Now its Global cooling or rather Solar cooling.

[TerraHertz]

A few minor googled items.

https://www.kane.co.uk/knowledge-centre/what-are-safe-levels-of-co-and-co2-in-rooms   

250-350ppm     Normal background concentration in outdoor ambient air
 350-1,000ppm     Concentrations typical of occupied indoor spaces with good air exchange
 1,000-2,000ppm     Complaints of drowsiness and poor air.
 2,000-5,000 ppm     Headaches, sleepiness and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be present.
 5,000     Workplace exposure limit (as 8-hour TWA) in most jurisdictions.
 >40,000 ppm     Exposure may lead to serious oxygen deprivation resulting in permanent brain damage, coma, even death.

400ppm  = 0.04%
2000ppm = 0.2%  (Roughly Earth's average through the Permian, Triassic, Jurassic, Cretaceous and Tertiary ages, ie the past 250 million years.)
5000ppm = 0.5%
Note that the observed effects in the text above for 1000-5000ppm CO2 in enclosed spaces probably has more to do with the drop in oxygen content you'd expect in those circumstances. The primary effect of increased blood CO2 is faster respiration, since the body uses blood CO2 sensing to control respiration rate. There is no blood oxygen sensing, but the effect of low oxygen in drowsiness and eventually loss of consciousness.

http://www.val-tronics.com/downloads/appnotes/NOTEA11.PDF

Carbon Dioxide in air (volume %)  Increased lung ventilation
0.1 to 1.0%  (1000 to 10,000 ppm) Slight and unnoticeable increase
2.0%                              50% increase
3.0%                              100% increase
5.0%                              300% increase, breathing becomes laborious
Ten percent (10%) in air can be endured for only a few minutes.  Twelve (12%) to fifteen (15%) percent soon
causes unconsciousness.  Twenty-five (25%) percent may cause death  in exposures of several hours. The
normal concentration of CO2 in fresh  air is 0.03% to 0.04% (300 to 400 ppm).

I know from my own caving experience, 2% to 3% CO2 is really noticable. Below 1% (10,000ppm) you wouldn't even know, so long as Oxygen stays up over 19%.

google: greenhouse farming ideal co2 level
http://www.novabiomatique.com/hydroponics-systems/plant-555-gardening-with-co2-explained.cfm
Gardening with CO2 explained

How much CO2?
It is well known that a CO2 level in the garden's air between 700 and 900 ppm improves crop development and yield. Most plants grown for their beautiful flowers or foliage optimally develop at about 800 ppm. Roses are distinctive as they require about 1200 ppm in carbon dioxide concentration for best results. For many fruits and vegetables, the ideal CO2 level in the garden should be at least between 1000 and 1200 ppm.

google: increased co2 reduces plant need for water
http://www.co2science.org/subject/t/summaries/transpiration.php

These several results, as well as those obtained from many other studies, suggest that as the air's CO2 content continues to rise, earth's plants will likely display reductions in stomatal conductance, which should reduce their rates of transpirational water loss.  As a result, most plants should be able to better deal with periodic water shortages and warmer temperatures, possibly even expanding their ranges into areas where it was too dry for them to successfully live and reproduce in the recent past.

We're already seeing this effect. Lots of reports of long-established desert areas starting to green-up now. One amusing side effect: Mad Max Fury Road having to be shot in Namibia since the original 3 Mad Max movie locations in Australian desert were 'too green'.

Ha ha... I see there are now some Warmist studies attempting to show that reduced plant expiration of water vapor would be a bad thing, because... drier local climate. Except the ones I skimmed made the assumption total plant biomass would remain the same. Which is insane. and the kind of ridiculous thing you would only assume if you were groping for something bad to say about results of increasing CO2, and hoped no one would notice you being a jerk.

google: sea levels geological history
http://www.curry.eas.gatech.edu/Courses/6140/ency/Chapter10/Ency_Oceans/Sea_Level_Variations.pdf
300 meter variations and more, with many dramatic swings. Take that 70mm variation and stick it. If it's even real/accurate, see next URL. Also you do realize we're still emerging from the last ice age, right?  There are innumerable instances in all civilizations of sea ports ending up 50 meters and more under water or up on hillsides. People adapt. That our present civilization is so stupid that we build massive cities on 'at sea level' flat land is just a demonstration of short-sighted stupidity, not any kind of argument about climate change. Which will continue no matter what we do. As for New Orleans... good grief.

