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Showing posts with label Planet and Environment. Show all posts
Showing posts with label Planet and Environment. Show all posts

Wednesday, 22 January 2020

Our current food system can only feed 3.4 billion people sustainably

Rice harvest in Williams, California. | Ken James / Getty Images

According to a recent analysis of global agriculture, as it stands, our food system can only feed 3.4 billion people before reaching sustainable global production limits. However, according to the analysis, reorganizing agricultural crops and making certain changes in diets would allow us to meet the food needs of 10 billion people on a sustainable basis.

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" We must not go further in the production of food at the expense of the environment, " says Dieter Gerten, of the Climate Impact Research Institute in Potsdam, Germany, and author of the study.

In 2009, researchers identified nine potential “planetary limits”: thresholds that we should not exceed if we want to keep the systems necessary for life on Earth viable.

Gerten's team examined four rules / limits that are relevant to agriculture: limiting the use of nitrogen (causes dead zones in lakes and oceans), limiting the withdrawal of fresh water from rivers and l exploitation of forests, and maintain biodiversity.

Very harmful food production in certain areas

The team's conclusion is that half of food production today exceeds these limits. However, this analysis is also the first to provide an overview of where, geographically, these are transgressed. By changing what is grown in specific places, the team says it would be possible to feed 10 billion people within the four limits.

Potential for sustainable recalibration of the food system. Increases in caloric intake are possible in the green areas; reductions due to overly detrimental food production are shown in red. Credits: Gerten et al. 2020

This would involve reseeding farms in areas where more than 5% of species are threatened, reforesting agricultural land where more than 85% of tropical forests have been felled, reducing water withdrawals for irrigation and d 'other purposes, as well as the reduction of nitrogen fertilization when the levels in surface waters are too high. The holdings could be enlarged in areas where these limits are not exceeded.

This could, for example, mean restricting the use of fertilizers in parts of eastern China and central Europe, and expanding it in parts of sub-Saharan Africa and the western United States.

Drastic measures in anticipation of 2050…

Such changes would allow the sustainable production of enough food for 7.8 billion people, roughly equivalent to the current global population. Reducing food waste and stopping excessive consumption of meat could then bring this figure to 10.2 billion, slightly more than the world population forecast for 2050.

However, the team warns that these solutions assume that the planet will not warm by more than 1.5 ° C. Subsequent studies will therefore look at the effects of global warming beyond this stage. But on the other hand, the team assumes in the study that the world depends only on existing technologies, and not on new approaches such as genome editing, the use of solar panels to grow food or new agricultural technologies, which could be a game-changer.


Feeding ten billion people is possible within four terrestrial planetary boundaries

Dieter Gerten, Vera Heck, Jonas J盲germeyr, Benjamin Leon Bodirsky, Ingo Fetzer, Mika Jalava, Matti Kummu, Wolfgang Lucht, Johan Rockstr枚m, Sibyll Schaphoff & Hans Joachim Schellnhuber

Nature Sustainability (2020)


Sunday, 8 December 2019

Plants emit sounds when stressed

At first considered more or less inert by science, plants have in fact turned out to be very dynamic entities that can detect and interact with their environment as animals do. After showing that plants can communicate with each other using a universal chemical language, and even travel short distances, researchers have recently discovered that they are also capable of producing sounds in response to different types of stress.

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Although it has been revealed in recent years that plants are able to see, hear and smell, they are still considered silent. But, for the first time, they were recorded producing sounds when stressed, which researchers say could open a new field for precision farming, where farmers would listen to crops lacking water or nutrients.

Itzhak Khait and colleagues at Israel's Tel Aviv University discovered that tomato and tobacco plants emit sounds when they are stressed by lack of water or when their stems are cut off at frequencies that humans can not hear. Microphones placed 10 centimeters from the plants received sounds in the ultrasonic range of 20 to 100 kilohertz, which insects and some mammals would be able to hear and detect within 5 meters.

Researchers even suggest that butterflies may not lay their eggs on a plant that seems stressed by lack of water. Plants could even hear that others lack water, and react accordingly. Previously, devices were installed on plants to record the vibrations caused by the formation and explosion of air bubbles - a process known as cavitation - inside xylem tubes used for transporting 'water.

Sounds produced in response to different types of stress

But this new study is the first to record plant sounds emitted from a distance. On average, drought-stressed tomato plants emitted 35 sounds per hour, while tobacco plants produced 11. When plant stems were cut, tomato plants averaged 25 sounds per hour. and those of tobacco 15. Unstressed plants produced less than one noise per hour, on average.

a) Experimental protocol used by the researchers. b), c) and d): Amplitudes and number of sounds emitted by tobacco plants and tomatoes lacking water or cut. Credits: I. Khait et al. 2019

It is even possible to distinguish the sounds to know what is the source of the stress. Researchers conducted a deep-learning algorithm to distinguish between plant sounds and wind, rain, and other noise from the greenhouse, correctly identifying in most cases whether the stress was due to drought or at a break, depending on the intensity and frequency of the sound. Tobacco stressed by lack of water seems to produce louder sounds than cut tobacco, for example.

