Climate Change, 'Greenhouse' effects: DENIAL

Message boards : Politics : Climate Change, 'Greenhouse' effects: DENIAL
Message board moderation

To post messages, you must log in.

Previous · 1 · 2 · 3 · 4 · 5 · 6 · 7 · 8 . . . 36 · Next

AuthorMessage
Profile ML1
Volunteer moderator
Volunteer tester

Send message
Joined: 25 Nov 01
Posts: 20265
Credit: 7,508,002
RAC: 20
United Kingdom
Message 1364179 - Posted: 3 May 2013, 23:28:49 UTC - in response to Message 1364036.  
Last modified: 3 May 2013, 23:29:32 UTC

So... All a game of 10 "myths" eh?

So myth me this one:


Slowdown in warming no argument for policy change

A recent slowdown in the rise of the Earth's surface temperatures has led some commentators to question whether scientists have exaggerated the global warming problem.

Scientific advances have removed any reasonable doubt that carbon emissions are warming the planet, especially since 1970. Most scientists agree that natural cycles of the sun and oceans explain some variation in temperatures, but [those natural variations] cannot explain much of the 0.7 degree Celsius warming since the beginning of the 20th century. ...

... Little evidence has emerged for changing the central estimate of around 3 degrees. In fact, recent analysis of climate change over the past 65 million years has broadly supported it. ...



... And all still far too fast to allow steady natural adaptation over a large number of generations.

And so you can really still always see the heat radiating from the candle in this experiment/demonstration?


Get real??...

All on our only one planet,
Martin
See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)
ID: 1364179 · Report as offensive
Profile betreger Project Donor
Avatar

Send message
Joined: 29 Jun 99
Posts: 11361
Credit: 29,581,041
RAC: 66
United States
Message 1364183 - Posted: 3 May 2013, 23:55:24 UTC - in response to Message 1364036.  

The home page of the source of your "facts" has this as it's introduction.


INTO CLIMATE CHANGE
WELCOME TO OUR WEBSITE
Save the scientific method from Big Green propaganda and faulty science.
The Sun is the main driver of climate change. Carbon Dioxide has nominal impact on temperature.


There appears to be a bit of bias, quite a bit.
ID: 1364183 · Report as offensive
Profile Bernie Vine
Volunteer moderator
Volunteer tester
Avatar

Send message
Joined: 26 May 99
Posts: 9954
Credit: 103,452,613
RAC: 328
United Kingdom
Message 1364189 - Posted: 4 May 2013, 0:07:53 UTC

A bit of research suggests that "Friends of Science" historically were anonymously funded but the oil industry. Now I am not saying there is anything wrong with that but I do not believe you can even slightly suggest these "10 Myths" have been disproved.

Further research will reveal several of the "Myths" are in fact "Confirmed".

Once again may people will ignore you "stories". I would love to believe what you do, but please quote an totally independent "foreign" source, more people will believe you then.
ID: 1364189 · Report as offensive
Profile William Rothamel
Avatar

Send message
Joined: 25 Oct 06
Posts: 3756
Credit: 1,999,735
RAC: 4
United States
Message 1364197 - Posted: 4 May 2013, 0:17:05 UTC - in response to Message 1364195.  
Last modified: 4 May 2013, 0:20:15 UTC

[quote]Scientific advances have removed any reasonable doubt that carbon emissions are warming the planet, especially since 1970. Most scientists agree that natural cycles of the sun and oceans explain some variation in temperatures, but [those natural variations] cannot explain much of the 0.7 degree Celsius warming since the beginning of the 20th century. ...


That's not how I read the facts-Man-made CO-2 is essentially noise in the other causes of global warming. Such as Solar output, water vapor, axis precession , Cloud cover etc, etc.

Are we even certain that we are warming and, if so, that this has never happened in our pre-industrial past. If you believe this then please explain how the Ice-age disappeared from North America and Europe.

If human-generated CO-2 is causing warming to an alarming degree, then what do you propose we do about it ??[
ID: 1364197 · Report as offensive
Profile Intelligent Design
Avatar

Send message
Joined: 9 Apr 12
Posts: 3626
Credit: 37,520
RAC: 0
United States
Message 1364410 - Posted: 4 May 2013, 15:16:36 UTC - in response to Message 1364179.  
Last modified: 4 May 2013, 15:17:06 UTC

So... All a game of 10 "myths" eh?

