Archive for the ‘temperature’ Category

Land and Sea Temperature: South West Australia Part II: TMin

November 29, 2016

This is a quick follow up to my last post, as an update:  I’ve been reminded to show Tmin as well.   My apologies.

In this post I examine minimum temperature for Winter in South-Western Australia, and Sea Surface Temperature data for the South West Region, all straight from the Bureau of Meteorology’s Climate Change time series page .

All temperature data are in degrees Celsius anomalies from the 1961-90 average.

Fig. 1:   Southwestern Australia Winter TMin Anomalies & SST

sw-tmin-sst

Note that TMin roughly matches SSTs, but there are differences from TMax.  CuSums will show this:

Fig. 2:  CuSums of Winter TMin and SST compared:

sw-tmin-cusums

Note that TMin has completely different change points, marked in red.  The major different ones are at 1949, 1956, 1964, 1990, 2000, and 2010.  There is a barely discernible point at 1976 (not 1975), so the next plots will use 1976 to show trends since then.

Fig. 3:  Trends in TMin:

sw-tmin-trends

Cooling since 1976 at -0.36C/100 years.

Detrending the data allows us to see where any of the winters “bucks the trend”.  In the following plots, the line at zero represents the trend as shown above.

Fig. 4:  TMin Detrended:

sw-tmin-detrended

2016 winter TMin is 0.5C below trend, and 0.38C below average, however winter this year in southwest WA was not as cold as 1986, 1990, 2001, 2006, 2008, or 2010- according to Acorn of course.

The action is with TMax.

Poles Apart

November 4, 2016

Satellite data from UAH (University of Alabama- Huntsville) are estimates of temperature in the Lower Troposphere, and thus a good indicator of whether greenhouse warming is occurring.  My next post about the length of The Pause in various regions will be ready in a few days’ time.  Meanwhile, I’ve been looking at the data in a different way.

In this post I will be examining how and when temperatures have changed in discrete regions of the globe, including over land and over oceans.  There are no startling revelations, but a different approach reinforces the need to understand climate variability in different regions.  The important regions of course are the Tropics and the Poles, and fortunately UAH data is available separately for just these three regions.

Firstly, Figure 1 shows the regions for which UAH has atmospheric data.

Fig. 1:  UAH Data Regions

regions

The Northern and Southern Extra-Tropics include the Polar regions, so there are three discrete regions which do not overlap: Tropics, North Polar, and South Polar.  It would be very helpful if Dr Spencer provided data for the Extra Tropical regions excluding the Polar Regions.

For this analysis I use CuSum, which is a simple test of data useful for detecting linearity or otherwise, and identifying sudden changes in trend, or step changes.  It can be used for any data at all- bank balance, car accidents, rainfall, GDP, or temperature.  It is simple to use:  find the mean of the entire data, calculate differences for every data point from this mean, then calculate the running sum (Cumulative Sum) of the differences.  If done correctly, the final figure will be zero.  Plot the CuSum usually by time and identify points of any sudden change in direction.  A generally straight or smoothly curving line indicates linearity, but points of sudden change mean a change in trend or a step change.  (Further, data series with identical start and end points, exactly the same number of data points, and anomalies from the same period- such as UAH- should produce directly comparable CuSums.)  These points, and ranges between them, are then checked in the original data. The usefulness of CuSums will become obvious as we go, especially as they are compared.

The next figures show CuSum plots for various regions.

Fig. 2:  UAH CuSums for all regions

cusums-all

Points to note:

The brown line at the top is the South Polar region.  The line wobbles about zero, indicating little relative change in temperature from the mean.  Contrast this with the North Polar region (the blue line at the bottom.)  The Polar regions are conspicuously different from the other regions and from each other.

The spaghetti lines clustered in the middle are CuSums for (in order from top to bottom): Southern Extra-Tropics; Southern Hemisphere; Tropics; Globe; Northern Hemisphere; Northern Extra-Tropics.

The red arrows point to wobbles coinciding with major ENSO events.  These changes in direction indicate trend changes or step changes in the original data.  There are other changepoints, notably 2002-2003.

The vertical red line joins changepoints in all the CuSums in mid-1991 following the eruption of Mt Pinatubo.

Fig. 3: UAH CuSums for the Tropics, South Polar, and North Polar regions

cusums-np-sp-tropics

Note there is little similarity between CuSums for the only regions with discrete data, and you have to look carefully to see North Polar CuSums changing some months after Tropics, but not always.

The next plots show the differing responses of Land and Ocean areas.

