Gulf Stream (1 Viewer)

[KnockerNorton]

see also this:

The Holocene

Climate changes leading to the present (Holocene) interglacial commenced around 13,000 bp with a series of rapid fluctuations in climate that culminated in the cold Younger Dryas interstadial. Recovery from the Younger Dryas has been estimated to represent a global warming of the order of 5°–8°C in a period as short as thirty years. Since that time, climate changes have been relatively subtle and related to factors other than the external climatic forcing caused by orbital changes. A range of data sources point to successive variations between warmer and colder periods causing minor retreats and advances of alpine glaciers. The warmest phase of the Holocene period recorded in ice cores was between 10,000 and 8,000 bp, although the traditionally recognized Holocene climatic optimum, termed the altithermal or hypsithermal, is usually described as occurring between 7,000 and 4,000 bp. Where this optimum of Holocene climate is recognized, it is thought to represent a warming of the order of 1°–2°C above the modern (preindustrial) levels. Post-optimal global cooling resulted in a neoglacial period of glacier readvance, but in early medieval times there was a return to more favorable conditions known as the Little Climatic Optimum or the Medieval Warm Period. This phase lasted from around 750 to 1300 and correlates with the climax of high medieval cultural development and energetic activity. Warmer summer temperatures at this time allowed the development of vineyards in the United Kingdom as far north as York. [See Medieval Climatic Optimum; and Younger Dryas.]

The best known of the climate fluctuations of the Holocene is that of the Little Ice Age. Its occurrence is well documented by a range of archival materials (including annals, chronicles, and ship’s records) and dendrochronological records. It corresponds to a period of cold and highly variable climate and glacial readvance following the Medieval Warm Period, lasting from around 1300 to 1800. The Little Ice Age had widespread consequences for human populations, including high incidences of crop failure (particularly wheat in the United Kingdom), difficult navigation at higher latitudes, abandonment of settlement in marginal areas (including the final decline of the Anasazi culture in the southwestern United States and abandonment of areas of the Scottish uplands), and extreme winter storms.

from here: http://www.oup.com/us/brochure/0195108256/sample.articles/climate/?view=usa

 

[James Blake]

James, there have been fairly substantial changes in climate in Britain over the past 5000 years (see above). There were e.g. sea level rises in the Bronze Age, a warmer climate in the Roman era followed by a much wetter colder period, and then the famous Little Ice Age later on.

But could we - potentially at least - be facing bigger changes now?

And does our high-tech lifestyle makes us more vulnerable to climate change?

James

 

[turkish van]

What absolute twaddle. Plants photosynthesise to create sugars, which they then respire. They cannot respire what they are not making. Plants also use the carbon compounds they synthesise to create their stems, leaves etc, hence they are net absorbers of carbon. Where would the net output of carbon come from after your tip-over point? They'd have to break themselves down to release it.

It's a theory and whether you think it's twaddle or not, it's a theory that many scientists believe is true. I should have said that apparently respiration rates would increase due to an increasing temperature. The increasing temperature could speed up decompostion rates, releasing more CO2. Plants don't respire all their sugars, obviously, they store sugar as well. So if respiration rates did increase, it's not like there would be no sugar available to drive it.

Don't have a go at me, I didn't make it up. I'm sure you know there are a lot of theories about, no one knows exactly what will happen.

 

[London Birder]

ta for response Jane, I'm learning

It is not clear what the relative contribution of "natural climate change" and man-made climate change are. What is clear is that there is only one part of that equation that we can affect. It is also not clear if it is already too late -in as much a we have already done enough damage to precipitate a train of evens that we can't halt, even if we managed to completely stop dumping CO2 into the atmosphere today - let alone 20% less in 20 years.

Over the last 5 years there have been two theories that have really scared me. The first is the potential for the Atlantic Conveyor to slow or stop. Till yesterday it was a theory which though based in fact, and was at some point inevitable if there was enough fresh water pumped into the artic ocean, was just a theory. Although it was a disaster waiting to happen - there was no evidence to say if it was 10, 100, 1000 or 10,000 years away. The major problem isn't ice melting in the arctic, its run off from siberian rivers btw.

Turn off the gulf stream and places that are warmed by it get cold... and places that are cooled by the returning cold Nordic current, get hot. Central and the northern part of south America gets a climate more like saharan africa. Rain forests die off in a few decades releasing huge amounts of CO2 raising global warming further! Large parts of the earth become too hot to live in. The real Doomsday scenario comes if the large amount of methane trapped in the Arctic are released into the atmosphere. Methane is a hugely more potent greenhouse gas than CO2 and we can wave goodbye to life as we know it.

The second is global dimming. There is very convincing evidence to say that the amount of particulates we have put into the atmosphere in the last 100 years (smoke mostly) have prevented a large amount of sunlight reach the earth's surface and warming it (30% less is the measured figure). This has lead to a dramatic underestimate of the real current rate of climate change.