Depending on the frequency and intensity of the sounds emitted, it is possible to identify the plant species and the stress they experience. Credits: I. Khait et al. 2019

Although Khait and his colleagues are only interested in tomato and tobacco plants, they think that other plants can also make sounds when stressed. In a preliminary study, they also recorded ultrasonic sounds from a cactus ( Mammillaria spinosissima ) and amoxicillam ( Lamium amplexicaule ). Cavitation is a possible explanation of how plants generate sounds.

Better understanding plant stress: towards micro-controlled agriculture?

Enabling farmers to listen to water stressed plants could "open a new path in the field of precision agriculture," the researchers suggest. They add that such capacity will become increasingly important as climate change exposes more areas to drought.

The authors warn that the results can not yet be extended to other stresses, such as salt or temperature, as they do not lead to sounds. In addition, no experiment was conducted to show whether a butterfly or any other animal could hear and respond to the sounds emitted by the plants. This idea remains hypothetical, for the moment.

If plants emit sounds when stressed, cavitation is the most likely mechanism, says Edward Farmer of the University of Lausanne, Switzerland. But he is skeptical about the results and would like to see more controls, such as the sounds of a soil that dries without plants.

Note: This is Still an experimental research which yet needs to be published in valid journal, this article is taken from review Journal


Tuesday, 3 December 2019

Scientists have found a place on Earth where there is no life

Hyperacid, hypersalated and hot ponds in the geothermal field of Dallol (Ethiopia). Despite the presence of liquid water, this multi-extreme system does not allow the development of life, according to a new study. Credits: Puri L贸pez-Garc铆a

"WHY A PLANET WITH  LIQUID WATER IS NOT ENOUGH, Forms of life have been found everywhere: in Antarctica, at the bottom of the deepest mines and even in the alkaline waters of the so-called Dead Sea, micro-organisms of all kinds proliferate. But to Dallol, in the depression of Dancalia, in Ethiopia, nothing seems to survive, says research published in Nature Ecology & Evolution"

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A volcanic crater full of salt that gives off smoky toxic gases, where the water boils in intense hydrothermal activity and the daily temperatures in winter can exceed 45 ° C. A hostile and multi-extreme environment: very hot, very salty and very acidic at the same time. We have not just crossed the gates of hell: we are at  Dallol , in the  Danakil depression , in Ethiopia. It is in this place that a team of Franco-Spanish scientists, led by biologists  Jodie Belilla and  Purificaci贸n L贸pez-Garc铆a of the French Cnrs, has discovered how it is impossible for forms of life to remain.

A few months ago,  another study - also conducted in Dallol and published in  Scientific Reports - which highlighted an opposite result: the  finding of nanobacteria . That territory, so apparently inhospitable, was described as a valid example for understanding the environmental limits of life, both on Earth and in other parts of the Solar System. And the geothermal area of ​​Dallol was proposed as a terrestrial analogue of a primitive Mars (as it was three billion years ago). The conclusions of L贸pez-Garc铆a and colleagues, now published in  Nature Ecology & Evolution, are of a different opinion . "After analyzing many more samples than the previous jobs - with appropriate controls to avoid contaminating them and with a well calibrated methodology - we verified that in these salty, hot and hyperacid pools the microbial life is absent. As it is absent in the adjacent salt lakes, rich in magnesium », emphasizes L贸pez-Garc铆a.

Yes, there is a great variety of  halophilic archaea (primitive microorganisms that live in highly saline environments) in the desert and in the canyons around the hydrothermal site," adds the biologist, "but not in the hyperacid and hypersaline pools, nor in the so-called black and yellow lakes of Dallol, where magnesium abounds. And this despite the fact that the microbial dispersion, in this area, is intense, due to the wind and human visitors ".

There are two obstacles to life that prevent micro-organisms from developing inside the ponds: the abundance of magnesium salts  caotropic - capable of breaking hydrogen bonds and causing protein denaturation - and the simultaneous presence of conditions such as l hypersalinity, hyperacidity and high temperature.

To confirm this, the team of scientists has used various research methods such as: massive sequencing of  genetic markers to detect and classify microorganisms, chemical analysis of  brines and  scanning electron microscopy combined with  X-ray spectroscopy , used to analyze silicon-rich mineral precipitates. «In other studies, in addition to the possible contamination of samples with  archaea from adjacent lands, these mineral particles may have been interpreted as fossilized cells, but in reality they form spontaneously in brines even if there is no life, "observes L贸pez-Garc铆a, pointing out that caution is needed in relying on the apparently cellular appearance - or "biological" - of a structure, because it could be non-living systems.

