CROP RESPONSE TO ELEVATED CO2 AND WORLD FOOD SUPPLY

Greenies have tried to ignore or play down the fact that CO2 is plant food and that increased CO2 would therefore lead to bigger crops. A scholarly comment below answers one of those attempts -- commenting on "Food for Thought" by Long et al., Science 312:1918 to 1921, 2006

Abstract

Recent conclusions that new free-air carbon dioxide enrichment (FACE) data show a much lower crop yield response to elevated CO2 than thought previously -- casting serious doubts on estimates of world food supply in the 21st century -- are found to be incorrect, being based in part on technical inconsistencies and lacking statistical significance. First, we show that the magnitude of crop response to elevated CO2 is rather similar across FACE and non-FACE data-sets, as already indicated by several previous comprehensive experimental and modeling analyses, with some differences related to which "ambient" CO2 concentration is used for comparisons. Second, we find that results from most crop model simulations are consistent with the values from FACE experiments. Third, we argue that lower crop responses to elevated CO2 of the magnitudes in question would not significantly alter projections of world food supply. We conclude by highlighting the importance of a better understanding of crop response to elevated CO2 under a variety of experimental and modeling settings, and suggest steps necessary to avoid confusion in future meta-analyses and comparisons of experimental and model data.

1. Introduction

A recent review of free-air carbon dioxide enrichment (FACE) studies concluded that the positive effects of elevated CO2 on several food crops are roughly half those shown by earlier experiments conducted in non-FACE environments (Long et al., 2006). On the basis of such strong differences, it was argued that crop models -- based on the old data -- may simulate response to elevated CO2 too strongly, thereby downplaying otherwise potentially large negative effects of future projected changes in temperature and precipitation on crop yields. Thus, estimates of world food supply for the 21st century, as reviewed by IPCC (2001), might be too optimistic and in need of substantial downward revisions (Long et al., 2006 and Long et al., 2005).

While discussions focusing on uncertainties of crop model projections of yield under climate change and elevated CO2 are important (e.g., IPCC TAR, 2001; Reilly et al., 2001 and Tubiello and Ewert, 2002), current literature shows that these recent conclusions are incorrect, for several reasons. Here we argue that:

(1) The meta-analysis of Long et al. (2006) does not show significantly lower crop yield response to elevated CO2 in FACE compared to non-FACE experiments.

(2) Simulated yield responses to elevated CO2, as implemented in most crop models used for climate change impact assessment, are consistent with FACE results.

(3) Any remaining differences in CO2 response based on FACE results would not significantly alter projections of world food supply in the 21st century.

[...]

4. Conclusions

Several decades of research on the effects of elevated CO2 concentration on crop growth and yield have produced a wealth of valuable information, critically increasing understanding of the dynamics of photosynthesis, biomass accumulation and crop yield that are necessary to project future impacts of climate change on agriculture. In particular, some key interactions between elevated CO2 effects and crop management, especially irrigation and fertilization regimes, are fairly well understood. Yet the jury is still out concerning the real strength of the effects of elevated CO2 on crop yields in farmersY_T fields, due to several key uncertainties. To this end, much more research is needed to increase understanding of the interactions of elevated CO2 with increasing temperatures, worsening air pollution, changes in moisture availability and mineral nutrition, and altered incidence of pests, diseases and weeds.

It is also necessary to assess response of crops other than the key cereal grains, and in climate regimes other than temperate, especially those of importance to developing countries in the sub-tropics. The strength of the CO2 effect in comparison to other drivers of change in the world food system (e.g., market forces) needs to be further assessed.

