Climate models fail to replicate tipping points

[Nederland]

An article in Nature Geoscience argues that current climate models are incapable of modeling the rapid changes in climate that Earth has seen in the past. This deficiency casts doubt on whether they can accurately model future tipping points.

<snip>

Critical thresholds may be inherent to the climate system. If so, they could lead to abrupt, and perhaps irreversible, changes to the Earth system. This possibility has caught the imagination of the public — often under the emotive term 'tipping points' — and has led to a huge growth in media and scientific publications on the topic in the past few years. If we are about to cross such a critical threshold, the implications for climate adaptation strategies could be significant. Likewise, knowledge of thresholds would have a strong influence on mitigation policy, not least by helping to define the meaning of the term 'dangerous climate change'.

Yet it is less clear exactly how such critical thresholds should be defined, whether they even exist and, if so, whether we are close to one. Expert elicitation is subjective. And attempts to identify early signals of catastrophic change with a variety of nonlinear system techniques are, in practice, unlikely to provide warning with sufficient lead times. Climate model simulations are the only other means for gaining advance knowledge of sudden climate change. It is therefore crucial to assess whether the available models are capable of investigating these phenomena.

I argue that climate models of the current generation, as used in the latest assessment of the Intergovernmental Panel on Climate Change (IPCC), have not proved their ability to simulate abrupt change when a critical threshold is crossed. I discuss four well-documented examples of past rapid climate change (Box 1). In two cases, the models did not adequately capture the basic climate configuration before abrupt change ensued, and in the remaining two examples, to initiate abrupt change the models needed external nudging that is up to ten times stronger than reconstructed. The models seem to be too stable.

<snip>


http://www.nature.com/ngeo/journal/v4/n7/pdf/ngeo1200.pdf

[HopeHoops]

1. Who is this "climate model" and does she pose nude?

:hide:

[dreamnightwind]

2. She's Mother Nature, of course

Few who see her naked live to tell, so careful what you wish for.

Interesting OP. I'll read the Nature article later. Somewhat scary that there may be tipping points that our climate change models can't foresee.

[pscot]

3. This doesn't sound like it's a good thing

Disaster could be on us before we know it.

[GliderGuider]

4. What was that noise???

:scared:

[pscot]

6. Don't you just love to be

surprised? :party:

[NickB79]

5. So, the climate models we're using are too conservative in their predictions?

That has dire implications for our current estimates of where global climate will shift over the next century. Hello worst-case scenarios!

[Nederland]

7. No

It simply means that we don't know. They could be over predicting temperature increases, they could be under predicting increases. The only thing that we do know is that they do not model climate correctly.

I would argue that this proves that we do not understand climate nearly as well as those who for years have been telling us "the science is settled". It is not settled, not even close. We know that CO2 is a greenhouse gas and we know its concentration in the atmosphere is increasing. However, despite the complete fixation on CO2, it is not the only factor. There are dozens of other factors involved, some of them much more important than CO2, and we are not even close to understanding how they all interact with each other. Our understanding of the planet's climate is in its mere infancy. The simple fact is this study proves that the models the IPCC has been using to make its case are missing some pretty fundamental components of climate and are in fact irreparably broken. Making policy decisions and pushing a radical restructuring of the global economy based upon computer models we know are broken is just plain dumb.

[GliderGuider]

8. Don't worry, nobody's going to undertake a radical restructuring of the global economy.

Or even a minor restructuring for that matter. We'll put in some curly lightbulbs, close some reactors, build a few windmills, slap each other on the back and go out for an organic microbrew. It doesn't matter if the science is right, wrong or undecided - it's going to be BAU all the way to the edge of the cliff no matter what.

Happy now?

[bananas]

9. From the article: "If anything, the models are underestimating change"

I don't think this article says what you think it says.

If anything, the models are underestimating
change, compared with the geological
record. According to the evidence from the
past, the Earth’s climate is sensitive to small
changes, whereas the climate models seem
to require a much bigger disturbance to
produce abrupt change. Simulations of the
coming century with the current generation
of complex models may be giving us a false
sense of security.

[JohnWxy]

11. the author of the article sited is not saying the climate models are "irreperably broken"

you state:

"The simple fact is this study proves that the models the IPCC has been using to make its case are missing some pretty fundamental components of climate and are in fact irreparably broken." ... to be replaced with what...casting bones or rummaging through animal entrails?

Seems to me he is just stating they aren't very good at predicting abrupt, thresh-hold events and could be improved.

Is this supposed to be a 'bulletin'? I don't think there is anybody in the climate research, scientific community who is so satisfied with the current models that they think there isn't room for improvement. What the author is really talking about here is improving the resolution of the various models' out-puts. And, actually that's what all the people in climate research are busting their butts to do. But first of all you have to get more data - more quality data ('smudged' data doesn't do you any good at all).

[bananas]

10. Yes: "If anything, the models are underestimating change"

From the last paragraph of the article:

If anything, the models are underestimating
change, compared with the geological
record. According to the evidence from the
past, the Earth’s climate is sensitive to small
changes, whereas the climate models seem
to require a much bigger disturbance to
produce abrupt change. Simulations of the
coming century with the current generation
of complex models may be giving us a false
sense of security.