Why Is Global Warming Stagnating?

[Lord Beria3]

http://www.spiegel.de/international/wor ... ernational

Climate experts have long predicted that temperatures would rise in parallel with greenhouse gas emissions. But, for 15 years, they haven't. In a SPIEGEL interview, meteorologist Hans von Storch discusses how this "puzzle" might force scientists to alter what could be "fundamentally wrong" models.

SPIEGEL: Just since the turn of the millennium, humanity has emitted another 400 billion metric tons of CO2 into the atmosphere, yet temperatures haven't risen in nearly 15 years. What can explain this?

Storch: So far, no one has been able to provide a compelling answer to why climate change seems to be taking a break. We're facing a puzzle. Recent CO2 emissions have actually risen even more steeply than we feared. As a result, according to most climate models, we should have seen temperatures rise by around 0.25 degrees Celsius (0.45 degrees Fahrenheit) over the past 10 years. That hasn't happened. In fact, the increase over the last 15 years was just 0.06 degrees Celsius (0.11 degrees Fahrenheit) -- a value very close to zero. This is a serious scientific problem that the Intergovernmental Panel on Climate Change (IPCC) will have to confront when it presents its next Assessment Report late next year.

SPIEGEL: Do the computer models with which physicists simulate the future climate ever show the sort of long standstill in temperature change that we're observing right now?

Storch: Yes, but only extremely rarely. At my institute, we analyzed how often such a 15-year stagnation in global warming occurred in the simulations. The answer was: in under 2 percent of all the times we ran the simulation. In other words, over 98 percent of forecasts show CO2 emissions as high as we have had in recent years leading to more of a temperature increase.

SPIEGEL: How long will it still be possible to reconcile such a pause in global warming with established climate forecasts?

Storch: If things continue as they have been, in five years, at the latest, we will need to acknowledge that something is fundamentally wrong with our climate models. A 20-year pause in global warming does not occur in a single modeled scenario. But even today, we are finding it very difficult to reconcile actual temperature trends with our expectations.

SPIEGEL: What could be wrong with the models?

Storch: There are two conceivable explanations -- and neither is very pleasant for us. The first possibility is that less global warming is occurring than expected because greenhouse gases, especially CO2, have less of an effect than we have assumed. This wouldn't mean that there is no man-made greenhouse effect, but simply that our effect on climate events is not as great as we have believed. The other possibility is that, in our simulations, we have underestimated how much the climate fluctuates owing to natural causes.

Always felt that natural causes have been big factors behind climate change and that although man is definately a key factor, it is only one of a number of major influences on climate change.

[Little John]

http://www.spiegel.de/international/wor ... ernational

Climate experts have long predicted that temperatures would rise in parallel with greenhouse gas emissions. But, for 15 years, they haven't. In a SPIEGEL interview, meteorologist Hans von Storch discusses how this "puzzle" might force scientists to alter what could be "fundamentally wrong" models.

SPIEGEL: Just since the turn of the millennium, humanity has emitted another 400 billion metric tons of CO2 into the atmosphere, yet temperatures haven't risen in nearly 15 years. What can explain this?

Storch: So far, no one has been able to provide a compelling answer to why climate change seems to be taking a break. We're facing a puzzle. Recent CO2 emissions have actually risen even more steeply than we feared. As a result, according to most climate models, we should have seen temperatures rise by around 0.25 degrees Celsius (0.45 degrees Fahrenheit) over the past 10 years. That hasn't happened. In fact, the increase over the last 15 years was just 0.06 degrees Celsius (0.11 degrees Fahrenheit) -- a value very close to zero. This is a serious scientific problem that the Intergovernmental Panel on Climate Change (IPCC) will have to confront when it presents its next Assessment Report late next year.

SPIEGEL: Do the computer models with which physicists simulate the future climate ever show the sort of long standstill in temperature change that we're observing right now?

Storch: Yes, but only extremely rarely. At my institute, we analyzed how often such a 15-year stagnation in global warming occurred in the simulations. The answer was: in under 2 percent of all the times we ran the simulation. In other words, over 98 percent of forecasts show CO2 emissions as high as we have had in recent years leading to more of a temperature increase.

SPIEGEL: How long will it still be possible to reconcile such a pause in global warming with established climate forecasts?

Storch: If things continue as they have been, in five years, at the latest, we will need to acknowledge that something is fundamentally wrong with our climate models. A 20-year pause in global warming does not occur in a single modeled scenario. But even today, we are finding it very difficult to reconcile actual temperature trends with our expectations.

SPIEGEL: What could be wrong with the models?