Fig. 4:   UAH CuSums for the Globe, Land and Ocean

cusums-land-ocean

Note that Land areas have greater relative temperature changes than the Oceans, and that the Global mean closely mirrors the Ocean CuSums (as the Globe is mostly Ocean).  The major turning point is in 1997-98.

Fig. 5:  UAH CuSums for the Tropics, Land and Ocean

cusums-tropics-land-ocean

Note once again the mean CuSums closely follow that of the Ocean as 20 degrees North to 20 degrees South is mostly water.  The changepoints are very distinct.

Fig. 6:  UAH CuSums for the North Polar region, Land and Ocean

cusums-np-land-ocean

Note that all CuSums are close, but after 1982 Ocean CuSum changes relatively more than Land- the blue line has switched to below the mean.  The main changepoints are 1991, 1993-94, 2002, 2009, and 2015.

Fig. 7:  UAH CuSums for the South Polar region, Land and Ocean

cusums-sp-land-ocean

Now that is interesting.  Note all three CuSums have similar changepoints, but Land varies more than Ocean and after 1992 Land is largely negative, Ocean is largely positive.  The Land CuSum range is about half of the North Polar equivalent.

Remember CuSums in Figure 4 showed Land temperatures must vary more than Ocean (though not in the North Polar region).  The next figures show plots of UAH original data (not CuSums).

Fig. 8:  UAH original data for the Globe, Land and Ocean

graphs-globe-land-ocean

I find a visual representation demonstrates greater relative variation in Land temperatures well.

Fig. 9:  UAH original data for the Tropics, Land and Ocean

graphs-tropics-land-ocean

Note much greater fluctuation with ENSO, and Land varying a little more that Ocean.

Fig. 10:  UAH original data for the North Polar region, Land and Ocean

graphs-np-land-ocean

Note the much greater variation, but Land is more often than not masked by Ocean.

Fig. 11:  UAH original data for the South Polar region, Land and Ocean

graphs-sp-land-ocean

Note the much greater range in Land data, with large non-linear multi-year swings- calculate a linear trend for Land at your peril.

Having found changepoints, we can now analyse periods between them.  One way is to calculate means, and step changes between periods.

Fig. 12:  UAH original data for the Tropics based on CuSum changepoints

steps-tropics

I deliberately ignored the 2001 changepoint- it made very little difference to means and appears to be a continuation of the series starting in 1997.  Note the step changes are very small, and the final step change is reliant on current data and will change.  While I have shown means and steps, the data are decidedly non-linear with sharp spikes and multi-year rises and falls.

Fig. 13:  UAH original data for the North Polar region based on CuSum changepoints

steps-np

Note the large step change in the mid-1990s occurs before the 1997-98 El Nino.  The range is much greater than the Tropics.

As the Land data for the South Polar region looks more interesting, I decided to use Land instead of the mean.

Fig. 14:  UAH original data for the South Polar region (Land data) based on CuSum changepoints

steps-sp-land

Up and down like a toilet seat!

Conclusions:

The data series are characterised by step changes and multi-year rises and falls.

The Polar regions are “poles apart” in their climate behaviours.  Explanations might include: different geography (an ocean almost surrounded by land but subject to warming and cooling currents vs a continent isolated from the rest of the world by a vast ocean); different snow and ice albedo responses; different cloud influences.

The Global mean combines data from regions with very different climatic behaviour.  Averaging hides what is really going on.  The Tropics are governed by ENSO events, and the Poles are completely different.

Please Dr Spencer can you provide separate data for 20-60 degrees North and South?

Comments and interpretations are most welcome.

When Tmax and Tmin Are Poor at Describing Weather

October 25, 2016

Last Sunday was a miserable day in Rockhampton- overcast with drizzling rain and cold all day.  Mean maximum for October is 29.7 degrees, so the maximum reported by the Bureau of 20.4 was 9.5 degrees below average, as expected.  However, that does not tell you anything like the whole story.

Here is the temperature graph from the Bureau for the period midday Saturday to midday Tuesday.  The solid horizontal line shows the duration of Sunday 23rd, and the thin black vertical lines show 9.00 a.m., which is the time when the daily minimum and the previous day’s maximum are recorded.   Temperatures at recording times are circled.

rocky-temp-23-oct

On fine, clear days, minima usually occur around sunrise and maxima in the early afternoon: you can see this on the 22nd, 24th, and (almost) on the 25th.  Sunday 23rd was wet.  As you can see the temperature was falling fairly steadily from Saturday afternoon until Monday morning.   The maximum for Sunday was 22.7 at midnight, and the coldest temperature on Sunday was 14.3 from 7.30 p.m. to 9.00 p.m. on Sunday night- not the 17.6 at 9.00 a.m.   The official maximum for Sunday of 20.4 degrees was actually the temperature at 9.00 a.m. on Monday!

