The IPCC report - is the science settled?

Thursday 3 October 2013, 15:44

Paul Hudson Paul Hudson

Last week the Intergovernmental panel on climate change (IPCC) issued their latest high profile report on the current understanding of climate change.

 

Their main conclusion is that there can be little doubt that man is responsible for at least half of the rise in global temperatures since the 1950s, due to man-made greenhouse gases.

 

As a geophysicist myself, I cannot argue with the science behind the greenhouse effect, which is based on sound physical principles.  

 

To that end, the science behind how greenhouse gases such as carbon dioxide would cause warming of the atmosphere, in my mind, is settled.

 

But there are areas of the science which cannot be described as anywhere near settled, where there are uncertainties that cannot be easily dismissed.

 

These uncertainties have been an area that I have focused on over the last few years on this climate blog.

 

The one area which is perhaps as crucial as any is that of climate model performance, because governments around the world are using climate projections to make long term planning decisions, in particular on future energy generation.

 

Judge for yourself if this part of the science is settled, from the IPCC report, Section D1: 

 

‘The observed reduction in surface warming over period 1998-2012 is due roughly in equal measure to a reduced trend in radiative forcing and cooling from internal variability, which includes a possible redistribution of heat within the ocean (medium confidence).’

 

‘There is low confidence in quantifying the role of changes in radiative forcing in causing the reduced warming trend.'

 

‘There may also be a contribution from forcing inadequacies and, in some models, an overestimate of the response to increase greenhouse gas and other anthropogenic forcing.’

 

To highlight this area of uncertainty further, in late 2009, I wrote an article which you can read HERE in which I look at the then apparent slowdown in global warming.

  

In it, I discuss research from the Met Office Hadley Centre.

 

In the research the authors discuss why they believe a levelling off of temperatures can be expected at times.

 

The research shows that near zero temperature trends for intervals of a decade or less can be expected due to the model’s internal climate variability.

 

But crucially, the research rules out zero (temperature) trends for intervals of 15 years or more.

 

We are now 15 years into the so called ‘pause’ in global temperatures and the research further illustrates that this crucial part of climate science is far from settled, and it’s disappointing that more time wasn’t given to this issue across the media in the days since the report was published.

 

That said the authors of this report are in little doubt that over the longer term, man is altering our climate by adding greenhouse gases to the atmosphere.

 

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Comments

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  • rate this
    +3

    Comment number 1.

    Paul

    as you must know the IPCC process is predominantly a political process. Politically, it was important that the message to policy makers was one of 'greater confidence'. The reality, however, is that the science is still in its infancy and there is a lot more unknown than known. Against that background the only surprise is that anyone believes that it is possible to model the climate. So, please keep pointing out the many failures of the climate alarmists. In the end it will turn out that you were right to do so.

  • rate this
    +1

    Comment number 2.

    So pleased that I am not the only one who thinks the science is NOT settled! I always think it is so ironic the stance the BBC takes and at the same time championing Darwin who was very science against the 'establishment' at the time! Perhaps the BBC should be renamed - the GBC (g=government!)

  • rate this
    0

    Comment number 3.

    1) If their main conclusion is that there can be little doubt that man is responsible for at least half of the rise in global temperatures since the 1950s, due to man-made greenhouse gases, what do they think caused the other half?

    2) How come the science is 'settled' when anyone argues the case against AGW - but there's 'much more research needed,' when the grant money's running out?

    3) What would the authors of the report be doing, if they weren't working for the IPCC?

  • rate this
    -1

    Comment number 4.

    "The IPCC report - is the science settled?"

    The science is never 'settled' (otherwise it wouldn't be science); but in the case of AGW, it's fair to say that the science is pretty well 'established'.

    By the by, UAH just posted +0.37C for September 2013; the joint third warmest September in its record. This makes 2013 (to date: Jan-Sep) currently the joint 5th warmest year on the UAH record. From the daily AMSU updates, it looks as though October has already started out on a very high temperature footing globally.

    ENSO conditions remain firmly neutral.

  • rate this
    0

    Comment number 5.

    newdwr54 - only the 3rd Oct. I think he's been reading your complaints about how long he takes to publishes 'warm' or 'cold' months!

  • rate this
    -1

    Comment number 6.

    5. lateintheday

    "newdwr54 - only the 3rd Oct. I think he's been reading your complaints about how long he takes to publishes 'warm' or 'cold' months!"

    I saw that! However, I note the he quickly bumped it off the top of the page with a fairly long and slightly innocuous post about cloud RF impact.

    I haven't got around yet to calculating the length of time taken for the 'burial' of warming updates by consequent posts on Dr Spencer's site. Even for me that would require a sustained period of inactivity.

    P.S. area a map of September heat anomalies from UAH (check out Antarctica): http://wattsupwiththat.files.wordpress.com/2013/10/september2013_map.png

  • rate this
    +1

    Comment number 7.

    The UAH record only covers the 30 year warming phase of the PDO (or Pacific Multidecadal Oscillation).

    On that basis there is nothing 'unprecedented' to be seen.

    Furthermore the slope of increasing temperatures during that period was much the same as the slope during the previous positive (warming) phase during the early 20th century and that was achieved without a significant human contribution according to the IPCC.

    Thus all we are seeing is a continuing recovery from the Little Ice Age with the interesting recent development of solar activity substantially reduced of late.