Storch: There are two conceivable explanations -- and neither is very pleasant for us. The first possibility is that less global warming is occurring than expected because greenhouse gases, especially CO2, have less of an effect than we have assumed. This wouldn't mean that there is no man-made greenhouse effect, but simply that our effect on climate events is not as great as we have believed. The other possibility is that, in our simulations, we have underestimated how much the climate fluctuates owing to natural causes.

Always felt that natural causes have been big factors behind climate change and that although man is definitely a key factor, it is only one of a number of major influences on climate change.

It's merely a matter of temporal resolution.

Given the massive number of variables involved in short to medium term climate, comparing the correlation of CO2/global temperature on a 20 year time-scale with CO2/global temperature on a 100 year or longer time-scale is like comparing the climate and the weather. It's basically silly.

The undeniably, mind-numbingly, in-your-face fact is that global climate average temperature correlates extremely highly with CO2 when viewed from the resolution of a century or longer.

You may also have noticed from that graph I have included that whilst these two variables are intimately correlated, they do not move in absolute, synchronous lock-step. Instead, they move around together like two weights connected by an elastic band. This means that temperature tends to overshoot in response to changes in CO2 (look at the peaks and troughs). All of which bodes very badly indeed, given where CO2 is currently at. If the current, extremely short-term, disconnect between climate temperature and CO2 levels suggests anything, it suggests that a massive overshoot response in global temperatures is now well overdue.

The graph below shows the kind of relationship between two variables that, say, market traders could only dream of. If you were trading on the basis of that graph, you'd put you life savings on it. Particularly so if your trade was a long term investment.

[UndercoverElephant]

http://www.spiegel.de/international/wor ... ernational

Climate experts have long predicted that temperatures would rise in parallel with greenhouse gas emissions. But, for 15 years, they haven't. In a SPIEGEL interview, meteorologist Hans von Storch discusses how this "puzzle" might force scientists to alter what could be "fundamentally wrong" models.

SPIEGEL: Just since the turn of the millennium, humanity has emitted another 400 billion metric tons of CO2 into the atmosphere, yet temperatures haven't risen in nearly 15 years. What can explain this?

Storch: So far, no one has been able to provide a compelling answer to why climate change seems to be taking a break. We're facing a puzzle. Recent CO2 emissions have actually risen even more steeply than we feared. As a result, according to most climate models, we should have seen temperatures rise by around 0.25 degrees Celsius (0.45 degrees Fahrenheit) over the past 10 years. That hasn't happened. In fact, the increase over the last 15 years was just 0.06 degrees Celsius (0.11 degrees Fahrenheit) -- a value very close to zero. This is a serious scientific problem that the Intergovernmental Panel on Climate Change (IPCC) will have to confront when it presents its next Assessment Report late next year.

SPIEGEL: Do the computer models with which physicists simulate the future climate ever show the sort of long standstill in temperature change that we're observing right now?

Storch: Yes, but only extremely rarely. At my institute, we analyzed how often such a 15-year stagnation in global warming occurred in the simulations. The answer was: in under 2 percent of all the times we ran the simulation. In other words, over 98 percent of forecasts show CO2 emissions as high as we have had in recent years leading to more of a temperature increase.

SPIEGEL: How long will it still be possible to reconcile such a pause in global warming with established climate forecasts?

Storch: If things continue as they have been, in five years, at the latest, we will need to acknowledge that something is fundamentally wrong with our climate models. A 20-year pause in global warming does not occur in a single modeled scenario. But even today, we are finding it very difficult to reconcile actual temperature trends with our expectations.

SPIEGEL: What could be wrong with the models?

Storch: There are two conceivable explanations -- and neither is very pleasant for us. The first possibility is that less global warming is occurring than expected because greenhouse gases, especially CO2, have less of an effect than we have assumed. This wouldn't mean that there is no man-made greenhouse effect, but simply that our effect on climate events is not as great as we have believed. The other possibility is that, in our simulations, we have underestimated how much the climate fluctuates owing to natural causes.

Always felt that natural causes have been big factors behind climate change and that although man is definately a key factor, it is only one of a number of major influences on climate change.

I think you don't understand the implications what you just posted, Beria. I might have got your intentions wrong, but if that's some form of "climate change skepticism", then you've got the wrong end of the stick. What it is saying is that there is currently a "larger than expected natural variation" keeping temperatures DOWN from where they would be if those fluctuations didn't exist. In other words, when the fluctuation balances itself out, then we are going to see very rapid rises in temperature.

[adam2]

It has certainly been cooler than usual in the UK, but I am not convinced that global warming overall has stopped or significantly slowed.
Temperatures in the Arctic continue to rise leading to significant melting of the ice.

