New study: Cooling cloud cycle caused global warming hiatus

Is this how it works? [image credit:]

An obvious problem with studies like this is that as soon as natural climate variation is invoked – to explain the lack of expected warming from so-called greenhouse gases – the argument that such gases could be a dominant factor in climate processes is then severely weakened to say the least. It is in effect an admission that such variations could cause warming as well as cooling. How long can a ‘hiatus’ last before it becomes the status quo?

Reinforcement of Climate Hiatus by Decadal Modulation of Daily Cloud Cycle
– By Jun Yin and Amilcare Porporato, Princeton University

Based on observations and climate model results, it has been suggested that the recent slowdown of global warming trends (climate hiatus), which took place in the early 2000s, might be due to enhanced ocean heat uptake.

Here we suggest an alternative hypothesis which, at least in part, would relate such slowdown to unaccounted energy reflected or re-emitted by clouds.

We show that the daily cloud cycle is strongly linked to pacific decadal oscillation (PDO) and that its decadal variations during the climate hiatus have an overall cooling effect. Such an effect may have partially, and temporarily, counteracted the greenhouse warming trends.

The slowdown of global warming in the early 21th century, referred to as the climate hiatus, raises growing political and public concerns. Observations and climate modelling results suggest that such a phenomenon is caused by the compounding effects of inter-annual and decadal variations of ocean circulation, aerosols, volcanic eruptions, and variation of solar irradiance.

While enhanced ocean heat uptake is regarded as one of its primary causes of the recent climate hiatus, there are still debates over which parts and depths of the ocean may be responsible for absorbing the imbalanced energy.

Such uncertainties stem in part from the temporal interpolation method used for satellite calibration and the sparse spatial/temporal sampling of the ocean heat content measurement.

It is thus logical to wonder whether the estimation of Earth’s energy balance might have missed some energy component linked to the finer temporal resolutions (e.g. sub-daily timescale).

Continued here.

via Tallbloke’s Talkshop

March 10, 2018 at 04:00AM

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