Posts Tagged ‘greenhouse gases’

Another Inconvenient Pause

January 15, 2019

The Pause in global temperatures may be past, but here is another, longer Pause, and one that is much more difficult to explain: at ideal Australian sites, increasing greenhouse gas concentrations have led to a decrease in downwelling longwave radiation- the very opposite of expectations.

Basically, the theory behind the enhanced greenhouse effect is that the increase in concentrations of anthropogenic greenhouse gases leads to an increase in downwelling infra-red (IR) radiation, which causes surface warming.

Is there evidence for increasing downwelling IR in recent years, as atmospheric concentration of carbon dioxide has been rapidly rising?

The authors of Skeptical Science think so:

Surface measurements of downward longwave radiation

A compilation of surface measurements of downward longwave radiation from 1973 to 2008 find an increasing trend of more longwave radiation returning to earth, attributed to increases in air temperature, humidity and atmospheric carbon dioxide (Wang 2009). More regional studies such as an examination of downward longwave radiation over the central Alps find that downward longwave radiation is increasing due to an enhanced greenhouse effect (Philipona 2004).

Time for a reality check.

The links in the above quote do not work for me, so I use data available for Australia.

Greenhouse gas concentrations are measured at Cape Grim in north-west Tasmania.  According to the CSIRO,

The Cape Grim station is positioned just south of the isolated north-west tip (Woolnorth Point) of Tasmania. It is in an important site, as the air sampled arrives at Cape Grim after long trajectories over the Southern Ocean, under conditions described as ‘baseline’. This baseline air is representative of a large area of the Southern Hemisphere, unaffected by regional pollution sources (there are no nearby cities or industry that would contaminate the air quality).

Fig. 1:  Cape Grim Baseline Air Pollution Station (looking almost directly south)

c grim photo

Fig. 2:  CO2 concentration, Cape Grim.

co2 c grim

Fig. 3:  Methane concentration, Cape Grim.

ch4 graph

Fig. 4:  Nitrous oxide concentration, Cape Grim.

n2o graph

There is no doubt that concentrations of greenhouse gases have been increasing.  We should therefore expect to see some increase in downwelling longwave radiation.

Downwelling IR data are available from the Bureau of Meteorology which maintains a database of monthly 1 minute solar data from a network of stations around Australia, including Cape Grim.

What better location than Cape Grim to study the effects of greenhouse gas concentrations from month to month on readings of downwelling IR.  The instruments are within metres of each other under “baseline” conditions at a pristine site.

The data include 1 minute terrestrial irradiance (i.e. downwelling IR striking a horizontal surface) from which I calculated mean daily IR for each month.  To remove the seasonal signal, I calculate anomalies from monthly means.

Fig. 5:  Downwelling longwave radiation anomalies, Cape Grim.

ir over time capegrim

Oops! IR has been decreasing for the full length of the record, 20 years (May 1998 to June 2018).   And monthly IR anomalies plotted against monthly CO2 anomalies show a similar story:

Fig. 6:  Downwelling longwave radiation anomalies, Cape Grim.

ir vs co2 cgrim

In the most suitable location in Australia, from May 1998 to June 2018 there has been no increase in downwelling infra-red radiation, despite an increase of 41.556 ppm atmospheric concentration of carbon dioxide, 104.15 ppb of methane, and 14.472 ppb of nitrous oxide.

So what factors do influence downwelling IR and thus surface warming or cooling?  Together with solar radiation, that other greenhouse gas, H2O.  Gaseous H2O (humidity) and clouds formed of liquid and ice H2O are by far the major players in returning heat to the surface.

We see this in a plot of downwelling IR against cloudiness (from nearby Marrawa).

Fig. 7:  Downwelling IR anomalies vs Cloudiness, Cape Grim.

ir vs cloud capegrim

Daytime cloudiness (an average of observations at 9.00 a.m. and 3.00 p.m.) increases downwelling IR.  We have no data for night time cloudiness unfortunately.

To illustrate the irrelevance of carbon dioxide, here is a plot of anomalies of solar radiation (global irradiance), downwelling infra-red radiation, daytime cloudiness, and carbon dioxide concentration at Cape Grim over the past 20 years.

