So when global temperatures failed to behave as models expected due to inevitable but hard to predict natural variation, they were forced to re-think – or just think? The GWPF concludes, at the risk of stating the obvious: ‘The lesson of the hiatus is that we do not understand internal climatic variability as much as many think we do, and our predictive power is less than many believe.’
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Researchers from the Universities of Princeton, California, Tokyo, Kyushu and the Scripps Institution of Oceanography, say the recent hiatus in global temperature increase has led to a surge in climate science.
The global effort to understand the global warming hiatus they say has led to increased understanding of some of the key metrics of global climate change such as global temperature and ice-cover.
Searching for an answer to the hiatus, they say, meant that the scientific community grappled with difficulties with these climate metrics, in particular the fact that they do not unequivocally portray the same story about global warming.
For instance, as the global surface temperature increase underwent an apparent slowdown, Antarctic sea ice expanded, and boreal summer Arctic sea ice declined rapidly, at least until 2007. Hot and cold extremes increased in northern hemisphere continents, and the Hadley circulation shifted poleward.
Many of the changes are not ones expected due to increasing greenhouse gas forcing. For some this called into question the viability of computer models of the climate and whether these changes indicated a fundamental lack in our understanding and ability to simulate radiatively forced changes, or indeed if internal climate variability alone is sufficient to explain the changes.
The researchers point out that since the hiatus was identified just over a decade ago it stimulated advances in our understanding of the multidecadal variability of these key metrics, providing insight into internal climate variability.
As well as drawing attention to biases in the temperature record it has also improved our understanding of the role of the tropical Pacific Ocean in mean global temperature.
Despite the research progress many challenges remain, especially due to the relatively short timescale of the observations.
There are also limitations of climate models in simulating internal, multidecadal climate variability and the way radiatively forced changes interact with that inherent variability.
Continued here.
via Tallbloke’s Talkshop
June 7, 2020 at 04:39AM
Iowa Climate Science Education 