Posts Tagged ‘UAH’

The Pause Update: March 2016 (Preliminary)

April 2, 2016

Well my last post certainly stirred up some Global Warming Enthusiasts who found it difficult to get their heads around the continued existence of The Pause.  What will they make of this month’s update?  The Pause refuses to go away, despite greatly exaggerated rumours of its death.

Dr Roy Spencer has just released UAH v6.0 data for March.  This is a preliminary post with graphs only for the Globe, the Northern Hemisphere, the Southern Hemisphere, and the Tropics.  Other regions will be updated in a few days’ time when the full data for March are released.  (These preliminary figures may change slightly as well.)

These graphs show the furthest back one can go to show a zero or negative trend (less than +0.1C/ 100 years) in lower tropospheric temperatures.    I calculate 12 month running means to remove the small possibility of seasonal autocorrelation in the monthly anomalies.  Note: The satellite record commences in December 1978- now 37 years and 4 months long- 448 months.  12 month running means commence in November 1979.  The graphs below start in December 1978, so the vertical gridlines denote Decembers.  The final plotted points are March 2016.

Except for the Tropics, where The Pause has reduced by three months, in other regions it has remained at the same length.



Mar 16 globe

Sorry, GWEs, The Pause is still an embarrassing reality!  For how much longer we don’t know.

And, for the special benefit of those who think that I am deliberately fudging data by using 12 month running means, here is the plot of monthly anomalies, which shows that The Pause is over in monthly anomalies by my rather strict criterion:

global monthly 2016 mar

I will continue posting these figures showing these scarey trends from monthly anomalies.  The Pause will return sooner with monthly anomalies than 12 month means of course.  Meanwhile, shudder at the thought of 18 years and 4 months with a frightening trend of +0.15C +/-0.1C per 100 years.

Northern Hemisphere:

Mar 16 NH

The Northern Hemisphere Pause refuses to go quietly and remains at nearly half the record.  It may well disappear in the next month or two.

Southern Hemisphere:

Mar 16 SH

For well over half the record the Southern Hemisphere has zero trend.


Mar 16 Tropics

The Pause has shortened by three months, but is still well over half the record long.

In a few days the full dataset will be released and graphs for the other regions will be plotted as soon as possible.  As I will be doing Jury duty for the next four weeks, posts and comments are likely to be few, and brief.

The Pause Update: February 2016

March 21, 2016


Firstly, I must apologise for the late posting.  We went away for a two week road trip in early March, during which my laptop died.  As well, we have had some family issues that have taken priority.

UAH v6.0 data for February have been released. Here are updated graphs for various regions showing the furthest back one can go to show a zero or negative trend (less than +0.1C/ 100 years) in lower tropospheric temperatures.    Note: The satellite record commences in December 1978- now 37 years and 3 months long- 447 months.  12 month running means commence in November 1979.

Despite the record TLT for February, I am sorry to disappoint GWEs that The Pause has not disappeared.  In some regions it has lengthened, in others it has shortened, and in the Northern Extra-Tropics it has disappeared (by my criterion)- but mostly it has remained at the same length.



Feb 16 globe

There has been zero trend for 18 years and 10 months.

Update:  Some commenters (see below) think that use of 12 month running means are some form of trick to hide the data, and that using monthly data will show no Pause.  Poor souls.  Here is the graph of global monthly anomalies:

global monthly

18 years 7 months- not much difference, and The Pause still lives!

Fools rush in….

Northern Hemisphere:

Feb 16 NH


Southern Hemisphere:

Feb 16 SH

For well over half the record the Southern Hemisphere has zero trend.


Feb 16 Tropics

Tropical Oceans:

Feb 16 Tropic Oceans


Northern Extra-Tropics (20-60N- where most people live):

Feb 16 NH Ext Trop

The Pause has ceased in this region as the trend since July 1998 is a tad over +0.1C (+/- 0.1C) per 100 years.

Southern Hemisphere Extra-Tropics (mostly water):

Feb 16 SH Ext Trop

But still strong in the South!

