Experiment Debunks Climate Claims of Greenhouse Effect ‘Back Radiation’
Observations on ‘Backradiation’ during Nighttime and Daytime (Nahle, 2011) presents a series of nighttime and daytime measurements using infrared thermometers and radiometers, concluding that the “greenhouse effect” from back radiation is physically impossible.
The published experiments of Professor Nasif Nahle of Monterrey, Mexico show that:
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Cooler objects cannot warm warmer objects – This would violate the second law of thermodynamics.
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Radiometers pointed at the sky are not measuring “backradiation” – Instead, they detect thermal radiation from rising globules of hot air, clouds (cirrus, stratus), water vapor, and dust particles at various altitudes.
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The atmosphere’s temperature follows the surface – Not the other way around. His measurements show atmospheric radiation decreasing as surface radiation decreases during the night.
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Earth’s actual average surface temperature is ~24°C – Not the -18°C derived from greenhouse effect calculations.
Key Measurements from the Experiment
| Time | Surface Radiation | Atmospheric Radiation |
|---|---|---|
| Night (21:00) | 308.2 W/m² | 61.93 W/m² |
| Night (04:00) | 280 W/m² | 46.48 W/m² |
| Day (16:00) | 336 W/m² | 65.96 W/m² |
The surface consistently emits far more radiation than the atmosphere returns.
The Experiment’s Key Points
The core observation is simple and intuitive: When you point an infrared thermometer at the sky, you’re measuring the temperature of whatever is in its field of view – clouds, water vapor, dust, or rising warm air. You are not measuring some mysterious “backradiation” from the entire atmosphere.
The experiment shows a consistent pattern: The ground is always warmer than the air above it, and it loses heat throughout the night. The atmosphere cools faster than the ground. At no point does the cooler atmosphere appear to transfer heat back to the warmer ground in a way that would warm it further.
The author’s key insight: The instruments commonly used to claim “backradiation” measurements are actually detecting thermal radiation from specific atmospheric features (clouds, temperature inversions, rising air parcels) – not a uniform downward flow of energy from cooler to warmer.
The theoretical argument: The paper argues that climate models incorrectly average solar input twice, leading to inflated atmospheric temperature requirements that don’t match observations. The author contends that actual measurements show Earth’s surface absorbs about 535 W/m² during daylight, consistent with a ~24°C average surface temperature – not the -18°C that greenhouse theory predicts without the effect.
The Bottom Line
Nahle’s paper offers a straightforward, observation-based challenge to greenhouse theory. Its strength lies in its simplicity: direct measurements showing that the ground is always warmer than the sky, and that instruments detect specific atmospheric features rather than a uniform “backradiation.” For skeptics, it provides a physically intuitive argument that aligns with everyday experience – the atmosphere feels cooler than the ground, and cool things don’t warm warm things.
How the Experiment Was Done
Nahle’s paper follows a clear structure: he sets up theoretical objections, then presents experimental measurements, then interprets the results. Here’s how he builds his case:
1. He Attacks the Calculation Methods First
Before any experiment, Nahle argues that climate scientists make specific mathematical errors:
The “double averaging” problem: He claims scientists take satellite measurements of solar radiation (already an average along Earth’s orbital path) and then divide by 4 again to account for day/night. He says this is physically meaningless because the original measurement is already an average.
The result of this error: He argues this produces an artificially low solar input figure (~340 W/m² instead of the actual ~1000 W/m² during daylight), which then requires an invented “greenhouse effect” to balance the energy budget.
The atmosphere’s emissivity problem: He states that air’s actual total emittance is about 0.201 (measured), but climate models treat the atmosphere as if it emits 5.7 times more than a blackbody would – which he calls physically impossible.
2. He Redefines What the Instruments Measure
Nahle’s central experimental claim is about instrument interpretation:
What climate science argues: Pyrgeometers and infrared thermometers pointed at the sky measure downward longwave radiation from the atmosphere – the “backradiation” that allegedly warms the surface.
What Nahle says they actually measure: The instruments have a cone-shaped field of view extending upward. They detect thermal radiation from whatever is in that cone – which includes:
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Rising globules of warm air (thermals)
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Cirrus and stratus clouds at 6+ km altitude
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Water vapor and dust particles
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Temperature inversions (where upper air is warmer than lower air)
He argues these are discrete, localized sources – not a uniform atmospheric “glow” returning energy to the surface.
