What effect if any, will a temperature rise and less rain fall have on local
land usage, is there some prediction from GW on how agriculture will change
locally?

Depends where you live. A little or a lot.

They'll be growing bananas on Antarctica.

"As if shrinking glaciers, rising seas, and catastrophic hurricanes weren't bad enough, global warming looks set to devastate the world's greatest vineyards. In regions like Bordeaux in France and the Napa Valley in California, maximum daytime temperatures have been relatively stable since 1930, says climatologist Gregory Jones of Southern Oregon University. But minimum nighttime temperatures have risen significantly, causing grapes to ripen faster and creating an imbalance between sugar and acid levels. " - Discover Magazine

http://discovermagazine.com/2006/oct/global-warming-wine/vineyard225.jpg

is there really less rainfall? in the short term rising temperatures would overall be more beneficial.

As far as rising seas, does anyhone know if there are noticeable chinges in salinity\SG?

Draw your conclusions...

http://math.ucr.edu/home/baez/temperature/65Myr.png

There are a few predictions kicking around, more need to be done.

http://news.bbc.co.uk/1/hi/sci/tech/6200114.stm

<i>The most significant impact of climate change on agriculture is probably changes in rainfall. Some regions are forecast to receive more rain, others to receive less; above all, it will become more variable.


The water supply to farms will become more variable in future
But increasing temperatures can also affect crops. Photosynthesis slows down as the thermometer rises, which also slows the plants' growth and capacity to reproduce.

Research published two years ago shows rice yields are declining by 10% for every degree Celsius increase in night-time temperature.

A study from the International Maize and Wheat Improvement Center (Cimmyt) in Mexico, yet to be published, projects a major decline in South Asia's wheat yield. The vast Indo-Gangetic plain produces about 15% of the world's wheat - but the area suitable for growing is forecast to shrink by about half over the next 50 years, even as the number of mouths to feed increases. </i>

What goes up must come down....May be we are in a downward slope now...wait for another 20 years for the down hill....

http://www.grida.no/climate/vitalafrica/english/graphics/01-temperature.jpg

Wait - how come the historical distribution is below the zero line?

Because the zero line is the period about 1940- 1970 or so.

Kmguru- what on earth do you mean? There is no known mechanism by which global temperatures will definitely decrease in the foreseeable future. (This is not counting strange goings on in the sun that we do not know about)

I meant in the second graph. Doesn't really matter tho: up is up.

Kmguru- what on earth do you mean? There is no known mechanism by which global temperatures will definitely decrease in the foreseeable future. (This is not counting strange goings on in the sun that we do not know about)

If you look at my first graph, global temperature has been steadly declining even from some 10 million years ago. What do you think the cause? Something does not make sense. Any ideas?

Ummm, pardon? Your worried about a 10 million year trend?

Anyway, all that stuff is caused by orbital forcing, volcanic changes, and changes in solar irradiance.

hmmm...you answered yourself....:D

I knew all that already. I thought, since this thread was on the topic of global warming, you meant the next century or so. If you wish to play mindgames, bugger off.

"As if shrinking glaciers, rising seas, and catastrophic hurricanes weren't bad enough, global warming looks set to devastate the world's greatest vineyards. In regions like Bordeaux in France and the Napa Valley in California, maximum daytime temperatures have been relatively stable since 1930, says climatologist Gregory Jones of Southern Oregon University. But minimum nighttime temperatures have risen significantly, causing grapes to ripen faster and creating an imbalance between sugar and acid levels. " - Discover Magazine

http://discovermagazine.com/2006/oct/global-warming-wine/vineyard225.jpg


Blast, i hope sugar cane is not effected.

Here is an interesting article about disappearing bees. (http://viewzone.com/lostbees.html)

http://viewzone.com/lostbees.pollen.jpg

Wait - how come the historical distribution is below the zero line?


the graph doesnt show the absolute temperature.
Only the magnitude of delta/differences/variation.

the graph doesnt show the absolute temperature.
Only the magnitude of delta/differences/variation.

Yes, cause it was warmer in the Middle Ages, right? They grew grapes in England in the 1200s. And didnt Vikings call Greenland "green" because back then it WAS green?

More on Greenland (http://en.wikipedia.org/wiki/Greenland)

and Medieval Warm Period (http://en.wikipedia.org/wiki/Medieval_Warm_Period)

Yes, cause it was warmer in the Middle Ages, right? They grew grapes in England in the 1200s. And didnt Vikings call Greenland "green" because back then it WAS green?

They grow lots of grapes in England nowadays, even up in the North of England. Nee grape varieties help, but there are more vineyards now than there were in the medieval period.

As for Greenland, the reason they called it that was both as a marketing tool, and because it was quite green when they got there. The countryside was quite well covered in grass and shrubs and small stunted trees. However this covered up the fact that the soil was thin and the growing season very short. So the Vikings who landed there managed to degrade the soil by their farming and cut down the trees for fuel. Needless to say, this meant that as the climate worsened things got bad for them and they died out. Read Jared Diamonds book "Collapse" for more information.

Still, it has got colder since the Medieval Warm Period - right? Then warmer again in last 30 years. Might stil be part of a natural swing, even if people are making it stronger.

Those Vikings sound just like the Brazilians...