Outside of Europe there have been some spectacular droughts and heat waves.

[woodburner]

Temperatures in the Arctic continue to rise leading to significant melting of the ice..

I suspect it's the ice melting that is holding temperatures down. There is a lot of heat involved in getting ice to melt, and when the ice has gone, temperatures will rocket.

[biffvernon]

I do wish that people who use phrases like "global temperature" would explain what part of the 'globe' they are referring to. Is it the surface atmospheric temperature, which we feel, or the deep ocean, where most of the energy actually goes?

[Little John]

I do wish that people who use phrases like "global temperature" would explain what part of the 'globe' they are referring to. Is it the surface atmospheric temperature, which we feel, or the deep ocean, where most of the energy actually goes?

Well, since I have used the term several times in my previous post, I was referring to the climate temperature as specified in the graph, which I am unsure refers to more than the gaseous atmosphere.

Whilst, for the purpose of short to medium term calculations, knowing the precise temperature of the oceans as well as the air and so knowing the ratio of heat distribution between the two is obviously important; For the purpose of determining gross, longer-range, historical changes to climate temperature it is only necessary to have the one measure, either from the gas or from the liquid. The reason being that knowing the one will allow you to broadly extrapolate the other.

[RevdTess]

The graph below shows the kind of relationship between two variables that, say, market traders could only dream of. If you were trading on the basis of that graph, you'd put you life savings on it. Particularly so if your trade was a long term investment.

Heh! Believe me when I was an oil market analyst I frequently tried trading off charts that looked even more obviously correlated than that one. It never ends well, especially if you've any uncertainty about the physical causal link. Traders often can't tell just how far apparently well-correlated time series can get out of sync with each other when new factors (unknowingly) come into play. And remember the old trading adage: "The markets can behave irrationally longer than you or I can remain solvent." If that chart were a trading model, temperature would skyrocket the very day after the scientists all admitted they were wrong and changed their models.

[biffvernon]

Too right. And with almost all the increased energy being absorbed where the Sun don't shine and out thermometers are few and far between, any short term variability in surface atmosphere temperatures are not to be pronounced upon as over-important.

[Little John]

The graph below shows the kind of relationship between two variables that, say, market traders could only dream of. If you were trading on the basis of that graph, you'd put you life savings on it. Particularly so if your trade was a long term investment.

Heh! Believe me when I was an oil market analyst I frequently tried trading off charts that looked even more obviously correlated than that one. It never ends well, especially if you've any uncertainty about the physical causal link. Traders often can't tell just how far apparently well-correlated time series can get out of sync with each other when new factors (unknowingly) come into play. And remember the old trading adage: "The markets can behave irrationally longer than you or I can remain solvent." If that chart were a trading model, temperature would skyrocket the very day after the scientists all admitted they were wrong and changed their models.

Now now Tess, you're not telling me you traded off charts with millennia-length time-series.... (or maybe you did....)

I guess what I am saying is that predicting tomorrow's weather presents a reasonable prospect of success by simply assuming it will be the same as today's; making reasonable predictions about the climate at the millennial scale is also, in principle, possible because any medium-term fluctuations will have been smoothed out and so gross, macro-level correlational or, even, causal relationships become more exposed.

On the other hand, making predictions on the basis of medium-term climate patterns is the one that is the right bugger because you no longer have the "tomorrow’s weather will be likely the same as today's" rule of thumb to rely on nor do you have the advantage of deep-time to smooth out the wrinkles of medium-term climate fluctuations. This principle of difficulty of making predictions seems to apply, also, to pretty much any organic, complex system; Weather and climate being no exception.

[RenewableCandy]

Lots of CC deniers have cited the measured global temperature "stagnation" since 1998. There is a well-known explanation for it which, iirc, involves the sun in a cyclical cooling. When that solar cycle turns, we're going to fry.

[clv101]

It'd be interesting to see the 'debate' if surface temperatures did rise by half a degree or more by ~2020!

[biffvernon]

It'd

Probable correction:
It'll

[JavaScriptDonkey]

Lots of CC deniers have cited the measured global temperature "stagnation" since 1998. There is a well-known explanation for it which, iirc, involves the sun in a cyclical cooling. When that solar cycle turns, we're going to fry.

I think people are just pointing out what was obvious all along - that CO2 is one of many factors that influence climate on our planet.

[emordnilap]

"2012: A jaw-dropping year for America"

"We're definitely, in my mind, in a cooling period."

"And this is not anecdotal, this is scientific temperature research surveys, we're actually cooling".

As Marx said, "Who are you going to believe, me or your own eyes?"