【Native Speaker每日综合训练—40系列】【40-19】科技 Drought

cherry6891

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Part I: Speaker

Bumper Corn Looks Dicey in Drought
Over the past decades, farmers have been getting bigger harvests from the same size plot of land. That story’s particularly true in the American Midwest, the world’s corn basket. The U.S. now grows more than 36 percent of the world’s corn.

One key is that breeders developed corn plants that can grow very close together. Newer varieties can better withstand stress and grow roots deeper to access water. So stalks are planted more densely and yields per acre are up.

But a study in the journal Science finds that as corn plants get closer together, they become more sensitive to drought. [David B. Lobell et al, Greater Sensitivity to Drought Accompanies Maize Yield Increase in the U.S. Midwest]

“What we did see for corn is that progress has been much greater for what we consider good weather conditions, so cooler, wetter conditions.” Study leader David Lobell of Stanford University, on Science’s podcast. “And when you get to the hottest conditions we see actually very little progress…the simple observation was that the sensitivity to those hot conditions seems to be growing over time.”

So in the hotter, drier climate predicted for the coming decades, the varieties of corn that currently produce bumper crops could be in trouble. “The impacts of drought are actually growing, at least in the case of maize.”
source:
http://www.scientificamerican.com/podcast/episode/bumper-corn-looks-dicey-in-drought1/
[Rephrase 1'15'']

cherry6891

Part II: Speed

Worst drought in half a century hits China’s bread-basket

Published: Aug 13, 2014 1:11 a.m. ET

time2

HONG KONG (MarketWatch) — China’s worst drought in half a century is sweeping across crucial agricultural regions, devastating harvests in its wake and threatening food security.

Part of the area hit by unusually dry weather — the northeastern Manchurian Plain — is known as China’s bread-basket, supplying much of the country’s corn, wheat and soybean production.

In a portion of the plain, in Jilin province, 10 major grain producing counties are facing the lowest rainfall since 1951, and many corn fields are facing “zero harvest,” according to report by the state-run Xinhua New Agency, citing Jilin’s provincial weather bureau

Next door in Liaoning province, there has been no rain at all since late July.

And with Jilin government meteorologist Yang Xueyan warning that the situation will likely get worse in the near future, concern over the drought has sent local corn futures rising more than 4% in less than two week, First Financial Daily reported Friday.

But the crisis isn’t confined to the Manchurian Plain alone — according to state broadcaster CCTV, the drought is impacting more than one-third of China.

This includes the central Chinese province of Henan, another agriculturally important area, which has seen the weakest flood season in 53 years, leaving some rural communities with no viable drinking water, let alone water needed for irrigation, for as long as three months, CCTV said.

In what may be a sign of things to come, the state-owned SDIC Zhonggu Futures brokerage is predicting a 40-million-ton corn deficit this summer.[246 words]

source：

http://www.marketwatch.com/story/worst-drought-in-half-a-century-hits-chinas-bread-basket-2014-08-13?siteid=rss&rss=1

Drought-Tolerant Corn Efforts Show Positive Early Results

Types of genetically modified corn could offer modest protection for drought tolerance and might help individual farmers recoup yield losses in drought conditions

Jul 27, 2012 |By Tiffany Stecker and ClimateWire

time3

In the midst of the nation's worst drought in 50 years, two of the world's largest agricultural companies are testing corn that is bred and genetically engineered to withstand low rainfall levels.

Monsanto's DroughtGard hybrid corn -- the first-ever hybrid genetically engineered for drought tolerance -- was planted this spring in initial field trials. Sowed amid sufficient rain and optimism for a record-breaking crop yield, the company has encountered a close to worst-case scenario to test its product.

In addition, DuPont Pioneer's hybrid AQUAmax corn -- developed using advanced breeding techniques rather than biotechnology -- debuted last year with five different versions. This year, the company is launching six more with drought tolerance traits combined with pest resistance and other high-yielding attributes.

But the drought ripping through the Midwest is persistent and widespread. Despite positive feedback from farmers, the companies admit that cutting-edge technology can only go so far.

"We know there's a limit; we know you cannot grow corn without water," said Jeff Schussler, senior research manager in maize stress product development for Dupont Pioneer. "There's nothing magical about these hybrids."

The western Plains states typically experience drought conditions nearly every year, but this year's arid weather is more widespread and is hitting the heart of corn country.

"I don't think there will ever be a solution for this severe of a drought," said Mark Edge, DroughtGard marketing lead at Monsanto. Instead, the company seeks to reduce losses.

"It's really about managing risk," he said. "It's still corn, and it still needs water."