So what was the Diurnal Temperature Range?  Was 20.6 (or 22.7) a good representation of how high the temperature “rose”?  The temperature in the early afternoon varied between 15 and 16.4, and this was about 14 degrees below normal for this time of the year (and two to three degrees below the official lowest maximum of 18.1 on 10th October 1982).

Which is one reason I don’t take a lot of notice of claims of hottest or coldest extremes.

The Pause Update: September 2016

October 18, 2016

The complete UAH v6.0 data for September have just been released. I present all the graphs for various regions, and as well summaries for easier comparison. The Pause has finally ended globally and for the Northern Hemisphere, and the Tropics, but still refuses to go away in the Southern Hemisphere.

These graphs show the furthest back one can go to show a zero or negative trend (less than 0.1 +/-0.1C per 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 10 months long- 454 months. 12 month running means commence in November 1979. The y-axes in the graphs below are at December 1978, so the vertical gridlines denote Decembers. The final plotted points are September 2016.

[CLICK ON IMAGES TO ENLARGE]

Globe:

pause-sep16-globe

The Pause has ended. A trend of +0.18 C/100 years (+/- 0.1C) since March 1998 is about one sixth of the trend for the whole record.

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:

pause-sep16-globe-monthly

Northern Hemisphere:

pause-sep16-nh

The Northern Hemisphere Pause has ended.

Southern Hemisphere:

pause-sep16-sh

For well over half the record, the Southern Hemisphere still has zero trend.  The Pause may end shortly.

Tropics:

pause-sep16-tropics

As expected, the Pause in the Tropics (20N to 20S) has ended.

Tropical Oceans:

pause-sep16-tropic-oceans

The Pause remains (just) for ocean areas.

Northern Extra Tropics:

pause-sep16-next

The minimal trend is creeping up- how high will it go before decreasing again?

Southern Extra Tropics:

pause-sep16-sext

The Pause is one month longer.

Northern Polar:

pause-sep16-np

Another big increase in temperature in this region but the minimal trend is still one seventh that of the whole record.

Southern Polar:

pause-sep16-sp

The South Polar region has been cooling for the entire record- 36 years 11 months.

USA 49 States:

pause-sep16-usa49

One month shorter.

Australia:

pause-sep16-oz

No change.

The next graphs summarise the above plots. First, a graph of the relative length of The Pause in the various regions:

pause-length-sep16

Note that the Pause has ended by my criteria in all regions of Northern Hemisphere, and consequently the Globe, and the Tropics, but all southern regions have a Pause for over half the record, including the South Polar region which has been cooling for the whole record.

The variation in the linear trend for the whole record, 1978 to the present:

trends-78-now

Note the decrease in trends from North Polar to South Polar.

And the variation in the linear trend since June 1998, which is about halfway between the global low point of December 1997 and the peak in December 1998:

trends-jun-98-sep-16

The imbalance between the two hemispheres is obvious. The lower troposphere over Australia has been strongly cooling for more than 18 years- just shy of half the record.

The next few months will be interesting. The Pause may disappear from the Southern Hemisphere soon. How long will the Pause last in the Southern Extra Tropics and South Polar regions?  ( I would like to see separate data for the Extra-tropical regions from 20 to 60 degrees north and south.)

Temperature Variation Due to ENSO

July 25, 2016

In this post I use the Multivariate ENSO Index (MEI) supplied by NOAA at http://www.esrl.noaa.gov/psd/enso/mei/index.html and lower tropospheric temperature data supplied by UAH to show how much of temperature variation over the past 20 years is due to ENSO and how little is due to CO2.  I will keep words brief and let graphics do the talking.

Firstly, here is the MEI data from 1950:

Fig. 1:  Monthly MEI from 1950

mei monthly

As an aside, this is how it compares with SOI data.  The SOI is inverted and both are scaled for comparison.