North Polar:

Feb 16 NP

The Pause has lengthened by three months.

South Polar:

Feb 16 SP

For the whole of the satellite record, the South Polar region has been cooling.  So much for a fingerprint of warming due to the enhanced greenhouse effect being greater warming at the Poles!


Feb 16 Aus

One month longer.

USA 49 states:

Feb 16 USA

Despite all expectations to the contrary, The Pause lives on!


Trending Trends Continued: An Alternative View

February 26, 2016

No matter how much and how well we explain the methods for calculating the length of The Pause, Global Warming Enthusiasts will accuse us of cherry picking the start date.

In this post I will replicate the IPCC’s predicted estimates for temperatures, and show alternative scenarios with a range of trends to the end of 2035, through using an alternative  view which will be sure to please our friends on the other side of the fence- but will demonstrate the limited extent of the joy they should feel at the expected demise of The Pause. As well,  I will also demonstrate what temperatures will need to do before we skeptics can claim victory (our opponents will never admit defeat- that would be heresy).

In these figures I plot running trends of 12 month means of Temperatures of the Lower Troposphere (TLT) anomalies from UAH (Version 6 Beta 5), but starting from the beginning of the record (12 month means from November 1979).  Running trends will be used in this post to demonstrate the effects of changing data values over time.

Fig. 1: Running trends for global TLT to the present

Trend to 2016 all

Fig. 2: Running trends for global TLT to the present, closer view.

trend to 2016 closeup

Note to GWEs: there is no cherry picking: the start is from the start of the record. Each new month’s data point will either increase or decrease the long term trend, but with decreasing effect as the record grows in length. Peaks correspond to warming events, troughs to cooling events. Note also that the recent long term trend is near the lowest it has been since 1998. With the expected increase in temperatures following the El Nino, I anticipate the long term trend to the end of 2016 will be about +1.2C per 100 years.

What of the future? Now according to the IPCC Assessment Report 5, warming for the next 20 years is locked in, no matter what emissions scenario.

“The global mean surface temperature change for the period 2016–2035 relative to 1986–2005 is similar for the four RCPs and will likely be in the range 0.3°C to 0.7°C (medium confidence). This assumes that there will be no major volcanic eruptions or changes in some natural sources (e.g., CH4 and N2O), or unexpected changes in total solar irradiance.”

( p8)

If I am still around in 2035, this prediction will not be a huge priority for me. However, to illustrate various possibilities, I shall calculate possible TLTs for the next 20 years. (Yes, I know the IPCC is talking about surface temperatures. However if tropospheric temperature change doesn’t reflect surface temperature change for another 20 years there are going to be some serious arguments in climate science circles!)

First, let’s replicate the IPCC predictions for 2016-2035- and in so doing, show The Pause in all its glory. The next figures plot running 12 month mean Temperatures of the Lower Troposphere (TLT) anomalies in degrees Celsius versus global atmospheric carbon dioxide concentration in parts per million (ppm), data from NOAA.  The global record commences in 1980.

Fig. 3: Running trend of Degrees C per 100 ppm CO2

Trend TLT v co2

Note again the peaks and troughs, and that the current trend is the lowest it has been since 1996.  The long term trend to December 2015 is +0.65C/ 100 ppm CO2. This is confirmed in the following plot:

Fig. 4: TLT anomalies vs CO2

tlt vs co2 1980-2015

Now let’s break the record in two: the first half of the CO2 rise and the second half.

Fig. 5:  TLT vs CO2: 1st 30.32ppm

tlt vs co2 1st half

Fig. 6:  TLT vs CO2: last 30.32ppm

tlt vs co2 2nd half

There you have The Pause: entirely un-cherry picked, as we are using exactly equal portions of the record: the first and last 30.32 ppm of the CO2 growth from 1980 to 2015.

The next graphs plot CO2 increase over time, from 2001 to 2015.

