efficiency of hydronic vs forced air?

hot_rod

ChrisJ said:

Fast is actually forced air's biggest issue.

We notice when things change fast, but slow changes we do not notice.
A system that responds very slowly and can still maintain a somewhat narrow temperature swing will be the most comfortable.

Every house I've ever been in with forced air was always incredibly noticeable when the system was on or off. With heat it feels cool when the system is off and too warm when it's on, always. Same with my air conditioning, it feels cooler when it's on than when it's off, even in low stage.

You're going to say that it's a benefit that air conditioning feels cooler when it's on, and that's true, if it's never off. But in the real world, it will very often be off and that will result in people either feeling too warm when it's off or too cool when it's on.


Forced air is also really efficient at spreading smell through a building.
I suppose that could be good, but it's very often bad. Radiant forms of heat do not spread smells.

If a family member is rocking their bedroom due to something they ate, I'd rather isolate it to that room.

Not only will a FA system ramp up quicker, but they don't tend to overshoot like a 4" radiant slab will, Regardless how many controls you throw at a slab, in these shoulder seasons they have a mind of their own. 35F when I got up, in the high 50's by afternoon here today.

ChrisJ

@hot_rod seriously

You too?

Voyager

ChrisJ said:

@hot_rod seriously

You too?

Hot Rod is simply stating the physics of a high mass radiator. Why does that surprise you?

JakeCK

@Voyager what was the heat loss at design for your log home? Seems like a lot of heat even for a house that large. But I'm not familiar with log homes.

Voyager

JakeCK said:

@Voyager what was the heat loss at design for your log home? Seems like a lot of heat even for a house that large. But I'm not familiar with log homes.

I don’t know. The HVAC company did the design and I did not check it.

There is no doubt I have way more heating capacity than I need. I think that attic units are 50K because that was the smallest available. Probably 20K would have been more than enough. The main unit in the basement is probably close to correct as it is heating 2800 or so square feet, but it could probably work fine at 100K.

Solid_Fuel_Man

That is a beautiful home @Voyager.

We all have different designs and different expectations from a structure we live in. As we certainly have seen in this thread. 

It has been very interesting. 

I will add however that my experience has been that as infiltration and r value decrease lots of systems struggle. A tight home will respond the best to and given HVAC system. 

I live in a thermos with a radiant slab and it works wonderfully as the heatloss curve is very flat. 

The looser the structure the worse the flywheel effect is with high mass. So a looser structure would work better with a lower mass system. HWBB and FA both can respond very quickly. Your church is likely lacking in radiation if it cannot recover from a setback in 4 hours. 

I have enjoyed the perspectives and bit of heat....pun intended.....in this discussion. 

Wellness

Trying to reconcile the statement that "you don't (need ac) in most of the US" with the claim that you only need ac when temps are 85 or above. The average July temperature in Philadelphia is 85 and presumably everything south of Philly is higher than 85 in July, thus requiring AC, at least in July, especially with climate change likely to push that average figure even higher in coming years, no?

Paul Pollets

I'd say more than 70% of US homes need A/C. It's a necessity, not a luxury. When I moved to Seattle from NY 31 years ago, Seattle had 4-5 days over 80. Now we have 15-20. Every customer asks what's available to cool the home. Split type A/C's are chosen most often.

Jamie Hall

All I can say about air conditioning is... if it's a necessity, as it seems to be from your comments, how ever did anyone live in this country before World War II? I'll grant that some regions weren't all that healthy -- letters from one of my ancestors suggest that yellow fever was a bit troublesome in New Orleans in the 1850s or so, for instance -- but somehow the topic of needing air conditioning wasn't mentioned. And some areas -- Miami, for instance -- weren't particularly settled until A/C came along. But most of the country?

Now I'll grant you I don't mind air conditioning when it's hot and humid (within reason -- stepping into a store from 90 outside and it's 72 inside is a bit much). But it's not a necessity much of the time. Whether it is or is not is a matter of both temperature and humidity (if the humidity is low, for instance, it is possible to work outside at 100 F or more -- ask an Arab) and life style.

We are a very soft and very inflexible culture. There's a reason for a siesta...

ChrisJ

@Jamie Hall
I guess technically no houses "need" electric or indoor plumbing or heat.

They're all wants.  

My house originally had a few wood stoves, no plumbing, no electric.

And people did just fine.