Fig. 2:  MEI compared with SOI inverted

mei vs soi

Now compare scaled MEI with Global UAH:

Fig. 3: MEI (scaled) and UAH

mei monthly w uah

Notice tropospheric temperatures appear to lag the MEI by some 5 months:

Fig. 4: MEI advanced 5 months and UAH

mei monthly advd 5m w uah graph

Notice both datasets are noisy, and there is a clear discrepancy in the early 1990s.  12 month running means show this more clearly:

Fig. 5:  12 month means of UAH and MEI advanced 5 months:

mei advd w uah 12m

The slump in UAH data is shown by the arrow.  Mt Pinatubo’s main eruption was in June 1991. (Without El Chichon in 1982, there may well have been a much higher spike in the mid-1980s).

Now let’s look at the correlation between monthly MEI and UAH.  Firstly, the whole period from December 1978:

Fig. 6:  UAH vs MEI advanced 5 months 1978 – 2016

mei monthly advd 5m w uah

About 13% of temperature variation is associated with MEI variation.  Doesn’t tell us much does it.  What if we exclude the UAH data for two years from April 1982, and from July 1991 to December 1995?

Fig. 7:  UAH vs MEI advanced 5 months 1978 – 2016 with periods after volcanic eruptions excluded

mei monthly advd 5m v uah excl volcanoes

Considering the fluctuations in both datasets, that shows a fairly strong correlation.

Next, we examine the periods, before, during, and after the Pinatubo influence.

Fig. 8:  :  UAH vs MEI advanced 5 months December 1978 – June 1991, excluding April 1982 to March 1984

mei monthly advd 5m w uah 78-91

Again we see a similar correlation.

Fig. 9:  UAH vs MEI advanced 5 months July 1991 – December 1995

mei monthly advd 5m w uah 91-95.jpg

The strong positive correlation of the previous plots has broken down.

Fig. 10:  UAH vs MEI advanced 5 months January 1996 – June 2016

mei monthly advd 5m w uah 96-16

The correlation is even higher.  Over half of temperature variation is associated with ENSO variation five months previously.  Here is the same 1996-2016 plot but with 12 month running means:

Fig. 11  UAH vs MEI advanced 5 months January 1996 – June 2016, with 12 month running means

mei  advd 5m w uah 96-16 12m

74% of temperature variation for the past 20 years and 6 months can be explained by previous ENSO variation alone.  In the same period, carbon dioxide concentration at Mauna Loa has increased by 44.77 ppm, which is more than 49% of the entire increase from 1958, and Global temperature as measured by UAH has increased by a little over 0.1 degree C.

No wonder Global Warming Enthusiasts were pinning their hopes on the 2015-16 El Nino to put an end to the Pause, but they must also hope for the ENSO- temperature correlation to break down shortly, as a deep La Nina will mean cooler temperatures and further embarrassment for them.  However, the correlation breaks down when volcanoes cause lower temperatures in El Nino conditions as we have seen, but what mechanism could there be for higher temperatures in La Nina conditions?  Perhaps that magical greenhouse gas CO2?  That would indeed be spectacular- there are no outliers at the low end of any of the above plots.  The most UAH has been higher than expected with low MEI is about +0.2C to +0.3C, and those values cannot be described as outliers.  Besides, UAH for June is already down to +0.34C, and we are only four months past the peak- the cooling has barely begun.

Finally, this is a plot of the centred 37 month mean MEI (because La Ninas can last for three years).

Fig. 12: 37 month centred mean MEI

mei 37m avg

Notice that before 1975 the 37 month average never exceeded +0.5, the majority of the time was in negative territory, and in the 1950s and 1970s reached below -1.0.  Since 1975 the MEI has dropped below -0.5 only once in 2000 and approached -0.5 in 2012, but has been in positive territory for the vast majority of the time, exceeded +0.5 in six events, and was above +1.0 in the early 1990s.  It would be surprising if global temperatures had not seen a large increase.

How low will the monthly MEI go with the coming La Nina, and how low will the following global temperatures go?  All depends on La Nina’s length and strength, but the monthly MEI data are falling fast.  Stand by.

Temperature and Mortality

May 24, 2016

We are all going to die, nothing is surer. “Nobody knows the day or the hour”, but one thing is clear: we are more likely to die in winter than in summer.

Death by unnatural causes (suicide, accident, bushfire, disaster, even acute illness) can come to otherwise healthy people of any age. Death by natural causes is more predictable.

Those vulnerable to death are the elderly, very young babies, those with chronic illness (e.g. asthma, diabetes) and weakened immunity, and those with respiratory and circulatory illness.

