Clearing the Path

English

You can see them on nature trails, carrying a smartphone in one hand and a large plastic bag in the other. These modern hunter-gatherers are after an all-too-common quarry: the trash left behind by others of the human species. Dr. Ron Milo of the Weizmann Institute’s Plant and Environmental Sciences Department and Dr. Dima Batenkov of the Mathematics Department are keen on cleaning up Israel’s outdoors; and they’re not alone.


When they met two years ago, their objective was to turn the Weizmann Institute into a green campus. But soon they had a much more ambitious plan, and they founded “Bishvilenu,” (a Hebrew pun meaning both “for us” and “on our paths”). This is a site for adopting a path – either in nature or in the city – and vowing to keep it clean. “People who join can see that they are not the only ‘crazy’ ones who care about cleaning up trash. There are actually a lot of people who pick up the garbage they see around their picnic site before sitting down to eat; or who want their children to walk to school on a clean sidewalk. The Bishvilenu site encourages them to act,” says Milo.
 
trash pick-up
 
 
 
Milo says he goes out at least once a week to pick up trash, either by himself or with his family or research group. “It makes me feel good, so I take every opportunity to clean up,” he says. The social aspect of the project is crucial: not only walking around an adopted area with others, but logging onto the site to post photos and updates on cleaning up, and checking out what other areas have been adopted. The last stage in the website development, says Batenkov, was to link the site to Facebook, so all of one’s friends can see when a path has been cleaned up. For those who cannot commit to adopting a path, the website suggests areas for one-time cleaning up.

The site is based on a concept called “gamification.” As the name implies, the idea is to get more people involved by making cleanup more fun, for example, by getting people to share, on various social media, their positive experiences of picking up trash on a nature trail.

Lately, the idea has blossomed further: Together with another “cleaning patrol,” Milo and Batenkov created “Shani” (an acronym for “keeping Israel clean”). This is a think tank for coming up with solutions not only for cleaning up, but for instilling a culture of cleanliness in the country. At the first meeting, a coalition emerged of representatives of government offices, the army, Keren Kayemet, the Israel Nature Authority, the City without Violence organization, community centers, educational networks, and other NGOs. At the third meeting, held recently in the city of Lod, more than 70 high school students from eight schools attended. Among the various ideas and means the teens encountered at the meeting was a presentation on the Bishvilenu site. “We hope these kids took our ideas home with them,” says Milo.

The meeting ended with the participants dividing up for round-table discussions. At one table, a group from the Umm Batin high school – a school for Bedouin students who come from all over the Negev – suggested organizing a cleanup competition among the classes in their school.

Milo and Batenkov are optimistic: “We are working to reach that critical point – for the site to go viral. We’re not there yet, but projects like this require patience. One day the idea of cleaning up will become ‘cool.’ On that day, we’ll see a revolution in the cleanliness of our landscape here in Israel.”

To learn more or adopt a path, log on to www.iclean.org.il.
 
 






 

Clearing the Path www.iclean.org.il.
Environment
English
  • Education
  • Mathematics
  • Plant and Environmental Sciences
  • Ron Milo

Paper Archives Reveal Pollution’s History

English
 
Some of the history preserved in old tomes and newspapers may be hiding in between the lines of print. A Weizmann Institute scientist has found that the paper in such collections contains a record of atmospheric conditions at the time the trees that went into making it were growing. By analyzing the carbon isotopes in bits of paper clipped from old magazines, Prof. Dan Yakir of the Environmental Sciences and Energy Research Department in the Faculty of Chemistry has traced the rising effects of atmospheric pollution from burning fossil fuel going back to beginnings of the industrial revolution.
 
Scientists generally reconstruct the record of past climate change from such sources as ice cores or tree rings. But a reliable tree ring history, says Yakir, requires an analysis of quite a few trees. “Rather than going to forests all over the world to sample trees,” says Yakir, “we went to the local library.” In the Weizmann library’s archives, Yakir found issues of the scientific journals Science, Nature and the Journal of the Royal Chemical Society going back over 100 years to the late 19th century. Removing small samples from the margins of successive volumes, he took them back to the lab for analysis.
 