http://wattsupwiththat.com/2014/04/28/sea-level-rise-slows-while-satellite-temperature-pause-dominates-measurement-record/

Dr. Curry draws the following conclusions based upon these measured and perhaps interrelated outcomes by noting:
“Once again, the emerging best explanations for the ‘pause’ in global surface temperatures and the slow down in sea level rise bring into question the explanations for the rise in both in the last quarter of the 20th century. And makes the 21st century of sea level rise projections seem like unjustified arm waving.”

Also yet another fine example in the opening there of how warmists routinely 'adjust' data to fit their expectations.

Oh, and don't forget to check out 'post glaciation crustal rebound' for extra fun.

[tom66]

@TerraHertz, That chart is quite interesting - and if true, would be a little bit of a deal-breaker. However... I have some concerns.

The first problem I have is the source for the temperature data.  http://scotese.com/climate.htm   The method used to determine temperature is given: "We can determine the past climate of the Earth by mapping the distribution of ancient coals, desert deposits, tropical soils, salt deposits, glacial material, as well as the distribution of plants and animals that are sensitive to climate, such as alligators, palm trees & mangrove swamps."

This is all well and good, but I would question the methodology. By looking at the chart we can see long flat periods where the temperature rarely changes. This doesn't really meet with prior expectations, even over short periods of time the temperature may vary by a degree or two either way. Secondly, the data is proxy, i.e. not direct - like all previous temperature measurements - but it makes a LOAD of assumptions, more than something like ice core measurements or trapped carbon measurements. How do we know that previous life was not compatible with higher or lower temperatures? Are we assuming that alligators have not adapted to their environment over time? etc.etc.

The second problem I have with the chart is that there's absolutely no accounting for historical variations in solar output or atmospheric changes. For example the precambian atmosphere is widely believed to be low on oxygen but very high on CO2 and nitrogen. We don't know how much that might affect climate forcing, in fact extreme amounts of CO2 could actually lead to a cooling effect if the CO2 reflects more solar energy back. That's not an excuse to pump even more CO2 out though.
 
The third problem I have is that there's a better chart available. From NASA. It doesn't try and get a proxy measurement for the past 600Mya -- such a measurement would have such uncertainty as to be basically useless. And it wouldn't be relevant to our current climate. We know, with reasonable certainty, that the atmosphere for the last 500,000 years has been roughly similar to the current atmosphere. This can be measured using ice core samples. The Sun is also fairly constant - solar output variations cannot account for such wild changes.

https://www.ncdc.noaa.gov/paleo/globalwarming/temperature-change.html

[zapta]

Even if I were to accept that, which I don't, you still have to account for other pollution. Releasing CO2 tends to be by combustion, which produces other waste that is harmful to human health and the environment more generally.

Do you have any justification for that, because without it your argument is largely irrelevant. Even if CO2 isn't a problem, the other stuff is and needs to be dealt with in basically the same way.

Well, we live longer than ever so it can't be that bad. Cheap energy on demand is good for life.

[Stonent]

[apis]

Well, we live longer than ever so it can't be that bad. Cheap energy on demand is good for life.

Right now, but what will the world look like in 200 years, or 500 if we continue like this? There is enormous thermal inertia in the earth system, if one is to prevent dangerous climate changes in the future we have to act now.

[Zero999]

What about the next ice age? In the past ice ages have had a huge negative impact on humanity. Will we have another ice age if CO₂ emissions continue to warm the planet? If not then how is this a bad thing or will the increase in temperature be worse?

[G7PSK]

The global warming lobby got its original kick start from Margaret Thatcher when as prime minister she wanted to bring the miners to heel and what better way than demonising coal, she then later began to have doubts about what she had started.

   http://www.telegraph.co.uk/comment/columnists/christopherbooker/7823477/Was-Margaret-Thatcher-the-first-climate-sceptic.html

[tom66]

I have never heard this theory and it makes very little sense to me. Thatcher wanted coal to continue (without subsidy as she was a conservative and believed in the free market); but she hated the unions. Demonising coal would distract from the problem.