JUGHNE

I am amazed at the number of younger people who run their AC at a constant 68.
Or they are disappointed if the system will not drop that far down when it is 95 outside.

Many go from the cold house, into the car, into the office, back into the car and then return home. The only outside time is from the car to office and back to car.

The body climatizes to those temps and that short walk across the parking lot will just about knock them down.

Also IMO, those temps put the body into "winter mode" of eating more calories to stockpile the body heat.....maybe contributing to obesity.

City relatives come to visit and it the AC isn't cranked on they suffer.
We were fine until they show up and shut it off and open the windows when they leave.

pecmsg

JUGHNE said:

I am amazed at the number of younger people who run their AC at a constant 68. Or they are disappointed if the system will not drop that far down when it is 95 outside. Many go from the cold house, into the car, into the office, back into the car and then return home. The only outside time is from the car to office and back to car. The body climatizes to those temps and that short walk across the parking lot will just about knock them down. Also IMO, those temps put the body into "winter mode" of eating more calories to stockpile the body heat.....maybe contributing to obesity. City relatives come to visit and it the AC isn't cranked on they suffer. We were fine until they show up and shut it off and open the windows when they leave.

Because there oversized. 

When it’s 90 + my 1-ton unit maintains 76 and 45% inside. 

Perfect. 

ChrisJ

pecmsg said:

JUGHNE said:

I am amazed at the number of younger people who run their AC at a constant 68. Or they are disappointed if the system will not drop that far down when it is 95 outside. Many go from the cold house, into the car, into the office, back into the car and then return home. The only outside time is from the car to office and back to car. The body climatizes to those temps and that short walk across the parking lot will just about knock them down. Also IMO, those temps put the body into "winter mode" of eating more calories to stockpile the body heat.....maybe contributing to obesity. City relatives come to visit and it the AC isn't cranked on they suffer. We were fine until they show up and shut it off and open the windows when they leave.

Because there oversized. 

When it’s 90 + my 1-ton unit maintains 76 and 45% inside. 

Perfect. 

95ish and mine will do 74-75ish.
That's with a dew point of roughly 75f.

I've been quite happy with that.

BennyV

This discussion is basically about retrofits and additions, so a LOT of other factors come into play, like what works in the existing structure or with the existing system. New construction homes that are well insulated have heating loads that are far too low to use radiant heat, and heat pumps are the obvious option.

For retrofits, radiant is the best for comfort in terms of heating, but where do you get the heat? The most common method is a gas fired boiler, and gas is still stupidly cheap in much of the US. But looking into the future as we electrify everything, ducted systems are pretty obvious... put in a heat pump. Not so for radiant, air to water isn't terribly efficient, and water to water is a bit better, still not great, and astronomically expensive end to end. Wood pellet boilers use local fuel in the Northeast, and have most of the benefits of gas oilers with 5:1 TDR, ability to serve a mix of low-temp, high-temp, DHW, and hydro-air, but have a high up-front cost.

Fire risk isn't really a significant issue with most forced air systems... unless something was done terribly wrong in the first place.

In newer homes (last 50-60 years or so), A/C adoption is a big reason why FHA is so common, as it's easy to do both with one system.

You can make a system that's reasonably well suited to both, either with two sets of registers that are changed over seasonally, or by configuring the ducts primarily for heat downstairs and primarily for A/C upstairs, and then they're correct 70%+ of the time.

I see a lot of houses that used forced air in the early 1940's, as I believe the steam and hot water systems of the time were impossible or nearly impossible to install due to the rationing for wartime, but small cookie-cutter houses were being built like crazy around large defense plants so that they could get more workers to live close by.

Radiant cooling is a silly idea in much of the US, as it's humid, and in significant parts of the Northern US, A/C is primarily dehumidifying, with cooling being secondary. However, in many northern climates, a couple of modest mini-split heads will provide enough cooling to be comfortable, but wouldn't be anywhere close to enough to heat the building, so a combination of mini-splits and hydronics may make sense, with the mini-splits handling heating in the shoulder seasons when the temps swing around before and after the radiant system is heated up.

Jamie Hall said:

If the ambient air temperature is below about 85 F you don't need air conditioning. Granted, you may want it. But you don't need it. A lot of people demand it and want it -- but they don't need it.

I can't sleep if it's humid or more than about 67. I could muscle through the day in the low- maybe mid-80s with humidity, but it's rather draining if at least one room isn't air conditioned to cool off in.

