Tag Archives: AR4

IPCC Climate predictions change in AR5

Shortly after I left town for a 2 week trip to the East Coast, the IPCC released their latest assessment on climate change, it’s Fifth Assessment is nicknamed AR5.  Today I pulled up some of the report from the web.    It was full of surprises.

The press did not surprise.  Gloom and doom has been everywhere these past two weeks.   Lost is all the hoopla is a significant change in the way the IPCC makes predictions.  They have become more circumspect.    Gone are absolute short term predictions like this one from AR4 made in 2007:

For the next two decades a warming of about 0.2°C per decade is projected for a range of SRES emissions scenarios. Even if the concentrations of all GHGs and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1°C per decade would be expected. Afterwards, temperature projections increasingly depend on specific emissions scenarios. {3.2}

AR4 included the following charts to help explain their short term temperature predictions:

https://www.ipcc.ch/publications_and_data/ar4/syr/en/fig/figurespm-5-l.png

Now look at what AR5 says:

It is more likely than not that the mean global mean surface air temperature for the period 2016–2035 will be more than 1°C above the mean for 1850–1900, and very unlikely that it will be more than 1.5°C above the 1850–1900 mean (medium confidence).

A quick peek at the East Anglia University  temperature data set will allow us to interpret what 1 degree C since 1900 really means:

The world average from 1850 to 1900 was about 0.7 degree C cooler than the year 2000 baseline used in AR4.   So the new report is saying that the world has about a 65% chance (more likely than not) of being about 0.3 degrees C warmer on average between 2016 and 2035 than it was in the year 2000.  They also say that temperature is very unlikely to be as high as 0.8 degrees C higher.

Compare that statement  to the chart from AR4.  The IPCC predicted  0.8 degree C above 2000 as a most likely case in the year 2035.    The AR5 report lowers their estimate and changes the way it is calculated.  AR5 deals with average temperatures over a period of time while AR4 made much more specific and higher predictions.  AR4 effectively ignored natural climate variation.  AR5 does not repeat the mistake.

AR5 includes two significant temperature prediction caveats.   They acknowledge that natural climate variation makes specific temperature predictions difficult in the short run and they included a statement on volcanic activity:

This projection is valid for the four RCP scenarios and assumes there will be no major volcanic eruptions or secular changes in total solar irradiance before 2035.

IF the earth experiences a significant  (Mt. Pinatubo equivalent) volcanic eruption, then IPCC projections will likely be wrong according to the IPCC.   How likely are Pinatubo equivalent eruptions?  Volcanic eruptions are measured using the Volcanic Explosivity Index (VEI).   Mt. Pinatubo was a 6.   A chart courtesy of Wikipedia describes VEI and offers their best guess for each classification.  Here it is:

https://climateswag.files.wordpress.com/2014/04/6ac18-veitable.jpg

This chart says both VEI 5 (Mt St. Helens) and VEI 6 (Mt. Pinatubo) eruptions happen at rates that are less than one every 100 years.   What are these guys smoking?    The Wall Street Journal published a chart that shows each VEI 5 or higher event in the last 200 years.

Between April of 1815 and August of 1991, the Earth produced 19 VEI 5 or greater eruptions.   Mt. Tambora,  got things started in April of 1815.   This category 7 event was really special.  5,000 feet of this Indonesian volcano disappeared in a single event.   There was so much crap in the air that 1816 was named the year without a summer.  It was followed by 14 category 5 events, and  4 category 6 events culminating with Mt. Pinatubo in 1991.

Recent history is going to give us the best data.  Recent history says the IPCC is ….well…wrong.   We probably will have a significant eruption before 2035.   I suspect wild ass guessing at the UN.  Mother Nature gave us 4 category 6 events in the 108 year period from August of 1883 (Krakatoa) to June of 1991 (Pinatubo).

I am glad AR5 noted the exclusion of volcanic activity and made some references to natural climate variation.  These inclusions make the work so much better. The admission really was necessary.  AR4 short term temperature predictions were so flawed that they had to do something to explain why they were so wrong.

AR4 was full of bad wild ass guessing….and at least  AR5 acknowledges that they might be wrong.  The IPCC admits that there is a one in three chance that they are being too aggressive simply because normal climate variation makes specific predictions difficult.  A VEI 6 Volcanic eruption will totally mess with their predictions.