Nevertheless, both companies are pleased with early anecdotal results of their work. About 250 farmers on close to 100,000 acres across the western Great Plains planted DroughtGard in the spring.

Among those is Clay Scott, a corn grower in western Kansas who volunteered to grow the engineered corn as part of Monsanto's field trials.

"We're starting to see some real winners in the plots," said Scott, whose land is located in a region in extreme to exceptional drought, according to the U.S. Drought Monitor. "I'm excited about it."[342 words]

time4

Last year, yields of AQUAmax corn were observed 8,000 times, with 680 of those considered to be in a stressed environment. AQUAmax yields were 7 percent higher in the stressed environments compared to conventional hybrids

Questionable gains to society

Drought resistance comes through the plant's ability not lose its hydration through respiration. The hybrids are bred or engineered to reduce the size of the plant's stomata, pores on the surface that regulate the flow of water inside and outside the plant. In addition, genes to improve and increase kernel development or combat pests increase yield despite the lack of available water.

In turn, the agriculture companies expect to produce corn plants with less leaf rolling, indicating that the crop is managing water stress better. AQUAmax corn growers have reported full and uniform corn silk, said Schussler, which facilitates successful pollination and forms an ear full of kernels.

Scott, the Kansas grower who draws his groundwater from the strained Ogallala Aquifer, expects to yield 200 bushels per acre for his irrigated corn and 100 bushels for dryland corn. If conditions continue, the National Corn Growers Association anticipates a 131-bushel national average, far below the 167 bushels per acre anticipated in the spring.

The Union of Concerned Scientists, a group advocating for the environment and scientific integrity, has been particularly critical of agricultural companies' claims, targeting the largest of them all: Monsanto.

The group released a report in June finding that Monsanto's drought-tolerant corn will only offer modest protection for drought tolerance. While it may help individual farmers recoup yield losses in drought conditions, it would not increase food production to sustain a climate-stressed world, the report says (ClimateWire, June 5).

DroughtGard would only increase productivity by less than 1 percent per year, said the report's author, Doug Gurian-Sherman, a senior scientist in the group's Food and Environment Program.

In the face of criticism, big agricultural companies have repeatedly said that advanced genetic manipulation -- through biotechnology or advanced breeding technology -- is no bull's-eye solution but is simply a tool to better manage arid conditions.

"We've always told farmers they need to have realistic expectations," Schussler said.

In a climate-stressed world, farmers will need to adapt with new management practices, and Edge hopes using drought-resistant hybrids will re-emphasize the importance of water conservation.

"We can make progress," he said. "But it's one step at a time."[395 words]

source:

http://www.scientificamerican.com/article/drought-tolerant-corn-trials-show-positive-early-results/

Drought Led to Collapse of Civilizations, Study Says

Study of fossilized pollen helps solve an intriguing historical mystery.

PUBLISHED OCTOBER 24, 2013

time5

A study of fossilized pollen particles taken from sediments at the bottom of the Sea of Galilee may have solved an intriguing historical mystery that has been troubling archaeologists for decades.

"In a short period of time, the entire world of the Bronze Age crumbled," says Israel Finkelstein, an archaeologist at the Institute of Archaeology at Tel Aviv University, who was one of the lead scientists in the study.

"The Hittite Empire, Egypt of the pharaohs, the Mycenaean culture in Greece, the copper-producing kingdom located on the island of Cyprus, the great trade emporium of Ugarit on the Syrian coast, and the Canaanite city—states under Egyptian hegemony—all disappeared and only after a while were replaced by the territorial kingdoms of the Iron Age, including Israel and Judah."

Wars, pestilence, and sudden natural disasters have all been postulated as possible causes, but now, thanks to sophisticated pollen-sampling techniques and advances in radiocarbon dating, Finkelstein and his colleagues believe they know the primary culprit: drought, or rather a succession of severe droughts over a 150-year period from 1250 BCE to about 1100 BCE.

These fairly precise dates come from core samples drilled into the sediments at the bottom of the Sea of Galilee. The drill cores extended 18 meters into the seabed and cut across a range of sediments deposited over the past 9,000 years.

Pollen: "Fingerprints" of Plants

"We focused our study on the time interval between 3200 BCE and 500 BCE," says Dafna Langgut, a University of Tel Aviv palynologist (one who studies ancient pollens). She, along with Finkelstein and University of Bonn geology professor Thomas Litt, authored the study, which appeared this week in Tel Aviv: Journal of the Institute of Archaeology of Tel Aviv University.

By studying pollen samples taken at 40-year intervals, the scientists were able to monitor changes in the vegetation. "Pollen grains are the 'fingerprints' of plants," says Langgut. "They are extremely helpful in the reconstruction of ancient natural vegetation and past climate conditions."