The analysis was based on a finding that the proportion of a carbon isotope – carbon 13 (13C) – to its lighter counterpart – carbon 12 (12C) – could provide information on the CO2 added to the atmosphere from burning fossil fuel. This is based on a cycle that begins with plants taking up CO2 in photosynthesis. All plants prefer to use CO2 made with the more common version of carbon, 12C, than the slightly heavier 13C. Plant biomass from millions of years ago was transformed into reservoirs of oil, gas and coal, and so these are naturally low in 13C, as well. When we started to burn those reservoirs following the industrial revolution, we began returning the 13C-poor CO2 to the atmosphere. Now the atmospheric 13C content has become increasingly diluted, and this is reflected in the carbon ratios in the trees milled for pulp and paper. Yakir’s work shows that this continuing dilution is, indeed, clearly recorded in the archival paper and, plotted over time, it demonstrates the increasing intensity of our fossil fuel burning in the past 150 years.
 
This project has been ongoing for about 14 years, with figures from new issues added over time. In the process, says Yakir, he has had to learn something about the paper industry. Some early issues, for instance, had been printed on rag paper (made of cotton, flax, etc.) rather than wood pulp, while blips in the data around the time of WWII led Yakir to suspect that the paper was either recycled, or again supplemented with rag content to make up for wartime shortages.
 
Anomalies aside, 13C levels in the paper, especially for two of the journals, were a good match for existing atmospheric records, and even revealed some local phenomena, including differences between American and European records. In addition to alerting climate scientists to a very well organized, untapped, source of global change records, says Yakir, the technique could be used to authenticate antique paper samples.
 
 
Prof. Dan Yakir’s research is supported by the Cathy Wills and Robert Lewis Program in Environmental Science and the estate of Sanford Kaplan.
 
 
The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,700 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.
 
 
Weizmann Institute news releases are also available at http://www.eurekalert.org
 
 
Environment
English
  • Atmosphere
  • Carbon dioxide
  • Dan Yakir
  • Environmental Sciences and Energy Research
  • Pollution

Dust to Gust

English

The health of the Brazilian rain forest depends on dust from one valley in Africa

 

More than half of the dust needed for fertilizing the Brazilian rainforest is supplied by a valley in northern Chad, according to an international research team headed by Dr. Ilan Koren of the Institute’s Environmental Sciences and Energy Research Department. In a study published recently in Environmental Research Letters, the scientists have explained how the Bodele valley’s unique features might be responsible for making it such a major dust provider.

 

It has been known for more than a decade that the Amazon rainforest depends for its existence on a supply of minerals washed off by rain from the soil in the Sahara and blown across the Atlantic by dust. By combining various types of satellite data, Dr. Koren and colleagues from Israel, the United Kingdom, the United States and Brazil have now for the first time managed to obtain quantitative information about the weight of this dust. Analyses of dust quantities were performed near the Bodele valley itself, on the shore of the Atlantic and at an additional spot above the ocean.

 

The data revealed that some 56 percent of the dust reaching the Amazon forest originates in the Bodele valley. They also showed that a total of some 50 million tons of dust make their way from Africa to the Amazon region every year, a much higher figure than the previous estimates of 13 million tons. The new estimate matches the calculations on the quantity of dust needed to supply the vital minerals for the continued existence of the Amazon rainforest.

 

The researchers suggest that the Bodele valley is such an important source of dust due to its shape and geographic features: it is flanked on both sides by enormous basalt mountain ridges, which create a cone-shaped crater with a narrow opening in the north-east. Winds that 'drain' into the valley focus on this funnel-like opening similarly to the way light is focused by an optical lens, creating a large wind tunnel of sorts. As a result, gusts of surface wind that are accelerated and focused in the tunnel lift the dust from the ground and blow it toward the ocean, allowing the Bodele valley to export the vast amount of dust that makes a life-sustaining contribution to the Amazon rainforest.   

  
Dr. Ilan Koren’s research is supported by the Samuel M. Soref and Helene K. Soref Foundation; and the Sussman Family Center for the Study of Environmental Sciences.
 


__________________________________________________
 


The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,500 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.

 

Weizmann Institute news releases are posted on the World Wide Web at
http://wis-wander.weizmann.ac.il/, and are also available at http://www.eurekalert.org/.
 
