Tag Archives: clouds

Cloud tipping point could yield a cataclysmic 14°C warming

Clouds could trigger a feedback effect. Stocktrek Images, Inc. / Alamy Stock Photo

Commonly 2°C has been seen as the threshold for dangerous climate change, although last year the IPCC report on 1.5°C revealed that at that lower level we enter a zone where tipping points may take us to 4°C and beyond.

Levels of 4°C threaten civilisation as we know it. At 6°C we worry about the survival of the human race. However, at that point Tapio Schneider and his team at the California Institute of Technology, Pasadena, have found that there may be a further tipping point which heats the planet another 8°C to make it 14°C above pre-industrial levels (New Scientist, so probably pay-walled.)

How is this so? Continue reading Cloud tipping point could yield a cataclysmic 14°C warming

More on cosmic rays and clouds

You will recall that we recently had a look at work done by Dr Jasper Kirkby and others in the CERN/CLOUD project.

The possible story in my words from cosmic rays to temperature change is this.

The earth is constantly being bombarded with galactic cosmic rays (GCR), high-energy particles from exploding stars. These act on tiny particles (aerosols) of sulphuric acid and ammonia molecules which cluster together to forms “seeds” called cloud condensation nuclei (CCN) from which clouds grow. Clouds are assumed to have a net cooling effect on surface temperature.

An active sun protects the Earth from GCRs to some extent. Conversely with a less active sun more cosmic rays get through. More cosmic rays mean more clouds and the cooler global temperatures.

It’s important to understand that CCNs can and do form without the assistance of GCRs, and that it is the change in GCRs operating at the margin which may or may not cause a significant change in temperature.

Every step of the way must be scientifically examined and proven. The mechanism must work, and in quantities large enough to make a difference. Continue reading More on cosmic rays and clouds

Climate clippings 43


The Scientific American reports on a paper by Andrew Dessler refuting a paper by Spencer and Braswell. Dessler’s analysis shows:

Clouds change in response to temperature changes. There is no evidence clouds can cause meaningful climate change… “Suggestions that significant revisions to mainstream climate science are required are therefore not supported,” he wrote.

In my words, the story goes Like this. Additional CO2 in the atmosphere traps additional heat from the sun, about 90% of which ends up in the ocean. The ocean is the prime driver of the world’s climate, including changes in cloud cover. There are other lesser drivers but that’s the main story.

In the alternative reality, decreased solar activity lets through more galactic cosmic rays, which increase cloud nucleation, which increase cloud cover, which changes (cools) surface temperature.

OR changes are simply due to internal variability. In any case CO2 has a minor effect and is basically irrelevant.

Skeptical Science looks at the issue here and here. In short Dessler:

found that the heating of the climate system through ocean heat transport was 20 times larger than TOA [top of the atmosphere] energy flux changes due to cloud cover over the period in question.

There’s more, with links, at Deltoid and here. Skeptical Science also has a post on denialoshere reaction and an earlier post on the net feedback from clouds. Continue reading Climate clippings 43

Climate clippings 6

These posts include a brief mention of a number of news items relating to climate change. They don’t preclude treating any of these topics at more length in a separate post.

They can also serve as an open thread so that we can keep each other informed on important climate news.

Clouds and climate sensitivity

Climate sensitivity is the temperature increase caused by a doubling of the trace gas CO2 in the atmosphere. The IPCC AR4 gave this as between 2 and 4.5 °C for short term “Charney” feedbacks, which is a large uncertainty range for such an important number. Clouds are largely to blame.

Recent research indicates less cloud cover as the sea surface warms. Thus uncertainty is taken away from the low side. Continue reading Climate clippings 6