So myth me this one:


Slowdown in warming no argument for policy change

A recent slowdown in the rise of the Earth's surface temperatures has led some commentators to question whether scientists have exaggerated the global warming problem.

Scientific advances have removed any reasonable doubt that carbon emissions are warming the planet, especially since 1970. Most scientists agree that natural cycles of the sun and oceans explain some variation in temperatures, but [those natural variations] cannot explain much of the 0.7 degree Celsius warming since the beginning of the 20th century. ...

... Little evidence has emerged for changing the central estimate of around 3 degrees. In fact, recent analysis of climate change over the past 65 million years has broadly supported it. ...



... And all still far too fast to allow steady natural adaptation over a large number of generations.

And so you can really still always see the heat radiating from the candle in this experiment/demonstration?


Get real??...

All on our only one planet,
Martin


There is a fixation with the federal government for forcing us to drive this car, you must live in a smaller home. You must be green so much so about being green its now indoctrination in our schools before the science has been settled.

The EPA has way too much power over us. It is NOT a branch of government. I seen YOUR so called scientist hit the Lame Stream News programs the last two years telling us all we can where shorts in December. Ummm, almost three feet of snow has hit the mid-west in April and May. And the best selling auto isn't a auto, its the F-150 pickup truck.There is no Facts with global warming, when it was warm out when it was to be cold your scientist called it global warming. Now, when its cold out when its to be warm its called climate change. I'm told to give my opinion, you have it.

What your type of politics is would be another way of redistribution of wealth. That's what this is really all about.
Must not conflict resolve by suggesting that someone should go sit on an ice pick...
ID: 1364410 · Report as offensive
Profile Intelligent Design
Avatar

Send message
Joined: 9 Apr 12
Posts: 3626
Credit: 37,520
RAC: 0
United States
Message 1364412 - Posted: 4 May 2013, 15:17:39 UTC - in response to Message 1364197.  

[quote]Scientific advances have removed any reasonable doubt that carbon emissions are warming the planet, especially since 1970. Most scientists agree that natural cycles of the sun and oceans explain some variation in temperatures, but [those natural variations] cannot explain much of the 0.7 degree Celsius warming since the beginning of the 20th century. ...


That's not how I read the facts-Man-made CO-2 is essentially noise in the other causes of global warming. Such as Solar output, water vapor, axis precession , Cloud cover etc, etc.

Are we even certain that we are warming and, if so, that this has never happened in our pre-industrial past. If you believe this then please explain how the Ice-age disappeared from North America and Europe.

If human-generated CO-2 is causing warming to an alarming degree, then what do you propose we do about it ??[


+10
Must not conflict resolve by suggesting that someone should go sit on an ice pick...
ID: 1364412 · Report as offensive
Profile ML1
Volunteer moderator
Volunteer tester

Send message
Joined: 25 Nov 01
Posts: 20265
Credit: 7,508,002
RAC: 20
United Kingdom
Message 1364482 - Posted: 4 May 2013, 18:10:27 UTC - in response to Message 1364197.  
Last modified: 4 May 2013, 18:18:47 UTC

... That's not how I read the facts-Man-made CO-2 is essentially noise in the other causes of global warming. Such as Solar output, water vapor, axis precession , Cloud cover etc, etc.

Are we even certain that we are warming and, if so, that this has never happened in our pre-industrial past. If you believe this then please explain how the Ice-age disappeared from North America and Europe.


There's nearly the full history of our Industrial Revolution of knowledge of the pollution from burning fossil fuels altering our atmosphere to change the heating effects for our atmosphere and planet.

We've argued for years now on these threads despite the physics and reality remaining the same. Rather than a few years of the discussions here, can you believe well over a hundred years of a singular consistent conclusion?