Environment
English
  • Environmental Sciences and Energy Research›Environment
  • Ilan Koren
  • Satellite image

Bacteria Beat the Heat

English
How do some microorganisms manage to exist and even thrive in surroundings ranging from Antarctica to boiling hot springs? A team of scientists from the Weizmann Institute’s Plant Sciences Department, led by Prof. Avigdor Scherz, has found that a switch in just two amino acids (the building blocks of protein) can make a difference between functioning best at moderate temperatures and being adapted to living in extreme heat. The results of their research, which recently appeared in Nature, might have implications for future attempts to adjust crops to differing climate conditions or improve enzyme efficiency in industrial processes.
   
The team compared two different kinds of bacteria – one found in moderate environments and the other, an intense heat lover. Both were photosynthetic (that is, using the sun’s energy to create sugars for food). The focus of the research was a reaction that takes place in enzymes in the photosynthetic 'reaction center' of the bacterial cell. While gradually raising the surrounding temperature, the scientists timed this reaction to see how reaction rates changed as things heated up.
 
A general rule for enzyme reactions states that as the heat rises, so does the reaction rate. Contrary to this rule, and the scientist’s expectations, both reaction rates peaked at a certain point, and remained steady thereafter. For each enzyme, the peak occurred in the bacteria’s 'comfort zone.' Further comparisons of the nearly identical enzymes turned up differences in just two of the hundreds of amino acids making up the enzyme sequence. When the scientists replaced these two amino acids in the enzyme adapted to the moderate temperatures with those of the heat-loving enzyme, they observed an increase of about 10 degrees in the average temperature at which the reaction rate peaked. Scherz: 'This study shows that enzyme efficiency is tuned to the average temperature of the bacterial habitat, rather than the immediate conditions. This may protect the cells from harmful swings in enzyme activity. We can envision using this knowledge, for instance, to facilitate enzymatic reactions in different applications, enhance crop production in areas subject to extreme temperature changes or create new resources for biofuel production that will not only provide more biomass per acre, but absorb more of the greenhouse gas, carbon dioxide, as well.'   
  
Prof. Avigdor Scherz’s research is supported by the Charles W. and Tillie K. Lubin Center for Plant Biotechnology; the Sylvia and Martin Snow Charitable Foundation; H. Thomas Beck, Toronto, Canada; the Canadian Society for the Weizmann Institute of Science; Samuel T. Cramer, Beverly Hills, CA; Mr. and Mrs. Abraham Kahn, Mexico; and Mrs. Sharon Zuckerman, Toronto, Canada. Prof. Scherz is the incumbent of the Yadelle and Robert N. Sklare Professorial Chair in Biochemistry.
Environment
English
  • Avigdor Scherz
  • Enzyme
  • Plant Sciences

Tiny Airborne Particles are a Major Cause of Climate Change

English

The local effect of atmospheric aerosols can be greater than the greenhouse effect

 

A scientist at the Weizmann Institute of Science and his colleagues caused a storm in the atmospheric community when they suggested a few years back that tiny air-borne particles, known as aerosols, may be one of the main culprits causing climate change – having, on a local scale, an even greater impact than the greenhouse gases effect. Attempts to understand how these particles influence clouds have generated many uncertainties.

 

A new paper by Dr. Ilan Koren of the Environmental Studies and Energy Research Department and Dr. Yoram Kaufman of the NASA/Goddard Space Flight Center, USA,* published in Science Express online, weaves together two opposing effects of atmospheric aerosols to provide a comprehensive picture of how they may be affecting our climate.
 
Cloud formation is dependent upon the presence of small amounts of aerosols such as sea salt and desert dust. These tiny particles serve as the seeds around which water vapor in the air condenses, forming tiny water droplets that rise as they release heat. As the small droplets rise, they collide and merge with larger droplets. When the droplets reach a critical size, gravity takes over, causing them to fall from the cloud in the form of rain.
 
One of the controversies surrounding the extent of aerosol impact on climate change is the duality of their influence. On the one hand, Koren and his colleagues previously found evidence to suggest that the extra seeds planted in the atmosphere by the emission of man-made aerosols (pollution, forest fires, and fuel combustion) leads to more, but smaller-sized water droplets. The formation of larger water droplets by the collision process is less efficient and therefore, rainfall is suppressed. The smaller droplets are lifted higher up into the atmosphere, creating larger and taller clouds that will persist for longer. Not only does this alter the whole water cycle, but the increased cloud cover reflects more of the sun's radiation back into space, creating a local cooling effect on Earth.

