Clouds played an important role in the history of climate, say researchers

Posted: June 14, 2022 by oldbrew in climate, Clouds, Ice ages, modelling, research, Uncertainty
Tags:

Cumuliform cloudscape over Swifts Creek, Australia
[image credit: Wikipedia]


Looking into the past and future of climatic conditions on computer models can give somewhat cloudy results, at least partly because “there’s considerable uncertainty about the simulation of clouds in global climate models”.
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Were Earth’s oceans completely covered by ice during the Cryogenian period, about 700 million years ago, or was there an ice-free belt of open water around the equator where sponges and other forms of life could survive?

Using global climate models, a team of researchers from Karlsruhe Institute of Technology (KIT) and the University of Vienna has shown that a climate allowing a waterbelt is unlikely and thus cannot reliably explain the survival of life during the Cryogenian, says Phys.org.

The reason is the uncertain impact of clouds on the epoch’s climate.

The team has presented the results of its study in the journal Nature Geoscience.

Viewed from space, Earth may have looked like a giant snowball during the global ice ages of the Cryogenian period. In the geosciences, this hypothesis that the oceans were completely frozen over has become established as the Snowball Earth theory.

But it’s still not clear how sponges, which are found in the fossil record, were able to survive in the very cold Snowball Earth climate. To explain that, some scientists have proposed the alternative theory of an ice-free equatorial waterbelt.

Life in spite of oceans that were probably icebound

Working with colleagues from the University of Vienna, researchers at KIT used global climate models and an idealized energy balance model to investigate Cryogenian climatic conditions. They expected to find a waterbelt in their simulation scenarios and wanted to investigate the conditions under which it would remain stable.

“We were surprised to find that this state wasn’t stable in the models,” says Christoph Braun from KIT’s Institute of Meteorology and Climate Research—Department Troposphere Research (IMK-TRO). This means life during the Cryogenian was probably subject to the harsh evolutionary conditions of globally icebound oceans.

The study resulted in new insights into the role played by clouds. “Clouds reflect radiation, and that’s important for the stability of a waterbelt. This strong influence was unknown until now,” says Braun, a Ph.D. student and lead author of the study.

With the cloud reflectivity mechanism proposed in the paper, the results of previous studies could be reinterpreted and possibly combined to yield a more coherent picture.

Clouds complicate our view of past climate

“With the global climate models and an idealized climate budget model, we can show the effects of cloud reflectivity and explain the underlying processes,” says Braun. “But that doesn’t enable us to assess how reflective clouds were in the Cryogenian, because there’s considerable uncertainty about the simulation of clouds in global climate models.”

The efficiency with which water droplets are converted into ice is crucial to reflectivity and depends in part on the type and amount of aerosols that can act as ice nuclei. These processes play out on scales of millimeters, while the computational grids used in the models thus far have scales on the order of more than 100 kilometers.

The results show that clouds are crucial to the prediction of climate changes and to our understanding of the dynamics of glaciation over geological time. “Clouds don’t just make it harder for us to see into the future, but also to look back into the past,” says Braun.

Full article here.

Comments
  1. […] Clouds played an important role in the history of climate, say researchers […]

  2. The modellers are beginning to inch slowly forward.

  3. catweazle666 says:

    “Clouds complicate our view of past climate”

    Heh, you don’t say!
    And present climate too, of course.

  4. stpaulchuck says:

    my Magic 8 Ball says, “Future Is Cloudy”

  5. Phoenix44 says:

    If we don’t know how climate works we don’t know much about climate modelers admit.

  6. Ned Nikolov, Ph.D. says:

    This paper by Braun et al. (2022: https://www.nature.com/articles/s41561-022-00950-1) like so many other papers before is trying to find an answer about Earth’s deep-past climate using faulty computer models running on CO2 “radiative forcing” that cannot even reproduce current climate conditions.

    The authors a-priori assume that the cloud albedo is a free parameter of the climate system that can be manipulated as needed to achieve a satisfactory outcome. This assumption is fundamentally wrong, because most of the cloud albedo is a byproduct of the energy in the climate system, and only a small portion of it can be influenced by external forcing such as Sun’s magnetic field or the solar wind. Here is a video that explains the role of albedo in climate based on empirical evidence, not “theory”:

  7. Chaswarnertoo says:

    No sh1 t Sherlock. And aren’t modelled.

  8. oldbrew says:

    More cloud conundrums…

    Uncertainties in Evaluating Global Electric Circuit Interactions With Atmospheric Clouds and Aerosols, and Consequences for Radiation and Dynamics
    Brian A. Tinsley
    First published: 21 February 2022

    Key Points
    Observations showing day-to-day correlations of clouds and surface pressure with electrical inputs from the solar wind and thunderstorms, are reviewed and updated

    Uncertainties in evaluating the agreement with a mechanism for electric charge effects on cloud microphysics are identified

    The effects are small, but may be more important for decadal variations, and as a neglected process in cloud microphysics

    https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2021JD035954

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