Lets assume VEI 6 eruptions happen every 40 years or so.   A VEI 6 volcanic eruption between now and 2035 carries a 50% probability.  We must then reduce the probability that the IPCC predictions are correct by that 50% since they admit they assumed a zero probability.

I’m just glad to see the IPCC adjusting to the real world…at least a little bit.

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IPCC Climate Synopsis Critique – Part 1

Any frequent reader of this blog knows I think the United Nations International Panel on Climate Change (IPCC) has been practicing sloppy science for at least the last 20 years. Wild Ass Guesses are their stock and trade.   I thought I’d take a few blogs to better explain myself.

Today’ Subject: Climate Forcing

The IPCC has been writing Synopsis Reports since 1992.  The latest is nicknamed AR4 (The 4th Assessment Report).  It was published in September of 2007.  UN Scientists (and politicians too because it is the UN) are working on AR5 right now.  It should be ready for public consumption in 2014.

The IPCC says the following in bold print in the beginning of section 2.4 of the 2007 Report:

Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations.

The term very likely is a defined term in the document which means that they are more than 90% certain but less than 95% certain.  Unfortunately most is not a defined term.  I’d guess they mean greater than 50 percent.  The document  never defines most and  is silent about all other possible reasons the world has warmed.  Man caused greenhouse gases (GHG) are the only subject discussed.

The document begins with the statement that the IPCC is 90% certain that man is responsible for more than 50% of the increase in worldwide temperatures since 1950.  The rest of the document is constructed around the assumption that man is responsible for measured changes seen in recent years.

Recent temperature increases are considered confirmation that they are correct.  Temperatures that are well within the range of normal climate variation.   OK?

Early in Chapter 2 of the 2007 Report,  a graph is presented that explains the forcing agents behind global climate change (Figure 2.4).  Here it is:

This chart drives me crazy!  LOSU means level of scientific understanding.  This chart says the IPCC knows a lot about long lived greenhouse gases (high LOSU) and nearly nothing about everything else including Aerosols and the Sun (both are low LOSU).  It also says that greenhouse gases are 22 times more important than changes in the Sun.  The math looks like this:

(1.66+.48+.16+.34)/.12= 22

Everything shown on the chart is anthropogenic except Solar Irradiance. If so, where do ice ages come from?

The IPCC states that before 1950 most warming was natural climate variation.   The AR4 document appears to be saying that variation in Solar Radiation reaching the earth surface is always a very small number and only contributes to warming, and never contributes to cooling.

Here is an Antarctic Ice Core, the Vostok Ice Core: (http://rubyelephant.files.wordpress.com/2007/12/vostok-ice-core.jpg)

Wow look at all that natural variation;  400,000 years worth.  About 12 degrees C of natural climate variation. 3 degrees warmer than 1950 and 9 degrees colder.  And even today we are within the very tight range of the last 11,000 years…a period of nearly no change.

The temperature changes in a cycle that averages about 100,000 years.  Today, and for the last 11,000 years, it has been warm.  Less warm than 130,00o years ago but much more stable. Solar Irridiance must have been much less than it is today just 20,000 years ago.

The IPCC says in the Synopses document that their Solar data is based upon the time period from 1750 to 2005.  It appears that the IPCC has taken a period of stable warming climate…and then assumed that is the only condition that can exist.  If they had started say….500 years earlier… the results would have been different.

Look at the Aerosol numbers in the chart. It could be very small or bigger than carbon dioxide….and the IPCC admits to now knowing much about it

And carbon dioxide appears to be a trailing rather than a leading indicator as this image demonstrates:

130,000 years ago, carbon stayed stable while temperature dropped.   And it lasted for 20,000 years.  About 20,000 years later temperature rose rapidly while carbon dioxide levels drifted a bit lower.  Recent data shows wild increases in carbon dioxide without the corresponding temperature rise.  A less than perfect correlation.

Other  Vostok ice core images include dust particles in the graph.  They show sudden increases in dust during some of the cooling periods.  My guess….super volcano eruptions.

The IPCC admits to lots of areas where their knowledge is weak and they admit that Aerosols could be very important (the number could be large), they have used a simplistic model of the sun and admit they don’t know much about many important subjects. And they are 90% sure man is mostly responsible.

Can you say SWAG.

Science the IPCC way.