I have couple of reservations about this paper.

First, increased temperature increases plant’s yield, including for crops – with all other variables constant. It is fundamental law. For example, reconstructions of past global temperatures (including “famous” Mann “hockey stick”) are based on assumption that tree ring in warmer year grows wider. All other local variables, including precipitation, are filtered out by averaging thousands samples around the world. So now what, it is wrong? Wider tree ring is for cooler year? We live in the coldest period in 1500 years?

Second, the study is purely statistical analysis of the non-existed effect – decrease in crop’s yield. Crops yields actually increased, and very substantially. For such studies it is critically important to have high-quality data, especially when we are talking about minuscule changes of temperature over very short period. LOFL.

They use monumentally biased, imprecise, and doctored data produced by IPCC pet “scientists” from East Anglia University (one of three specially designated by IPCC facilities to supply them temperature data to justify their existence). By famous Dr. Jones. Based on data of whopping 2000 weather stations for Earth surface of 200 000 000 square miles. Dozen times corrected and cherry picked – without archiving and unassessible for independent verification. Both raw data, corrections, statistical methods, etc. are refused to be disclosed to anybody (including their peer-reviewers). That’s right. The data on which computer model prediction of the end of the world is based is kept secret and was never repeated or verified. It is also vastly different from way more precise satellite and weather balloons measurements, which are silently disregarded by IPCC. This theme is widely discussed on climateaudit.org Details of this travesty are just terrifying.

Garbage in – do not expect anything useful out, whatever sophisticated methods you use.

Andrey, your ever growing delusions of science conspiracy and hoax are quite astounding. Judging from your previous web citations I suspect denialist conspiracy sites are having quite a large impact on you. If you have legit arguments with climate change why not take them to climate scientists who actually give up their time to answer #*#& like this? Go over to realclimate and have it out with them!

Read this, Marcus:

http://www.climateaudit.org/?p=1240

As for conspiracy… AGW crowd is not mentally fit to make it.

As for realclimate… Their explanations are just laughable. Not to mention the style of their rhetoric.

Andrey,

I do wonder how accurate tree rings can be, and I've got my doubts about Mann's work and the way he's been sidestepping inconvenient questions. The Hockey stick does indeed have no medieval warm period, when other reconstructions do. But climate audit goes way over the top with their criticism and elevates the issue way beyond what's justified.

Individual plants do have an optimum temperature and exceeding those will yield heat stress and reduced growth.

But, I think adaptation can go a long way. Think of the yields you get from oil palms and compare to canola say, and oil palms are very sensitive to cold.

Personally, I think a combination of irrigation, crop choices, genetic engineering and moving agriculture will likely yield increased food production for up to about 3 degrees C reasonably easily, beyond that, we'd have to think about irrigating Siberia/Canada to still get a benefit, and that's a bit too much optimism even for me, at least when considering the period up to 2100.

The main crop issue isnt the temp itself but the unstable weather the climate changes it brings has created. Farming isnt a total crapshoot some places are good farmland BUT climate change changes that..AMAZING BUT TRUE!!!!!!!!! It also can decrease rainfall making farming either impossible or more expensive for those who cant dwitch to drier crops or GM crops that handle drought. It also changes where and how intense bug [;amgues are and various molds and other damaging thingies that effect crops.

The us is ok we migh be farming corn in montana and sugarcane in texas but we have enough north to south span and enough shear size to find croplands after climate change.

A country like say isreal or france however is screwed. France will likely loose its entire wine industry and as a result french people will be sober for the first time in history... tgat cant be good. Israel.. well.. if what I saw was in fact going to happen then the entire area is fubared.

Lets put it this way if there is no water at all and the temps hit 140 your NOT in cropland.

Heiko:

US Academy of Science evaluations of Mann’s hockey stick (Wegman and NAS reports) effectively buried it. It is history.

Dendrological (tree ring) temperature reconstruction is valuable tool, but of course tricky one. Dozens of dendrological proxies clearly mark both Medieval Warm Period and Little Ice Age. Beautiful picture of it is here:

http://en.wikipedia.org/wiki/Image:2000_Year_Temperature_Comparison.png

Note: I do not have much face into added instrumental record, you know why.