See:

How the burning of fossil fuels was linked to a warming world in 1938

BBC News environment correspondent Richard Black traces key milestones, scientific discoveries, technical innovations and political action

The History of Climate Science

The Discovery of Global Warming

YouTube: Earth - The Climate Wars


More of a question is why we have procrastinated about doing anything positive about industrial scale CO2 pollution for so long... We've known about the atmospheric "greenhouse effect" since 1824. We've known of the significance of the CO2 part of that since 1896. Problems of world-wide pollution reached widespread awareness in the 1960s and 1970s. We've already changed our ways to overcome devastating problems of acid rain, ozone depletion, industrial soot, smogs, and most recently vehicle exhaust noxious gases and particulates. CO2 pollution amelioration comes next?


As for the "ice age" melts: Note that when our ancient climate has gone into "Snowball Earth" mode, the ice age persists until 'something' breaks the feedbacks that maintain the snowball climate. Only afterwards when CO2 or CO2 + methane are liberated does a 'global warming' effect come into play to carry on the warming further.

We have relied upon that from our last ice age to give the benign conditions upon which we have flourished through to today.

As far as we know, this is the first time our planet has seen an artificial extreme and rapid increase in CO2 that is the one primary cause for the seen global warming. The present rate of change is far too fast for most creatures to naturally adapt over too few generations.


If human-generated CO-2 is causing warming to an alarming degree, then what do you propose we do about it ??

Change our ways. That doesn't mean a zero-technology green apocalypse. In many cases, it just means a change in politics and 'fiscal policies' to encourage new technology and to put a cost on ALL the pollution from polluters.

Unfortunately, we're locked in a financial and lobbying stranglehold of the big fossil fuels business.

As a certain other apocalyptic poster of Ultimate Solutions on these forums is very fond of reminding us, the next crunch to come after we've saved our planet from a heat/storms death, is that of saving the planet from overpopulation. We should be a long way away from the population problem for the moment. For that one, a good question is whether education and culture can save the planet... (A few bits of religions and politics will be quite a problem to overcome for that one...)


This is out only one world.

All on our only one planet,
Martin
See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)
ID: 1364482 · Report as offensive
Profile William Rothamel
Avatar

Send message
Joined: 25 Oct 06
Posts: 3756
Credit: 1,999,735
RAC: 4
United States
Message 1364639 - Posted: 5 May 2013, 0:02:10 UTC
Last modified: 5 May 2013, 0:04:02 UTC

The ice age ended long before any hint of the industrial revolution. This suggests that the planet is subject to cycles of temperature all on it's own without any human involvement.

For the record: today in Tennessee is a cold record of all recorded time. Sort of like the stock market --ups and downs and short and long term trends.
ID: 1364639 · Report as offensive
W-K 666 Project Donor
Volunteer tester

Send message
Joined: 18 May 99
Posts: 19048
Credit: 40,757,560
RAC: 67
United Kingdom
Message 1364641 - Posted: 5 May 2013, 0:08:47 UTC - in response to Message 1364639.  

The ice age ended long before any hint of the industrial revolution. This suggests that the planet is subject to cycles of temperature all on it's own without any human involvement.

For the record: today in Tennessee is a cold record of all recorded time. Sort of like the stock market --ups and downs and short and long term trends.


All to do with variations in the Earth’s movements, such as Orbital shape, Axial tilt, Axial precession, Apsidal precession and Orbital inclination. Although there are still some problems with this theory, read this as a starting place Milankovitch cycles
ID: 1364641 · Report as offensive
Darth Beaver Crowdfunding Project Donor*Special Project $75 donorSpecial Project $250 donor
Avatar

Send message
Joined: 20 Aug 99
Posts: 6728
Credit: 21,443,075
RAC: 3
Australia
Message 1364642 - Posted: 5 May 2013, 0:19:19 UTC

Forgetting of cause that natural CO2 buit up over 10's of thousands of years we have sent the CO2 up from approx. 250ppm to 400ppm in only 150 yrs and added 80% of that in only 100yrs
We now put out more CO2 In 1 day than we where doing in 50yrs from 1900-1950 but that could not have a effect on the atmosphere could it after all how long did it take us to stuff the ozone up and that one will take another 50yrs to correct itself I believe ?????????
ID: 1364642 · Report as offensive
Profile betreger Project Donor
Avatar

Send message
Joined: 29 Jun 99
Posts: 11361
Credit: 29,581,041
RAC: 66
United States
Message 1364643 - Posted: 5 May 2013, 0:20:03 UTC - in response to Message 1364639.  