 

But to complicate matters, Koren, in another study, showed that certain types of aerosols – those containing black carbon – can also decrease cloud cover, ultimately leading to a warming effect. This occurs as black carbon absorbs part of the sun's radiation, warming the surrounding atmosphere and reducing the difference in temperature between the Earth’s surface and the upper atmosphere. This combination prevents atmospheric instability – the condition needed to form clouds and rain. A stable atmosphere means fewer clouds; fewer clouds mean less reflection of sunlight; less reflection of sunlight and absorption of radiation lead to warming.

 

Policy makers have argued that in the bottom line, the warming effect of the greenhouse gases and the (mainly cooling) aerosol effect may balance each other out so that the net global climate change will be small. Koren argues that it is the local climate change that is problematic: Clouds may persist without releasing their rain over regions where they would normally precipitate, such as rainforests, and move to precipitate over regions where rain is not needed, such as oceans. Or the effect could lead to the warming up of cold and the cooling down of hot regions. These additional effects to the already problematic warming by greenhouse gases could have disastrous repercussions in the long-run.
 
Also controversial is the question of how such tiny localized particles affect weather systems thousands of kilometers away from their sources. There is no doubt that aerosols do play a role, but the skeptics believe it is negligible compared to meteorological key players such as temperature, pressure, the amount of water vapor in the air and wind strength.
 

What Koren needed was a way to separate meteorological from aerosol influences – something which was lacking in his previous studies. Together with Kaufman, he used a network of ground sensors (AERONET) to measure the effect of aerosol concentration on cloud cover. Radiation absorption is less affected by meteorology, so if the skeptics are right and meteorology is the main influence, then the correlation between aerosol absorption and cloud cover should have been seen in only a few circumstances. But this was not the case. They observed the duality effect on clouds: As total aerosols increase, cloud cover increases; and as radiation absorption by aerosols increases, cloud cover decreases – for all locations, for all seasons.  Backed up with a mathematical analysis, it becomes harder to deny that it is, in fact, aerosols that have the major influence.
 
'We hope that this study has finally provided closure,' says Koren. 'Hopefully policy makers will start to tackle the issue of climate change from a different perspective, taking into account not only the global impact of aerosols and greenhouse gases, but local effects too.'

 

*     Dr. Yoram Kaufman, one of the leading researchers in atmospheric aerosols, was recently killed while riding his bike near the Goddard Space Center.


Dr. Ilan Koren’s research is supported by the Samuel M. Soref and Helene K. Soref Foundation; and the Sussman  Family Center for the Study of Environmental Sciences.


 
The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,500 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.

 
Weizmann Institute news releases are posted on the World Wide Web at http://wis-wander.weizmann.ac.il/, and are also available at http://www.eurekalert.org/.

Environment
English
  • Aerosols
  • Climate change
  • Cloud formation
  • Ilan Koren

And the Mountain Moved

English

A Weizmann Institute scientist reveals how a mountain may have moved.


The mountains skipped like rams…
– Psalm 114

'Moving mountains' has come to mean doing the impossible. Yet at least once in the past, one mountain relocated a fair distance away. This feat took place around 50 million years ago, in the area of the present-day border between Montana and Wyoming. Heart Mountain was part of a larger mountain range when the 100 km (62 mile) long ridge somehow became detached from its position and shifted about 100 km to the southwest. This 'migrating mountain' has garnered interest from geologists and geophysicists around the world who have tried to solve the mystery behind the largest known instance of land movement on the face of any continent. Dr. Einat Aharonov of the Weizmann Institute’s Environmental Sciences and Energy Research Department, working in collaboration with Dr. Mark Anders of Columbia University in New York, recently published a paper in the scientific journal Geology that offers an explanation for the phenomenon.
 
Aharonov and Ander’s explanation is based on dikes – vertical cracks in the rock that fill with hot lava boiling up from deep in the earth. In Heart Mountain, these dikes formed a passage for the lava, three kilometers deep, through the limestone aquifer (a porous, water-soaked layer). There, the sizzling lava would have heated the water to extreme temperatures, causing tremendous fluid pressures. The scientists developed a mathematical model (based on the number of dikes in the mountain and their structure) that allowed them to calculate the temperatures and pressures that would have been created deep within the base of the mountain. The results showed that the infiltrating hot lava would have turned the water in the aquifer layer into a sort of giant pressure cooker, releasing enough force to move Heart Mountain from its original spot to its present site.
 
