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Field-Scale Impacts of Elevated CO2 on the World’s Major Crops [Copy link] 中文

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Post time 2013-2-22 02:58:35 |Display all floors
This post was edited by sansukong at 2013-2-22 02:11

Field-Scale Impacts of Elevated CO2 on the World’s Major Crops (19 Feb 2013)

Reference


Vanuytrecht, E., Raes, D., Willems, P. and Geerts, S. 2012. Quantifying field-scale effects of elevated carbon dioxide concentration on crops. Climate Research 54: 35-47.
Working with peer-reviewed publications that report the results of Free-Air CO2-Enrichment (FACE) studies - which they acquired via searches of the ISI Web of Science citation database (Thomson) and the ScienceDirect citation database (Elsevier BV) - Vanuytrecht et al. (2012) conducted a meta-analysis of 529 independent observations of various plant growth responses to elevated CO2 that they obtained from 53 papers that contained relevant data in graphical or numerical format pertaining to the following major crops: wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), rice (Oryza sativa L.), soybean (Glycine max L.), potato (Solanum tuberosum L.), sugar beet (Beta vulgaris L.), cotton (Gossypium hirsutum L.), maize (Zea maysL.) and sorghum (Sorghum bicolor L.), as well as the two major pasture species of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.).Considered en masse, Vanuytrecht et al. determined that for an approximate 200-ppm increase in the air's CO2 concentration (the mean enhancement employed in the studies they analyzed),water productivity was improved by 23% in the case of aboveground biomass production per unit of water lost to evapotranspiration, and by 27% in the case of aboveground yield produced per unit of water lost to evapotranspiration, which two productivity increases would roughly correspond to enhancements of 34% and 40% for a 300-ppm increase in the atmosphere's CO2 concentration.It is also important to note in this regard that although "the FACE technique avoids the potential limitations of (semi-) closed systems by studying the influence of elevated CO2 on crop growth in the field without chamber enclosure," as the team of Belgian researchers write, other studies have demonstrated a significant problem caused by the rapid (sub-minute) fluctuations of CO2concentration about a target mean that are common to most FACE experiments, as described by Bunce (2011, 2012), who found most recently that total shoot biomass of vegetative cotton plants in a typical FACE study averaged 30% less than in a constantly-elevated CO2 treatment at 27 days after planting, while wheat grain yields were 12% less in a fluctuating CO2 treatment compared with a constant elevated CO2 concentration treatment.Looking toward the future, getting higher crop yields per unit of water used in the process of obtaining them will be a key element of mankind's struggle to feed our ever-increasing numbers over the next four decades, when our food needs are expected to double (Parry and Hawkesford, 2010); and with both land and water shortages looming on the horizon, we are going to need all of the help we can possibly get to grow the extra needed food. Fortunately, the results of this meta-analysis coming out of Belgium point to one important avenue by which such very substantial help can come, but it will only come if the air's CO2 content is allowed to rise unimpeded.Additional References
Bunce, J.A. 2011. Performance characteristics of an area distributed free air carbon dioxide enrichment (FACE) system. Agricultural and Forest Meteorology 151: 1152-1157.
Bunce, J.A. 2012. Responses of cotton and wheat photosynthesis and growth to cyclic variation in carbon dioxide concentration. Photosynthetica 50: 395-400.Parry, M.A.J. and Hawkesford, M.J. 2010. Food security: increasing yield and improving resource use efficiency. Proceedings of the Nutrition Society 69: 592-600.
Archived 19 February 2013




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Post time 2013-2-22 11:32:32 |Display all floors
China and Russia block UN Security Council climate change action



Last updated on 19 February 2013, 8:40 am

By Ed King

Russia and China blocked efforts last Friday to have climate change recognised as an international security threat by the UN Security Council (UNSC).

The council met in New York to discuss the potential effects of global warming, but according to Bloomberg the two permanent members objected to it being a ‘formal session’.

Despite the participation of UN Secretary-General Ban Ki-moon this meant the session – planned by Pakistan and the United Kingdom – had few political implications.

China, Russia, India and more than 100 developing countries oppose climate becoming a UNSC issue as the council does not operate under the principles of Common But Differentiated Responsibility, which underpins the UN climate talks.

They are concerned that securitizing the issue would place a greater burden on poorer nations with large greenhouse gas emissions to take action.

The Security Council is mandated to take primary responsibility for the maintenance of international peace and security (Pic: UN Photos)


Small island states vulnerable to sea level rises have pushed for climate to be discussed at this level for over two decades.

Marshall Islands representative Tony deBrum expressed frustration with Russia and China’s stance, explaining that 35 years on from gaining independence from the USA the very existence of his country is now in question.

“Our roads are inundated every 14 days,” he said. “We have to ration water three times a week. People have emergency kits for water. We can no longer use well water because it’s inundated with salt.”

The meeting – the third in UNSC history – was convened by council President Pakistan and permanent member the United Kingdom, which despite domestic criticism over its low carbon strategy appears to be embarking on a new initiative to inject momentum into global efforts to cut emissions.

The UK’s new climate envoy Rear Admiral Neil Morisetti is pushing for climate change to be framed as a global security concern.

“The UK believes that the impacts of a changing climate pose a significant and emerging threat to a country’s national security and prosperity,” a Foreign Office spokesman told RTCC.

“The UK is engaging with our international partners and through international forums to better manage this risk.”

Risk multiplier

A 2009 report commissioned by the council identified climate change as a ‘threat multiplier’, stressing it would hit food supply lines and affect the territorial integrity of island states.

And in 2011 it discussed whether ‘green helmet’ climate peacekeepers could be required to prevent conflicts caused by resource scarcity.

Addressing the session, leading German scientist Joachim Schellnhuberexplained that rises in global temperatures were likely to have catastrophic consequences.

“With unabated greenhouse-gas emissions, humankind would venture into an uncertain future that is much hotter than ever before in its history – so from a scientist’s perspective, climate change is a global risk multiplier,” he said.

The World Bank’s Rachel Kyte told delegates cities must take the lead in developing low carbon infrastructure, in terms of transport, urban planning and managing water resources.

In a statement Oxfam International’s Tim Gore urged the UNSC to debate the issue further, warning the global food system was already under severe stress as a result of droughts across the US, Africa and Asia.

“Droughts or floods can wipe out entire harvests, as we have seen in recent years in Pakistan, in the Horn of Africa and across the Sahel,” he said.

“And when extreme weather hits major world food producers – like last year’s droughts in the US and Russia – world food prices rocket. This presents a major risk to net food importing countries, such as Yemen, which ships in 90% of its wheat.

“The food riots and social unrest seen in the wake of the 2008 food price spikes were not a one-off phenomenon, but a sign of the risks we face through our failure to feed a warming world.”



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Post time 2013-2-22 16:05:24 |Display all floors
Adaptation to climate change is an area of active research.

Most of the conclusions is that climate change is a negative on food supply.

Extreme weather is of course a big negative.

Adaptation of bugs happens faster than the plants are able to handle. This stresses the plants.
Plant defenses against bugs are compromised requiring even more pesticides....a no good feed back loop.
I've made my living, Mr. Thompson, in large part as a gambler. Some days I make twenty bets, some days I make none. There are weeks, sometimes months, in fact, when I don't make any bet at all because ...

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Post time 2013-2-22 16:07:36 |Display all floors
China and Russia block UN Security Council climate change action.....



What else is new?
I've made my living, Mr. Thompson, in large part as a gambler. Some days I make twenty bets, some days I make none. There are weeks, sometimes months, in fact, when I don't make any bet at all because ...

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