[apis]

What about the next ice age? In the past ice ages have had a huge negative impact on humanity. Will we have another ice age if CO₂ emissions continue to warm the planet? If not then how is this a bad thing or will the increase in temperature be worse?

Another ice age would also be really bad. The thing is, even if we stop emissions completely today there is already enough co2 in the atmosphere that there won't be another ice age. But we are not stoping emissions or even slowing down, the rate of greenhouse gas emissions is accelerating...

http://www.bbc.com/news/science-environment-16439807

[tom66]

It probably is time to research how to reverse damage caused. How practical is building the world's largest CO2 scrubber? The Apollo 13 astronauts did it...

[apis]

There have actually been some pretty desperate things suggested already, among others adding SO2 to the atmosphere. SO2 would cause cooling in the same way as large volcanic eruptions. But nobody likes that because it will have side effects, most of which are unknown and probably not pleasant either. But it may be better than uncontrolled warming if it comes to that?

[Zero999]

There have actually been some pretty desperate things suggested already, among others adding SO2 to the atmosphere. SO2 would cause cooling in the same way as large volcanic eruptions. But nobody likes that because it will have side effects, most of which are unknown and probably not pleasant either. But it may be better than uncontrolled warming if it comes to that?

A very bad idea. It would cause acid rain. Damage to trees, crops and worsen ocean acidification.

[apis]

Exactly, and probably have other unforeseen negative effects as well. Better to cut down on greenhouse gas emissions.

[G7PSK]

I have never heard this theory and it makes very little sense to me. Thatcher wanted coal to continue (without subsidy as she was a conservative and believed in the free market); but she hated the unions. Demonising coal would distract from the problem.

She decided that it would be easiest to get rid of the miners union by getting rid of the coal industry and running power plants on gas, she has been quoted as saying that if anyone can find a scientific reason not to use coal she would ensure that they got all the research funds they could want. I am not saying this from a political point of view as I supported Mrs Thatcher and still think that on the whole she was good for the country and without her we would still be subsidizing coal and cars that broke down and rusted away before you got round the M25.

[Sigmoid]

If we had as much as a 5% fluctuation in solar "output", I'm quite sure the only ones left alive on Earth would be water bears and bacteria.

Anyway, AGW has been proven over and over again. It's really, really simple. We can measure CO2 content, we can measure Methane content, we know where these gases come from, and we understand what they do in the atmosphere.

Even if the solar minimum would result in a cooling of Northern climate as it has during the "dark ages", agriculture is immensely more equipped to deal with such an event and keep producing. What we are NOT equipped to deal with is desertification, lack of fresh water and a rise of ocean levels.

Both have the potential to cause food shortage, but the latter is worse and less manageable.

[Stonent]

Even if I were to accept that, which I don't, you still have to account for other pollution. Releasing CO2 tends to be by combustion, which produces other waste that is harmful to human health and the environment more generally.

Do you have any justification for that, because without it your argument is largely irrelevant. Even if CO2 isn't a problem, the other stuff is and needs to be dealt with in basically the same way.

Well, we live longer than ever so it can't be that bad. Cheap energy on demand is good for life.

Just think what cheap energy could to for the poorest parts of the world.  I'm talking about the commercials with children drinking from the same water that cattle are being bathed in and such.

[tom66]

Not much without the infrastructure to transport it and use it.

What the poorest people in the world need is lighting, heating, cooking power. That is best provided using solar/wind and battery technology, or local diesel power, as wires and pylons built across long stretches of land are, a) likely to be robbed for copper/aluminium content and b) very expensive to build over long plains of land, and not likely to return much revenue, given the low energy usage.

[zapta]

Anyway, AGW has been proven over and over again. It's really, really simple. We can measure CO2 content, we can measure Methane content, we know where these gases come from, and we understand what they do in the atmosphere.

Sigmoid, when you say 'AGW has been proven', are you referring to a measurable CO2 increase due to human activities or the predictions of cities covered with waters, dwindling food supply and significant increase in catastrophic storms?