Dr. Einat Aharonov’s research is supported by the Sussman Family Center for the Study of Environmental Sciences; and the Samuel M. and Helene Soref Foundation. Dr. Aharonov is the incumbent of the Anna and Maurice M. Boukstein Career Development Chair.
 
 
 
 
The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,500 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.

Weizmann Institute news releases are posted on the World Wide Web at
http://wis-wander.weizmann.ac.il,and/ are also available at http://www.eurekalert.org/.
 
Environment
English
  • Einat Aharonov
  • Mathematical model

Solar energy project at the Weizmann Institute

English

Solar Energy Project at the Weizmann Institute Promises to Advance the use of Hydrogen Fuel


Innovative solar technology that may offer a 'green' solution to the production of hydrogen fuel has been successfully tested on a large scale at the Weizmann Institute of Science in Israel. The technology also promises to facilitate the storage and transportation of hydrogen. The chemical process behind the technology was originally developed at Weizmann, and it has been scaled up in collaboration with European scientists. Results of the experiments will be reported in August at the 2005 Solar World Congress of the International Solar Energy Society (ISES) in Orlando, Florida.


The solar project is the result of collaboration between scientists from the Weizmann Institute of Science, the Swiss Federal Institute of Technology, Paul Scherrer Institute in Switzerland, Institut de Science et de Genie des Materiaux et Procedes - Centre National de la Recherche Scientifique in France, and the ScanArc Plasma Technologies AB in Sweden. The project is supported by the European Union's FP5 program.


Hydrogen, the most plentiful element in the universe, is an attractive candidate for becoming a pollution-free fuel of the future. However, nearly all hydrogen used today is produced by means of expensive processes that require combustion of polluting fossil fuels. Moreover, storing and transporting hydrogen is extremely difficult and costly.


The new solar technology tackles these problems by creating an easily storable intermediate energy source form from metal ore, such as zinc oxide. With the help of concentrated sunlight, the ore is heated to about 1,200°C in a solar reactor in the presence of wood charcoal. The process splits the ore, releasing oxygen and creating gaseous zinc, which is then condensed to a powder. Zinc powder can later be reacted with water, yielding hydrogen, to be used as fuel, and zinc oxide, which is recycled back to zinc in the solar plant. In recent experiments, the 300-kilowatt installation produced 45 kilograms of zinc powder from zinc oxide in one hour, exceeding projected goals.


The process generates no pollution, and the resultant zinc can be easily stored and transported, and converted to hydrogen on demand. In addition, the zinc can be used directly, for example, in zinc-air batteries, which serve as efficient converters of chemical to electrical energy. Thus, the method offers a way of storing solar energy in chemical form and releasing it as needed.


'After many years of basic research, we are pleased to see the scientific principles developed at the Institute validated by technological development,' said Prof. Jacob Karni, Head of the Center for Energy Research at Weizmann. 'The success of our recent experiments brings the approach closer to industrial use,' says engineer Michael Epstein, project leader at the Weizmann Institute.


The concept of splitting metal ores with the help of sunlight has been under development over the course of several years at the Weizmann Institute's Canadian Institute for the Energies and Applied Research, one of the most sophisticated solar research facilities in the world, which has a solar tower, a field of 64 mirrors and unique beam-down optics. The process was tested originally on a scale of several kilowatts; it has been scaled up to 300 kilowatt in collaboration with the European researchers.


Weizmann scientists are currently investigating metal ores other than zinc oxide, as well as additional materials that may be used for efficient conversion of sunlight into storable energy.


The research from this press release was presented at the ISES 2005 Solar World Congress - Bringing Water to the World, which took place during August 6-12, 2005 in Orlando, Fl  US  http://www.swc2005.org/


Prof. Jacob Karni's research is supported by the Sussman Family Center for the Study of Environmental Sciences; the Solomon R. and Rebecca D. Baker Foundation; the Angel Faivovich Foundation for Ecological Research; Mr. Nathan Minzly, UK; the Abraham and Sonia Rochlin Foundation; Mr. and Mrs. Larry Taylor, Los Angeles, CA; Dr. and Mrs. Robert Zaitlin, Los Angeles, CA; and the Arnold Ziff Charitable Foundation.