Fig. 7: CO2 growth (12 month running mean)

co2 to 2015 formula

Using this trend equation it is possible to estimate CO2 for the next 20 years, and from that, using (A) the trend of the first half of TLT vs CO2, i.e. rapid warming; (B) that of the whole 1980-2015 period, i.e. continuing the present long term trend; and (C) that of the second half of the CO2 growth, i.e. The Pause, calculate three theoretical estimates for the TLT in the best way- from observations. Here are series A and B.

Fig. 8:  Theoretical trends calculated from observations

Series A B calcs

Note that series A approximately tracks the observed TLTs until about 2002, when the disparity begins. This shows clearly why The Pause is so inconvenient, and why so much effort has been made to eradicate it.

Amazingly, the 2016-35 high mean of 0.7 above 1986-2005, and the low mean of +0.3, as predicted by the IPCC, have been replicated almost exactly by series A and B. (The UAH 1986-2005 mean is +0.02C).  It appears that the temperature trend for the rapidly warming phase up to 2001 exactly matches the trend needed to create the upper limit of their prediction for 2016-35, and the trend overall to 2015 is very close to that of the lower limit. The IPCC is banking on the warming trend from now to 2035 being at least as much as the 1980-2015 trend, and as much as that of the rapid warming to about 2001. Any continuation of a slowdown makes that much harder.

Obviously these series are imaginary, showing the theoretical TLT calculated from CO2 concentration, and without any of the bumps and dips caused by natural variation- volcanoes, ENSO events, and the like. However, they can be used to simulate what temperatures might do over the next 20 years.

I illustrate this with these scenarios, and a fourth, below.

Scenario A allows the 2016-2035 mean to be 0.7C above the 1986-2005 mean and necessitates temperatures sharply rising then continuing at the rate of the higher of the theoretical series (A). Scenario B very slightly exceeds the lower IPCC expectation of +0.3C, and represents a continuation of the current trend. Scenario C is calculated by multiplying expected CO2 concentration by the TLT per CO2 trend for the second half of CO2 growth, indexed to the 1996-2015 mean. As expected it is virtually flat with the 2016-35 mean at +0.14C. This represents an extension of The Pause by another 20 years. Scenario D shows a sharp drop to a 20 year plateau (shown as flat as we have no idea how temperatures may fluctuate) at -0.11C, the lowest 12 month mean of the last 20 years, and about the same average as the 1980-95 period. I have smoothed the beginning months of all four scenarios.

I repeat- these scenarios are entirely imaginary and represent approximate calculated values IF TLT responds to CO2 concentration as it has to now, and nothing else.

Fig. 9: Four scenarios to 2035

Scenarios to 2035

I have marked in the trend line for UAH to now.  Scenario A shows what would happen if The Pause came to an abrupt end, with temperatures rising to a record high for 2016, and then keeping on rising at the theoretical rate as if The Pause had never happened. I’m sure there are some Global Warming Enthusiasts who expect temperatures will do just that.

But the IPCC has an out clause- Scenario B. If the current long term trend continues, TLTs will reach IPCC expectations. Which is why GWEs are desperate for The Pause to end and warming to resume at (at least) the slow if not steady +1.1 to 1.2C per 100 years. If it doesn’t they’re in trouble.

Temperatures will need to trend below this to falsify the predictions- and not even as much as Scenario C, which represents an extension of The Pause. Scenario D represents a significant decrease.

The next plot compares the trends under these four scenarios.

Fig. 10: Trends in degrees Celsius per 100 years to 2035 under four TLT scenarios.

Trend scenarios to 2035

Ignore the artificial shape of the curves. At December 2035 the trend for each scenario will be about:
Scenario A: 2.1C/ 100 years
Scenario B: 1.2C
Scenario C: 0.6C
Scenario D: 0.0C

The IPCC expects trends to be between those of Scenarios A and B. A small step up (to a new 20 year mean of say +0.25C) and a new pause- which is entirely possible- would probably still be claimed to be “the hottest decade ever” and “consistent with global warming projections”. We need to emphasise that a pause doesn’t have to be completely flat. A 30 year period with a trend of +0.3C per 100 years should be enough to bring the global warming models into question. However, there will need to be a significant drop in temperatures, or a much longer plateau, for us to claim victory. A 57 year pause would be most embarrassing- but then they would probably blame it on volcanoes!