Jamie Hall said:

I wasn't going there -- but it brings up an interesting point. How and why (calling @DanHolohan !!!) did the "normal" temperature for heating come about? What is normal about 72 or so?

If you're in Florida. That's scorching hot in the northeast, ours is 65F. Some go a bit warmer or colder depending on a lot of factors.

Jamie Hall said:

All I can say about air conditioning is... if it's a necessity, as it seems to be from your comments, how ever did anyone live in this country before World War II?

For one, it wasn't as hot as often back then. Secondly, not that many people lived in the south prior to mechanical air conditioning. Thirdly, the ones who did lives in houses and cities designed for natural cooling, as evidenced by the designs of porches, windows, ceilings, etc. And then sometimes all that wasn't enough and they were just really hot and gross.

JakeCK

I cool my entire downstairs(~700sq ft) with a 14k btu window shaker. Does just fine. 

That said the planet is a tad wee bit warmer than it was 100 years ago. Courtesy of all the fuel we've burned heating and cooling our houses.

pecmsg

JakeCK said:

I cool my entire downstairs(~700sq ft) with a 14k btu window shaker. Does just fine. 

That said the planet is a tad wee bit warmer than it was 100 years ago. Courtesy of all the fuel we've burned heating and cooling our houses.

Now how about when the last ice age ended some 12,000 years ago?

ChrisJ

pecmsg said:

JakeCK said:

I cool my entire downstairs(~700sq ft) with a 14k btu window shaker. Does just fine. 

That said the planet is a tad wee bit warmer than it was 100 years ago. Courtesy of all the fuel we've burned heating and cooling our houses.

Now how about when the last ice age ended some 12,000 years ago?

I think the little ice age is more appropriate for this discussion

MaxMercy

My dad once told me a story about when his father installed central heating in their home sometime in the mid 20s. My dad couldn't wait to go to bed that night so he could wake up in the morning and see what it was like to put his feet on a warm floor in the middle of winter. He wasn't disappointed.

My mom (97 God bless her) often tells stories of being a little girl during the Depression. They often had "soup" for dinner which was stale Italian bread with milk poured over it. They also had an outhouse instead of an indoor privy. She loved that time in her life because they didn't know what they were missing.

What do we really need to get by? We don't need indoor plumbing, central heat, central air, or 8 AC outlets and wifi in every room, but they have almost become necessities.

With regard to hot weather, I LOVE it. I'm the guy who drives with his windows down when it's mid-80s outside. The central AC in my house is original (two separate systems top floor/bottom floor), and they're both running perfectly because I don't turn it on in April and turn it off in September like my best friend does. Since 1993, I replaced a fan motor on the lower unit and a relay/contactor on the upper unit. I have a whole house fan as well and as long as the humidity is reasonable, we use the house fan.

But there are probably 4-6 weeks total worth of nasty humid weather in CT, and on those 90 degree nights with high humidity, AC is as much as a necessity as heat is in winter.

JUGHNE

Yes, I neglected to mention that all the AC's referred to are oversized by a ton or so.

I can cool my 2000'+ house with 2 tons (2 2 ton units, one shut down after pull down for the visitors) .

So when we are in the utopia of no fossil fuels, do you think wood, pellets, corn or coal will be allowed?

Coal burning was forcefully banned in London in 60-70's.....for good reason.
Fireplaces were bricked shut and a small electric heater would sit on the hearth.
Look at old structures there and there were about 4 chimney stacks per living unit.

Talking to older folks, the London "Fog" was terrible.
Going way back, someone would walk in front of the carriages (horseless or otherwise) with a lantern, flashlight (electric torch) to avoid accidents.

The Fog was deadly also, stories of multiple deaths from respiratory attach's.

We have come a long ways from that type of situation.

But to be totally green I thing the "warriors" will pursue any cloud of smoke if given the power.

Jamie Hall

Somebody up there mentioned solid fuels -- such as pellet boilers. Nope. Not if the objective to the exercise is to decarbonise. In order of evil on carbon, you have hydrogen (none), natural gas/bio gas (methane, almost none), LP (getting there), light liquid hydrocarbons e.g. gasoline (hmm), diesel a little worse, heavy oils not good. And then, way out there on the grubby bad news fringe, coal and wood. with the result that coal and wood are, or will be outright banned long before the other fuels are -- and, indeed, already either are banned or severely restricted in many places. You may or may not be allowed to use fireplaces -- in the UK, you aren't or won't be in a few years (the schedule is a little flexible).