Fig. 8:  Anomalies of IR, Global Irradiance, CO2, and Daytime Cloud at Cape Grim 1998-2018

98 to 18 full range capegrim ir global co2 cloud anoms

And zooming in on 2008 to 2010:

Fig. 9:  Anomalies of IR, Global Irradiance, CO2, and Daytime Cloud at Cape Grim 2008-2010

98 to 18 2008 2010 capegrim ir global co2 cloud anoms

There is a feedback mechanism: cloudiness inhibits daytime temperature and increases IR and nighttime temperature; decreased cloudiness means decreased IR; but less cloud and higher daytime temperature will increase IR as well if sustained; and higher IR also increases daytime temperature.  Further, sustained decrease in global radiation due to increased cloud cools the surface, thus decreasing IR.

Carbon dioxide concentration changes have no detectable effect.

A desert location, where humidity is typically very low and rain and cloudiness very infrequent, would also be ideal for checking on downwelling IR from carbon dioxide.  Alice Springs in the central desert is such a location with available irradiance data.

At Alice Springs as well, since March 1995 downwelling IR has been decreasing.

Fig. 10:  Downwelling longwave radiation anomalies, Alice Springs.

ir over time alice

The relationship between cloud and IR is even more evident.

Fig. 11:  Anomalies of IR, Global Irradiance, CO2, and Daytime Cloud at Alice Springs 2008-2010

2008 2010 alice ir global co2 cloud anoms

Fig. 12:  Downwelling IR anomalies vs Cloudiness, Alice Springs.

alice ir v cloud

Cloudiness has an even greater influence on IR in desert than maritime locations.

TAKE AWAY FACT:-  For over 20 years, at what are arguably the most suitable sites in Australia, increasing greenhouse gas concentrations have had no detectable effect on downwelling longwave radiation.  Natural factors including cloudiness changes have vastly overwhelmed any such effect and have instead led to a decrease in downwelling longwave radiation.

That is indeed a most inconvenient pause.

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To replicate these findings:

Go to http://reg.bom.gov.au/climate/reg/oneminsolar/index.shtml

You will need to register with a username and password.  Then click on an irradiance observation station.  Select year and month.  Download the zip file, and open in your preferred application.  (I use Excel).  IR data are in Column W- the values are wattminutes of IR striking a horizontal surface of area one square metre.

My method:  Order the data in ascending order to remove null values.  Count the minutes of valid data and calculate the percentage valid of all possible minutes in that month.  (I discard months with less than 80% valid data.)   Divide the total minutes by 1,440 to convert to days.  Sum the valid data and divide by 60,000 to find kilowatthours; divide by the number of days to find the mean daily value; then multiply by 3.6 to convert to Megajoules.  Plot monthly values against time or carbon dioxide concentration.

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The Chicken or the Egg?

May 3, 2018

Climate scientists assert that increasing concentrations of carbon dioxide and other greenhouse gases in the atmosphere have caused and will continue to cause global temperature to increase.  Real world evidence to support this is sadly lacking.

I use CO2 data from NOAA at Mauna Loa and HadSST3  Sea Surface data to compare both over the same period, as oceans cover most of global surface.

There have been 60 years of continued and accelerating CO2 increase.

Figure 1: 60 years of carbon dioxide concentration

CO2 abs trend

Ocean temperatures have also increased:

Figure 2:  HadSST3 Sea Surface Temperature from 1958

Hadsst3

While you may note the distinct lack of warming before the mid 1970s, and that although a quadratic trend line fits the data, the increase is not smooth but a series of steps with some large spikes at about the time of ENSO events, climate scientists insist that it is the overall trend that is important.

The following plot appears to support the greenhouse warming theory.

Figure 3:  Global Sea Surface Temperature anomalies as a function of CO2 concentration

SST vs CO2

It seems that nearly three quarters of the temperature change since 1958 can be explained by the increase in CO2 concentration.  This accords with the theory.

But what if we reverse the axes in Figure 3?

Figure 4:  CO2 concentration as a function of Sea Surface Temperature anomalies

CO2 vs SST

It is equally valid to propose that nearly three quarters of the increase in carbon dioxide concentration can be explained by increasing sea surface temperatures, although that is not the point of this exercise.