Finally, even if this El Nino is followed by a strong La Nina, as suggested by NOAA,  it is unlikely The Pause will return until the beginning of 2018, perhaps a little earlier. However, that is not important. The important thing is what happens next. Watch the next two or three ENSO cycles- especially the La Nina dips.

Global Warming Enthusiasts are desperate for rapid warming to resume at least as much as Scenario B. The long term trend must rise above the current rate if they are to feel vindicated. But then, who knows what the actual temperatures will do.

Time will tell.

The Pause Update: January 2016

February 13, 2016

UAH v6.0 data for January were released this week.  The dataset has moved to Beta 5, which has caused some interesting changes.  Remember, Version 6.0 is a work in progress, with slight tinkering, until the final version is released.

Here are updated graphs for various regions showing the furthest back one can go to show a zero or negative trend (less than +0.1C/ 100 years) in lower tropospheric temperatures.   In some regions the pause has lengthened, in others it has shortened.  Note: The satellite record commences in December 1978- now 37 years and 2 months long- 446 months.  12 month running means commence in November 1979.



trends jan 16 globe

There has been zero trend for 18 years and 11 months.

Northern Hemisphere:

trends jan 16 NH

The Pause is back!

Southern Hemisphere:

trends jan 16 SH

The Pause has lengthened again.  For well over half the record the Southern Hemisphere has zero trend.


trends jan 16 tropics

Tropical Oceans:

trends jan 16 tropic oceans

22 years 5 months.

Northern Extra-Tropics (20-60N- where most people live):

trends jan 16 nh extr

Southern Hemisphere Extra-Tropics (mostly water):

trends jan 16 sh extr

North Polar:

trends jan 16 NP

The Pause is 13 years 11 months long- 13 months short of 15 years.

South Polar:

trends jan 16 SP

For the whole of the satellite record, the South Polar region has been cooling.  So much for a fingerprint of warming due to the enhanced greenhouse effect being greater warming at the Poles!


trends jan 16 Aust

20 years 10 months.

USA 49 states:

trends jan 16 USA49

The Pause lives!


The Disconnect Between Theory and Reality- Part 2: Winters vs Summers

February 12, 2016


It was two years ago in 2013 that I last posted on the difference between climate scientists’ expectations and reality, so in this series of posts I bring these points up to date, and add a couple of related points.

What the climate scientists tell us:

Dr Karl Braganza in The Conversation on 14/06/2011 lists the “fingerprints” of climate change (my bold).

These fingerprints show the entire climate system has changed in ways that are consistent with increasing greenhouse gases and an enhanced greenhouse effect. They also show that recent, long term changes are inconsistent with a range of natural causes…..
…Patterns of temperature change that are uniquely associated with the enhanced greenhouse effect, and which have been observed in the real world include:
• greater warming in polar regions than tropical regions
• greater warming over the continents than the oceans
• greater warming of night time temperatures than daytime temperatures
greater warming in winter compared with summer
• a pattern of cooling in the high atmosphere (stratosphere) with simultaneous warming in the lower atmosphere (tropopause).

And later

Similarly, greater global warming at night and during winter is more typical of increased greenhouse gases, rather than an increase in solar radiation.

In this post I look at whether there is a pattern of greater warming in winter than summer.

This indicator appears to be FALSIFIED for both Northern and Southern Hemispheres:

Fig. 1:  Winter vs Summer, Northern Hemisphere (UAH)

summ win NH

Fig. 2:  Winter vs Summer, Southern Hemisphere (UAH)

summ win SH

And at the Poles:

Fig. 3: Winter vs Summer, Northern Polar region (UAH)

summ win NP

Summers warming faster than winters.  And in Antarctica:

Fig. 4: Winter vs Summer, Southern Polar region (UAH)

summ win SP

Winters (which are mostly night) are cooling much faster than summers.

In Australia overall however, winters are warming faster than summers.