And before someone mentions catalytic afterburners and the like, remember: it's CO2 -- carbon dioxide -- that is the problem people are after, and if you are getting your energy by breaking carbon to carbon bonds (such as wood and coal) and adding oxygen, you get... carbon dioxide. And there's no simple way to get rid of it. Cats and filters can and do reduce particulates and nitrogen oxides, but they do nothing for CO2.

delcrossv

Unless it's either 90% humidity or above 80 at night we run a whole house fan. My folks had one installed when they built their house in the mid 50's and I put one in my 1920's farmhouse when I moved in.

Don't know why they're not SOP these days- they work for almost the whole cooling season and are cheap to run compared to AC.

Voyager

Solid_Fuel_Man said:

That is a beautiful home @Voyager.

We all have different designs and different expectations from a structure we live in. As we certainly have seen in this thread. 

It has been very interesting. 

I will add however that my experience has been that as infiltration and r value decrease lots of systems struggle. A tight home will respond the best to and given HVAC system. 

I live in a thermos with a radiant slab and it works wonderfully as the heatloss curve is very flat. 

The looser the structure the worse the flywheel effect is with high mass. So a looser structure would work better with a lower mass system. HWBB and FA both can respond very quickly. Your church is likely lacking in radiation if it cannot recover from a setback in 4 hours. 

I have enjoyed the perspectives and bit of heat....pun intended.....in this discussion. 

Thanks. A lot of effort went into it and still does. Log homes are nice to look at and pretty nice to live in, but suck to maintain. I would not build another one at my current age, but when I was 40 everything seemed possible.

I agree. I enjoy open and even spirited debates, but it seems far too many today have think skin and want to run and hide as soon as they are challenged. That is sad, but I guess just a sign of our times.

Voyager

Jamie Hall said:

All I can say about air conditioning is... if it's a necessity, as it seems to be from your comments, how ever did anyone live in this country before World War II? I'll grant that some regions weren't all that healthy -- letters from one of my ancestors suggest that yellow fever was a bit troublesome in New Orleans in the 1850s or so, for instance -- but somehow the topic of needing air conditioning wasn't mentioned. And some areas -- Miami, for instance -- weren't particularly settled until A/C came along. But most of the country?

Now I'll grant you I don't mind air conditioning when it's hot and humid (within reason -- stepping into a store from 90 outside and it's 72 inside is a bit much). But it's not a necessity much of the time. Whether it is or is not is a matter of both temperature and humidity (if the humidity is low, for instance, it is possible to work outside at 100 F or more -- ask an Arab) and life style.

We are a very soft and very inflexible culture. There's a reason for a siesta...

How did we live before the 1700s? No central heat back then unless you were a Roman with under stone radiant floor heat, which, by the way, was provided by air mostly. 😁

Voyager

Getting rid of CO2 is stupid easy … the technology is called … wait for it … a TREE.😂

ChrisJ

Voyager said:

Getting rid of CO2 is stupid easy … the technology is called … wait for it … a TREE.😂

TAG

The problem with both Log and SIP is the services .... having built both -- they take a lot of planning. SIP's are very tight homes ...much tighter than any traditional. I have done two SIPs -- both modified boxes ===one with a reconstructed barn built inside and the other was an 900' extension to my studio. Having rehabbed an old barn earlier into living space .. you don't do another. Both SIP had heat loads too low for full radiant. My studio extension can be heated with a match and the SIP had partial where I had used a Bradford White Combination tank (the one with the coil for radiant inside) to heat the kitchen floor and bathrooms. Using the floor heat always overheated the areas -- but, it was toasty. The BW tank was used because I had used it before to warm up a kitchen/mudroom/bath extension on an older house over a crawl space.

Every house has a solution -- as houses have become tighter the line in the country where radiant can make a case for itself heads north. Modern houses just don't loose heat like the old ones -- radiant fails in areas with long shoulder seasons. I end up using both the radiant and the ducted most of the time anyway -- with a nice zoned ducted it's often possible to move the heat around from both sun and just the slow lag of a radiant slab.

After 30+ years of fun I'm nearing the end of my projects .... with this PA build -- I'm not sure I will be doing another northern build where radiant can be justified. I have done enough with really good forced air to know that unless there are odd areas radiant is overkill.

