This animation shows how the same temperature data (green) that is used to determine the long - term global surface air warming trend of 0.16 °C per decade (red) can be used inappropriately to «cherrypick» short time periods that show a cooling trend simply because the endpoints are carefully chosen and the trend is dominated by short -
term noise in the data (blue steps).
The argument has always been fundamentally flawed, because as The Escalator shows, it's based entirely on cherry picking short -
term noise in the data.
above: animation showing how the same temperature data (green) that is used to determine the long - term global surface air warming trend of 0.16 °C per decade (red) can be used inappropriately to «cherrypick» short time periods that show a cooling trend simply because the endpoints are carefully chosen and the trend is dominated by short -
term noise in the data (blue steps).
This animation shows how the same temperature data (green) that is used to determine the long - term global surface air warming trend of 0.16 °C per decade (red) can be used inappropriately to «cherrypick» short time periods that show a cooling trend simply because the endpoints are carefully chosen and the trend is dominated by short -
term noise in the data (blue steps).
Not exact matches
In nearly all real - world data, there are short - term fluctuations, random effects, and other influences that create «noise» in the values that we observ
In nearly all real - world
data, there are short -
term fluctuations, random effects, and other influences that create «
noise»
in the values that we observ
in the values that we observe.
With all the high frequency
data available these days, like weekly economic
data, and market pricing by the second, it can sometimes be good to tune the
noise levels down and take a look at some longer
term trends to help keep things
in perspective.
Other
data are often just
noise: For example, it's interesting that children enrolled
in Head Start may be less likely to take to crime as adults, but it's pretty much irrelevant to judging the efficacy of an expensive government program that's failed to show much
in terms of student performance.
[Response: That is true if you show a sufficiently long stretch of
data — then the trend is obvious even above the short -
term noise in monthly
data.
There is certainly
noise in the record due to varying amounts of
data, quality control problems, and internal variability of the climate system but the long -
term trend seem robust.»
Since ENSO is the dominant mode of interannual variability, this variance relative to the expected trend due to long -
term rises
in greenhouse gases implies a lower signal to
noise ratio
in the satellite
data.
An analysis using synthetic proxy
data with spatial sampling density and proxy signal - to -
noise ratios equivalent to those of the D'Arrigo et al (2006) tree - ring network suggest that these discrepancies can not be explained
in terms of either the spatial sampling / extent or the intrinsic «noisiness» of the network of proxy records.
HOWEVER if you look at the long
term ACE
data, which is admittedly uncertain,
in DOES look a bit like the AMO, with a lot of
noise.
Linear trends are appropriate for the time period after 1990 where the
data are described well by a linear trend plus interannual
noise (that's why we show a linear trend for the satellite sea level
in our paper), but they don't capture the longer -
term climate evolution very well, e.g. the nearly flat temperatures up to 1980.
If there was a lot of
noise in the
data, it would look statistically different too, with unrealistic interannual amplitudes and short -
term frequencies.
You mention» standard deviation of a set of non-random numbers» The numbers were generated on a spreadsheet using Excel's random number generator so they the net result was what,
in electronic
terms, I would say was real
data (signal) and unwanted randomness (
noise).
Not only are these short -
term «pauses» just
noise in the
data, but observations show that they are entirley expected, and predicted by climate models (i.e. see Meehl el al. 2011).
The problem with using longer cycles like the PDO or the AMO is that we probably don't have enough
data to accurately estimate how reliably they are correlated with
noise in the long
term trend.
As SkS has discussed at length with Dr. Pielke Sr., over short timeframes on the order of a decade, there is too much
noise in the
data to draw any definitive conclusions about changes
in the long -
term trend.
General Introduction Two Main Goals Identifying Patterns
in Time Series
Data Systematic pattern and random
noise Two general aspects of time series patterns Trend Analysis Analysis of Seasonality ARIMA (Box & Jenkins) and Autocorrelations General Introduction Two Common Processes ARIMA Methodology Identification Phase Parameter Estimation Evaluation of the Model Interrupted Time Series Exponential Smoothing General Introduction Simple Exponential Smoothing Choosing the Best Value for Parameter a (alpha) Indices of Lack of Fit (Error) Seasonal and Non-seasonal Models With or Without Trend Seasonal Decomposition (Census I) General Introduction Computations X-11 Census method II seasonal adjustment Seasonal Adjustment: Basic Ideas and
Terms The Census II Method Results Tables Computed by the X-11 Method Specific Description of all Results Tables Computed by the X-11 Method Distributed Lags Analysis General Purpose General Model Almon Distributed Lag Single Spectrum (Fourier) Analysis Cross-spectrum Analysis General Introduction Basic Notation and Principles Results for Each Variable The Cross-periodogram, Cross-density, Quadrature - density, and Cross-amplitude Squared Coherency, Gain, and Phase Shift How the Example
Data were Created Spectrum Analysis — Basic Notations and Principles Frequency and Period The General Structural Model A Simple Example Periodogram The Problem of Leakage Padding the Time Series Tapering
Data Windows and Spectral Density Estimates Preparing the
Data for Analysis Results when no Periodicity
in the Series Exists Fast Fourier Transformations General Introduction Computation of FFT
in Time Series
As long as the long
term trends you describe clearly show that the rates themselves have been increasing, readers can see these very short
term variations as
noise, but I thought the point deserved some attention, particularly because of prominence of Figure 2
in Barry Bickmore's post, and tbe NOAA
data for the past few years.
However, I think that Roger Pielke, Jr. has a point when he suggests that accurate short -
term forecasts are used to show how reliable the GCMs are, but inaccurate short -
term forecasts are attributed to random
noise in the actual
data.