Fig. 5: Winter vs Summer, Australia (UAH 1979-2015):

summ win Oz uah

And Acorn surface data since 1979:

Fig. 6: Winter vs Summer, Australia (Acorn 1979-2015):

summ win Oz acorn 7915

And since 1911:

Fig. 7: Winter vs Summer, Australia (Acorn 1911-2015):

summ win Oz acorn 19112015

However, the patterns are very different in different Australian regions.  North Australia has winters warming faster than summers:

Fig. 8: Winter vs Summer, Northern Australia (Acorn 1911-2015):

summ win Oz nth

While Southern Australia has exactly the reverse:

Fig. 9: Winter vs Summer, Southern Australia (Acorn 1911-2015):

summ win Oz sth

Let’s look at different parts of the South, first the South East:

Fig. 10: Winter vs Summer, South Eastern Australia (Acorn 1911-2015):

summ win Oz SE

And the South West:

Fig. 11: Winter vs Summer, South Western Australia (Acorn 1911-2015):

summ win Oz SW

This shows a particularly strong summer warming effect.

In the North, the pattern seems driven by greater summer rainfall and drier winters:

Fig. 12:  Summer and Winter rainfall anomalies, Northern Australia

summ win Oz rain Nth

There has been much less winter rain in the Southwest (in the Southeast, there has not been as much variation):

Fig. 13:  Summer and Winter rainfall anomalies, South Western Australia

summ win Oz rain SW

In both the North and Southwest, there are distinct changes in rainfall in the late 1960s or early 1970s:

Fig. 14:  Northern Summer rainfall changes

summ rain Nth

Note the long term slow decrease to 1973, the wet 1970s and dry 1980s, and all except 6 wetter than average seasons since 1991.

By contrast, the South Western rainy season shows a long term slow increase with great variability until the 1960s, with a sharp step down in 1969, and another in 2001, with less year to year variability.

Fig. 15:  South Western Winter rainfall changes

winter rain SW

This shows up in trend maps of summer and winter rainfall 1970-2014:

Fig. 16:  Trends in summer rainfall

summ rain 19702014

Fig. 17:  Trends in winter rainfall

winter rain 19702014

The effect of less winter rain on temperatures in the following summer in South Western Australia is clearly seen in this scatterplot:

Fig. 18:  Summer means and previous winter rain:

summ T vs win rain SW

While the IPCC and its acolytes in the Climate Council predict less rainfall for southeastern and southwestern Australia, this would not be difficult given the trend for southwestern Australia had been established for 20 years before the IPCC was even formed, and 45 years before AR5. Northern Australian rainfall is not mentioned.

Assessment of this evidence for the enhanced greenhouse effect: FAIL.  Tropospheric data show this to be falsified in both Hemispheres and both Poles.  Australia appears to go against this pattern, but drastic changes in rainfall patterns in the Northwest and Southwest appear to be involved in the difference between north and south.

Theory has been mugged by reality yet again.

Trending trends

January 17, 2016

In this post I demonstrate my template that shows linear trends in data from any given point in time to the most recent month, (which is how I determine the starting point and length of The Pause.) It can be quickly seen how trends change over time and where these changes occur so they can be investigated. This can be used for any data at all, from monthly TLT anomalies to road fatalities. In future posts I will use this with Australian surface temperatures and rainfall. It does not replace, but supplements, normal time series graphs.
Up to now I have used monthly UAH temperature anomalies to study The Pause, but I have recently learnt that there can still be a weak seasonal signal, so from now on I will use 12 month running means of monthly anomalies. This leads to some changes in trends and the start of The Pause in some regions, notably Australia, but overall gives similar results. Importantly it reduces the impact of outlier individual months, especially at the start of the record and as each new month is added.
As well, my previous Pause criterion (a linear trend of less than +0.01 degree Celsius / 100 years) has been too strict. While UAH data are to two decimal places, the uncertainty range is +/- 0.1C. Accordingly, for 2016 my Pause criterion will be a trend of less than +0.1C per 100 years. (This is still far too lenient on Global Warming Enthusiasts- compared with trends above 1C per 100 years, anything below about +0.3C is an embarrassing slowdown.) Further, it is important to be transparent. All available data should be shown, not just those that create The Pause.
Finally I note, thanks to Christopher Monkton, that

In 2008, NOAA’s report on the State of the Global Climate, published as a supplement to the Bulletin of the American Meteorological Society, said: “The simulations rule out (at the 95% level) zero trends for intervals of 15 yr or more, suggesting that an observed absence of warming of this duration is needed to create a discrepancy with the expected present-day warming rate.”