The Weizmann Institute of Science in Rehovot, Israel, is one of the world's top-ranking multidisciplinary research institutions. Noted for its wide-ranging exploration of the natural and exact sciences, the Institute is home to 2,500 scientists, students, technicians and supporting staff. Institute research efforts include the search for new ways of fighting disease and hunger, examining leading questions in mathematics and computer science, probing the physics of matter and the universe, creating novel materials and developing new strategies for protecting the environment.


Weizmann Institute news releases are posted on the World Wide Web at http://wis-wander.weizmann.ac.il/, and are also available at http://www.eurekalert.org/

 

Environment
English
  • Hydrogen fuel
  • Jacob Karni
  • Solar Energy

Greenhouse Gas Might Green Up the Desert

English

Weizmann Institute study suggests that rising carbon dioxide levels might cause forests to spread into dry environments

Missing: around 7 billion tons of carbon dioxide (CO2), the main greenhouse gas charged with global warming.  Every year, industry releases about 22 billion tons of carbon dioxide into the atmosphere. And every year, when scientists measure the rise of carbon dioxide in the atmosphere, it doesn’t add up -- about half goes missing. Figuring in the amount that could be soaked up by oceans, some 7 billion tons still remain unaccounted for. Now a study conducted at the edge of Israel’s Negev Desert has come up with what might be a piece of the puzzle.

 
A group of scientists headed by Prof. Dan Yakir of the Weizmann Institute’s Environmental Sciences and Energy Department found that the Yatir forest, planted at the edge of the Negev Desert 35 years ago, is expanding at an unexpected rate. The findings, published in the current issue of Global Change Biology, suggest that forests in other parts of the globe could also be expanding into arid lands, absorbing carbon dioxide in the process.
 
The Negev research station is the most arid site in a worldwide network (FluxNet) established by scientists to investigate carbon dioxide absorption by plants.
 
The Weizmann team found, to its surprise, that the Yatir forest is a substantial 'sink' (CO2-absorbing site): its absorbing efficiency is similar to that of many of its counterparts in more fertile lands. These results were unexpected since forests in dry regions are considered to develop very slowly, if at all, and thus are not expected to soak up much carbon dioxide (the more rapidly the forest develops the more carbon dioxide it needs, since carbon dioxide drives the production of sugars). However, the Yatir forest is growing at a relatively quick pace, and is even expanding further into the desert.
 
Why would a forest grow so well on arid land, countering all expectations ('It wouldn’t have even been planted there had scientists been consulted,' says Yakir)? The answer, the team suggests, might be found in the way plants address one of their eternal dilemmas. Plants need carbon dioxide for photosynthesis, which leads to the production of sugars. But to obtain it, they must open pores in their leaves and consequently lose large quantities of water to evaporation. The plant must decide which it needs more: water or carbon dioxide. Yakir suggests that the 30 percent increase of atmospheric carbon dioxide since the start of the industrial revolution eases the plant’s dilemma. Under such conditions, the plant doesn’t have to fully open the pores for carbon dioxide to seep in -- a relatively small opening is sufficient. Consequently, less water escapes the plant’s pores. This efficient water preservation technique keeps moisture in the ground, allowing forests to grow in areas that previously were too dry.
 
The scientists hope the study will help identify new arable lands and counter desertification trends in vulnerable regions.
 
The findings could provide insights into the 'missing carbon dioxide' riddle, uncovering an unexpected type of sink. Deciphering the atmospheric carbon dioxide riddle is critical since the rise in the concentrations of this greenhouse gas is suspected of driving global warming and its resulting climate changes. Tracking down carbon dioxide sinks could help scientists better assess how long such absorption might continue and lead to the development of efficient methods to take up carbon dioxide.
 
The Yatir forest. grows on arid land
 
Prof. Dan Yakir
 
The Yatir forest was planted by Keren Kayameth LeIsrael-Jewish National Fund. The study was supported by the European Union, the Israel Science Foundation, the Israel Ministry of Science, Culture and Sport, and the Ministry of Environment.
 
Prof. Yakir's research is supported by the Avron-Wilstaetter Minerva Center for Research in Photosynthesis, the Philip M. Klutznick Fund,  Minerva Stiftung Gesellschaft fuer die Forschung m.b.H., estate of the late Jeannette Salomons, the Netherlands and Sussman Family Center for the Study of Environmental Sciences.
 