Analysing mortality is made difficult because the sample population is always changing. Excess deaths in one month may be followed by further excess deaths in the following month, or because so many vulnerable people have already died, there will be fewer than expected deaths in the next month or months, or even the next couple of winters. Similarly, if fewer than expected deaths occur, there will be a larger cohort of the vulnerable in the following months, getting older and with probably poorer health. Population growth, aging, migration, improved vaccines, and public education programs all play a part as well.

In this analysis, I use mortality and population data from the Australian Bureau of Statistics (ABS), and temperature data from the Bureau of Meteorology (BOM), for Victoria, as it is a small and compact state which is subject to large temperature changes and also severe heat waves. Monthly mortality data are difficult to find, so this study is restricted to the period January 2002 to December 2011. A 10 year period is hardly sufficient for meaningful averages, however some useful insights can be found.

Mortality statistics are available by month, but population figures are by quarter, therefore I interpolated estimated monthly population figures based on three month growth.

Firstly, this plot shows the total deaths for every month from January 2002 to December 2011.

Fig. 1:

act D per mnth
Note the seasonal spikes and dips. The apparent increase in deaths can be compared with Victoria’s population increase:

Fig.2:

Population Vic
By dividing the total deaths by the population in thousands we can calculate the death rate:

Fig. 3:

Death rate per yr

Note the mortality rate has decreased, and that, in spite of heatwaves, bushfires, and flu pandemics, 2009 had a lower death rate than 2008.

Because months have varying numbers of days, a better analysis can be made by calculating the Daily Death Rate for each month (by dividing each monthly rate by 31, 30, 29, or 28 days).

Fig. 4:

mortality per month

For the state of Victoria for the 10 years to 2011, on average more deaths occurred for each day in August than for any other month. The lowest Daily Death Rate was in February.

Now compare with monthly averages (2002 to 2011) for maximum and minimum temperatures:

Fig. 5:

Tmax Tmin avg

The death rate peak lags July temperature by about a month. Cooler months (June to September) are deadlier than warmer (December to April).

The relationship with temperature can be shown with scatter plots:

Fig. 6:

DDR v Tmax

Fig. 7:

DDR v Tmin

Which merely reinforce that deaths are more likely in winter!

Now we look at the question of estimating how many deaths are likely in a given period, by multiplying the average daily death rate for each month by the number of days in each month and by the estimated total population for each month. By subtracting this figure from the actual number of deaths we get a mortality “anomaly”.  The following graph shows this anomaly for each year:

Fig. 8:

Act minus exp deaths per year

And each month:

Fig. 9:

Diff act minus exp Deaths per mnth

Note the peaks in the winters of 2002 and 2003, and also in the summer of 2008-2009. Note also that both graphs show that in spite of a killer heatwave, the Black Saturday bushfire, and the swine flu pandemic, deaths in 2009 were below what could be expected.

To put the anomaly for January 2009 into context, we can compare actual daily deaths per 1,000 population for all months from 2002 to 2011:

Fig. 10:

act daily D per mnth

Note that the extreme figure for January 2009, while extremely high for January, is still below those of the lowest extremes of June, July, and August.

Perhaps higher mortality in the winter months is coincidence and due to some other factor than temperature- seasonal flu incidence for example. I now look at the month of August with the highest average mortality rate:

Fig. 11:

Act minus exp deaths vs Tmin August

There is fairly decent correlation showing that for every degree warmer in minima, the August death toll will be around 150 less than expected.

February, with the lowest rate:

Fig. 12:

Act minus exp deaths vs Tmin Feb

Even in summer, warmer minima mean fewer deaths.

In summer, do higher maxima cause more deaths?

Fig. 13:

Act minus exp deaths vs Tmax Feb

Even including the 173 deaths in the Black Saturday bushfires in the 200 extra deaths for February 2009, there is no trend.

January, whose data include the 2009 heatwave:

Fig. 14:

Act minus exp deaths vs Tmax Jan

A very small trend, but the 2009 heatwave outlier is obvious and skews the data. (Victorian health authorities say there were 374 excess deaths in the week to 1 February 2009).

Extreme heatwaves are indeed killers. Normal hot summers up to two degrees above average are not.

Conclusion:

Improved public health measures, influenza vaccines, and improved public awareness – plus warmer winters- have led to a decrease in the Victorian mortality rate in the period 2002-2011.

Extreme heatwaves are dangerous in Victoria and cause hundreds of extra deaths especially amongst the elderly (>75 years old). However, these are rare events. Severe and Extreme Heatwaves are newsworthy precisely because they are unusual.