A look at some of the graphs shown below will show why this is a valid statement. Certainly trends of 10 to 15 years give an indication of what has been happening, but I will agree that 15 years is about the length of time needed for trend values to settle without too much undue impact from the short term fluctuations in recent values.
Let’s begin.
Fig. 1: Running linear trend values in degrees Celsius per 100 years in Global UAH TLT anomalies from December 1978 to December 2015 (12 month means)

Trend whole
The plot shows the value of the linear trend from any given month to the most recent.
It should be plainly obvious that trends constructed from less than 10 years of data are spectacularly meaningless. This is weather.
The trend for the whole data series is about +1C/ 100 years.
The trend line crosses the zero value in 1997-98, so The Pause starts there.
Now I reduce the scale, and demonstrate how the graph may be interpreted.
Fig. 2: Running trend in degrees Celsius per 100 years in Global UAH TLT anomalies from December 1978 to December 2015 (12 month means)

Trend globe all

The trend for the entire record is +1.11C per 100 years.
A higher bounce in the trend indicates that earlier Temperatures were cooler relative to recent values, and a lower trend, a dip, the reverse. If recent temperatures are low enough compared with past values, the trend will reduce to zero or below, as it has above.
I have drawn a horizontal line showing +0.1 C, below which the trend cannot be distinguished from zero, unless it is below -0.1, in which case it is definitely negative.
The trend line crosses +0.1C in 1997. I have drawn in a horizontal black line from 2015 back to this point showing the length of The Pause. I can now refer to my spreadsheet table to find the exact month for the commencement of The Pause- April 1997- and graph it.
Fig. 3: UAH v6.0 anomalies for the Globe in blue, with data since April 1997 in orange.

Globe graphs all

The Pause is highly dependent on the El Nino generated 1998-99 spike. However showing the whole record makes the following plateau plainly obvious.
Now, what about the mysterious disappearing Northern Hemisphere Pause? In graphs of 12 month means, it’s back!
Fig. 4: Running trend in degrees Celsius per 100 years in Northern Hemisphere UAH TLT anomalies from December 1978 to December 2015 (12 month means)

Trend NH all

Of course, this is very much dependent on values in the next few months, as it will probably disappear again!
You will note the series of bumps and dips in the trend values. The small upward bounces coincide with cooling events such as La Ninas or explosive volcanoes, while the dips coincide with warming events such as El Ninos.
So, we have a Northern Hemisphere Pause again, if only briefly, and Global Warming Enthusiasts will surely accuse me of cherry picking. But remember, values will continue to be applied to the right hand end.
Fig. 5: UAH v6.0 anomalies for the Northern Hemisphere with the whole series in blue, and with data since October 1997 in orange.

NH graphs all

The next graph illustrates how using 12 month means can alter the Pause length. Monthly data had Australia’s Pause lasting for 18 years and 1 month, but this has shortened to 15 years and 3 months (which still meets NOAA criteria).
Fig. 6: Running trend in degrees Celsius per 100 years in Australian UAH TLT anomalies from December 1978 to December 2015 (12 month means)

Trend Aust

As the next graph shows, the Australian Pause starts from near the bottom of a La Nina cooling. No cherry picking there.
Fig. 7: Australian crawl: UAH v6.0 anomalies for Australia with the whole series in blue, and with data since October 2000 in orange.

