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OKIsItJustMe

(19,937 posts)
Mon Feb 2, 2015, 09:35 PM Feb 2015

Global warming slowdown: No systematic errors in climate models

Last edited Mon Feb 2, 2015, 10:27 PM - Edit history (1)

http://www.mpg.de/8925360/climate-change-global-warming-slowdown
[font face=Serif][font size=5]Global warming slowdown: No systematic errors in climate models[/font]

[font size=4]The rate of global warming in the 21st century has been significantly slower than all the models had predicted. Evidently, this was merely due to random variations.[/font]

January 30, 2015

[font size=3]Sceptics who still doubt anthropogenic climate change have now been stripped of one of their last-ditch arguments: It is true that there has been a warming hiatus and that the surface of the earth has warmed up much less rapidly since the turn of the millennium than all the relevant climate models had predicted. However, the gap between the calculated and measured warming is not due to systematic errors of the models, as the sceptics had suspected, but because there are always random fluctuations in the Earth’s climate. Recently, Jochem Marotzke, Director at the Max Planck Institute for Meteorology in Hamburg, and Piers M. Forster, a professor at the University of Leeds in the UK, have impressively demonstrated this by means of a comprehensive statistical analysis. They also clearly showed that the models do not generally overestimate man-made climate change. Global warming is therefore highly likely to reach critical proportions by the end of the century - if the global community does not finally get to grips with the problem.

Climate is subject to chance and chaos - which makes life difficult for climate researchers. No wonder that these two unpredictable climate factors lie at the root of a mystery that has baffled scientists since the start of the 21st century. Since then, the temperature of the Earth’s surface has increased by only around 0.06 degrees Celsius – much less than had been predicted by all 114 model simulations considered in the climate report by the IPCC. Jochem Marotzke and Piers M. Forster have now explained the warming pause in terms of random fluctuations arising from chaotic processes in the climate system. Even more importantly for the two researchers and their colleagues around the world: they did not find any conceptual errors in the models. Most notably, the models do not generally react too sensitively to increases in atmospheric carbon dioxide.

“The claim that climate models systematically overestimate global warming caused by rising greenhouse gas concentrations is wrong,” says Jochem Marotzke. Climate sceptics often make precisely this claim, citing the warming pause as evidence. Yet they cannot deny that nine of the ten warmest years since systematic climate observations began have occurred in the new millennium and that global warming has slowed at a very high level. The sceptics also ignore the fact that ocean temperatures continue to rise as rapidly as many models have predicted.

“On the whole, the simulated trends agreed well with the observations”

…[/font][/font]
http://dx.doi.org/10.1038/nature14117
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Global warming slowdown: No systematic errors in climate models (Original Post) OKIsItJustMe Feb 2015 OP
I'm not sure I understand what's being said here pscot Feb 2015 #1
“The rate of global warming in the 21st century has been significantly slower…” OKIsItJustMe Feb 2015 #2
I have another question pscot Feb 2015 #3
I think that's a coincidence caraher Feb 2015 #4

pscot

(21,024 posts)
1. I'm not sure I understand what's being said here
Mon Feb 2, 2015, 10:52 PM
Feb 2015

On the one hand,

The rate of global warming in the 21st century has been significantly slower than all the models had predicted
.

On the other hand,
On the whole, the simulated trends agreed well with the observations”


The two statements seem contradictory.

OKIsItJustMe

(19,937 posts)
2. “The rate of global warming in the 21st century has been significantly slower…”
Mon Feb 2, 2015, 10:59 PM
Feb 2015

“Evidently, this was merely due to random variations.”

“Climate is subject to chance and chaos…”

pscot

(21,024 posts)
3. I have another question
Wed Feb 4, 2015, 08:04 PM
Feb 2015

What are the 114 models mentioned here? I take that to refer to the simulations run in the course of the study, rather than the climate models used by the IPCC to track climate variations. There are 114 possible discrete, 15 year segments between 1900 and 2014, and these were analyzed using the IPCC models. Is that your understanding also?

caraher

(6,278 posts)
4. I think that's a coincidence
Wed Feb 4, 2015, 09:54 PM
Feb 2015

The writing is pretty clear in saying there are 114 climate models used in compiling the IPCC report. "For each year between 1900 and 2012 they considered the temperature trend that each of the 114 available models predicted for the subsequent 15 years." So they started with the year 1900, then predicted the 15 years with each of 114 models. Next, do it for 1901, etc.

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