Normal Victorian winters are even more dangerous with on average 17.5% more deaths in winter than summer every year, but because this is normal and expected, this regular annual spike in deaths is unremarkable and not newsworthy- much less regarded as a natural disaster. While 374 excess deaths in a week in a heatwave is shocking, even with these included, the highest January’s Daily Death Rate (in 2009) is below that of the lowest of any winter month.

Warmer minimum temperatures are associated with lower death rates at all times of the year, but especially in August in Victoria, where for every degree of extra warmth, about 150 fewer deaths can be expected. I hope, for the sake of those who are sick or elderly, that we have a warm winter this year.

Antarctic Trends

April 17, 2016

Data from UAH Version 6.0 show the South Polar region to be unique in that it has a Pause, if not very mild cooling, for the whole of the satellite record, since December 1978. In this post I dig in a little deeper, and also look at surface data from Australia’s Antarctic bases.

Fig.1: Monthly TLT for the South Polar region (60- 85 S)

SP monthly

Fig. 2: Three Monthly TLT

SP 3m

Both plots show no evidence of any warming. However, Land areas are warming:

Fig. 3: SP Land: 3 month means

SP land 3m

While the Ocean area is cooling:

Fig. 4: SP Oceans: 3 month means

SP ocean 3m

Summers are warming:

Fig. 5: South Polar Summers (Yearly)

SP summer

While winters are cooling rapidly:

Fig. 6: South Polar Winters

SP winter

Especially Ocean winters, when the sea ice is at its greatest and thickest extent.

Fig.7:  SP Ocean Winters

SP ocean winter

Perhaps the sea ice insulates the atmosphere from the water below the ice? If so, in summer, with sea ice extent much reduced, the atmosphere above the ocean should be warmed much more than above the land, which is almost totally covered by ice. Let’s check:

Fig.8:  SP Ocean Summers

SP summer ocean

Fig.9:  SP Land Summers

SP summer land

Nope- TLT above land area is warming at four times the rate of ocean areas.

It’s not a great mystery. Here’s why.

We should not read too much into whether individual months create records or not, nor should we stress about the seasonal differences. Here’s an example of individual Octobers.

Fig.10: Octobers from 1979-2015

SP land october

Note the rising and falling pattern: a series of below average Octobers is followed by a series of above average Octobers.  A trend using only Octobers would show warming, as the record starts with below average Octobers and ends with above average. (Just like some global datasets!)

These patterns are evident, but with different values, in all months, which is why winters appear to be cooling and summers appear to be warming.

Fig.11:  SP Ocean Junes from 1979-2015

SP ocean junes

The most we can say is that the long term trend of ALL months shows no evidence of any warming, i.e. a Pause.

So is this just an artefact of the fairly short satellite record? We can check against surface data from Australia’s Antarctic stations at Mawson and Davis. (There is insufficient overlap to make a useful splice between closed and open sites at Casey.) These stations are on the coast far from the Antarctic Peninsula.

Fig. 12:  Monthly mean temperatures, Mawson Base

mawson mean

There is a Pause, or slight cooling, over the past 62 years.

Fig. 13: Monthly mean temperatures, Davis Base

davis mean

At Davis, a Pause, or slight warming, over the past 47 years.

The Pause in the South Polar region is real.

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

February 12, 2016

UPDATE:  PLEASE NOTE UAH DATA FOR THIS POST ARE FROM 6.0 BETA 4.  BETA 5 WILL GIVE DIFFERENT RESULTS.

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.

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.
 
Tropics:

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: November 2015 Update

December 18, 2015

UAH v6.0 data for November were released a couple of days ago.  Here are updated graphs for various 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.   For the second month of the climb towards the El Nino peak, there is still NO pause in the Northern Hemisphere trend.  However, in some regions the pause has lengthened.  Note: The satellite record commences in December 1978.  The entire satellite record is now 37 years long- 444 months.

[CLICK ON IMAGES TO ENLARGE]

Globe:

nov globe

There has been zero trend for exactly half the record, (and for an increase in CO2 concentration of 37 ppm).

Northern Hemisphere:  No Pause

Southern Hemisphere:

nov SH

The Pause has lengthened again.  For more than half the record the Southern Hemisphere has zero trend.

Tropics:

nov tropics

The pause has shortened significantly.

Tropical Oceans:

nov tropic oceans

Unchanged from last month.

North Polar:

nov N Pol

The Pause has lengthened by two months.

South Polar:

nov S Pol

At -0.11C/ 100 years, the cooling trend is now undeniable.  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!

Australia:

nov aus

No change.

USA 49 states:

nov usa

One month longer!

The Pause lives!