My guess is we are in the natural cycle, but man has contributed some too due the the population and human activity. How much is that is debatable. If it is too much, then the swings will be high. If we can figure out, how much and if it is too much, then we could do something...like setting up a lot of nuclear power plants to suck the CO2 and push it underground when we took the oil out. That is quick and cost effective. And who knows, the nature could convert them to oil....

Still, it has got colder since the Medieval Warm Period - right? Then warmer again in last 30 years. Warmer in the last couple of hundred years, accellerating in the last 30.

The Medieval Warm Period was not as warm as it's getting now, and the temps didn't swing as fast. The Little Ice Age is the thing you want to use in rhetorical persuasion - it doesn't work, but the other guy has to spend paragraphs going into obscure technicalities and explaining how it doesn't mean some natural cycle explains this or that.

The central problem is that we are midway between glaciations, probably on the cooling side of a huge natural cycle. So trends in climate have a lot of noise to contend with, from the glaciation effects, and a general cooling tendency to consider (from the Milankovitch cycle). The point is that all this stuff has been considered. The CO2 buildup is measured, it's fact. The effects of a CO2 buildup are physical, its immediate influence is calculable using basic, well-understood physics. The effect on the climate is very complicated, but reasonable probabilities and consequences can be worked out.

This isn't BS, and whatever happens now is not going to be just part of another natural cycle - no matter what it is. There's too much CO2 in the air. The natural cycles are going to be strongly affected, and we need to handle what that means for us. Further, since we just spent 500 years and much effort setting up for the old climate on several continents, we must be on the lookout for the ways our setup is not going to work.

the other guy has to spend paragraphs going into obscure technicalities and explaining how it doesn't mean some natural cycle explains this or that.

The central problem is that we are midway between glaciations, probably on the cooling side of a huge natural cycle. So trends in climate have a lot of noise to contend with, from the glaciation effects, and a general cooling tendency to consider (from the Milankovitch cycle). .

I supose a lot of politicians want to look at the noise and not the big cycles.

Even in the worst case though, warming climate wont kill us all off like the dinosaurs. People change and so does farming. Somebody can always carry on, and countries with big land areas like USA, Canada, Russia, China, Australia and so on will surely always have SOME land they can farm, though it might not be the same as what they farm today.

Sure, but put it this way- it may well not be you that surives.

Sure, but put it this way- it may well not be you that surives.

Im old enough that it doesnt matter much. Give me another 20 years good rain here in Jamaica, thats plenty. :m:

Ahhh, if everyone thinks that way, we're all doomed.
Bastards.

Somebody can always carry on, and countries with big land areas like USA, Canada, Russia, China, Australia and so on will surely always have SOME land they can farm, though it might not be the same as what they farm today. Extinction is not the prediction: disaster is.

Sure, there will always be farmable land, in some manner by someone. How many someones, waht kind of land, and how exactly are they going to farm it? Those are critical questions.

Regarding the Medieval Warm Period, there is some doubt about whether this was a global phenomenon. Some people believe it was confined to North West Europe, an area uniquely warmed by an oceanic drift (the Gulf Stream), which may well be subject to variations that have no impact elsewhere in the world.

I think a clue lies in sea level, which rises in globally warmer times (due to expansion, rather more than the melting of ice). Undoubtedly there was some medieval rise in sea level -- as anyone familiar with Dutch history knows. After lesser encroachments, in 1282 an extraordinary flood (surely one of the most dramatic meteorological events of the last thousand years) created the Zuider Zee.

However, anyone familiar with the history and geography of London must know that sea level has never been higher (in historic times) that it is now. Ancient Westminster Abbey would be regularly flooded if it were not for the embanking of the Thames. Inundation in medieval times (when the building was moated for defence!) was rare. The ground levels of excavated buildings predating the fire of London confirm that a Thames Barrier was not required in medieval times. For anyone visiting London, a visit to the fine old Buckingham Water Gate provides a dramatic revelation of how much higher the river is now than in the past.

So I would say: taking sea level as an index, today's global warming very much eclipses the medieval warm period. I imagine there is evidence from other historic seaports which would tally with my own observations.

Remember, just to confuse things, London and that part of England has been sinking since the last ice age. Isostatic rebound.

I thought isostatic rebound made land rise. A big deal in Scotland as the ice retreated, but not significant in Southern England over the last thousand years. (But I'm willing to be further informed.)

I am confused now, i watch the archaeological program Time Team in that
many areas that are now part of the land scape were islands.

Scotland has been rising, but England has been sinking- teh weight of the ice pushed the north down, raising the south.

Scotland has been rising, but England has been sinking- teh weight of the ice pushed the north down, raising the south.

But that makes no sense, parts of England were islands in the near past,
but are now joined to the mainland, surly that means that England has risen,
ship building docks have been found far inland.

Scotland has been rising, but England has been sinking- teh weight of the ice pushed the north down, raising the south.
You make it sound like a seesaw with a log running along underneath between Carlisle and Newcastle. Are you quite sure about this? :confused:

Dont know bout England, but Caribean during the Ice age wouldve been an intersting place. Lots of the little atolls would be joined together, Jamaica might be joined with Cuba (wouldnt Castro luv that!) Thered be much bigger coral reefs , with more shallow seas which are too deep now.