The time frame under reference here is 10 years or so - I am well aware that the earth has gone through ice ages and such. To define the problem more narrowly - I pick the duration to be 1991 to 2000.
assumption 1. - annual heat received from the sun to the oceans/water bodies is a constant for each of the years 1991, 92 …2000. Is this correct ?
Assumption 2. - If provided 1 is correct, on the average, equal amounts of water evaporated and formed clouds in equal measure each of these years.is this correct ?
Reasoning 3. - there is equal amount of annual global precipitation (although geographically distributed differently) in each of these years. Is this correct ?
I am not a meteorologist, but I think your error is here. I’d say that the heat received by Planet Earth is constant, but the amount that gets through the atmosphere is variable. Not by much, but enough to answer your question in the negative. On any given day, the total cloudage (is that a real word?) throughout the world could easily differ slightly from the previous day. If so, then simply by adding up random fluctuations, one year can differ from another.
Someone who knows more than I can weigh in on whether a long stretch of cloudy days is likely to create more clouds, or the reverse.
Depends on how thin you slice it, but the answer is mostly “no”. Averaged over a timespan of over a decade, the amount of sunlight directly striking the upper atmosphere of the Earth is roughly constant. Under any other interpretation of your question, though, it’s not correct. For one, the total output of the Sun varies with the solar cycle-- That’s why you have to average over the cycle (about 11 years). That’s a relatively minor point, however. Much more significantly, that sunlight, once it reaches the upper atmosphere, does not always have the same heating effect. The heating produced by sunlight depends on the cloud cover, the snow cover, and the carbon dioxide content of the atmosphere, and all of those (especially the carbon dioxide content) have changed significantly in recent history.
I was afraid this thread will go into speculation territory with CO2 and cloud cover and the like and hence chose a specific period.
Is there specific data for the years 1991 through 2000 that heat received by the oceans in one year was higher than some other year ? Or data that some years were more cloudy than the others ?
I’m tired and going to bed, but to give a quick answer to your question, assumption #1 is not true and it means that any conclusion reached using that assumption is not true as well.
There is also a basic misunderstanding about the amount of “heat” received by the oceans. Shortwave radiation like UV from the sun is virtually transparent to 99% of atmospheric gases (oxygen and nitrogen). It passes through to the land and ocean with no heat transferred. The land and ocean re-radiate as long wave radiation, which is affected by greenhouse gases and causes heating. You can’t simply discount CO2 and albedo and other factors as they are almost 100% responsible for atmospheric heat.
As a simple example, if there were a major volcanic eruption during that time (there wasn’t), that would have a huge effect on year to year radiation hitting the earth.
If an eruption occurred in 2007, the latter years of your time frame would mean the Earth would have received much less radiation and been a lot cooler than before the eruption. As an example of something that did happen recently, last year’s extensive snowfall and long-term snow coverage over much of the Northern Hemisphere meant much less radiation reaching the earth (much of it reflected straight back into space as shortwave radiation) than in years with less and shorter duration of snow cover and less ice extent in the Arctic.
The Stephan-Boltzmann Law is a good a place as any to start to learn about this process.
You don’t have to understand the math to get the gist of it.
Another complicating factor is that evaporation rate is determined by the sea surface temperature. This is related to, but not fully determined by the insolation. An obvious cyclic if somewhat unpredictable phenomenon is the Southern Oscillation - the el Nino - la Nina pair. Where one side of the Pacific is in drought, and the other side is in flooding rain, and then it swaps. It isn’t a given that the two even out. Differences in the area of heated or cooled water may mean that there is an overall bias in one direction. Other effects are also important. The North Atlantic Conveyor is responsible for warming Europe, and its bias to the sea surface temperature is responsible for more rain than you would otherwise expect. The Conveyor is showing some signs of weakening. This could drive a colder and dryer Europe, and this may even be happening.
Another, somewhat contentious, one is the sunspot cycle. The Maunder Minimum is associated with a significant change in climate. Whether this is coincidence or not is hotly debated. However there are possible causative mechanisms - with changes in upper atmosphere cloud cover driven by changes in solar wind. Right now we are seeing a very quiet sun. This may prove interesting.
A problem is that there are both positive and negative feedback mechanisms in the climate. Many are not all that well understood, and it is hard to tease them apart. But one critical thing is that the climate is driven to a very large extent by the surface conditions of the planet. It is the temperature of the top few feet of ocean, and top inch of land that matters. Effects that modify those have huge impacts on the climate. Whereas the sun is responsible for supplying the energy to heat the surface of the Earth up, there are many local effects than can dominate the critical temperatures.
Okay agree on your premise. Is there data on annual global precipitation in the years 1991 to 2000 ? Is there data on average cloud coverage for these years ? I suppose CO2 in the atmosphere for these years was fairly constant - don’t you ? I see a lot of theory here but very little data to support.
I specifically wanted to rule out such events and hence the choice of the years.
Emphasis - mine. Please quantify how much less radiation - 10% compared to 2012 or 5% or 50% ?
If it helps, I have modeled combustion characteristics with more than 200 species to predict flame characteristics, particle formation and NOx profiles. I think I have a good understanding of how different species absorb/emit thermal radiation.
This site shows that the average sea surface temperature kept within 0.5F over the period 1991 - 2000. Would you say it is still a significant contributor for this time period ?
It can’t be an exact constant, because there are several periodicities taking place that are out of synch. One example, is that what is defined by western observers as a calendar year can have a variable number of lunar-cycle events. A simple analogy is that a person paid weekly does not have a constant monthly income, because some months have four paydays and some have five.
Similarly, some years have 12 periodic lunar events, and some have 13.
If by “global warmers”, you mean “the people who are warming the globe”, then their main pretense seems to be “We can keep burning all of the fossil fuels we like and nobody can stop us”.
It is hard to say from this statistic. The numbers are a global average, so a drop in one place counters a rise somewhere else. Thus as a rough approximation, el Nino and la Nina episodes are invisible. Further it doesn’t tell us what the variation was. OTOH, the last decade does seem to be very flat, so there is some hint that things have been much more even.
One does note that 0.5F is enough to significantly change the range of tropical cyclones, which can make a big difference. This is part of the problem, some things are not linear, and especially with things like tropical cyclones, there is a sharp knee in the curve, after which different weather starts to happen. Tropical cyclones can result in insane amounts of rain, and not just locally. Here in Oz, a cyclone over the northwest can inject so much moisture into the upper atmosphere that it can flood down here in Adelaide, which is a few thousand kilometers away. Like a few days of an inch of rain each day.