The ice age ended long before any hint of the industrial revolution. This suggests that the planet is subject to cycles of temperature all on it's own without any human involvement.

For the record: today in Tennessee is a cold record of all recorded time. Sort of like the stock market --ups and downs and short and long term trends.

Your true statement does not at all refute whether industrialization is adding it's own flavor. One special effect is ocean acidification. One can not deny the changing ph, coral reef and oyster declines.
ID: 1364643 · Report as offensive
Nick
Avatar

Send message
Joined: 11 Oct 11
Posts: 4344
Credit: 3,313,107
RAC: 0
United Kingdom
Message 1364812 - Posted: 5 May 2013, 15:56:02 UTC

The burning question, "Does increase in co2 output lead to global warming or does
global warming lead to increased output in co2" Mainly the latter since something
clearly has to fundamentally change with the planet to cause this change in co2
output. Both global warming and cooling are cyclical in nature so a major cycle
of an event occurring or events occurring must be to cause. For all we know,
the rises in co2 noted during this planets life may actually be a defence
mechanism, natures own, to offset the worst coming from this warming event.
Hence the reductions in this co2, again natures defence, to offset set the worst
coming from global cooling. Strange to think that man could actually be
contributing towards the defence of this planet by adding his component of co2.
Strange, for this current global warming period we have currently experienced
has not been nearly as warm as the last one we had 600 years ago.

The Kite Fliers

--------------------
Kite fliers: An imaginary club of solo members, those who don't yet
belong to a formal team so "fly their own kites" - as the saying goes.
ID: 1364812 · Report as offensive
Profile ML1
Volunteer moderator
Volunteer tester

Send message
Joined: 25 Nov 01
Posts: 20265
Credit: 7,508,002
RAC: 20
United Kingdom
Message 1365419 - Posted: 7 May 2013, 12:52:23 UTC - in response to Message 1364812.  
Last modified: 7 May 2013, 13:03:29 UTC

The burning question, "Does increase in co2 output lead to global warming or does global warming lead to increased output in co2"

That's the wrong (too narrow) question... The 'simple' answer is both.


For those a little more interested:

The Earth started out with a CO2 rich atmosphere. The planet was nicely kept warm by that in the early history of the Earth and that also compensated nicely for the slightly cooler sun for those millions of years.

Life developed and converted the CO2 into O2. Life evolved to the new conditions.

Over the millions of years, and millions of years before we walked the planet, there have been a number of cycles of changing climate between 'hot and tropical' and ice ages. The continents have drifted around the planet also, radically changing the worldwide ocean currents and climate.

Note that we're talking grand geological timescales here where there has been an 'assumption' of 'slow geological-like change'.

A contradictory curiosity has been that across those 'geological time scales', there have been rapid mass extinctions on a world-wide scale. So rapid that we mark the transition between some of the geologic periods by such extinctions...

Research over the last century or so now shows that the world climate can radically shift into a new stable and radically different pattern over the space of just a few years. Far too fast for most creatures to adapt and so hence the worldwide mass extinctions that we have seen.

CO2 concentration is implicated in such rapid changes. What typically is seen is that some natural combination of circumstances contrive to nudge the climate a little, natural feedback mechanisms cause a change in CO2 concentration, and then when the natural nudge is additionally aided by the change in CO2, a positive feedback is set in motion that gives a rapid change until the CO2 level stabilizes. A crude analogy is that the change in CO2 acts as a turbo-boost to any change that has already been set in motion.


Mainly the latter since something clearly has to fundamentally change with the planet to cause this change in co2 output. Both global warming and cooling are cyclical in nature so a major cycle of an event occurring or events occurring must be to cause.


We know that change in CO2 levels reinforce whatever changes are set in motion. This time around, uniquely, our industrial world-wide scale pollution is preemptively increasing the levels of CO2 and subsequent atmospheric heating.

We also know there are various natural positive feedback mechanisms to release yet vastly more CO2 and methane once the atmosphere becomes warm enough...

For the turbo-boost analogy, it's as though we are revving up the turbo even though nature is maintaining the same natural force on the gas pedal... You inadvertently get to go faster/hotter...