The scientists noticed a sharp decline around 1250 BCE in oaks, pines, and carob trees—the traditional flora of the Mediterranean in the Late Bronze Age—and an increase in the types of  plants usually found in semiarid desert regions. There was also a big drop in the number of olive trees, an indication that horticulture was on the wane. All are signs, say the researchers, that the region was in the grip of regular and sustained droughts.[409 words]

time6

Shortages and Unrest

The most crucial years of the collapse were probably between 1185 and 1130 BCE, says Finkelstein, but the entire process extended over a longer period of time.

"I think that climate change can be seen as a sort of a 'prime mover' that initiated other processes," says Finkelstein. "For example, groups of people in the northern regions were uprooted from their homes because of destruction of the agricultural output, and [they] started moving in search of food. They could have pushed other groups to move by land and sea. And this in turn caused destructions and disruption of the delicate trade system of the eastern Mediterranean."

The dates the researchers came up with via pollen analysis correspond nicely to the few remaining historical records of the period, which mention shortages of grain, disruption of trade routes, civil unrest, and pillaging of cities as people began to fight over diminishing resources. The Late Bronze Age was also a period when marauding bands known as the Sea Peoples raided coastal areas in the eastern Mediterranean.

The tumultuous period ended only when rains returned and uprooted groups began to settle down again.[192 words]

source:

http://news.nationalgeographic.com/news/2013/10/131024-drought-bronze-age-pollen-archaeology/

cherry6891

Part III: Obstacle

Climate change models fail to accurately simulate droughts
By Ashutosh Jogalekar | April 18, 2013
Most of my day job involves simulating the behavior of molecules like drugs and proteins using computer models. The field is more an art than a science, partially because the systems that are being modeled are too complex and ill-understood to succumb to exact solutions. Success often depends on experience and intuition gained by working on similar systems. That does not mean there are no correct predictions, but it does mean that surprises are more common than we think and that many phenomena are impossible to model within a very precise window of accuracy. The failure of a model can sometimes be traced to a simple inability to simulate the behavior of an essential component of the system. In several cases this component is simply the water that surrounds a protein; water remains a substance that’s as enigmatic as any other. In other cases it could be the entropy of the system. The problem is that these factors are very hard to calculate even when we know that they are responsible for the limitations of our model.

A recent report on the failure of climate change models to predict the timing of major droughts in the Southwest made me think of some of the problems in my own field. Unfortunately the actual paper is not out yet so we will have to wait for the details, but the news piece in Nature has a good summary.

Sloan Coats of Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York, and his colleagues tested whether a state-of-the-art climate model could simulate the droughts known to have occurred in the southwest during the past millennium. The model incorporated realistic numbers for factors that affect temperature and rainfall, such as atmospheric carbon dioxide levels, changes in solar radiation and ash from volcanic eruptions. It also incorporated changes in the El Niño/Southern Oscillation (ENSO).

The results were puzzling. Although the simulation produced a number of pronounced droughts lasting several decades each, these did not match the timing of known megadroughts. In fact, drought occurrences were no more in agreement when the model was fed realistic values for variables that influence rainfall than when it ran control simulations in which the values were unrealistically held constant. “The model seems to miss some of the dynamics that drive large droughts,” says study participant Jason Smerdon, a researcher at Lamont-Doherty who studies historical climate patterns.

Other climate models tested by the team fared no better, he says. In particular, the models failed to reproduce a series of multi-decadal droughts that occurred in the southwest during the Medieval Climate Anomaly, a period between AD 900 and 1200 when global temperatures were about as high as they are today.

The team goes on to provide several possible explanations for the failure of the models, most likely related to their inability to account for details in the ENSO cycle. The researchers also note that the models may not capture some important features of the biosphere.

In addition to their failure to reproduce El Niño and La Niña, existing models do not fully capture other factors that influence rainfall, such as clouds and vegetation. But Smerdon adds that the atmospheric and oceanic dynamics that inhibit rainfall and favour prolonged drought may be essentially random and so almost unpredictable.

This is in fact a problem that has plagued computer models of climate since their very inception in the 1950s. The early general circulation models (GCMs) included the motion of the atmosphere and factors like wind speed, temperature and pressure. Over time these atmospheric circulation models became quite sophisticated, account for radiation transport and the opacity of various gases. The strengths and weakness of these models largely carried over into modern day climate modeling.