Aust graphs all

I’ll conclude with a warning that as each month’s data point is appended, the trend graph will change (unlike temperature graphs where all past data points are fixed.) Don’t be confused by this- we are simply re-calculating linear trends.

Earth and Water

January 13, 2016

Graphs of The Pause are valuable as a means of confounding Global Warming Enthusiasts by showing how little temperatures have increased in the past couple of decades, but there are many other gems in monthly Temperature of the Lower Troposphere (TLT) anomalies. In this post I take a different look at monthly data using UAH v.6.0 for various regions.
Click on images to expand them.
First, here is the complete TLT record for the globe from December 1978 to December 2015.

Globe all
A trend of +1.14C/ 100 years, although anomalies have definitely flattened (the Pause) since about 2002.
But here are the Land and Ocean data separately:

Global land

Global ocean

Due to the oceans’ greater thermal inertia, it is to be expected that land areas would warm faster than oceans in any warming scenario no matter its cause. The Pause remains as well.
Notice the arrow at the beginning of 1998, marking the spike of the 1997-98 El Nino.  Note that the Land data after this are flatter and slightly stepped up from the data before this. The Ocean data give no hint of this, where since June 1994 the trend has been less than +0.1C (+/- 0.1C) per 100 years. Globally, Oceans have contributed nothing to global warming for well over half the satellite era.
Is this step change evident in other Land regions?

Northern Hemisphere:

NH land
Southern Hemisphere:

SH land
There is no sign of a step change in these data.   The step change is limited to the Northern Hemisphere.

Trop land

There is a flattening in the Land data from about 2001-2002, but no apparent step change.  The step change is limited to the Northern Hemisphere, but outside the Tropics.

North Polar:

NP land
No step change in 1998, although temperatures began changing in the mid-1990s.
Therefore, the 1998 step change must be in the data from the Northern Extra-Tropics (20-90 North), and specifically from 20N to 60N.

Nextr land

There’s the culprit. There is a clear discontinuity at the beginning of 1998. This graph shows it more clearly, with plots of data before and after this step change.

Nextr 2 parts
The whole record for the Northern Extra Tropics Land shows a linear trend of +2.04 degrees Celsius per 100 years. But the trend for the first half of the record (229 out of 445 months) is only +0.6C/ 100 years, and for the past 18 years only +0.36C/ 100 years. The rapid rate of warming overall is largely due to a step change in early 1998.
Here is the plot for the Northern Extra Tropics Ocean data:

Nextr ocean
The step change is not clearly defined, but the trend change is dramatic: +0.84C/ 100 years to zero.
This graph shows Land and Ocean data on the one plot, together with mean temperatures for both of them before and after the step change. The scale has been changed to highlight the differences.

Nextra land and ocean
Land data steps up by +0.48C and Ocean data by +0.26C.
What have we learnt?
The different behaviours of Land and Ocean data suggest that global warming trends are difficult to interpret.
Land TLT is warming faster than Ocean TLT.
North of 20S, Tropical and Northern Extra Tropical Land TLT data show warming above +2C, nearly 50% more than Southern Extra Tropical Land. (There is not much land compared with water south of 20S).
Global warming, by whatever cause, is dominated by Land warming, and by the Northern Hemisphere (which has most of the land area).
Warming in the Northern Hemisphere is dominated by a step change of nearly +0.5C at the beginning of 1998 in data for the Lower Troposphere over Land areas between 20N and 60N- by far the largest Land area on the planet, and the most heavily populated and industrialised region.
Significantly, this warming step change also contributed to the Pause, as temperatures since then have flattened.
We live in interesting times. Indeed, we are on the cusp of finding, over the next 4 to 5 years, whether the Pause has been a temporary slowdown as temperatures step up to a higher level, a longer period of levelling temperatures, or a brief plateau before a cooling phase.

The Pause: Further Update December 2015, including Northern Hemisphere

January 9, 2016

Complete UAH v6.0 data for December for all regions were released yesterday- sooner than I expected! Here are graphs for the remaining regions showing the furthest back one can go to show a zero or negative trend (less than +0.01C/ 100 years) in lower tropospheric temperatures. (See my previous post for Global, Southern Hemisphere, and Tropical regions). Note: The satellite record commences in December 1978. The entire satellite record is now 37 years 1 month long- 445 months.