Our analyses show that crop yield responses to elevated CO2 are similar across FACE and non-FACE experimental data. Not only is this important for interpreting existing projections of global food supply, but it also has implications for the future of experimental work on plant response to elevated CO2 and environmental stress. In particular, our results indicate that many experimental frameworks, from controlled environments to FACE, have useful roles. While FACE systems are invaluable in many respects, several considerations --for instance cost, interest in evaluating CO2- temperature interactions, or the need to test at CO2 levels higher than 550 ppm -- make it important to know that controlled environmental chamber, greenhouse, closed-top or open-top field chambers, or gradient tunnel approaches can continue to be used with reliable results. Such approaches can provide at least valuable initial screening of the effects of multiple environmental stresses on crop yields, even if eventually one might hope to examine field-level consequences in a FACE environment.

Importantly, even greater co-operation is warranted between experimentalists and modelers, and across disciplines, so that key questions of importance to crop yield, crop production and food supply under future climate, environmental and socio-economic change can be framed within comprehensive and mutually beneficial research programs.

FULL PAPER here






BRITAIN: HOUSING SHORTAGE TO TRUMP THE GREENS?

Property developers were given the go-ahead yesterday to build on the green belt with radical proposals to speed up the construction of homes and shops. Kate Barker, the economist commissioned by Gordon Brown to address planning delays, called for an urgent review of green-belt boundaries. She suggested that some of it could meet housing needs. Ms Barker also proposed giving the go-ahead for more supermarkets and shopping malls, both in town centres and on their outskirts. She made it clear that the market, rather than councils, should dictate development.

The Barker Review of Land Use Planning argues that economic and social benefit should take precedence in siting future developments, even if that meant encroaching on undeveloped land. Many of her proposals, including a new planning commission for national projects such as nuclear power stations, are expected to be contained in a White Paper next year.

The report, which enraged environment and rural groups such as Friends of the Earth, says that business developers and communities face high costs due to a slow and bureacratic planning system. Current restrictions had also stifled competition and choice while more houses were desperately needed.

Ms Barker, a member of the Bank of England's Monetary Policy Committee, argued that green belt boundaries often led to increased emissions and pollution caused by commuters in cars, buses and trains. She recommends redrawing the green belt to include "green wedges" or "green corridors" with spaces for homes and other developments. Much of the green belt, which accounts for 12.9 per cent of all land in England, was "low value agricultural land with little landscape quality and limited public access", Ms Barker said. Much of the urban fringe was run down and could be used to develop homes or businesses, she argued, citing a poll suggesting that most people were unaware how little land was already developed. But Friends of the Earth said that her recommendations would give business and supermarket chains a much bigger say and have a "devastating impact on the environment and local democracy".

Hugh Ellis, Friends of the Earth's planning adviser, said: "Barker's vision of uncontrolled development will mean communities have little or no say in how their local area is developed." The Campaign to Protect Rural England said that her recommendations would speed up urban sprawl all over the countryside. "Green belts have never been entirely sacrosanct, nor should they be, but they are one of England's most effective, best known and most popular planning tools," Shaun Spiers, the CPRE's chief executive, said.

Caroline Spelman, the Shadow Communities Secretary, said: "The Conservatives will oppose the plans for a new, undemocratic government quango to impose development on local communities. I fear that Gordon Brown, the arch-centraliser, is consigning local democracy to the scrapheap."

Although Ms Barker has suggested that the current presumption in favour of building first in town centres should remain, her proposals will encourage building on outskirts. Property experts said that retailers would be given freer rein to develop out-of-town hypermarkets and warehouse-style stores if her recommendations are accepted.

Ms Barker has suggested the removal of the "needs test", under which local authorities can block retail, housing or commercial property development if a community is already well served with such facilities. "Investors who are risking their capital and whose business it is to assess likely customer demand are better placed than local authorities to determine the nature and scale of demand," she said.

However, Stuart Robinson, head of planning at CB Richard Ellis, the property company, said: "She might as well rip up the whole town-centre-first policy. There is no way local authorities could prevent a whole raft of different buildings going straight out to unsustainable locations."