Will note that as much as I love radiant -- and I do ... don't think there are any savings over other systems in a house.

MaxMercy

delcrossv said:

Don't know why they're (whole house fans) not SOP these days- they work for almost the whole cooling season and are cheap to run compared to AC.

There's nothing like a STRONG cool breeze on a warm summer night. We love ours and it get's used about 80% of the time as opposed to our central air, and it's not because of cost, but because we love the feel. Of course, the wear and tear on the central AC is reduced. Ours is almost 30 years old and it's still running fine with just minor repairs.

The only problem with a whole house fan is the occasional skunk who decides at 3 AM it's in danger. One summer about 5 years ago we were getting blasted by skunk spray almost every night. I finally closed all the windows for the summer and switched the AC on and left it that way. Why God created skunks I have no idea.

BennyV

MaxMercy said:

But there are probably 4-6 weeks total worth of nasty humid weather in CT, and on those 90 degree nights with high humidity, AC is as much as a necessity as heat is in winter.

At this point, in CT A/C is necessity for about 5 months.

Jamie Hall said:

Somebody up there mentioned solid fuels -- such as pellet boilers. Nope. Not if the objective to the exercise is to decarbonise. In order of evil on carbon, you have hydrogen (none), natural gas/bio gas (methane, almost none), LP (getting there), light liquid hydrocarbons e.g. gasoline (hmm), diesel a little worse, heavy oils not good. And then, way out there on the grubby bad news fringe, coal and wood.

That's not how it works. The pollution issue has been solved with very clean burning pellet stoves and boilers, as well as wood stoves that are extremely clean. Wood is an incredible carbon-neutral fuel, as it sucks up all the carbon when it is growing, gives it back off, etc, endlessly. There are some practical issues with the cost of pellet boilers, but environmentally, they are a winner, at least for several million more homes as well as schools and businesses worth of fuel in the northeast that we can sustainably harvest within the northeast. I think there's a niche for pellet boilers as well as pellet stoves in the northeast, but heat pumps are still the primary tool for decarbonisation.

Hydrogen is a dirty mess because still most of it is cracked from natural gas. Methane biogas maybe, but we still don't have great feedstocks for it at scale. Gas grids also leak like crazy, and methane is a GHG too.

TAG said:

Modern houses just don't loose heat like the old ones -- radiant fails in areas with long shoulder seasons.

In the strictest sense, you're 100% correct. However, my logic in the northeast would be that you need A/C anyway, so put in a heat pump and use that to handle the shoulder, and then run the radiant for a couple months when it's really cold out. Of course in places like here in CT, you'd get maybe 3-4 months out of the radiant, tops, so is it worth it? Maybe?

Another approach is instead of hydronic radiant floor heat, you could put in hydronic radiant floor warming, which is undersized to the room so that it runs at a warmer reset temperature more of the time, and then have a hydro air coil in a hybrid heat pump system to make up the difference to the design load when it's really cold out.

EDIT: Due to the design loads being overly conservative along with the thermal mass of the floor warming system, you wouldn't need the hydro air much anyway, and could use it for setbacks overnight while the floor warming kept running on very cold nights.

Jamie Hall

The argument on wood heat being carbon neutral just doesn't add up. Sorry. A plantation grown softwood will take about 30 years to grow to a harvestable size. You can burn that all up in one cold night. Not that you would burn a softwood in most residential boilers -- or at least you shouldn't. So... a reasonable sized ash or oak (much better firewood) might take 50 or 60 years.

In a sense, though, I suppose that you could justify the assertion. If you have a well managed wood lot of say, 10 acres, grown on a 50 year rotation, you can heat a normal sized residence with the wood, and stretching the point a bit (you have to take into account the fuel use in harvesting; not everyone uses a team of horses as we do) you could argue that that operation is approximately carbon neutral.

For that residence.

It is, at best, a niche argument.

Several million homes were mentioned in the northeast (we'd be delighted -- it's my daughter's and son-in-laws business) so we are looking at perhaps 20 to 30 million acres of forest. 31,000 square miles -- a square 176 miles on a side. All of Connecticut, Massachusetts, and Rhode Island plus half of New Hampshire and Vermont. All of it in active forest management for firewood (possibly some recreation might be allowed -- but nothing else). I'm not sure how well this would go over...

For the privileged who have the land and resources, yes perhaps.

