Natural warming is much stronger than CO2, natural warming and cooling overshadows CO2 to the point that it is hard to see where the CO2 warming is.
This is a mute question at best considering that the absorptivity/ emissivity thermal property of carbon dioxide diminishes as its density increases and as the temperature increases. This happens because the infrared radiation absorption margin is very narrow (wavelengths from 12-18 micrometers) and so the opacity of carbon dioxide to infrared radiation increases with altitude. As atmospheric CO2 increases and the column of CO2 gains height, its opacity to infrared radiation increases. So, it has less effect. When the concentration of atmospheric carbon dioxide increases, the strong absorption lines become saturated. Thereafter its absorptivity increases logarithmically not linearly or exponentially; consequently, carbon dioxide convective heat transfer capacity decreases considerably. Warming is still occurring, but future increases will have considerably less effect.
The only natural cooling of the Earth is radiation. Radiation is what CO2 blocks. When the CO2 stabilizes, the natural cooling will equalize that decreased radiation when the Earth reaches a higher temperature, one high enough to radiate through the CO2.
More resistance to cooling requires a higher temperature to balance the incoming radiation from the Sun.
There are dozens of inputs into world climate change and many more sub inputs associated with the main drivers. At this point most of the drivers tend toward a gradual cooling over geological time... hundreds of thousands or millions of years. Today the rapid increase in CO2 from burning fossil fuels over a very short 'historical' time period... less than 200 years since the beginning of the Industrial Age has trumped most of the factors that could be construed to cause 'cooling'.
Some folks keep mentioning that forty or more years ago some people felt that a cooling trend was in the works given the data they had at the time. Back then the CO2 index hadn't been well researched out....climate research only began during the International Geophysical Year in 1958. Since then millions of data points on this subject have been gathered and the data indicates that the planet is gradually retaining more heat than it manages to radiate into space in any given 24 hour period. While the rate of retention is small, it's growing and it accumulates
It's not a matter of 'belief', it's a matter of understanding the data, the physics, the math and the science.
It's a matter of the stable states in the climate. From geologic records, we know there are three stable states. The ice age which we're in now, the warm Earth where no land or sea ice would exist and snowball earth. The ice age is the least stable of the three, the top of the hill between two valleys. Our contributions to CO2 are small but it is pushing the boulder towards the slope towards the warm earth, if the boulder should start rolling down that slope, it would take far more effort than the gentle pushing we have done to stop it. Natural cooling would be on the other slope.
11/28/2012 Global Warming ended/ confirmed= all non solids like co2, exhaust, smoke, gases that rise into the upper atmosphere separate into nothingness so the suns rays can warm earth as earth rotates to grow plants that yield food and oxygen so all species can survive. Mike
Pay no attention to Ian. He is an idiot.
Except for the Milankovich cycles, which can only cause 0.1C per century warming and only a 0.01C per century cooling, most natural cycles, such as ENSO, PDO, sunspots and volcanoes only have short term warming and cooling effects.
Recent warming was not caused by the Sun or by PDO.
http://www.woodfortrees.org/plot/gistemp...
In a pronounced spell of natural warming, such as that associated with some of the oceanic oscillations, we could see temperatures change by about 0.1°C per decade. If several warming influences combine together we would see changes as much as 0.15°C. The cooling influences are of the same magnitude.
Warming from increased greenhouse gas concentrations is approx 0.15 to 0.20°C, the peak we reached in the 90’s was 0.177°C.
If we have manmade warming equivalent to +0.15°C occurring when cooling is –0.15°C then there will be no net change in temperatures. If the warming continues and the natural cycles switch to positive then we could gave warming in the order 0f 0.3°C.
This is essentially what’s happened for the last 100+ years – since manmade warming took off.
The rise in temps isn’t a steady year on year increase, more that it happens in upward steps. At the moment temps are level because natural processes are cancelling the manmade warming. At some stage within the next few years the natural cycles will switch to positive and we’ll take another upward step.
At the moment the main cooling influences are a negative Pacific Decadal Oscillation, this has a pronounced impact on temps and now appears to be in transition from negative to positive.