Ms Barker argues that other guidelines, including a "sequential test", which determines that developments must opt for a town-centre location if at all possible, and an "impact assessment", which examines the economic and environmental impact of developments, would promote towncentre development. But her report indicates that more out-of-town development would be desirable in promoting competition among retailers. They gave a cautious welcome to Ms Barker's recommendations. Tesco said that the proposals would speed up planning decisions and reduce the complexity of the system.

Lucy Neville-Rolfe, Tesco's corporate and legal affairs director, said: "This should lead to smoother and faster development, wind turbines included, but it reiterates support for the town-centres-first policy." A spokesman for Asda said: "We believe these changes in the planning regime would be good for customers by increasing choice, while being consistent with sustainable development."

Source






SEA LEVEL RISE IS NOT ACCELERATING: NO RELATIONSHIP TO ATMOSPHERIC CO2 RECORD

Discussing: Larsen, C.E. and Clark, I. 2006. "A search for scale in sea-level studies". Journal of Coastal Research 22: 788-800.

Background

The authors, who are employed at the U.S. Geological Survey's National Center in Reston, Virginia, note that "the concept of proportionality between CO2 and sea level implies that the rate of sea-level rise accelerates in tandem with an exponential increase in CO2 and atmospheric temperature," and that "this simple concept has been used to argue that the rate of sea-level rise was low over the past 6000 years, began to increase during the 19th century, and will continue to increase during the next century."

What was done

In an analysis of this concept, which is essentially the climate-alarmist view of the matter, Larsen and Clark considered data bases that represent three different time scales: (1) the last 6000 years, based on radiocarbon-dated organics from basal peat deposits below salt marshes and estuarine sediments along stable or apparently subsiding coasts, (2) the last 1000 years, based on peat samples and benthic foraminifers from coastal salt marshes, and (3) the historic record of the last few hundred years, based on actual tide gauge data.

What was learned

The researchers report that when the three scales of sea-level variation are integrated, adjusted for postglacial isostatic movement, and replotted in terms of depth relative to present mean high water, they are able to "view the historic record as a continuation of the past rather than as a perturbation." In addition, they thereby demonstrated the strong linearity in the historic rate of sea-level rise over the past century and a half, which, as they describe it, "shows no indication of the pronounced mid-20th-century increase in temperature indicated by Mann et al. (1999)," noting further that "neither is there a relationship to the atmospheric CO2 record."

What it means

In contrast to the oft-stated claim that the rate of sea-level rise has been accelerating in tandem with the rate of rise in the air's CO2 concentration and/or its temperature, Larsen and Clark could find no evidence that supports that contention.

Source

The relevant journal abstract follows:

A search for scale in sea-level studies

By: C.E. Larsen and I. Clark

Many researchers assume a proportional relationship among the atmospheric CO2 concentration, temperature, and sea level. Thus, the rate of sea-level rise should increase in concert with the documented exponential increase in CO2. Although sea surface temperature has increased in places over the past century and short-term sea level rose abruptly during the 1990s, it is difficult to demonstrate a proportional relationship using existing geologic or historic records. Tide gauge records in the United States cover too short a time interval to verify acceleration in the rate of sea-level rise, although multicentury tide gauge and staff records from the Netherlands and Sweden suggest a mid-19th-century acceleration in sea-level rise. Reconstructions of sea-level changes for the past 1000 years derived using benthic foraminifer data from salt marshes along the East Coast of the United States suggest an increased rate of relative sea-level rise beginning in the 1600s. Geologic records of relative sea-level rise for he past 6000 years are available for several sites along the US East Coast from 14C-dated basal peat below salt marshes and estuarine sediments. When these three scales of sea-level variation are integrated, adjusted for postglacial isostatic movement, and replotted, the range of variation in sea level suggested by basal peat ages is within [+ or -] 1 meter of the long-term trend. The reconstruction from Long Island Sound data shows a linear rise in sea level beginning in the mid-1600s at a rate consistent with the historic record of mean high water. Long-term tide gauge records from Europe and North America show similar trends since the mid-19th century. There is no clear proportional exponential increase in the rate of sea-level rise. If proportionality exists among sea level, atmospheric CO2, and temperature, there may be a significant time lag before an anthropogenic increase in the rate of sea-level rise occurs.