Voyager

Jamie Hall said:

The argument on wood heat being carbon neutral just doesn't add up. Sorry. A plantation grown softwood will take about 30 years to grow to a harvestable size. You can burn that all up in one cold night. Not that you would burn a softwood in most residential boilers -- or at least you shouldn't. So... a reasonable sized ash or oak (much better firewood) might take 50 or 60 years.

In a sense, though, I suppose that you could justify the assertion. If you have a well managed wood lot of say, 10 acres, grown on a 50 year rotation, you can heat a normal sized residence with the wood, and stretching the point a bit (you have to take into account the fuel use in harvesting; not everyone uses a team of horses as we do) you could argue that that operation is approximately carbon neutral.

For that residence.

It is, at best, a niche argument.

Several million homes were mentioned in the northeast (we'd be delighted -- it's my daughter's and son-in-laws business) so we are looking at perhaps 20 to 30 million acres of forest. 31,000 square miles -- a square 176 miles on a side. All of Connecticut, Massachusetts, and Rhode Island plus half of New Hampshire and Vermont. All of it in active forest management for firewood (possibly some recreation might be allowed -- but nothing else). I'm not sure how well this would go over...

For the privileged who have the land and resources, yes perhaps.

You are looking at it wrong. Where did the carbon in the tree come from? For that matter, where did the carbon in oil and coal come from? That is one question the global warming fanatics will never answer.

Jamie Hall

I'm hardly a fanatic, @Voyager -- although I do feel that it would be helpful to avoid climate modification as much as possible, as most of my Doctorate and post-Doc research (in geophysics and climate dynamics) has suggested. But it's not worth the time and effort to argue, and debate is not an option.

JakeCK

I find it somewhat amusing we're still arguing this debate almost 166 years after Eunice Foote discovered the heat trapping effect of carbon in 1856. And later again John Tyndall in 1859. The petrochemical industry didn't just take a page from big tobacco's playbook. They stole the whole damn book, hired the lawyers and ran like hell with it.

And most people on this planet are so wound up in their own echo chamber they can't see past their own nose.

Voyager

I’m not a fanatic either, but the CO2 effect has been hyped beyond all reason. And you didn’t answer my question as to where the carbon in trees originally came from and the carbon in oil and coal? Did space aliens bring it?

Voyager

JakeCK said:

I find it somewhat amusing we're still arguing this debate almost 166 years after Eunice Foote discovered the heat trapping effect of carbon in 1856. And later again John Tyndall in 1859. The petrochemical industry didn't just take a page from big tobacco's playbook. They stole the whole damn book, hired the lawyers and ran like hell with it.

And most people on this planet are so wound up in their own echo chamber they can't see past their own nose.

Where did the carbon in trees, oil and coal come from originally?

JakeCK

It was here when the planet was formed from the primordial solar system. You're trying to confuse the issue, and I suspect you know that...

As life evolved it modified the environment to bring it to what it is today and most of that carbon has been sequestered in to the ground by various processes. We have been releasing that into the atmosphere for several hundred years now at an accelerating pace. The issue is our species and most species alive today have evolved to live in an environment with parameters that no longer or will soon no longer be true. We have drastically changed those parameters in an infinitesimal time frame. Both the ecosystem and our society that relies on it will not be able to adapt quick enough. There will be a collapsed. 

Physics doesn't care if you believe it or not, it just is. And we'll all know what's true and what isn't soon enough. Even you old retiree's will probably be around long enough to bare witness to the fruits of our labor.

Jamie Hall

The carbon in oil and coal accumulated mostly in swamps over a period of some 40 million (that's million) years, starting around 320 million years ago. The climate at the time was considerably warmer than today's climate -- but there weren't any land critters around to worry about that. The era ended with a rearrangement of continents which resulted in a generally drier, but yet warmer, climate.

The carbon in trees -- and, for that matter, almost all living things -- is continuously recycled in the atmosphere and in the oceans (carbon dioxide is quite soluble in water). The cycle is actually quite stable, and tends to self-correct, as additional atmospheric carbon dioxide both warms the atmosphere, overall, and results in greater plant growth -- which in turn takes up additional carbon dioxide. It is not particularly difficult to determine what effect various concentrations of atmospheric carbon dioxide have on average global atmospheric temperatures -- although it is considerably more difficult to determine what the climate impact of the changes in various locations will be (some of the world's largest supercomputers are used in these calculations, and some of the best scientific mathematicians and programmers are engaged in developing and running these models, and the programs are huge -- my own meagre contribution, the code used to model continental and subcontinental glaciation in response to climate -- runs to 25,000 lines of densely packed Fortran!)(for the computer geeks out there -- these supercomputers all run Fortran, as it is far more powerful than the common user programming languages, but much harder to write and ill-suited to user input and output).

