Zhang et al 2007

Although rising of temperature will, at least for a while, increase total bio-productivity according to biological principles, recent research suggests that the negative effects of global warming on agriculture seems greater than the positive effects 34 Our temperature data come from the most comprehensive and latest published records of the NH annual temperature trajectory, supplemented by the SH and global temperature trajectories The feedback mechanism explains why there were time gaps between the turning points of temperature variation and the war—peace cycles in various NH continents in the late 17th and late 18th centuries Fig.

The cells had lower oxygen consumption rates and reduced mitochondrial electron transport chain activities. As this data series is only in year intervals, we estimated the annual agricultural production index by using cereal prices and population sizes.

Such a feedback effect can also be seen in Europe in the late 18th century. When agricultural production went down, wheat prices went up in both Europe and China. Paleo-temperature variation and its impact on Europe and China, A.

Some of these theories may explain certain wars, and some of the theories may even explain sizable classes of wars, but none of them can explain the temporal and spatial patterns of warfare presented above. Our quantitative results also show the importance of the roles of some other human adaptive choices in mitigating war outbreak and population decline.

However, the change of economy after A. Zhang et al 2007 gradual increase in time delays for NH population declines as we moved into the modern era may reflect that at least some social mechanisms may becoming more effective over time at the macroscale.

In severe cases, the economic burden would cause conflict for resources and intensify social contradictions and unrest as we have seen in the past. The important direct impact of the change from the climate cooling was on agricultural production that dominated the economy of agricultural societies.

The results also have implications for the following outstanding issues. Other Pathways for Human Adaptation. Although we have more robust social institutions at both international and national levels, and much more advanced social and technological developments at present, a much larger population size, higher standard of living, and more strictly controlled political boundaries will limit some adaptive choices to climate change.

Our results not only answered when and where most of wars occurred, but also imply that relative food scarcity was a fundamental cause of war outbreaks according to our quantitative analysis on various physical and social components and in different geographical regions. The European grain yield ratio followed temperature change very closely Fig.

For food supply per capita, it is represented by historical cereal prices because it is determined by supply agricultural production and demand population size.

We are now in the warmest climatic phase of the past two millennia, another climatic extreme like the 17th century in LIA, which was the coldest period of the past two millennia This study clearly indicates that an autophagy defect has a functional impact on various aspects of mitochondrial functions and suggests a critical role of autophagy in mitochondria maintenance.

Nevertheless, only the cereal price data for Europe 41 and China 42 are long enough time series for our data analysis see SI Text. Other direct impacts of global warming, such as sea level rising, spread of tropical diseases, increase of extreme weather events and glacial retreat, would also add costs on the current economy that is supported by cheap energy.

Although the climate was mild and agricultural production was high, the rapid increase in population dampened the food supply per capita prices increasedand then the number of wars started to go up.

Here we used yeast as a model system to characterize the cellular consequence of ATG autophagy-related gene deletions.

Population growth rates were influenced by both war frequency and food supply per capita reflected in cereal prices and dramatically dropped to negative values when agricultural production was at its lowest levels, cereal prices reached their highest level, and peaks in war frequency occurred.

At the country and local scales, these social mechanisms might have lessened, postponed, or even eliminated on occasion war outbreak and population declines during bouts of mild or short cooling. A change of one key component in the ecosystem under global warming would likely cause disastrous results in human societies dependent on the existing human ecosystem.

Besides, it has been confirmed that a cold period LIA existed globally during the last millennium 3637 see SI Text. Perhaps we are reaching the point at which it might break the balance of a human ecosystem that has been long established at a lower temperature, and in addition, many secondary and tertiary effects of global warming cannot be predicted based on current knowledge.

The second one is the estimated annual values of agricultural production for Europe and China, which are calculated by population size over cereal price see SI Text. C Detrended population size solid lines and population growth rate dotted curves 22 It has been shown that elevated levels of war outbreak and population decline in populated areas occurred during a cold climate in the past millennium.

The first one is the grain yield ratio in relation to seed for Western and Central Europe 18but the data are in year intervals. Organisms bearing deletions of the essential autophagy genes exhibit various pathological conditions, including cancer in mammals and shortened life span in C.

The correlation coefficients between the factors listed in Fig. Both higher and lower temperatures would lead to change of the human ecosystem.

However, we believe that the greater threat from global warming comes from the uncertainty of the ecosystem change, because the current high global average temperature which has never been experienced in the last two millennia is continuing to rise at an accelerated speed.

After the slump in population size, food supply per capita increased as reflected in decreased pricesand the incidence of war in the late 17th century declined even as the climate was cold and agriculture production was still low.

The level of average correlation is shown by the thickness of the lines in SI Fig.

The authors declare no conflict of interest. Sadly, scholars have made at best modest progress on the problem even though members of all of the social sciences have addressed it Our approach has not been to examine causes of individual wars, but to investigate the frequency of all wars during a specific period of human history and find out when, where, and why the war—peace cycles occurred.Ecosystem services and dis-services to agriculture Wei Zhanga,⁎, Taylor H.

Rickettsb, Claire Kremenc, Fig. 2–Ecosystem services and dis-services to and from agriculture. Solid arrows indicate services, whereas dashed arrows (Klein et al., ). Bees comprise the dominant taxa. (Zhang et al., ); in contrast, ordinary macrobubbles quickly rise and burst at the surface of water (Takahashi et al., ).

Therefore, microbubbles are a highly efficient means of delivering dissolved gas into a solution. A crucial characteristic of the microbubble is that they are elec. Solar and interplanetary sources of major geomagnetic storms (Dst ≤ − nT) during – Authors. J. Zhang, Melbourne, Florida, in March The two workshops focused on the major geomagnetic storms of solar cycle 23, specifically the 88 events from First, as suggested by Zhang et al.

May 25,  · GFDL - Geophysical Fluid Dynamics Laboratory Skip to content. Events; Research. Zhang et al. ; Zhang et al.

). Work is proceeding on methods to reduce coupled model biases that can harm forecast performance; one such method is through the use of flux adjustments, which aim to improve the model climatology.

Krus et al. also examined frequency of Chinese wars and found that the periods that non-Confucian ethical systems dominated China had more wars. However, the periods often were cold and dry, and such climate drove the northern and western tribal states to enter central China, thus changing original Confucian ethical systems.

Zhang DD ().

Global climate change, war, and population decline in recent human history

et al., ; Alfarra et al., ], but recent results with SOA formed from diluted diesel exhaust yield a spectrum very similar to the most common ambient OOA [Robinson.

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Zhang et al 2007
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