Global cooling

nw30 · Posted: Thu Apr 23, 2015 9:30 pm Post subject:

Our climate models are WRONG: Global warming has slowed - and recent changes are down to ‘natural variability’, says study
Duke University study looked at 1,000 years of temperature records
It compared it to the most severe emissions scenarios by the IPCC
Found that natural variability can slow or speed the rate of warming
These 'climate wiggles' were not properly accounted for in IPCC report

Global warming hasn't happened as fast as expected, according to a new study based on 1,000 years of temperature records.

The research claims that natural variability in surface temperatures over the course of a decade can account for increases and dips in warming rates.

But it adds that these so-called 'climate wiggles' could also, in the future, cause our planet to warm up much faster than anticipated.

The study compared its results to the most severe emissions scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC).

'Based on our analysis, a middle-of-the-road warming scenario is more likely, at least for now,' said Patrick Brown, a doctoral student in climatology at Duke University. 'But this could change.'

The Duke-led study says that variability is caused by interactions between the ocean and atmosphere, and other natural factors.

They claim these 'wiggles' can slow or speed the rate of warming from decade to decade, and exaggerate or offset the effects of increases in greenhouse gas concentrations.

If not properly explained and accounted for, they may skew the reliability of climate models and lead to over-interpretation of short-term temperature trends.

The research, uses observed data, rather than the more commonly used climate models, to estimate decade-to-decade variability.

'At any given time, we could start warming at a faster rate if greenhouse gas concentrations in the atmosphere increase without any offsetting changes in aerosol concentrations or natural variability,' said Wenhong Li, assistant professor of climate at Duke, who conducted the study with Brown.

The team examined whether climate models, such as those used by the IPCC, accurately account for natural chaotic variability that can occur in the rate of global warming.

To test these, created a new statistical model based on reconstructed empirical records of surface temperatures over the last 1,000 years.

'By comparing our model against theirs, we found that climate models largely get the 'big picture' right but seem to underestimate the magnitude of natural decade-to-decade climate wiggles,' Brown said.

'Our model shows these wiggles can be big enough that they could have accounted for a reasonable portion of the accelerated warming we experienced from 1975 to 2000, as well as the reduced rate in warming that occurred from 2002 to 2013.'

'Statistically, it's pretty unlikely that an 11-year hiatus in warming, like the one we saw at the start of this century, would occur if the underlying human-caused warming was progressing at a rate as fast as the most severe IPCC projections,' Brown said.

'Hiatus periods of 11 years or longer are more likely to occur under a middle-of-the-road scenario.'

Under the IPCC's middle-of-the-road scenario, there was a 70 per cent likelihood that at least one hiatus lasting 11 years or longer would occur between 1993 and 2050, Brown said.

'That matches up well with what we're seeing.'

There's no guarantee, however, that this rate of warming will remain steady in coming years, Li stressed.

'Our analysis clearly shows that we shouldn't expect the observed rates of warming to be constant. They can and do change.'

Read more: http://www.dailymail.co.uk/sciencetech/article-3052926/Our-climate-models-WRONG-Global-warming-slowed-recent-changes-natural-variability-says-study.html#ixzz3YBpo9d2f

LHDR · Joined: 22 Jun 2007 Posts: 528

"Climate models are WRONG" !?

It's possible that the "journalist" above did not understand what the research findings mean. Or, perhaps more likely, someone intentionally invented a catchy title, propaganda at its best, and, naturally, right wingers fall for it?

The research suggests that the most severe scenarios for global warming outlined by the IPCC are not very likely to be true but that "middle of the road" warming predictions are more consistent with the findings. The research does not support denial of CO2 driven global warming. In the researchers' own words from above:

'By comparing our model against theirs, we found that climate models largely get the 'big picture' right but seem to underestimate the magnitude of natural decade-to-decade climate wiggles,' Brown said.

'Based on our analysis, a middle-of-the-road warming scenario is more likely, at least for now,' said Patrick Brown,

'At any given time, we could start warming at a faster rate if greenhouse gas concentrations in the atmosphere increase without any offsetting changes in aerosol concentrations or natural variability,' said Wenhong Li, assistant professor of climate at Duke, who conducted the study with Brown.

techno900 · Joined: 28 Mar 2001 Posts: 4161

mac said:

mrgybe · Joined: 01 Jul 2008 Posts: 5180

"It's important to note that California's drought, while extreme, is not an uncommon occurrence for the state. In fact, multi-year droughts appear regularly in the state's climate record, and it's a safe bet that a similar event will happen again.

This report builds on earlier studies, published in September in the Bulletin of the American Meteorological Society, which found no conclusive evidence linking human-caused climate change and the California drought."
http://www.noaanews.noaa.gov/stories2014/20141208_californiadrought.html

Perhaps our expert has forgotten more about water than NOAA also. Or perhaps they are being intentionally obtuse. This type of fake alarmism is precisely why so many of us are skeptical about the views of the "experts".

isobars · Joined: 12 Dec 1999 Posts: 20935

mac · Posted: Fri Apr 24, 2015 12:46 pm Post subject:

Techno--run a trend analysis for Mammoth, compare it to a trend analysis for the rest of the Sierra, and get back to me. I'll send your material on to my friends at Scripps so we can all have a laugh.

uwindsurf · Joined: 18 Aug 2012 Posts: 968 Location: Classified

mac · Posted: Fri Apr 24, 2015 1:33 pm Post subject:

mrgybe is the master of cherry-picking one fact out of a wall of facts and using it to express his scorn, or support his biases. There will not be a serious discussion with these clowns about what climate models can, or can't do. I don't believe for a second that Techno came up with the snowfall totals for Mammoth Lake on his own, or he can render a coherent argument about what he thinks it means. There are a host of knuckle-dragging web sites, and he didn't name his source. this is how it goes in the denier industry. Lots of money to be made lying for big oil.

mrgybe · Joined: 01 Jul 2008 Posts: 5180

Our self proclaimed expert clearly stated that the CA drought was partially due to the impact of global warming on the Sierra snowpack. Techno provided a chart, with a link, that provided evidence to the contrary. NOAA clearly stated that there is no conclusive evidence to indicate the current drought is caused by global warming. Our self proclaimed expert has produced nothing to suggest that the Techno's data is inaccurate or that NOAA is wrong. Rather he resorts to scornful putdowns, name calling and accusations.

swchandler · Joined: 08 Nov 1993 Posts: 10588

For those of us in the know, the amount of snowfall that Mammoth experiences is statistically far greater than many other areas of the Sierra Nevada range. That's why the snow and the ski season lasts there well into June on a regular basis. It's highly questionable to assume that Mammoth's record of snow depths can taken to represent the Sierra as a whole. Cherry picking at its worst.