I am not in position to comment on Climateaudit. It is indigenous blog of climate science professionals (mostly), and if somebody has right to harsh critique it is them.

3 degree C of climate warming… I do not want even think about it. Fortunately, it is not even on horizon, at least as I understand it. And antropogenic GHG emission have nothing to do with warming, that’s for sure. For last 6 years global temperature was stable, for 3 years Global Ocean slightly cooled, last year El Nino was exceptionally weak, and astronomers uniformly predict beginning of cooling trend in couple of years –according to their very intriguing theories. One respected climate scientist said that chances for cooling or warming right now are 50/50. What trick CO2 atmospheric concentrations will pull – nobody knows.

Andrey, you seem brainwashed by hack websites. Who is Steve McIntyre? Certainly no climate scientist. Who is John Daly? Certainly no climate scientist. Who are the Fraser Institute? Certainly not a bunch of climate scientists. They are all hacks with an agenda. Who are these "respectible scientists" you keep quoting? Why not just give their names? All I'll do is check their publication record on climate. Its a simple litmus test for hack vs scientist. You should try it sometime and perhaps you may learn something about some of your ideological gurus.

Getting back to the GW thing, I note that efforts at climate engineering could bear fruit:  if we blocked enough solar radiation to offset our GHG's and eliminate the heat stress, the added CO2 in the atmosphere would give us a significant bump in crop yields.

This may be what happened after the Pinatubo eruption, after which the Keeling curve flattened out for about 2 years.

Engineer-Poet:

I bumped some time ago in web-sites (can not find it) with list of GEOENGINEERING means to combat GW. At least two projects did not deal with reduction of CO2.

One was highly controversial proposition to add sulfur to jet fuel to be used in intercontinental flights. Emitted in mid-atmosphere sulfur oxides will serve as nuclei for cloud formation, which will increase amount of solar radiation reflected back to space. The advantage of such trick is that once stopped, sulfur will be washed down in a matter of couple of months.

Another one was quite simple. About 1% of surface in US is used for artificial structures, such as roofs and mostly pavement (compared to about 35% for agricultural land, as I recon). By painting roofs white, and for adding crushed glass to asphalt ( GLASSPHALT, proved and used practice to recycle glass) it is possible to increase asphalt albedo twofold. Calculations showed that it would be enough to offset GHG effect of antropogenic emissions. No word was said about health effect of inevitable fine glass dust in the air.

E-P,

it could get even better than that according to work by Teller.

If the aerosols are engineered right, they could scatter ozone, giving a further boost to crop yields and reducing the incidence of skin cancer.

It's a little known fact that the natural ozone layer isn't very effective close to the equator. Or at least it isn't appreciated by the general public fed on alarmist ozone hole stories.

While the ozone hole does make a bit of a difference, it only away from the equator, where UV isn't very high, it's the equivalent of moving a little towards the equator, and at the equator it makes little difference, not least because the ozone layer is pretty ineffective there.

There's a reason people close to the equator have dark skin ...

What I find interesting/strange is how accepting people are of "natural" background levels.

You'd think that enhancing the world's protection against ozone beyond the poor protection afforded by the ozone layer (at least very poor close to the equator), would be an important priority, both to decrease disease (skin cancer, eye problems) and raise crop yields.

Sorry, meant to say scatter UV.

Andrey,

I've read most of thos reports, and I wouldn't put it like that. There's a good case that Mann have probably understated natural variability in the climate record and have been evading questions they should really answer.

Their line of defense is, "oh well, we got the most important thing right, recent years are warmer than anytime in the last 1000 years, probably anyway".

And the other reconstructions you cite do agree with that, so does the NAS, with the quibble that for beyond 400 years data aren't good enough to eg exclude the possibility of a super Nino sometime in the Medieval Warm Period edging 1998 by 0.01C with greater 95% probability.

As for your last paragraph, I buy the IPCC scenarios, you clearly don't, and I don't buy your interpretation of recent temperature readings and "uniform" astronomer opinion.