3. He Uses Nighttime Cooling as His Key Evidence
The experiment tracks radiation every hour from 21:00 to 04:00:
The pattern he documents:
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Surface radiation decreases steadily: 308 W/m² → 280 W/m² (about 4 W/m² per hour)
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Atmospheric radiation also decreases: 62 W/m² → 46 W/m²
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The atmosphere cools faster than the surface (ΔT of 19 K vs 7 K over the night)
His interpretation: If the atmosphere were really “backradiating” energy to warm the surface, we’d expect the surface cooling to slow down or reverse. Instead, both cool together, with the atmosphere always lagging behind the surface temperature. The surface drives the atmosphere’s temperature – not the reverse.
4. He Invokes the Second Law of Thermodynamics
This is his theoretical anchor:
The claim: Heat flows spontaneously only from hotter to cooler objects. A cooler atmosphere (say, -1.6°C equivalent temperature) cannot transfer net heat to a warmer surface (say, 23.7°C).
His extension: Even if individual photons can travel both directions, the net energy flow must be from warm to cold. He argues that “backradiation” as described by greenhouse theory would require the cooler atmosphere to warm the warmer surface – which he calls a violation of fundamental thermodynamics.
5. He Calculates What “Backradiation” Would Require
Nahle works backward from the claimed greenhouse effect:
His calculation: If the surface absorbs 160 W/m² from the atmosphere (a typical greenhouse budget figure), and the atmosphere’s actual emissivity is 0.201, then the atmosphere would need to be at 143°C to emit that much radiation.
His conclusion: Since the atmosphere is nowhere near 143°C, the claimed backradiation is physically impossible. He says the “greenhouse effect” is an invented process to make incorrect energy budget calculations balance.
6. He Offers an Alternative Explanation
Instead of backradiation, Nahle proposes:
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The surface absorbs solar energy during the day
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It stores some as heat and transfers the rest to the atmosphere via convection, conduction, and radiation
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The atmosphere carries this energy upward and eventually to space
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The surface temperature is determined by solar input and surface properties (absorptivity ~0.7)
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The atmosphere’s temperature follows the surface, not the other way around
7. He Addresses the “But It’s Cold at Night” Objection
His explanation for why surfaces cool at night: The surface radiates to space (which is at ~3 K) and to the atmosphere (which is cooler than the surface). The atmosphere itself cools by radiating to space. There’s no need for “backradiation” to explain nighttime cooling – the surface simply loses energy to colder surroundings.
Summary of His Method
| Step | What Nahle Does |
|---|---|
| 1 | Identifies mathematical errors in climate calculations |
| 2 | Redefines what instruments actually measure |
| 3 | Conducts direct nighttime/daytime measurements |
| 4 | Shows surface and atmosphere cool together, not in a warming feedback loop |
| 5 | Invokes thermodynamics (2nd law) as the theoretical foundation |
| 6 | Calculates that claimed backradiation would require impossible atmospheric temperatures |
| 7 | Offers an alternative: surface heats atmosphere, atmosphere carries heat away |
The author’s approach is essentially: “The instruments don’t measure what you think they measure, the math is wrong, and the physics violates basic thermodynamics. Here’s what’s actually happening.”
Professor Nasif Nahle has mathematically assessed the rate at which heat is retained by CO2 molecules; his work was endorsed by the Faculty of Physics of the University of Nuevo Leon (Mexico).
Nahle found the “mean free path” for a quantum wave to pass through the atmosphere before colliding with a CO2 molecule is about 33 meters. Such a wide chasm between molecular collisions would appear to undermine a visualization of CO2 functioning like a blanket does.
Even more saliently, Nahle determined that the rate at which CO2 molecules can retain heat at the surface may only last about 0.0001 of a second.
If heat-loss is slowed down at a rate of 0.0001 of a second by CO2 molecules, the atmospheric CO2 concentration – whether it’s 300 ppm or 400 ppm – effectively doesn’t matter. The time lapse differential would be immaterial for either concentration.
Consequently, Nahle concludes “carbon dioxide has not an effect on climate changes or warming periods on the Earth”.