Microbial cells (left) can be easily confused with silica-rich mineral precipitates (right). Credits: Karim Benzerara, Puri L贸pez-Garc铆a et al

"We would never expect to find life in similar environments on other planets, at least not life that is not based on a biochemistry similar to that on earth," says L贸pez-Garc铆a, insisting on the need to have more clues and analyze all possible alternatives before reaching a conclusion. "Our study shows that there are places on the earth's surface, such as the pools of Dallol, which are sterile even if they contain water in the liquid state," concludes the researcher, remarking as a criterion such as the presence of liquid water, often used to suggest the habitability of a planet, does not necessarily imply the presence of life.


Article: Hyperdiverse archaea near life limits at the geothermal polyextreme Dallol area

Authors: Jodie Belilla, David Moreira, Ludwig Jardillier, Guillaume Reboul, Karim Benzerara, Jose M. Lopez-Garcia, Paola Bertolino, Ana I. L贸pez-Archilla, Purification L贸pez-Garc铆a

Magazine: Nature Ecology & Evolution
Vol .: 3, pages 1552-1561

DOI: 10.1038 / s41559-019-1005-0

Wednesday, 6 November 2019

Scientists declare "climate emergency" and set indicators for an effective global plan of action

A global coalition of scientists, including 11,000 signatories, believes that "indeterminate human suffering" is inevitable without drastic, deep and lasting changes in human activities that contribute to greenhouse gas emissions. Other factors related to climate change are also targeted.

" Despite 40 years of major global negotiations, we continued to act as if nothing had happened and we did not manage to cope with this crisis, " said William J. Ripple, co-director of coalition - alongside Christopher Wolf - and distinguished professor of ecology at the OSU College of Forestry. " Climate change has arrived and is accelerating faster than expected by many scientists  ."

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In an article published yesterday in the journal BioScience , the authors, as well as more than 11,000 scientific scientists from 153 countries, declare a climate emergency. They include graphs of adverse trends and vital signs to measure progress. They finally propose a set of effective mitigation measures.

Scientists point to six areas in which humanity should take immediate action to slow the effects of global warming:

Energy . Implement massive conservation practices; replace fossil fuels with low-carbon renewable energies; leave the remaining stocks of fossil fuels in the soil; eliminate fossil fuel business subsidies; and impose carbon royalties high enough to limit the use of fossil fuels.

Short-lived pollutants . Rapidly reduce emissions of methane, soot, hydrofluorocarbons and other short-lived climate pollutants; This could reduce the short-term warming trend by more than 50% in the coming decades.

Nature . Restore and protect ecosystems such as forests, grasslands, peat bogs, wetlands and mangroves, and enable more of these ecosystems to reach their ecological potential for the sequestration of atmospheric carbon dioxide. one of the main greenhouse gases.

Food . Consume more plants and less animal products. The regime change would significantly reduce emissions of methane and other greenhouse gases and release agricultural land for the production of human food rather than feed. Reducing food waste is also crucial. Indeed, scientists say that at least a third of all food produced ends up in garbage.

Economy . Convert the current economy into a carbon-free economy to address human dependence on the biosphere and away from gross domestic product growth and the pursuit of wealth. Curb the exploitation of ecosystems to maintain the long-term sustainability of the biosphere.

Population . Stabilize a global human population growing by more than 200,000 people per day, using approaches that ensure social and economic justice.

" Mitigating and adapting to climate change while respecting human diversity implies major transformations in the ways in which our global society operates and interacts with natural ecosystems, " the document says.

" We are encouraged by the recent worry. Government agencies make declarations of climatic urgency. Schoolchildren are hitting. The court cases for ecocide continue in the courts. Citizen movements are demanding change, and many countries, states and provinces, cities and businesses are responding. As a global coalition of scientists, we are ready to help policymakers in a just transition towards a sustainable and equitable future, "reads.

The vital sign graphs in the document illustrate several key indicators and drivers of climate change over the last 40 years, since scientists from 50 countries gathered at the first World Climate Conference in Geneva in 1979.

Evolution of human activities in the world from 1979 to today. These indicators are linked at least in part to climate change. In graph (f), the annual loss of forest cover can be due to any reason (forest fire, harvest in tree plantations, conversion of forests to agricultural land, etc.). For graph (h), hydroelectricity and nuclear energy (missing) are shown in a separate graph. The rates shown in the tables are percentages of variation over the entire range of time series. Annual data are indicated in gray dots. The black lines are local regressions smoothed of trends. Credits: William J. Ripple, Christopher Wolf, Thomas M. Newsome, Phoebe Barnard, William R. Moomaw

In recent decades, many other global assemblies have agreed that urgent action is essential, but greenhouse gas emissions continue to increase rapidly. Other worrying signs of human activities include the steady increase in meat production per capita, the loss of global forest cover and the number of air passengers.

