Friday, December 13, 2024

Earth's Albedo is Decreasing Due to Fewer Low Clouds

This is from a paper in Science last week, "Recent global temperature surge intensified by record-low planetary albedo," Goessling et al, Science 6-Dec-2024. [Link

I can only make this chart so big, so expand it if you want a bigger picture. Same since Blogger insists on publishing fuzzy pictures (for me anyway). 

Top graph A is surface temperature; the relevant graph as a cause is the bottom graph F, low cloud cover, and to a lesser extent total cloud cover E. The units for both E and F are percentages relative to 2001-2022 (viz., the entire interval).

Then in Table 1 (below) they give their numbers: among them, the planetary albedo (reflectance) has decreased by about -0.4% (negative change => smaller albedo => less reflectance of sunlight => warmer temperature). What's causing reduced lower cloud cover? 

"Utilizing satellite and reanalysis data, we identify a record-low planetary albedo as the primary factor bridging this gap. The decline is apparently caused largely by a reduced low-cloud cover in the northern mid-latitudes and tropics, in continuation of a multi-annual trend. Further exploring the low-cloud trend and understanding how much of it is due to internal variability, reduced aerosol concentrations, or a possibly emerging low-cloud feedback will be crucial for assessing the current and expected future warming."

So if the planetary albedo was the canonical 0.30 (30% reflectance), it is now 0.2988. (Round that however you like.) Not much, but enough to matter.

3 comments:

Entropic man said...

Lots of discussion regarding the 2023/2024 temperature surge.

Here for example.

https://www.realclimate.org/index.php/archives/2024/12/nature-2023-part-ii/

Be interesting to read the report on the ABU meeting last Tuesday.

David Appell said...

Thanks. I got that link in an email, and placed it in the "read in a day or two" category. It's been there for over a week. Thanks for the reminder.

Layzej said...

So much for an iris effect.