To determine if CO2 is the cause of increasing temperature, or vice versa, we need to compare SST anomalies and CO2 concentration as a function of time.  If SST and CO2 both change at the same time, we are no further advanced, but if CO2 changes before SST (due to thermal inertia of the oceans), then that would be evidence for CO2 increase being the driver of temperature increase.

Both CO2 concentration and SST anomalies have pronounced trends, so for comparison both datasets are detrended, and the large seasonal signal is removed from CO2 data to calculate monthly “anomalies”.

Remember, it is increasing CO2 which is supposed to cause increasing temperature, not a static amount, so change in CO2 and SST must be our focus.

My measure of change in SST and CO2 is 12 monthly difference: for example January 2000 minus January 1999.  The next plot shows 12 monthly difference in both SST and CO2 anomalies from 1959 to 2018.  (SST is scaled up for comparison).

Figure 5:  12 monthly change in detrended SST and CO2 anomalies

12m chg Hadsst3 co2

SST appears to spike before CO2.  In the next plot, SST data have been lagged by seven months:

Figure 6:  12 monthly change in detrended SST (lagged 7 months) and CO2 anomalies

lagged 7m 12m chg Hadsst3 co2

There appear to be differences in some decades- the lag time varies from four months to eight or nine months.

Here’s the plot of CO2 vs lagged SST:

Figure 7:  12 month change in CO2 as a function of 12 month change in SST, lagged 7 months

lagged 12m SST vs CO2

Correlation co-efficient of 0.57 is not bad considering we are comparing all ocean basins and the atmosphere.

As SST change generally precedes CO2 change by about seven months (sometimes less, sometimes more), there is NO evidence that CO2 increase causes temperature increase.

But we are still left with the increase in CO2 from 1958 while SST paused or decreased for 19 years.

Figure 8:  Sea Surface Temperature and CO2 concentration, 1958-1976

Hadsst and CO2 58 76

While it is difficult to attribute decadal CO2 increase to non-existent SST rise, there is no evidence for CO2 driving temperature increase in this period.

However, plotting 12 month change of CO2 and SST clearly reveals their relationship.

Figure 9: 12 month change in detrended CO2 and SST anomalies

12m chg Hadsst and CO2 58 76

Figure 10: 12 month change in detrended CO2 and SST anomalies, lagged 7 months

lagged 12m chg Hadsst and CO2 58 76

It is clear that 12 monthly change in temperature drives 12 monthly change in CO2 concentration.

The continual rise in CO2 from 1958 to 1976 while SST declined indicates there must be an underlying increase in CO2 unrelated to immediately preceding temperature, but there is definitely no evidence that it causes sea surface temperature increase at any time.

Summary:

  1. Increase in CO2 concentration is supposed to be the cause of the increase in temperature we see in the SST data (and satellite data).
  2. However, analysis shows that CO2 changes about four to seven months (and longer) after sea surface temperature changes.
  3. Therefore, atmospheric CO2 increase cannot be the cause of surface temperature increase. Real world data disproves the theory.

Fingerprints of Greenhouse Warming: Poles Apart

February 26, 2018

If global warming is driven by the influence of carbon dioxide and other man made greenhouse gases, it will have certain characteristics, as explained by Karl Braganza in his article for The Conversation (14 June 2011).

As water vapour is a very strong greenhouse gas, it will tend to mask the influence of man made greenhouse gases, and because solar radiation is such a powerful driver of temperature, this also must be taken into account.  Therefore, the characteristic greenhouse warming fingerprints are best seen where solar and water vapour influences can be minimised: that is, at night time, in winter, and near the poles.  So we would look for minimum temperatures rising faster than maxima; winter temperatures rising faster than summer, and polar temperatures rising faster than the tropics.  Indeed, polar temperature change in winter should be an ideal metric, as in Arctic and Antarctic regions the sun is almost completely absent in winter, and the intense cold means the atmosphere contains very little water vapour.  We can kill three birds with one stone, as winter months in polar regions are almost continuously night.

So let’s look at the evidence for greater winter and polar warming.

