Model results now
show natural variability will decrease in magnitude under warmer conditions, altering the mechanisms causing it and its influence on warming rates.
The research does
show natural variability in the Atlantic playing a more significant role in modulating the planet's temperature record earlier in the last century, however.
The blue colour on the left - hand side
shows the natural variability periods, the yellow = early 20th century, red = late 20th century, and the grey and black denote data from SODA and HadlSST (scaled with NCEP / NCAR SAT) respectively.
Figure 1.4 http://cybele.bu.edu/courses/gg312fall02/chap01/figures/figure1.4.gif
shows the natural variability of the annual mean surface temperature on several different spatial scales from a climate model simulation for 200 years.
Not exact matches
Spracklen and Garcia - Carreras
show through their analysis that deforestation has reduced rainfall, but the reduction is currently smaller than the
natural variability in the system.
But the tree ring data
show that the dry spell, while rare in its severity, was not outside the realm of
natural climate
variability, researchers report online March 14 in Science Advances.
«Although this widening is considered a «
natural» mode of climate
variability, implying tropical widening is primarily driven by internal dynamics of the climate system, we also
show that anthropogenic pollutants have driven trends in the PDO,» Allen said.
This record also seems to
show that the rise in methane levels in the last 10,000 years — thought by some to be a result of human agriculture — could simply be the result of
natural variability in the decomposition of plants in boreal forests and wetlands.
Climate records derived from the analysis of sediments
show that ice shelves off the peninsula have been absent in several earlier eras, when
natural variability warmed the world.
Its results
show a large range of
natural summer temperature
variability and identify distinct phases of rapid change.
The fact that the observed long term trend
shows warming strongly suggests that there isn't an underlying long term cooling trend and the overall warming is unlikely to be due to
natural variability.
Global temperatures averaged out annually can
show trends and shed light on
natural climate
variability.
These analyses, whilst not disproving the anthropogenic global warming theory, do
show that the climate we are in today is not unusual in recent history, and therefore the possibility of
natural variability causing the warming can not be ruled out, as it seemingly has been by many «independent» scientists, and the IPCC.
While observational data from satellites
show less warming than predicted by most models, Santer and his co-authors demonstrate that the observed warming is consistent with models including both human and
natural forcings, but inconsistent with models using only
natural forcings and
variability.
Observed changes in ocean heat content have now been
shown to be inconsistent with simulated
natural climate
variability, but consistent with a combination of
natural and anthropogenic influences both on a global scale, and in individual ocean basins.
Regarding all these hypotheticals of Earth - ssytem timescale feedbacks, etc - before results are brought forward with high confidence and reach a level of minimal academic disagreement, they should be understood physically, be exhibited in a range of models from simple to complex, begin to emerge in observations against
natural variability, are
shown to be robust to methodological choices and interpretation, and are borne out paleoclimatically.
He writes: «the data of landfalling hurricanes in the U.S. is less than a tenth of a percent of the data for global hurricanes over their whole lifetimes», and
shows that from such a small subset of data and given the amount of
natural variability, there is no way you would be able to detect a trend by now.
While this methodology doesn't eliminate your point that the trends from different periods in the observed record (or from different observed datasets) fall at various locations within our model - derived 95 % confidence range (clearly they do), it does provide justification for using the most recent data to
show that sometimes (including currently), the observed trends (which obviously contain
natural variability, or, weather noise) push the envelop of model trends (which also contain weather noise).
Completely independently of this oceanographic data, a simple correlation analysis (Foster and Rahmstorf ERL 2011)
showed that the flatter warming trend of the last 10 years was mostly a result of
natural variability, namely the recently more frequent appearance of cold La Niña events in the tropical Pacific and a small contribution from decreasing solar activity.
The interest in these records is for what they can tell us about
natural variability, spatial patterns of change, responses to solar or volcanic forcing, teleconnections etc. — it's all interesting and useful, but it is nothing like as important as the outside interest
shown in these studies might suggest.
A simple comparison of observations with projections based on real world climate forcings
shows a very close match, especially if we take
natural unforced
variability into account as well (mainly ENSO).
With the anthropogenic perturbation likely to be around 2C and maybe more in the next 100 years (that's a global average, it will be much more over northern hemisphere land where we actually live), there are simply no comparable sources of
natural variability, and the historical record
shows that such temperatures have not been approached in the last 2000 years.
In so far as M&M are trying to distort the climate data over the last 1000 years to
show that the so - called «Medieval Warm Period» replicates or exceeds the current warming — and so
natural variability could possibly account for that warming — I thought it worthwhile to put out some information about Medieval climate.
If there was more
natural variability in the past as
shown in MBH98 / 99, e.g. as the Moberg reconstruction
shows, that doesn't necessary lead to the conclusion that climate is more responsive to greenhouse gases (GHGs).
