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How the temperature datasets tell us extra CO2 has little effect
It came to me this morning that the trends in the surface and lower troposphere datasets contain information about the strength of the ‘enhanced greenhouse effect’ caused by the extra co2 in the atmosphere which has been building up more rapidly over the last five decades of measurement at Mauna Loa. Here are the trends since mid 2006:
The reason the satellite gathered lower troposphere trends are rising over the last six years while the surface temperature trends are falling is due to the phenomenon I first identified around five years ago by examining the sea surface, land surface and lower troposphere datasets and comparison of the Outgoing Longwave Radiation (OLR)dataset, and the solar activity dataset tells us about the rate that energy is headed back into space compared to the rate it is coming in at. I’ll go through some background for new readers, so bear with me.
One of the first things I discovered was that land surface temperatures mimic sea surface temperatures a few months later. The ocean is therefore the big dog in the Earth’s climate system not the atmosphere. It can contain as much heat in the top six feet as the entire atmosphere above it. The Sun heats the ocean because it’s rays penetrate 300 feet down into it. The ‘back radiation’ from greenhouse gases can’t directly heat the ocean because it is long wave radiation emanating from a cooler sky to a warmer sea. There is more upward radiation from the sea surface than downward from the sky. The net flux is up.
Of course the warmies say this doesn’t stop an atmosphere that has more greenhouse gases in it from slowing down the rate the ocean cools at by ‘trapping outgoing radiation’ thus making the air warmer and therefore harder for the ocean to shed heat into, and indeed this is what most of the blogging warmies think has happened. But there’s an obvious problem with their theory, which is that the amount of radiation leaving Earth’s atmosphere for space increased over the global warming period 1978-2004, rather than being increasingly trapped and partly redistributed downwards.
The logical explanation is that the diminished cloud cover (as verified by ISCCP weather satellite data and now two new ground based studies from Spain and China) over the period allowed more sunshine into the oceans, thus raising their temperature. This of course raised the temperature of the near surface air over the land as well, and so made it have a stronger differential to the coldness of space leading to faster loss. That’s why the more sophisticated explanation of how the ‘enhanced greenhouse effect’ is supposed to work fails.
In that explanation, the ‘effective altitude of emission’ rises due to the extra co2 making the atmophere more opaque to outgoing radiation, and since the higher altitude is colder, the surface has to rise in temperature to get the atmosphere to warm and emit at a higher temperature so it can lose as much energy back to space as arrives from the Sun. But the atmosphere is already at a higher temperature at a higher altitude because of the additional energy it has been soaking up from the sun via the oceans.
So this theory is back to front. The increased OLR proves that more energy from outside the system must have been getting in. Otherwise the increased OLR would mean that the system would have been cooling rather than warming. CO2 doesn’t create energy, it just slows down its transmission outwards from Earth. But since the surface warmed while OLR increased too, additional energy must have been reaching the surface from outside.
Since the Sun only varies by around 0.1% over the 11 year cycle, and increased by around the same again over the C20th, it’s additional output must be amplified by changes in cloud cover, and this is indeed what prof. Nir Shaviv of Tel Aviv university found in his study on using the oceans as a calorimeter to measure the effect of increased insolation at the surface. His findings were published in a paper at the Journal of Geophysical Research, but you can read it for free here:
http://sciencebits.com/calorimeter
The increase in OLR proves that this must have had a bigger effect than an increase in co2 can have, and so less cloud and more sunshine must be the majority cause of the warming we saw in the late C20th. That this is so is also backed up by studies which compare changes in sunshine hours to changes in surface temperature. The correlation is much closer than that between temperature and co2 levels.
But things have changed. The ISCCP weather satellites have measured an increase in cloud since the turn of the millennium and this is confirmed by another method of measuring how much sunlight is being reflected back into space. The Earthshine project measures the brightness of the light being reflected by the Earth onto the moon’s surface, and this has increased over the same period, showing that more sunlight is being reflected away before it can get to the surface.
So what has all this got to do with why it is that the lower troposphere temperature has increased over the last 6.5 years while the surface air temperature has fallen?
Since the sun went quiet and cloud cover consequently increased again, not as much sunshine has got into the oceans, and consequently they have started cooling slightly since 2004. This makes the sea surface has cool down, and since land surface temperatures mimic what the sea surface does a few months later, they have cooled too. But the lower troposphere higher up above the ground has warmed, because the excess energy stored in the oceans while the sun was very active and cloud diminished between 1975 and 2004 is now being emitted back out, warming the atmosphere at cloud level, and from there heading out to space.
But how come this energy being emitted into the atmosphere from the oceans isn’t being trapped by the extra co2 and then re-radiated back down to the surface and warming it up?
The answer is that it is trying its best, but the effect is much less powerful in relation to the effect of a more active sun in the warming period and a less active sun now, than the warmist theoreticians believed. This is because they didn’t take into account the effect of the active sun causing diminishing cloud cover, and so the sea surface and ground is cooling and the heat is escaping back to space now the sun has become much less active, but is keeping the troposphere at cloud level warm on its way.
Solar cycle 24 is very low, even though it should be near maximum now, and if the methods the talkshop research team has developed for predicting solar activity are correct, then solar cycle 25 won’t be any stronger.
And that’s the memo, as our dear friend Luboš Motl will, I hope, be saying for many years to come.
2012-09-21 01:40:36
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