 

The Weizmann Institute of Science, in Rehovot, Israel, is one of the world’s foremost centers of scientific research and graduate study. Its 2,500 scientists, students, technicians, and engineers pursue basic research in the quest for knowledge and the enhancement of humanity. New ways of fighting disease and hunger, protecting the environment, and harnessing alternative sources of energy are high priorities at Weizmann.

Prof. Dan Yakir
Environment
English
  • Carbon dioxide
  • Dan Yakir
  • FLUXNET
  • Yatir forest

Solar Technology Breakthrough

English
An innovative solar power system was presented at the ISES congress. The system has been under development since 1996, within the framework of the US-Israel Science and Technology Foundation, by a consortium, which includes BOEING, ORMAT, and Rotem Industries in collaboration with the Weizmann Institute of Science. The initial technologies were developed within the solar consortium Consolar in the framework of MAGNET program of the Ministry of Industry and Trade.
 
The system makes it possible to power state of the art combined cycle power plants by both natural gas and solar energy. Gas fired power plants built today with provision for the addition of solar collectors will be usable in the future as solar powered power plants. When powered by solar energy, the efficiency of the plants will be much higher that of photovoltaic cells.
 
BOEING, as the project team leader, is responsible for system integration, the heliostat field, the master control system, the tower and tower reflector. ORMAT is responsible for the power conversion system and for the fluid loop integration, and Rotem is responsible for the air receiver and its associated optics. The Weizmann Institute of Science through its commercial arm, Yeda, will transfer the unique solar technologies to industry and will also host the prototype system in the Institute's solar test facility. The prototype plant construction will be completed by the end of 1999.

Electricity transport has recently become competitive with natural gas pipelines for transporting electricity to distances of up to 5,000 km, making it possible to site power plants near the gas wells, rather than near the electricity consumers. Wherever gas fields are developed in sparsely populated areas with high solar intensity, there is a substantial advantage in constructing power plants close to the gas field: the initial investment in conventional gas fired plants, at competitive prices (with only minor modifications in the combustion systems), can be enhanced in the future, as gas fields deplete, by adding solar collectors and using the plants as solar powered plants. This will extend the useful life of the plants and power transmission lines for decades beyond the exhaustion of the gas resources.

In the conventional approach, where gas is transported to consumption areas, gas pipelines and power plants become useless when gas reservoirs are used up. Using the proposed strategy, the life of power plants can be extended, avoiding the expense of de-commissioning power plants and pipelines. This innovative scheme can thus provide truly sustainable power supply to densely populated areas.


Background information Rehovot, July 6, 1999

 

The new system is implemented in a pilot solar plant, the first of its kind in the world, which uses solar energy for directly powering gas turbines in order to produce electricity. It is located at the Weizmann Institute of Science and will be completed by the end of 1999.

The pilot plant is being set up as a collaboration between the Weizmann Institute, the U.S. company Boeing and Israel's Ormat and Rotem Industries. It makes use of technologies, particularly special optics and an innovative air receiver, developed on the basis of research conducted at the Weizmann Institute's Canadian Institute for the Energies and Applied Research. These technologies reflect, concentrate, and convert sunlight to provide the high temperatures necessary to directly power gas and steam turbines in a combined cycle and thus generate electricity.

The innovative solar system is equipped with highly reflective mirrors (heliostats), which track the sun in two axes and reflect sunlight up to another reflector atop a central tower. This reflector redirects the sunlight back down to a matrix of optical concentrators, capable of concentrating the light 5,000 to 10,000 times, compared to natural sunlight reaching the earth. The concentrated radiation then enters a unique group of solar receivers, located on the ground, which heats up compressed air to be used for driving the turbogenerator that produces electricity.

The pilot system's advantages stem from a unique combination of technologies. Firstly, the production facilities, including the concentrators, receivers and turbogenerator, are located on the ground rather than at the top of the tower (as they were in previous systems). This innovation will make construction of the tower, whose sole function will be to support the reflecting mirror, significantly simpler and cheaper.

Secondly, the sophisticated design of the concentrators, based on pioneering research at the Weizmann Institute, will make it possible to concentrate sunlight sufficiently in order to heat the air to the temperature needed for driving advanced gas turbines.