Ok, so 1998 is still the record and that was a year with a strong el Nino, but temperatures are only rising by 0.01-0.03 degree C per year at the moment with interannual variability of 0.2C or something like that. Recent temperature data don't disagree with IPCC predictions.

Heiko:

I do not really think that combination of tree ring proxy data with instrumental records is such a good idea. Kind of comparison of apples with oranges. Would be nice to see proxy reconstructions (there are couple, but kind of murky) going back from, say, 2005. There also are traditional arguments like vineyards in England and Vikings in Greenland. But of course it could be regional, thought region is quite big.

Well, time will tell.

I just have read interesting article of Akasofu :

http://www.iarc.uaf.edu/highlights/2007/akasofu_3_07/Earth_recovering_from_LIA.pdf

Quite interesting hypothesis.

Have a nice weekend.

There is an excellent article about global warming at

http://www.lewrockwell.com/miller/miller21.html

Here are a few sentances:

There is another theory of global warming and cooling that Gore does not address in An Inconvenient Truth. The Solar/Cosmic Ray Theory posits that cosmic rays, not humans, cause climate change. The Chilling Stars: A New Theory of Climate Change (2007) by Henrik Svensmark and Nigel Calder.

The sun’s role in climate change is due not so much to changes in intensity of its visible and/or invisible

I had some problems posting. must be those
those damn alarmists. :)

Here are a few sentances:

There is another theory of global warming and cooling that Gore does not address in An Inconvenient Truth. The Solar/Cosmic Ray Theory posits that cosmic rays, not humans, cause climate change. The Chilling Stars: A New Theory of Climate Change (2007) by Henrik Svensmark and Nigel Calder.

The sun’s role in climate change is due not so much to changes in intensity of its visible and/or invisible rays, or irradiance, but to its magnetic effect on cosmic rays. Changes in the sun’s magnetic activity have a four- fold greater effect on the Earth’s temperature than variations in its irradiance.

The Modern Warming is not confined to this planet. Mars, Jupiter, Pluto, and Triton (Neptune’s largest moon) in the solar system are also warming.

Triton's warming appears to be due to its seasons; it's having an extreme southern summer.

Even if cosmic ray variations drove much of historical climate change, it doesn't mean that the same phenomenon is behind the current trend.  For one thing, solar activity has been relatively flat since 1950; for another, there were no great increase in greenhouse gases.  You can get warm from exercise, but being warm doesn't mean you just exercised; you could have a fever or just be overdressed.

I agree with Mark A, you have to speak with farmers.
Here in Argentina yields are increasing continuously thanks to glyphosate, direct seeding, genetic modification on seeds and hard fertilization and effects of climate change are hardly to discriminate.
But what happens with land depletion, is very difficult to return all the minerals (and is economically no feasible)that are going out with every truck of soy, corn or wheat. ¿Is it sustainable?
Biofuels and the race for croplands are increasing deforestation in the north of Argentina (the rest is already deforestated), Brazil, Paraguay and others countries.As it concerns to climate change is not the same an acre of tropical forest than an acre of soy.
We are worried with new deals between US and Brazil (and possibly Argentina) about biofuels.

My pet goose Honker also has his theory about global warming which I think Al Gore ignored completely, despite the obvious validity and mounting evidence supporting this theory. He says that in fact the whole universe is heating due to the gradual increase in entropy, its just the second law of thermodynamics. He has a degree from Goose university so I believe him totaly and more importantly it just kind of sounds right. He says that he has found that when I feed him, his food is warmer than it used to be. Those alarmists! How can they ignore my goose like this!

Well Marcus, in the same tessitura I had a consult with George W. and old turkey who lives in the forest near my house. He disagrees with your goose and says that the whole universe is cooling because its expansion and gravity is not able to reverse the situation. He also has another evidence, a depletion in its sexual desire due to a cooler clima.
¿How do you say in US?, "eat the turkey and ---- the indians " , or something else.

"Celestial Climate Driver: A Perspective from Four Billion Years of the Carbon Cycle" (Geoscience Canada 2005;32:13-30) show that the variability in the Earth’s temperature over the past 500 million years correlates well with the intensity of cosmic rays hitting the planet when it passes in and out of the spiral arms of the Milky Way. They found that at one point atmospheric CO2 levels were 18 times higher than they are today, and they were 10 times higher when the planet was an "icehouse" during the Ordovician glacial period (450 million years ago).