We
show in this study that even short - periodic
natural variations of climate forcing can lead to significant long - term
variability in the climate system.
That means that the potential for
natural variability to be more dominant on shorter time scales is high — and indeed, Connolley and Bracegirdle
show a lot of variance in the model output on those time scales.
Now — apparently — if the next 20 years fail to
show the expected level of increase — then it's all down to
natural variability.
To
show, in a peer - reviewed scientifically defensible way that there is no reason to expect the climate to warm in a monotonic type fashion, that there is
natural variability along with anthropogenic forced warming and we shouldn't expect each year to be warmer than the next or even a run of 10 years always to
show warming.
It is just another illustration that short - term trends like this are not robust, due to
natural variability and (as
shown here) due to data uncertainty.
As presented below, the temperature record of each of these groups (available at the URLs given at the bottom of this message)
shows the same features: (i) a warming of about 0.9 °C (1.6 °F) over the past 150 years and (ii)
natural variability with both short and long periods.
It presents a significant reinterpretation of the region's recent climate change origins,
showing that atmospheric conditions have changed substantially over the last century, that these changes are not likely related to historical anthropogenic and
natural radiative forcing, and that dynamical mechanisms of interannual and multidecadal temperature
variability can also apply to observed century - long trends.
Conversely, if «climate sensitivity» for a doubling of CO2 is based on recent measurements and CO rates, and past
natural variability is underestimated — as you've
shown here — then this implies our estimates of sensitivity per CO2 doubling is too high, not too low.
Independent analyses, such as those described in the Santer et al PNAS article,
show that this warming is inconsistent with
natural variability, i.e. it is likely only explainable in terms of anthropogenic forcing.
Other models also
show comparable «hiatuses» due to
natural climate
variability.
Law Dome ice core
shows that there is a
natural variability of 10 ppmv from the Middle age maximum to the little ice age of the 17th century.
variability a reconstruction
shows, the higher sensitivity to
natural forcings and / or the higher
natural — chaotic climate
variability we should expect.
A series of sensitivity tests
show that our detection results are robust to observational data coverage change, interpolation methods, influence of
natural climate
variability on observations, and different model sampling (see Supplementary Information).
Everyone can see that you are the one who has been unable to 1) cite any peer reviewed science that empirically falsified the null climate hypothesis of
natural climate
variability as the continued primary cause of climate warming, and 2) cite any peer reviewed science that empirically
shows that anthropogenic CO2 was the primary cause of the late 20th century warming.
Thanks for posting Hansen's own graph — which actually
shows only normal warming due to
natural climate
variability [but the red line on the exaggerated x-axis does make it scary, huh?]
«That you can't support your claims with any substantive body of research...» The empirical data
shows that
natural climate
variability is still the primary cause of the climate warming of the past century.
This quite clearly
shows that current temperatures are well within «
natural variability» and certainly nothing to worry about.
You climate alarmists are the deniers, denying the fact that the empirical data
shows that
natural climate
variability is still the primary cause of climate warming.
Your and all your other fellow climate alarmists provide evidence that these observations of eminent scientists is correct, because none of you can cite any peer reviewed science that empirically falsifies the null climate hypothesis of
natural variability still being the primary cause of climate change, or cite any peer reviewed science that empirically
shows that anthropogenic CO2 has been the primary cause of the late 20th century climate warming.
This decreasing trend has been
shown to be outside the range of
natural internal
variability estimated from models.
Past temperature records and computer predictions both
show that periods of slower rises are to be expected as part of the
natural variability of the planet's climate.
I was reacting to Chris Colose comment re: «Models all produce
natural variability, many of which
show temperature flatlines over decadal timescales.»
Models all produce
natural variability, many of which
show temperature flatlines over decadal timescales, and given the wide importance of
natural variability over < 10 year time scales and uncertain forcings, one can absolutely not claim that this is inconsistent with current thinking about climate.
Apparently you are having trouble understanding that this graph
shows the monthly anomalies for a period that encompassed the 2015 - ’16 El Nino warming event and its denouement only, and it was used to demonstrate the speciousness of attributing cherry - picked warming anomalies to humans, and dismissing cherry - picked cooling anomalies as «
natural variability.»
Natural variability from the ensemble of 587 21 - year - long segments of control simulations (with constant external forcings) from 24 Coupled Model Intercomparison Project phase 3 (CMIP3) climate models is
shown in black and gray.
Lead author Dr Debbie Polson, of the University of Edinburgh's School of GeoSciences, said: «This study
shows for the first time that the drying of the monsoon over the past 50 years can not be explained by
natural climate
variability and that human activity has played a significant role in altering the seasonal monsoon rainfall on which billions of people depend.»