 

[KnockerNorton]

It's a theory and whether you think it's twaddle or not, it's a theory that many scientists believe is true. I should have said that apparently respiration rates would increase due to an increasing temperature. The increasing temperature could speed up decompostion rates, releasing more CO2. Plants don't respire all their sugars, obviously, they store sugar as well. So if respiration rates did increase, it's not like there would be no sugar available to drive it.

Don't have a go at me, I didn't make it up. I'm sure you know there are a lot of theories about, no one knows exactly what will happen.

I'm not having a go, I just don't see how it can be at all possible. Plants derive their carbon from CO2 to make sugars, some of which is stored, some of which is respired. So they cannot possible release more than they take in because some of what they take in is locked away and only part of it is respired. If you're saying that more CO2 would be released throughmore decomposition, well that's true, but has nothing to do with respiration rates of living plants. More CO2 can only mean bigger bushier plants locking more carbon away than smaller plants.

Do you have any references?

 

[turkish van]

I'm not having a go, I just don't see how it can be at all possible. Plants derive their carbon from CO2 to make sugars, some of which is stored, some of which is respired. So they cannot possible release more than they take in because some of what they take in is locked away and only part of it is respired. If you're saying that more CO2 would be released throughmore decomposition, well that's true, but has nothing to do with respiration rates of living plants. More CO2 can only mean bigger bushier plants locking more carbon away than smaller plants.

Do you have any references?

This is a good page -

http://www.co2science.org/scripts/CO2ScienceB2C/articles/V2/N23/EDIT.jsp

for giving all (or some) sides of the story. It doesn't agree with that theory completely (and neither do I) but it explains it more.

I can't find anywhere the exact science behind how the CO2 would be released with increasing respiration. As for your last comment, well maybe that's not strictly true - common sense says that eventually there is a saturation point inall plants where the physically cannot store any more carbon.

Googling 'scholes 1998 sink saturation' gives some more websites and references.

 

[Edward woodwood]

Now, that's not supportable really.

well, it's the accepted facts at the moment

http://www.globalchange.umich.edu/globalchange1/current/lectures/samson/climate_patterns/

for those not wanting to plough thru it it states that current changes far exceed any others they mention including the dryas

 

[pduxon]

well if the GW theories are wrong and we act on them we waste a lot of money

but if the GW theories are correct and we ignore them we screw our planet up

which would be the worst scenario...................

 

[TexasFlyway]

Yikes, I do hope you mean Yellowstone Park's caldera and not the Grand Canyon! Haven't heard about the GC volcano -- where can I find out more?

Sorry, indeed Yellowstone.

 

[TexasFlyway]

I think there's some confusion about the Earth's core cooling. It is cooling, but at an extremely slow rate and there's no evidence to suggest it will just "switch off" suddenly. There are two sources of heat within the interior of the Earth. One is accreted heat which is residual heat trapped when the planet was formed; this has diminished through geological time and has been lost into space, but even so, it still contributes about 20% of the heat flow in the core. The other heat source is decay of radioactive elements in the core, mantle and crust. Even though this too has diminished over geological time it is still more than sufficient to drive convection in the outer core and mantle for a couple of billion years or so.

Don't panic!

Gus

Exactly my point Gus. Yet there are reputable investigators with PHd's purporting catastrophic change within as little as a hundred years. They are theories, so should we worry about every single latest measurement or theory that predicts our doom.

There are so many scenarios for wiping out all life on our planet, and more reported every day, that one wonders why anyone gets out of bed in the morning.

We might as well enjoy what we have, while we have it.

 

[paj]

as i thought

nothing to worry about

Right now, it seems that the Earth's field is rapidly decreasing, and should fall to near zero in a few thousand years. It's done that many times in the past. The record of these events, where the field actually reverses directions, can be found in the layers of magnetized rocks near the surface.

good evidence for 'sea floor spreading' though

That's right Tim...it is due for a flip.....just make sure you're not flying when it decides to go!
From memory, the jury's still out on whether the flips happen as in 'bang it's gone' or if it's a gradual change.

Frank

 

[paj]

That's right Tim...it is due for a flip.....just make sure you're not flying when it decides to go!
From memory, the jury's still out on whether the flips happen as in 'bang it's gone' or if it's a gradual change.

Frank

p.s. Just noticed your other posting saying it's a gradual thing..phew!

 

[paj]

That's not exactly true in this case. We have gone from the situation where the conditions are in place that might precipitate a shutdown in the conveyor when an undetermined threshold amount of freshwater entring the Arctic oceans occured.... so a theoretical risk of serious cooling in the N.Atlantic (and equivalent heating elsewhere in).