For all we know, the rises in co2 noted during this planets life may actually be a defence mechanism, natures own...

You can dream Gaia as you wish, and we all get sacrificed for being so naughty and greedy.

Or you can look at natural feedback mechanisms and see how the world climate will settle into stable conditions, until there is some disturbance to nudge the system to go wandering around lost and chaotic until another island of stability is established.

The level of CO2 in our atmosphere is an important part of the balance of feedback mechanisms. We are measurably rapidly changing that to 'unbalance the applecart'... With all the pollution, something is going to break. Meanwhile, arguing over the last 0.01 deg C average is facile.


Yet another example of old research news that is describing the start of yet another extinction for one group of animals is given in:


Mercury exposure linked to dramatic decline in Arctic foxes

... foxes in Arctic regions who feed on ocean prey are being exposed to dangerous levels of mercury.

On one Russian island where the population of foxes has crashed, the researchers believe the toxin has played a key role in the decline. ...

... Mercury levels in the world's oceans have doubled over the past 100 years, according to the UN, with more mercury deposited in the Arctic than on any other part of the planet.

The Arctic Council says there has been a ten-fold increase in the levels of mercury found in top predators in the region over the past 150 years.

Hair of the dog

Now a team of researchers says it has found significant levels of mercury in different populations of Arctic foxes in different environments. ...

... Mercury levels there have for decades been linked to industrial pollution but recent research from Nasa has suggested that declining levels of sea ice in the region could be helping to push up levels of the substance.

Global efforts to contain the poisonous effects of the element received a boost earlier this year when more than 140 countries agreed on a legally binding treaty to curb mercury pollution.



The feedback mechanism for that is described in:

Sea Ice Driving Arctic Air Pollutants

Drastic reductions in Arctic sea ice in the last decade may be intensifying the chemical release of bromine into the atmosphere, resulting in ground-level ozone depletion and the deposit of toxic mercury in the Arctic...

... called a "bromine explosion." These reactions rapidly create more molecules of bromine monoxide in the atmosphere. Bromine then reacts with a gaseous form of mercury, turning it into a pollutant that falls to Earth's surface. ...

... "Shrinking summer sea ice has drawn much attention to exploiting Arctic resources and improving maritime trading routes," Nghiem said. "But the change in sea ice composition also has impacts on the environment. Changing conditions in the Arctic might increase bromine explosions in the future." ...



And still we cheaply pollute for an ever more costly future.

Or rather, we continue to allow the fossil fuels industry to bamboozle us into a polluted now for their profits, and for an ever more costly future for everyone else. Meanwhile, the levels of pollution and fossil-fuels sponsored FUD grow ever greater.


All on our only planet,
Martin
See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)
ID: 1365419 · Report as offensive
Profile William Rothamel
Avatar

Send message
Joined: 25 Oct 06
Posts: 3756
Credit: 1,999,735
RAC: 4
United States
Message 1365444 - Posted: 7 May 2013, 14:30:10 UTC - in response to Message 1365419.  

The Earth started out with an atmosphere of Methane most likely.

If we quit dumping garbage and sewage into the oceans and polluting our ground water with various sludges we would see the health of the coral reefs vastly improve.
ID: 1365444 · Report as offensive
Darth Beaver Crowdfunding Project Donor*Special Project $75 donorSpecial Project $250 donor
Avatar

Send message
Joined: 20 Aug 99
Posts: 6728
Credit: 21,443,075
RAC: 3
Australia
Message 1365603 - Posted: 8 May 2013, 4:50:09 UTC - in response to Message 1365444.  

The Earth started out with an atmosphere of Methane most likely.

If we quit dumping garbage and sewage into the oceans and polluting our ground water with various sludges we would see the health of the coral reefs vastly improve.


The great barrier reef is die ing because of coral bleaching which is caused when the ocean temp goes to high the other reason coral reefs die is to much run off from farms and city's that put to much silt and nutriants into the water and the last reason for the great barrier reef die ing is the crown of thorn's star fish which I believe is a introduced species
ID: 1365603 · Report as offensive
W-K 666 Project Donor
Volunteer tester

Send message
Joined: 18 May 99
Posts: 19048
Credit: 40,757,560
RAC: 67
United Kingdom
Message 1365845 - Posted: 8 May 2013, 20:22:08 UTC

EU finally realises that those solar panels are not as efficient as some people think. After most European manufacturing and research has been halted.

