carbon dioxide level dropped. Carbon dioxide is a greenhouse gas that is contributing to the increased global temperatures on Earth today.

The scientists pinpointed the threshold for low levels of carbon dioxide below which an ice sheet forms at the South Pole. Matthew Huber, a professor of earth and atmospheric sciences at Purdue, said roughly a 40 percent decrease in carbon dioxide occurred prior to and during the rapid formation of a mile-thick ice sheet over the Antarctic approximately 34 million years ago.

“The evidence falls in line with what we would expect if carbon dioxide is the main dial that governs global climate; if we crank it up or down there are dramatic changes,” Huber said. “We went from a warm world without ice to a cooler world with an ice sheet overnight, in geologic terms, because of fluctuations in carbon dioxide levels.”

Having an ice-covered South Pole appears to be the tipping point for cooling the rest of the planet.  The team found that the threshold level of carbon dioxide necessary for ice formation is about 600 parts per million.  For reference, today’s carbon dioxide level is approximately 390 parts per million.  This is why ice sheets still remain on Earth today.

With carbon dioxide levels forecast to rise to 550-1,000 parts per million in the next 100 years, when will the ice sheets completely melt away?  Because the melting of an ice sheet is different than starting an ice sheet, and because the process is not linear, scientists can’t say for sure.  But it’s clear that once the carbon dioxide levels rise high enough, the Earth will have reached a tipping point in the warming direction and the ice sheets will melt away.

Huber next plans to investigate the impact of an ice sheet on climate.

“It seems that the polar ice sheet shaped our modern climate, but we don’t have much hard data on the specifics of how,” he said. “It is important to know by how much it cools the planet and how much warmer the planet would get without an ice sheet.”

So how warm will Earth be in the future?  What’s the cooling impact of the ice?  Will greenhouse gases continue to rise?  Will increased cloud cover compensate for the lack of ice?

Explore how greenhouse gases and ice affect Earth’s temperature and learn more about feedback and tipping points in the High-Adventure Science climate investigation.

http://www.sciencedaily.com/releases/2011/12/111201174225.htm

What caused the Paleocene-Eocene Thermal Maximum?

December 7th, 2011 by Sarah Pryputniewicz

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

December 5th, 2011 by Sarah Pryputniewicz

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

Finding Fossil Aquifers on Earth

October 5th, 2011 by Sarah Pryputniewicz

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

October 3rd, 2011 by Sarah Pryputniewicz

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

Irrigation and Climate Change

September 19th, 2011 by Sarah Pryputniewicz

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

Digging into Permafrost

September 13th, 2011 by Sarah Pryputniewicz

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

Ocean Currents–The Big Unknowns

June 30th, 2011 by Sarah Pryputniewicz

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