Tropical Oceans:

dec tropic ocean
One month shorter.

North Polar:

dec NP
The Pause has lengthened again, by 10 months.

South Polar:

dec SP
For the whole of the satellite record, the South Polar region has had a negative trend. So much for a fingerprint of warming due to the enhanced greenhouse effect being greater warming at the Poles!


dec Aus
No change.

USA 49 states:

dec USA
No change.

Northern Hemisphere:
Now, about the disappearance of the Pause in the Northern Hemisphere- here’s a curious thing. While there is no Pause overall, Northern Hemisphere Land data do show a Pause, albeit short:

dec NH Land
Only 6 years 6 months- but still a pause. Northern Hemisphere Ocean data show a much more impressive Pause:

dec NH Ocean

18 years and 11months. So the Pause hasn’t disappeared- it’s just hiding in the ocean!
In my next post, later today or tomorrow, I’ll compare Land and Ocean data for various other regions.

The Pause: Interim Update December 2015

January 6, 2016

UAH v6.0 data for December were released last night.  Here is an interim post with updated graphs for some regional data (Globe, Southern Hemisphere, Tropics) as released by Roy Spencer, showing the furthest back one can go to show a zero or negative trend (less than +0.01C/ 100 years) in lower tropospheric temperatures.   For the third month of the climb towards the El Nino peak, there is still NO pause in the Northern Hemisphere trend.  Note: The satellite record commences in December 1978.  The entire satellite record is now 37 years 1 month long- 445 months.



dec Globe

The length of the Pause has remained the same, with zero trend for one month short of half the record.  While CO2 has increased by 37 ppm, energy consumption by 187 billion tons of oil equivalent, and population by 1.3 billion people, temperatures have remained flat.

Northern Hemisphere:  No Pause

Southern Hemisphere:

dec SH

The Pause has shortened by four months.  For more than half the record the Southern Hemisphere has zero trend.


dec tropics

The Pause has shortened again as the El Nino peaks, but is still more than half the record.

The remaining charts will be posted when data for the remaining regions are released later in the month.


Rain and Surface Temperature Part 3

December 2, 2015

I have recently shown how the difference between surface maxima for Northern Australia and Temperature of the Lower Troposphere (TLT) for Australia as a whole is very largely due to rainfall variation in the Northern Australian region alone.
Fig. 1:  Northern Australian rainfall compared with the difference between North Australian surface maxima and Australian TLT (120 month means)

Nth rain v nth diff 120m
Now I turn to comparison with another region: that of Tropical Land.  All but six degrees of Latitude of the Northern Australian region is in the tropics, so most of it will be covered by TLT for Tropical Land. How much influence does Northern Australian rainfall have on the difference between Northern Australian surface maxima and TLT for all land in the tropics around the globe?
Fig. 2: Northern Australian rainfall compared with the difference between North Australian surface maxima and Global Tropical Land TLT (12 month means)

Nth rain v tropic land diff 12m

Fig. 3: Northern Australian rainfall compared with the difference between North Australian surface maxima and Global Tropical Land TLT (decadal means)

Nth rain v tropic land diff 120m

Considering that the Tropical Land TLT measures temperature above large tracts of Africa, South Asia, and Central and South America as well as tropical Australia, this result is amazing: on a decadal timescale, Northern Australian rainfall variation alone accounts for the same proportion of the surface- tropospheric difference of northern Australia surface maxima- Australia TLT as northern Australia surface maxima- tropical land TLT.

Surface temperatures cannot be understood separately from rainfall, and especially tropical rainfall. We can also conclude that as the decadal comparison of North Australian rain and surface-atmospheric differences have similar results for both Australia and Tropic Land datasets, UAH Version 6.0 represents TLT in various regions very well. Further, if the rest of the world’s tropical land areas behave as Australia does, then the world’s climate is dominated by tropical rainfall.