There are also encouraging signs, including a drop in the birth rate worldwide and a decrease in forest loss in the Brazilian Amazon, as well as an increase in wind and solar energy, but even these measures are tinged with worry. For example, the decline in the birth rate has slowed over the last 20 years and the rate of extinction of the Amazonian forest seems to be starting to increase again.

" Global surface temperature, ocean heat content, extreme weather and cost, sea level, ocean acidity, and US burned area are on the rise,  " Ripple said. " Overall, the ice is rapidly disappearing, as evidenced by the decrease in the minimal summer Arctic ice pack, the ice sheets of Greenland and Antarctica and the thickness of the glaciers. All these rapid changes underline the urgent need for action, "concludes Ripple


Saturday, 2 November 2019

The 2 million years ancient ice reveals crucial information about the Earth's carbon cycle

A team of scientists worked more than two years to achieve these results: the oldest complete ice core provided a reliable snapshot of the atmosphere of our planet as it was nearly 2 million years ago. years. And the data presented is not what we would have expected.

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We know that about a million years ago, the cycle of the Earth's ice ages suddenly changed: since that change, deeper and longer gels only occur every 100,000 years or so, once every 40,000 years.

Nothing on our planet could explain this "brutal" change, better known as the middle Pleistocene transition known  as  MPT  (English Mid-Pleistocene transition), and with few other explanations, some hypothesized long-term decline in CO2 concentrations in the atmosphere, cooling the planet to a new threshold.

But the old air bubbles trapped in the Antarctic ice floe revealed somewhat different information. Indeed, dating back to about 1.5 million years ago, these tiny amounts of our ancient atmosphere reveal " incredibly low " CO2 levels , according to palaeoclimatologist Yige Zhang, of Texas A & M University, who did not participate in the study and stated that he found the results "quite interesting".

These are the first direct observations of greenhouse gases in the atmosphere before the intervals between the Ice ages on Earth begin to lengthen. These observations also suggest that something else that a long-term decline in CO2 has been involved in the change in the complete cycle of the ice age of our planet.

Blue ice near the Allan Hills area in Antarctica. Environmental conditions in this area attract old ice to the surface. Scientists analyzed the air trapped in a core of ice drilled in this region, to obtain the first direct measurements of carbon dioxide levels in the atmosphere, dating back two million years ago. Credits: Sean Mackay

The oldest ice sample that we could test for CO2 levels prior to this new core, dates back only 800,000 years ago: other estimates based on sediment chemistry Earth are only useful as indirect indicators of greenhouse gas levels, they are not useless, but additional verifications are needed.

But the new ice analysis, which exploited more precise measurements than before, revealed that: " although the CO2 levels during the glaciations have remained much higher than the troughs recorded in the ice depths during the 800 ' In the last few years, maximum CO2 concentrations during the interglacial periods have not decreased,  "said Eric Wolff, Earth Science Scientist at the University of Cambridge, who wrote a report on the research.

"  One of the important results of this study is that the carbon dioxide level is temperature-related at the beginning of this period, " said Atmosphere Specialist Ed Brook of Oregon State University. " This is an important baseline for understanding climate science and calibrating predictive models of future change ," he added.

In other words, the relationship between CO2 levels and temperature in Antarctica has not changed much during this period. And, according to scientists, the low levels of CO2 during ice ages are probably only a consequence of the shorter glacial periods that occurred before TWA.

The authors also found that the lowest levels of CO2 did not occur during the first 40'000 years after MPT. " Our results seem to contradict the assumptions that attribute the transition to a world from 100,000 years before a change, to a long-term decline in atmospheric CO2, both interglacial and glacial," the researchers write.

In his report of the research, Wolff congratulated the researchers for their precise estimates, but also argues that "  s complete and undisturbed chronological eries" is needed to bring CO2 levels in context.

Fortunately, the old ice core, discovered in the Allan Hills, Antarctica, may soon have company. Indeed, researchers predict that the ice cover dates back to 2.7 million years or more. " We do not know the age limit in this area,  " Brook said.

And, given the extent of ice movement in this region, new cores that researchers will be analyzing soon will most likely come in discontinuous sections. "  There could be much older elements in some places. That's why we're going back. To grow beyond two million years would be truly incredible, "added Brook. As a result, their future information can help us learn more about some of the mysteries of the planet.

VIDEO: Ice reveals crucial information about the ancient Earth's atmosphere