To a situation where the conveyor has already shown a 30% decrease in flow over an incredibly short period and in a period when it should be naturally increasing.

I agree that the consequences cannot be precisely calculated... except they will be far reaching, very bad news for you and us and have the potential to rapidly escalate GW.

They did say that they were not sure if the 30% decrease was a seasonal
or regular effect and that now the sensors were in place, they would know more in a years time.

Frank

 

[Tyke]

That's right Tim...it is due for a flip.....just make sure you're not flying when it decides to go!
From memory, the jury's still out on whether the flips happen as in 'bang it's gone' or if it's a gradual change.

Frank

Polarity is quite patchy. There are patches of reversed flux in both hemispheres-particularly in the SH in the southern Atlantic-inwardly directed between the tips of South America & South Africa.Also the intensity of the field is very variable over the globe with intense inward-directed flux beneath Siberia & N America, and intense outward directed beneath Antarctica. Between 1980& 2000 the reversed flux patches have grown in size & moved closer to the poles.
It is postulated that reversed flux patches proliferate & eventually overwhelm normal polarity, thus causing a global reverse.
Global reversals in the past have occurred over periods 4k to 10k years, but also tens of millions of years.The Cretaceous Super Plume 120 MYA probably disrupted the vorticese in the outer core which cause the magnetic field. There was an absence of reversed polarity for the ensuing 40miliion years.

Source-Gary A Glatzmaier & Peter Olsen-Probing the Geodynamo-Special Edition of SCientific American

I wonder what happens after a reversal, to those species-including birds- which navigate by tracking magnetic currents?!

Colin

 

[Wickham]

Global warming but local cooling

I also heard the reports that the gulf stream is two thirds weaker than normal near the UK as it has increased towards north Africa and the trend should continue, resulting in more easterly Siberian winds. This will result in cooler winters.

Relating all the previous posts to birds...

I presume this should mean that the eels that have migrated towards Iceland will return south to the west of Scotland and provide food for our sea birds again since the water is too warm for them now. I hope.

 

[Egret]

Recently saw a science show on the decreasing magnetic field of the Earth. It has decreased some 10% in a very short period of time (decades). So now the prediction is the earth's core is cooling and causing the collapse of the magnetic field. The thing is, it could shut off at any time since we don't know the exact mechanisms that sustain the core. When that occurs the Earth will have no protection from the solar winds and radiation will cook us all and the earth will look like Mars.

So something else to worry about, along with global warming/ice age, Gulfstream failure, rainforest deforestation, etc, etc.

And don't forget about that drunk driver headed your way also! :eek!:

...and you forgot asteroid impact and "supervolcanos"

Andy

 

[Egret]

I also heard the reports that the gulf stream is two thirds weaker than normal near the UK as it has increased towards north Africa and the trend should continue, resulting in more easterly Siberian winds. This will result in cooler winters.

Relating all the previous posts to birds...

I presume this should mean that the eels that have migrated towards Iceland will return south to the west of Scotland and provide food for our sea birds again since the water is too warm for them now. I hope.

...and the Scottish ski industry will be saved.

Andy

 

[Terry O'Nolley]

try a few of the climate websites for more info

Good advice. I went to http://www.wunderground.com/education/abruptclimate.asp and read this:

We now know that that major regional and global climate shifts as recently as 8200 years ago have occurred in just a few decades or even a single year.

This is, of course, something we all must know. What still needs to be explained is how it is that so many people have decided that, of all the rapid climate shifts the earth has experienced for millions of years, this particular climate shift (which has, "coincidentally", occurred during the "information age" when mass hysteria can be transmitted, by anyone, to hundreds of millions of people via the internet) is caused by people?

Another odd thing is how all of the people that leap to the foreground to play the part of Chicken Little still drive automobiles, heat their homes, use plastics, etc, etc, etc.

Fascinating Captain.....

 

[Edward woodwood]

Good advice. I went to http://www.wunderground.com/education/abruptclimate.asp and read this:

We now know that that major regional and global climate shifts as recently as 8200 years ago have occurred in just a few decades or even a single year.

What still needs to be explained is how it is that so many people have decided that, of all the rapid climate shifts the earth has experienced for millions of years, this particular climate shift (which has, "coincidentally", occurred during the "information age" when mass hysteria can be transmitted, by anyone, to hundreds of millions of people via the internet) is caused by people?


Fascinating Captain.....

because a lot of very intelligent people who study it deeply have worked it out.... compared to the man in the street rubbish we get on here

the current change is alarmingly quick compared to past changes

 

[Terry O'Nolley]

the current change is alarmingly quick compared to past changes

Would you be referring to one of the "major global climate shifts which have happened in a single year"?

If so, I am glad I live in America! I have heard people blaming humans for over a decade and yet the USA has been spared the effects of this major global climate shift that happened in a single year.