It's called bolting the stable door after the horse has bolted.

http://www.telegraph.co.uk/finance/newsbysector/energy/10045150/Europe-on-verge-of-trade-war-with-China-over-cheap-solar-panels.html
ID: 1365845 · Report as offensive
Profile Bernie Vine
Volunteer moderator
Volunteer tester
Avatar

Send message
Joined: 26 May 99
Posts: 9954
Credit: 103,452,613
RAC: 328
United Kingdom
Message 1365850 - Posted: 8 May 2013, 20:48:22 UTC - in response to Message 1365845.  

EU finally realises that those solar panels are not as efficient as some people think. After most European manufacturing and research has been halted.

It's called bolting the stable door after the horse has bolted.

http://www.telegraph.co.uk/finance/newsbysector/energy/10045150/Europe-on-verge-of-trade-war-with-China-over-cheap-solar-panels.html

Not sure where in the article you linked to does it mention solar panel efficiency, or mention that research has been halted. Seems to be a complaint about cheap Chinese solar panels causing European firms to complain. Or am I reading it wrong?
ID: 1365850 · Report as offensive
W-K 666 Project Donor
Volunteer tester

Send message
Joined: 18 May 99
Posts: 19048
Credit: 40,757,560
RAC: 67
United Kingdom
Message 1365923 - Posted: 9 May 2013, 2:37:23 UTC - in response to Message 1365850.  

EU finally realises that those solar panels are not as efficient as some people think. After most European manufacturing and research has been halted.

It's called bolting the stable door after the horse has bolted.

http://www.telegraph.co.uk/finance/newsbysector/energy/10045150/Europe-on-verge-of-trade-war-with-China-over-cheap-solar-panels.html

Not sure where in the article you linked to does it mention solar panel efficiency, or mention that research has been halted. Seems to be a complaint about cheap Chinese solar panels causing European firms to complain. Or am I reading it wrong?

Not in that article, it was in an article I reported some time ago.

http://www.guardian.co.uk/business/2012/oct/22/siemens-pulls-out-loss-solar-power
ID: 1365923 · Report as offensive
Darth Beaver Crowdfunding Project Donor*Special Project $75 donorSpecial Project $250 donor
Avatar

Send message
Joined: 20 Aug 99
Posts: 6728
Credit: 21,443,075
RAC: 3
Australia
Message 1365940 - Posted: 9 May 2013, 4:15:02 UTC - in response to Message 1365923.  
Last modified: 9 May 2013, 4:17:35 UTC

EU finally realises that those solar panels are not as efficient as some people think. After most European manufacturing and research has been halted.

It's called bolting the stable door after the horse has bolted.

http://www.telegraph.co.uk/finance/newsbysector/energy/10045150/Europe-on-verge-of-trade-war-with-China-over-cheap-solar-panels.html

Not sure where in the article you linked to does it mention solar panel efficiency, or mention that research has been halted. Seems to be a complaint about cheap Chinese solar panels causing European firms to complain. Or am I reading it wrong?

Not in that article, it was in an article I reported some time ago.

http://www.guardian.co.uk/business/2012/oct/22/siemens-pulls-out-loss-solar-power


am I reading your last link rong cause it seems that is also about Asia making cheap solar panels toooo nothing about them being not efficient
ID: 1365940 · Report as offensive
rob smith Crowdfunding Project Donor*Special Project $75 donorSpecial Project $250 donor
Volunteer moderator
Volunteer tester

Send message
Joined: 7 Mar 03
Posts: 22190
Credit: 416,307,556
RAC: 380
United Kingdom
Message 1365957 - Posted: 9 May 2013, 5:02:26 UTC

Both articles are talking about manufacturing costs and efficiency, not the amount of energy produced per square metre, or Euro/Dollar selling price.
Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?
ID: 1365957 · Report as offensive
Previous · 1 · 2 · 3 · 4 · 5 · 6 · 7 · 8 . . . 36 · Next

Message boards : Politics : Climate Change, 'Greenhouse' effects: DENIAL


 
©2024 University of California
 
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.