Value chain · CLM-0936
In plain terms
The IAA's 2011 assessment says that enough solar power satellites to supply the whole world would warm the Earth by less than 0.006 degrees C. A footnote gives the full method, and redoing the sum with the source's own numbers gives 0.0062 degrees C, slightly more than the bound the sentence states. The same footnote's other figure, for a single satellite, does check out. So the method is sound and the word "less" is wrong: it should say about 0.006 degrees C.
The claim as recorded
The IAA assessment publishes an upper bound on SPS thermal forcing that its own stated method does not support, and the defect is in the word "less". Verbatim, p.100: "several thousand SPS with a total delivered power of about 15,000 GW (equivalent to the total global consumption of power circa 2005-2010) would result in less than 0.006 [degree sign]C increase to Earth's temperature". Footnote 25 on the same page supplies every input, and reproducing the calculation from those inputs gives 6.189e-3 degrees C, 3.1 per cent ABOVE the stated bound (CALC-108). The companion figure on the same page passes: a single 1.5 GW SPS reproduces at 6.189e-7 against its published "less than 0.000001 [degree sign]C". The two differ by exactly 10^4 in input and the relation is linear, so one arithmetic step produces both, and the one that passes is what shows the method was read correctly. The correct wording is "about 0.006 degrees C".
Evidence behind this: T4, taken from SRC-029's own row, because this record is a statement ABOUT that source and can be no stronger than the inputs the source states. The arithmetic is a T0 derivation and the quotation is verified first-hand, but neither raises the tier: what is being asserted is that a T4 document's stated method does not support its own stated bound, and the inputs are entirely that document's.
Scope and limits
THIS IS A ROUNDING DEFECT AND MUST NOT BE INFLATED INTO A SUBSTANTIVE ONE. 6.189e-3 rounds to 0.006 at one significant figure; the source rounded correctly and then attached "less than" to the rounded value. SRC-029's substantive point survives intact - the same sentence calls it "an extremely tiny amount compared to the aggregate thermal effects of similar power production from fossil fuels", and 0.0062 and 0.006 are the same answer for that purpose. NOTHING HERE TESTS WHETHER THE MODEL IS THE RIGHT MODEL. The footnote applies no albedo, treats intercepted flux as absorbed, and uses one global mean temperature; this record adopts all three because the object under test is the source's internal consistency. 6.189e-3 K IS NOT THIS REGISTER'S ESTIMATE OF THE EFFECT and must not be cited as one. The source itself calls the analysis "this high-level calculation" and "this first-order calculation" on the same page, and a first-order calculation is entitled to one significant figure - it is not entitled to call that figure a ceiling.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
This is the project's own working, shown in full:
Read first-hand at PDF p.100. THE PRINTED TEXT USES THE DEGREE SYMBOL AND THIS FILE IS ASCII, SO THE CHARACTER IS REPLACED BY ITS NAME IN EVERY QUOTATION ABOVE AND NOTHING ELSE IS ALTERED - the draft of this record substituted the words "degrees C" inside the quotation marks, which would have been a paraphrase presented as verbatim, and it is corrected here. Footnote 25, verbatim: "This analysis used the Stephan-Boltzmann law relating energy emitted to temperature and assumed the Earth was in energy balance, with an estimated total solar flux intercepted by Earth of 1.746 * 10^17 watts, a nominal average terrestrial temperature of 15[degree sign] Celsius and an estimated average emissivity for Earth of 0.8875." (The exponent renders as "1017" in the text layer; it is 10^17.) Reproduction in CALC-108. In energy balance, dT/T = (1/4)(dP/P), so emissivity, area and the Stefan-Boltzmann constant cancel and the result cannot be rescued by disputing them. At T = 288.15 K and P = 1.746e17 W, dP = 1.5e13 W gives 6.189e-3 and dP = 1.5e9 W gives 6.189e-7. For the 15,000 GW bound to hold as written the reference temperature would have to be 6.2 degrees C rather than the 15 stated. CALC-108 also re-derives P from the footnote's own emissivity and temperature, getting 1.7696e17 W, on which the figure is 6.106e-3 - still above the bound, so the finding does not turn on which flux is used.
Related records
- Answers question
- QST-008 not published in this release
Cite this
energyaperture.com/c/clm-0936
CLM-0936, Energy Aperture, as of 2011.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-029
- CLM-0928In 2011 an international study group said the last whole-system analysis of space solar power was done in 1997. The American National...CLM-0929A search of the 2011 international assessment finds no power-density limit set by the ionosphere, and it mentions the ionosphere only twice...CLM-0937A 2024 law review article quotes a 2011 assessment's figure for how much solar power satellites would warm the Earth. The assessment said...