Unfortunately, not all of the relevant parameters are known with as much precision as we would like, and the relevant equations involved are dismayingly sensitive to some of these parameters, which is why there is -- or should be in honest reporting -- a range of results for various scenarios. Perhaps worse, there are also other drivers for climate variation besides carbon dioxide (and methane and other trace gases), some of which are of geologic origin but some of which are astronomical in origin, and not all of which are well understood (it is these drivers which account for ice ages and interglacial periods with the present arrangement of continents).

I mentioned above that the effect of carbon dioxide and other trace gases is fairly straighforward to model, as these things go. Unfortunately, the actual climate -- the long term weather patterns and oceanic patterns -- is not so simple, as it turns out that overall there are several stable climate patterns for any given energy regime, and which one is present at any time depends not only on what the energy regime is, but on the history of how that regime is achieved -- the pre-existing conditions. Our present climate pattern is the result of a recovery now about 10,000 years in process from a previous "ice age", but is very close to tipping to one characteristic of interglacial periods as seen over the last several hundred thousand years. These tipping points are not simply reversible; that is once tipped into one stable pattern, it takes a considerable change in energy regime to tip back -- you can't simply lower the temperature overall, for instance, by half a degree. At the present time there is a very lively debate in the climate modelling community as to how close our climate is to this tip, and some scientists (myself included) are of the belief that the tipping point has, in fact, been passed. This is -- or will be according to others -- seen in the behaviour of the Greenland and Antarctic ice sheets. The regime to which we may be entering is more similar which existed for most of the past one million years or so, and is characterized by significantly higher sea levels relative to the continental margins and somewhat more energetic atmospheric circulation and significant changes in some oceanic currents (the major one being the Gulf Stream moving farther south where it crosses the Atlantic Ocean).

My own view of the current climate or "global warming" debates is informed by this, and my emphasis is that our efforts to avoid "global warming" or whatever are between 50 and a hundred years too late. The horse, as they say, has already left the barn and we would be very wise to pay much less attention to shutting the gate, as it were, and much more to coping with the new reality.

It's going to be interesting.

I hope the above didn't bore anyone unduly...

JakeCK

Jamie, you are 100% correct about it being to late. We can only attempt to adapt. I suspect we will fail. 

Hey maybe Putin has the right idea. Maybe a nuclear winter will be a large enough change in energy to revitalize the glaciers? It'll also lighten the human load on the planet and maybe jump start evolution with some random mutations. O.o

Voyager

Well, as one who wrote many thousands of lines of F77 and VAX-11 Fortran, I never found user I/O to be an issue. And structured Fortran was much easier to read than C and C++ for me.

I believe the trees and oil and coal came from carbon that was once in the atmosphere so returning some of it to the atmosphere does not overly concern me. And we have been through many warming and cooling cycles over the millennia. And a good many very sound scientists disagree with those who are climate alarmists and for good reason. ALL of the climate models have been wrong and all have been wrong on the side of overestimating the temperature rise of the earth. There are simply too many variables that are either unknown, known and not included or not able to be accurately measured.

And many, probably most, climate models underestimate the self-regulating aspects of our ecosystem. higher CO2 levels encourage more plant growth which consumes more carbon. This and other natural control systems make modeling fraught with peril and error.

JakeCK

Voyager said:

And a good many very sound scientists disagree with those who are climate alarmists and for good reason. 

Please provide sources and references. I suspect you are substantially over exaggerating both the number and quality of scientists who disagree with current accepted climate models and scientific consensus. 

Voyager

JakeCK said:

Voyager said:

And a good many very sound scientists disagree with those who are climate alarmists and for good reason. 

Please provide sources and references. I suspect you are substantially over exaggerating both the number and quality of scientists who disagree with current accepted climate models and scientific consensus. 

Start with this which debunks the broad 97% claim. https://www.forbes.com/sites/alexepstein/2015/01/06/97-of-climate-scientists-agree-is-100-wrong/?sh=3296c3313f9f