In addition there’s something termed the Asian Brown Cloud. The booming Asian economies are releasing huge amounts of pollution, just as we used to do decades ago. Among these pollutants are high levels of sulphates and black particulate matter. The sulphates, particularly sulphur dioxide, induces cooling as it’s reflective to incoming solar radiation, the BPM absorbs solar radiation and collectively they reduce the amount of heat energy we receive from the Sun. Quite how much cooling this is causing is hard to say, it’s probably no more than 0.05°C per decade.
Another unknown is the enhanced heat flow from the atmosphere to the oceans. The heat content of the oceans has very significantly increased in recent years, a lot of heat is being lost from the atmosphere.
Total Solar Irradiance (TSI) is a measure of heat energy from the Sun, this has declined very slightly since the 1970’s and will also be inducing cooling, perhaps in the order of 0.01°C per decade.
Unusually, a lot of the natural variations are in their negative phases at the same time (AMO being the notable exception). If we take manmade warming out of the equation then we should be seeing a very pronounced level of cooling, probably of around 0.2°C per decade. In time of course, the natural oscillations and cycles will switch phases and there will be a cooling influence, over several decades the cooling and warming will cancel each other out, leaving behind the manmade warming signal.
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RE: YOUR ADDED DETAILS
For all intents and purposes Earth only has one source of heat energy – the Sun. We get tiny amount of heat from tidal friction, radioactive decay, geothermal sources, direct heating etc; together these account for just 0.03%, the other 99.97% of heat within the Earth system originates from the Sun.
We have observed that the Earth is warming, this can only happen for one of two reasons. Either there is more heat entering the system or there is less heat escaping from it (or it could be a bit of both).
We can measure the flow of energy both into and out of the Earth system. This is achieved from satellite measurements at the edge of space, more specifically it’s the energy transfer across a plane perpendicular to Earth’s surface at an altitude of 100,000 metres.
What we’ve seen since the 1970’s is a very slight decline in total solar irradiance (about 0.1W/m2, the mean is 1363W/m2). At the same time there has been an observed decrease in energy leaving the system, this equates to an equivalence of 0.8W/m2 at ground level.
There’s no more heat entering the system, but less is leaving it. It’s no surprise of course that it’s the greenhouse gases that are trapping heat energy as it tries to escape from Earth into space.
We therefore need to look close to home to see what’s happening. Could there be natural cycles here on Earth that cause warming or cooling?
There are in fact numerous of them, a lot have to do with the way that heat circulates within oceanic and atmospheric cycles and how heat is exchanged between the two media.
Some of the cycles are quite apparent and people have known about them for centuries, others are less obvious, undoubtedly some remain undiscovered.
Most of these oscillations have little impact on climates, they are too short lived and of such magnitude as to be ineffective. Being cyclical means they have positive and negative phases which, over the course of a full cycle, cancel each other out.
What we would need to find is a strong oscillation that lasts for many decades. There is only one and that’s the Pacific Decadal Oscillation or PDO. The cycle takes about 60 years and it can cause warming or cooling in the order of 0.1°C to 0.15°C per decade.
Unfortunately the phases of the PDO do not correlate with changes in temperature. The PDO amplifies and attenuates periods of warming but doesn’t change the underlying trend.
Again, it’s cyclical so the phases balance. If the PDO were to blame for warming then we’d see approx 30 years of warming followed by 30 years of cooling. This isn’t happening.
What we see instead is that warming slows or stops during the negative phase, then takes off again during the positive phase. This means the ave global temp is going up in a series of steps.
Also, do bear in mind that if it were natural cycles then it means the greenhouse effect has to fail and if that were the case then Earth would have no mechanism for retaining heat and it would have an average temperature of –18°C.
Another thing to remember is that the greenhouse effect and the role of greenhouse gases is no great mystery; it can be demonstrated in just about any science lab. It’s irrefutable that more greenhouse gases leads to more warming. There will be natural influences along the way but the underlying trend will always be an upward one, and this is what we’re observing in the real world.
Any alarmist can tell you that a cooling trend is always natural and warming is always due to man made C02 emissions.
Then why can't natural warming be as strong as CO2 warming?