A third innovation is the use of the Weizmann Institute-designed solar receiver (nicknamed "Porcupine") that contains hundreds of ceramic pins arranged in a geometric pattern that maximizes the collection and use of sunlight. Compressed air that flows across the pins is heated and channeled to the gas turbines. Sunlight enters the device through a special cone-shaped quartz window that can withstand higher pressure than can a similarly designed steel cone.
 

The Weizmann Institute of Science is a major scientific research graduate study located in Rehovot, Israel. Its 2,500 scientists, students and support staff are engaged in more than 1,000 research projects across the spectrum of contemporary science.
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  • Canadian Institute for the Energies and Applied Research

Sudden Climate Warming Took Place in Africa 2,000 Years Ago, Weizmann Institute Study Reveals

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REHOVOT, Israel - August 14, 1998 -A sudden warming of climate lasting several centuries took place in equatorial Africa some 2,000 years ago, according to a new study reported by a Weizmann Institute-led team in the August 14 issue of Science.

The scientists performed an isotopic analysis of the sediments from Hausberg Tarn, a small lake at an altitude of 4,350 meters on a slope of Mt. Kenya, a dormant volcano in East Africa whose top (at 4,600-4,700 meters) is covered by permanent glaciers. They found that a rapid and significant warming of lake water - by about 4°C - took place between the years 350 BCE and 450 AD, reflecting a warming of climate in equatorial East Africa.
 
This study helps determine how the climate fluctuated naturally long before modern industries began releasing large quantities of greenhouse gases into the atmosphere. Such research may, in turn, throw light on today's climate. It may allow scientists to distinguish between natural climate variability and the global warming believed to be affecting our planet in recent years due to man-made factors.

"Our findings show that the climate can warm up suddenly without any connection to human activity," says research leader Prof. Aldo Shemesh, head of the Environmental Sciences and Energy Research Department at the Weizmann Institute of Science. He conducted the study with Prof. Wibjorn Karlen of the University of Stockholm in Sweden and Weizmann Institute graduate student Miri Rietti-Shati.

"Documenting climatic changes that took place in the past in various parts of the globe may help scientists make more precise predictions about the potential effects of modern activity on the climate of the future," Shemesh says.

While periods of ancient warming have been identified in numerous parts of the world, the new study makes a unique contribution to this area of research because it was conducted on the equator, a region that plays a crucial role in determining the climate system throughout the planet. Moreover, it's the first quantitative assessment of a past warming period on the equator to be performed at such a high altitude, where evidence of past climate changes is particularly direct due to the close proximity of mountain glaciers.


Mt. Kenya's hidden "archive"


The scientists, accompanied by local porters, reached Hausberg Tarn following a long and arduous hike lasting several days. Using boats and special drilling equipment they carried with them, they obtained a nearly 2-meter-long core of sediment from the bottom of the lake. This sediment, containing fossil algae deposits, was later analyzed at the Weizmann Institute.

Using carbon-14 dating, the scientists first determined that the core contained deposits which had accumulated over 3,000 years, between 2,250 BCE and 750 AD.

Then, using a new method developed by Prof. Shemesh, the researchers studied the ratio of oxygen isotopes in the remains of the algae skeletons, called biogenic opal, which accumulated in the sediment. Isotopes are versions of the same element that are almost identical in their chemical properties but differ in weight and in other physical properties. Thus, for example, the most common isotope of oxygen is O-16, but there is also a heavier oxygen isotope, O-18.

The relative quantities of these two oxygen isotopes in biogenic opal are the result of climatic conditions prevalent in the area when the sediment formed; they reflect the lake's temperature and the isotopic composition of its water at the time of sediment deposition. Thus, when the water was cooler, the opal contained relatively more O-18 compared with O-16. By studying the ratio of the isotopes, the scientists were able to identify the period of sudden warming.

This research has also established that the measurement of biogenic-opal oxygen isotopes in lake sediments is a unique and valuable way to investigate past climate.

"Our research has shown that sediments from high-altitude lakes provide a unique isotopic archive of climatic changes," Shemesh says.

The scientists note in their paper that the warming on Mt. Kenya may have been part of a more global climatic phenomenon because a warm period occurring during approximately the same period had been recorded in two other parts of the world - in the Swedish part of Lapland and in the northeastern St. Elias Mountains (southern Yukon Territory and Alaska).

The Weizmann Institute of Science is a major center of scientific research and graduate study located in Rehovot, Israel.
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  • Aldo Shemesh
  • Carbon-14
  • Climate change

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