Figure 1: North Polar Summers:

NP summers

Figure 2:  North Polar Winters:

arctic all winters

Yep, North Polar winters are warming very strongly, at +2.58C/100 years, and much faster than summers (+1.83C/100 years)- strong evidence for anthropogenic global warming.  And warming is much faster than the Tropics (+1.023C/100 years):

Figure 3: Tropics

Tropics TLT

Unfortunately for the theory, the opposite happens in the South Polar region:

Figure 4: South Polar Summers

SP summers

Figure 5:  South Polar Winters:

antarctic all winters

While summers are warming (+0.58C/100 years), winters are cooling strongly at -1.66C/100 years.  Over land areas, with little influence from the ocean, very low moisture, and very little solar warming, winters are cooling even faster:

Figure 6:  Antarctic winters over land:

antarctic land winters

This is the exact opposite of what is supposed to happen in very dry, cold, and dark conditions- at night, in winter, at the poles.  Can this be because carbon dioxide and other greenhouse gases are NOT well mixed, and are in fact decreasing in concentration near the South Pole?

Figure 7: Carbon Dioxide concentration at Cape Grim (Tasmania):

C Grim CO2

Figure 8:  South Polar region TLT (all months) as a function of CO2 concentration:SP vs co2

No, while Cape Grim data show CO2 concentration to be increasing in the Southern Hemisphere, but without the marked seasonal fluctuations of the Northern Hemisphere, there is NO relationship between CO2 and temperature in the South Polar region.

Is it because the oceans around Antarctica are cooling?

Figure 9: South Polar Ocean TLT:

SP ocean

Nope- -0.01C/100 years (+/- 0.1C).  Neither cooling nor warming.

The cold, dry, dark skies over Antarctica are getting colder in winter.  Summers show a small warming trend.

Conclusion:  The fingerprints of man made greenhouse warming are completely absent from the South Pole, and differences between North and South Polar regions must, until shown otherwise, be due to natural factors.

Data sources:

https://www.nsstc.uah.edu/data/msu/v6.0/tlt/uahncdc_lt_6.0.txt

http://www.csiro.au/en/Research/OandA/Areas/Assessing-our-climate/Latest-greenhouse-gas-data

Mandated disclaimer:-

“Any use of the Content must acknowledge the source of the Information as CSIRO Oceans & Atmosphere and the Australian Bureau of Meteorology (Cape Grim Baseline Air Pollution Station) and include a statement that CSIRO and the Australian Bureau of Meteorology give no warranty regarding the accuracy, completeness, currency or suitability for any particular purpose and accept no liability in respect of data.”

The Hottest Year, but NOT due to Greenhouse Warming

January 7, 2014

ACORN-SAT- the gift that keeps on giving!

Unfortunately for doomsayers, the fact that 2013 was the hottest year on record in Australia is no evidence for the effects of greenhouse warming.  In fact, it is the very opposite.

Why?  Any sort of warming will eventually produce the hottest year on record.  But warming due to the enhanced greenhouse effect is quite special.  Warming due to greenhouse gases is evidenced by

greater warming of night time temperatures than daytime temperatures”

amongst other things, according to Dr Karl Braganza (http://theconversation.com/the-greenhouse-effect-is-real-heres-why-1515)

I discussed this in April  last year.  Now, with the updated data for 2013, it’s time for a reality check to see whether there is now evidence of greenhouse warming in Australia (a region as large as Antarctica, Greenland, the USA, or Europe, and supposed to be especially vulnerable to the effects of global warming.)

Once again I am using data straight from the Bureau’s website.

Fig. 1: Monthly maxima and minima with 12 month smoothing, December 1978 – December 2013, from http://www.bom.gov.au/climate/change/index.shtml#tabs=Tracker&tracker=timeseries&tQ%5Bgraph%5D=tmax&tQ%5Barea%5D=aus&tQ%5Bseason%5D=01&tQ%5Bave_yr%5D=0

max v min linear

For the past 35 years, there is much LESS warming of night time temperatures than daytime temperatures.  And the divergence is increasing:

Fig 2: fitted with a 2nd order polynomialmax v min poly

Sorry, but this is not evidence of greenhouse warming over the period of the satellite era, when greenhouse gases have been increasing rapidly.  It is merely evidence of warming.