Source






Can British Wine Grapes Resolve a Global Warming Question?

By Dennis T. Avery

British wine grapes are suddenly in the midst of the global warming controversy. Historic records tell us that Britain grew wine grapes 2000 years ago during the Roman Warming, and 1000 years ago during the Medieval Warming. Since 1300, however, Britain has been too cold for wine grapes. The debate: Is human-induced warming boosting British temperatures to "unnatural" levels, or is the gradual warming a repeat of previous cycles?

The website English-wine.com says there are more than 400 vineyards in Britain today, and ". . . the good news about English wine [is] how good, even superb, it can be." It certainly sounds like Britain has gotten warmer recently, but why? The same web site has a "History" section, which reveals: "In England [today], it is only in about 2 years in every 10 that grape production will be really good, 4 years will be average and 4 years poor or terrible-largely due to weather and/or disease exacerbated by weather." (Sounds as if we aren't quite to "wine country warmth yet, doesn't it?)

The same web site also says: "In the 1990s the increase in the number of vineyards and the acreage under cultivation has leveled off, maybe even declined a little. There are a number of reasons for this- many English vineyards have undoubtedly been established with little knowledge of, or even concern for, their financial viability. A saying has grown up that the best way to get a small fortune is to have a large fortune and buy an English vineyard. Whilst this is cruel, it is also pretty certain that it is true."

The web site RealClimate, though it believes fervently in man-made global warming, accurately laid out the last 1000 years of British wine-making on July 12, 2006: "The earliest documentation that is better than anecdotal is from the Domesday Book (1087 AD) . . . Selley quotes Unwin (J. Wine Research, 1990) who records 46 vineyards across Southern England [at that time] . . . production clearly declined after the 13th century, and had a modest resurgence in the 17th and 18th centuries, only to decline to historic lows in the 19th century when only 8 vineyards are recorded. . . . English and Welsh wine production started to have a renaissance in the 1950s. By 1977, there were 124 reasonable-sized vineyards in production-more than at any other time over the previous millennium."

So, British wine-making thrived during the Medieval Warming, failed during the Little Ice Age (1300 to 1850), and began to make a comeback in the 1950s, after major world temperature surges between 1850-70 and 1920-40. The uncertain quality of today's British wine grapes indicates that Britain still isn't as warm now as during the Roman and Medieval Warmings.

This argues that we're in a long, natural climate cycle. So does the fact that more than 70 percent of the planet's recent warming occurred before 1940, and thus before humans emitted much CO2. Ice cores and seabed sediments show the 1500-year cycle extending back 900,000 years, and carbon 14 isotopes say it's linked to variations in the sun's irradiance.

British wine-growers are likely to have several more moderately warmer centuries in which to prosper. And wine-lovers will have more-pleasant weather in which to enjoy the wines than they did during the cold, cloudy and stormy Little Ice Age. A reduction in fossil fuel use might be a good strategy for the future, but apparently would have little impact on earth's climate.

Source

Mr Avery might also have mentioned that modern British winegrowing is materially assisted by modern agricultural techniques, including selective breeding of varieties suited to different climates and the use of hardy American rootstocks that were not available in Britain prior to a certain voyage by Christopher Columbus

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Many people would like to be kind to others so Leftists exploit that with their nonsense about equality. Most people want a clean, green environment so Greenies exploit that by inventing all sorts of far-fetched threats to the environment. But for both, the real motive is to promote themselves as wiser and better than everyone else, truth regardless.

Global warming has taken the place of Communism as an absurdity that "liberals" will defend to the death regardless of the evidence showing its folly. Evidence never has mattered to real Leftists

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