Other cycles that drive climate change include the Earth’s 100,000-year elliptical orbit around the sun and its 41,000-year axial tilt cycle. (In the most elliptical phase of the Earth’s orbit, the sun’s rays must travel 3 percent farther to reach the planet. The Earth’s axial tilt ranges from 22.1 to 24.5 degrees and is currently at 23 degrees.) And then there is the 1,500-year solar cycle.

S. Fred Singer and Dennis T. Avery describe the 1,500-year solar warming and cooling climate cycle in their book Unstoppable Global Warming: Every 1,500 Years (2007). It has 528 references, a glossary, and an index. This well written book is arguably the best book to date on the politics and science of global warming. In addition to presenting evidence for the 1,500-year solar cycle, first proposed by European researchers in 1996, the authors address both the Greenhouse and Solar/Cosmic Ray theories of climate change."

http://www.realclimate.org/index.php/archives/2006/11/avery-and-singer-unstoppable-hot-air/#more-373

Rick, Marcus,

I think it's confusing to argue about "the" cause of global warming.

The IPCC clearly say that there are several effects, some with different signs. As E-P says, you may be warm, because of exercise, or because of a fever, or because you are in a sauna, you may be warm because of all of these factors together,

and you can't conclude from the fact that you were warm because of exercise one year ago, that you are warm of exercise and nothing but exercise today.

I think the IPCC would give a 100% probability that greenhouse gases cause increased temperature. The main reason they can't say with 100% certainty that present temperatures are up due to anthropogenic influences is I think aerosols.

It is possible that anthropogenic aerosols are nearly entirely cancelling out greenhouse gases, but it's low likelihood.

It is very likely though that they cancel out a substantial portion.

And, suppose all the greenhouse gas warming was cancelled by aerosols at the moment, would that prove global warming isn't real? Of course, it wouldn't.

Our concern is mainly about what'll happen in the future, with constant or even declining forcing from aerosols, and increasing forcing from greenhouse gases.

Heiko:
Let me put it straight.
IPCC AGW statement, if boiled down to uppermost simplicity and having at hand corresponding graphs, boils down to quite primitive reasoning:
We are catastrophically heating-up the Earth, because:
global temperatures are rising for two centuries, because:
CO2 in atmosphere rises for a century, because:
We emit too much CO2 for half a century.
It could be reasonable assumption only for creature traveling backward in time.
Well, it is only core deficiency of AGW theory; arguable it is wrong in practically all of it initial data, valuations, and prediction components. Not to mention shameful spin and deception.
The question what and how our climate is really driven, indeed is extremely puzzling and intriguing.

Hi Andrey,

you may have heard Lindzen's standard line about how the relationship between greenhouse gas forcing and concentration is logarithmic, and also there's methane and NO and CFC's, and their combined effect is 70% of a doubling of CO2 already, yet temperature is not up by 2.4C, but by much less.

The standard response is that, we'd indeed by up by over 2C already, if it wasn't for aerosols and thermal lag (the time required to heat the oceans).

This also is the line for why we've got a 1940's peak, greenhouse gases, including methane, were already up significantly then when considering their forcing.

Temperatures then went down as temporarily aerosols overpowered the greenhouse gas effect.

You know it's one thing to point out that Mann underplays natural variability and that some things about his work are questionable, or that the media and indeed a great many scientists are alarmist without an objective scientific basis,

but quite another to imply that greenhouse gases aren't proven to heat the Earth.

"Global warming extends to Mars, where the polar ice cap is shrinking, where deep gullies in the landscape are now laid bare, and where the climate is the warmest it has been in decades or centuries.

The sun's increased irradiance over the last century, not C02 emissions, is responsible for the global warming we're seeing, says the celebrated scientist, Dr. Habibullo Abdussamatov, and this solar irradiance also explains the great volume of C02 emissions.

"It is no secret that increased solar irradiance warms Earth's oceans, which then triggers the emission of large amounts of carbon dioxide into the atmosphere."