In general the models are quite good at simulating the motions of the atmosphere but are still inadequate in accounting for the complex processes in the biosphere, including the behavior of the soil, forests, rivers, mountains and the various plants and animals that inhabit these environments. This discrepancy between accurate atmospheric simulation and lackluster biospheric simulation may be responsible for many of the defects in climate modeling. And as the researchers say, the models are still not great at capturing fine-grained details of clouds and their influence on water. It’s striking to me that both molecular models and climate models struggle in modeling that simplest and most ubiquitous of substances – water. No wonder they have a hard time predicting droughts and precipitation. Finally, the lack of difference in the results when the key factors are held constant and when they are allowed to vary points to an independent and possibly unknown set of factors that are influencing model results.

Nonetheless as the article says, the major predictions about global precipitation seems to be clearer and are based on extensive field studies across the globe; climate change is much more than computer modeling. The problems though are in predicting local precipitation patterns and unfortunately it’s these kinds of predictions that drive public policy at local and state levels. The most important result from such modeling data of course is the knowledge it provides about the strengths and limitations of climate change models. And knowledge is always useful.[866 words]

source:
http://blogs.scientificamerican.com/the-curious-wavefunction/2013/04/18/climate-change-models-fail-to-accurately-simulate-droughts/

slave918

Speaker:
Although the harvest in US increases since the corn plant grow cloeser and deeper, it may actually leads to drought.

T2 2:16
A drought in China.

T3 2:26
two accompanies are focus on the invention of corn which can resisit drought.
But it's effection is limited.

T4 2:21
the companies change the gene of plant so improve the pore and respiration rate.
However, someone critic the behavior of these companies since the improvement of the plant is mild.

T5 2:36
recently, the finding of the seeds of fingerplant and some kinds of tress indicates that the collapse of a civilization.

T6 1:17
the drought leads that people uproot their house and search food in another place.

T7 7:25
the author found out that models often can't accuratly simulate the drought.
Reasons: water and ??
2 experiments to demonstrate the inability of the model.
The author concludes that although this model have defects, but it is still important.

onlychloelou

FIRST DAY!!YAY!!!

[Time 2] 1'01" China is experiencing its worst drought which affect one third of the country and the harvest is considerably low.
[Time 3]1'31"  Two of the world's largest agricultural companies are testing corn and they consider that technology can’t compensate the shortage of water.
[Time 4]1'34"  Although the big companies do whatever they can do improve, there is no substantial increase in yield and. The companies suggest the farmers to be realistic.
[Time 5]1'17" Pollen-sampling techniques and advances in radiocarbon dating help scientists discover that the drought is the hint to Bronze Age. Also Pollen samples aid scientists in monitoring changes in vegetation.
[Time 6]35"  The dates the researchers came up with via pollen analysis correspond nicely to the few remaining historical records of the period, which mention shortage and unrest.

心愿湖畔

00:59
The worst drought in half century is impacting one-third of China, leaving some places with no viable drinking water, let alone irrigating water.
01:29
Drought-tolerant corn effort shows positive results, and some farmers are excited about it.
01:56
It’s one step at a time.
01:33
Successive heavy drought may account for the disappearing civilizations.
00:52
Rapid climate change triggers/initiates a series of processes, disrupting the trade system necessary for civilization.

KKCarpeDiem

有二十天缺席阅读小组了，如果坚持下来我应该已经阅读能力提高很多了。之前因为读了打开却还是不知道意思就放弃了，最近看了阅读的方法，觉得自己太放松自己了。现在继续跟着小组练习，希望能坚持！

2.16 2.01 2.32 2.34 1.27

洋沫沫

time2:2'18
time3:3'26
time4:3'50
time5:3'
time6:1'25
a study finds that the bronze age collapsed because the drier whether.
they find pollen as the fingerprint of plants,finding that...all kinds of plants suffered from draught
because of this, people moved away.
when whether got better, the new period would come back.

Obstacle: 9'03

the model cannot predict everything very acurately.
and especially drought is hard to be predicted.
maybe three reasons:
(1) one factor involved in the model cannot be acurately measured.
(2) some other factors that have important influence cannot be find
(3) some factors are unpredictable.
generally, biosphere is harder to forcast than atomsphere. however, the knowledge the professional collect is very useful.

公元前334

2:00 China is facing worset drought in 1/3 land, including Jilin and Henan.
2:40 DuPont and Monsnto's anti-drought corn are trial in China, corn heart area.
2:57 While it may help individual farmers recoup yield losses in drought conditions, it would not increase food production to sustain a climate-stressed world.
3:27 Pollen peals that drought causes the Bronze Age crumbled.
1:37 Drought causes tumultuous until rains come back in eastern Mediterranean.

jfire

time1 00:01:19.5
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obsta 00:02:52.7