#  2025 Study: Cloud Effects Reduce Downwelling Longwave Radiation, Overriding The CO2 Impact

- Link: https://climatescience.press/?p=452732
- Published: 2026-06-28T04:21:55-07:00
- Author: uwe.roland.gross

![](https://i0.wp.com/climatescience.press/wp-content/uploads/2026/06/0-ChatGPT-
2025-Study-Cloud-Effects-Reduce-Downwelling-Longwave-Radiation-Overriding-The-CO2-
Impact.png?resize=840%2C560&ssl=1)

From [NoTrickTonet](https://notrickszone.com/2026/06/26/2025-study-cloud-effects-reduce-downwelling-longwave-radiation-overriding-the-co2-impact/)

_By [Kenneth Richard](https://notrickszone.com/author/kenneth-richard/) _

#### **More observational evidence emerges showing CO2’s effects are too small to drive climate.**

The oft-cited **[Feldman et al. (2015)](https://www.nature.com/articles/nature14240)**
paper proposes to isolate the CO2 impact by only considering a “clear-sky” atmosphere
at two sites: the North Slope of Alaska and the Southern Great Plains (USA). In 
other words, that study can only claim to assess what occurs in an imaginary atmosphere
where clouds do not exist – even though clouds are present about 60-70% of the time
in the real-world atmosphere.

Results indicated that CO2 enhances the downwelling longwave radiative forcing (
DLRF) trend, the greenhouse effect, by just 0.2 W/m² per decade (accompanying a 
22 ppm CO2 increase from 2000 to 2010).

![](https://i0.wp.com/climatescience.press/wp-content/uploads/2026/06/image-285.
png?resize=840%2C573&ssl=1)

Image Source: **[Feldman et al., 2015](https://www.nature.com/articles/nature14240)**

But a **[2025 paper](https://www.nature.com/articles/s41586-024-08323-x)** quietly
published in _Nature_ also assessed the contributors to the DLRF trend from 1996-
2018 at the Southern Great Plains, even extending their measurements to all land
surfaces across the globe from 60°S to 60°N.

But instead of employing only a simulated atmosphere where clouds do not exist, 
Liu and colleagues provided the _all-sky_ values. So, unlike the Feldman paper, 
they employed the real-world atmosphere which have clouds contributing to (and dominating)
the DLRF trend.

They found observed trends in downwelling longwave show the cloud DLRF contribution
actually serves to reduce the greenhouse effect impact by -0.77 to -1.77 W/m² per
decade.

Since the CO2 contribution enhances the trend by only 0.2 W/m² per decade, clouds
therefore have been observed to easily outclass and even nullify (net) the effect
of CO2 increases.

The tiny “finger printed” (FP) decadal effect of CO2 in a real-world, all-sky atmosphere
is illustrated (red bar) in the DLRF trend (W/m² per decade) graph. Notice how insignificant
the CO2 contribution is compared to the effect of clouds (gray bar).

Perhaps this is why Feldman and colleagues chose to use an imaginary-world, clear-
sky-only atmosphere instead of a real-world, all-sky atmosphere.

![](https://i0.wp.com/climatescience.press/wp-content/uploads/2026/06/image-286.
png?resize=840%2C608&ssl=1)

Image Source: **[Liu et al. 2025](https://www.nature.com/articles/s41586-024-08323-x)**

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