    It takes about ten to 15 years for solar effects to filter through the ocean system so the next 5 years should be interesting if the sun remains inactive.

  • rate this
    0

    Comment number 8.

    There is little doubt that the IPCC wants to loose any funding. There is huge doubt to many of their statements though

  • rate this
    +1

    Comment number 9.

    @1 NTropywins

    I actually agree with you that the IPCC process is rubbish and the polical aspects help no one. In my view it's too slow, cumbersome, lacks PR awareness and just a bit rubbish.

    All the leaks just added to the whole mess.

  • rate this
    +1

    Comment number 10.

    too many cooks?

  • rate this
    0

    Comment number 11.

    "It takes about ten to 15 years for solar effects to filter through the ocean system"

    How does that work? If the Sun goes quiet then the cooling should begin immediately. The oceans are still gaining heat though.

  • rate this
    -1

    Comment number 12.

    7. Stephen Wilde

    "The UAH record only covers the 30 year warming phase of the PDO (or Pacific Multidecadal Oscillation)."

    PDO has been cooling at a rate of -0.58 per decade since January 1998: http://jisao.washington.edu/pdo/PDO.latest

    In that period, UAH has warmed at a rate of +0.06C/decade. Not only that, but the last 5 years in UAH (60 month period ended September 2013) is the warmest continuous 5 year period in the record, and the long term (30 year) trend just rose another notch, from +0.17 to +0.18C/decade.

    When do you expect the PDO to start causing UAH to cool?

  • rate this
    +2

    Comment number 13.

    "By the by, UAH just posted +0.37C for September 2013; the joint third warmest September ."

    AND RSS for August was the 3rd lowest this century.

    One month proves nothing at all.

    Also the 12 month average for UAH at the end of Sep is exactly the same as August.

  • rate this
    +2

    Comment number 14.

    All of the global temps are now out for Aug - the 12-month averages are still pretty much in line with the 10-year ones.

    http://notalotofpeopleknowthat.wordpress.com/2013/10/04/global-temperature-reportaugust-2013/

    Also worth noting that the last few months have been ENSO neutral. The last long period of neutral conditions was 2001-2. HADCRUT so far this year is actually running slightly lower than then

  • rate this
    +1

    Comment number 15.

    12. newdwr54

    "PDO has been cooling at a rate of -0.58 per decade since January 1998: http://jisao.washington.edu/pdo/PDO.latest"

    DW I get what you are driving at and you might be right, but are you sure you are quoting apples for apples? PS don't react, I am not sure either!

    The link you give is to the PDO Index where as UAH is actual temps:-

    "PDO INDEX"

    "Updated standardized values for the PDO index, derived as the
    leading PC of monthly SST anomalies in the North Pacific Ocean,
    poleward of 20N. The monthly mean global average SST anomalies
    are removed to separate this pattern of variability from any
    "global warming" signal that may be present in the data. "

    Not really sure what that means with regard to actual temps but if IIRC the PDO area SSts have been warming. Think Bob Tisdale has some data. If I get chance will try and have a look later

  • rate this
    +1

    Comment number 16.

    John Cogger

    it is no way to do science and putting aside all the banter the only thing that really interests me is scientists doing science. Your comment is appreciated.

  • rate this
    -2

    Comment number 17.

    15. greensand

    As far as I know that's the official PDO record. As it states, the SST element is removed using statistical methods (I think PC refers to 'principal component'). The idea is to identify the internal pattern of change within the PDO absent any changes caused by 'global warming'.

    Stephen Wilde's reference to "the 30 year warming phase of the PDO" implies that the only reason we've seen warming in UAH over the past 30 years is because the PDO was in warming phase. Anyone can check to see that PDO has been in a negative trend since 1998; so for the past 15+ years UAH has been monitoring lower troposphere temperatures during the cooling phase of the PDO.

    Despite this, UAH has shown a warming trend over that period, and it's most recent 7 monthly updates have all set new warmest consecutive 5-year period records. Not really any sign of imminent cooling. I was just wondering if Stephen had any ideas as to when this cooling influence from PDO was expected to kick in?

  • rate this
    +1

    Comment number 18.

    "Anyone can check to see that PDO has been in a negative trend since 1998"

    I believe the PDO entered the negative phase in 2007 - so only 6 years thus far out of a probable 30-40 years.

  • rate this
    -1

    Comment number 19.

    13. Paul Homewood

    "... RSS for August was the 3rd lowest this century.

    One month proves nothing at all."

    No one's suggesting that it does. But if most climate change is natural and we've been in a PDO cooling trend for over 15 years with reduced TSI over the same period, then surely we should be starting to see significant cooling? Instead, the signs coming from UAH at least indicate the opposite, if anything.

    Re RSS: yes either RSS is wrong or UAH is wrong (or both) because they disagree strongly with one another over the past 15 years in terms of trend (RSS +0.02C/dec, UAH +0.14C/dec). So much for the satellite data.

    Which do you prefer? I think Christopher Monckton described the UAH data as "the least wrong" temperature data set we have. Would you agree with him?

  • rate this
    +1

    Comment number 20.

    #17. newdwr54
    "Despite this, UAH has shown a warming trend over that period, and it's most recent 7 monthly updates have all set new warmest consecutive 5-year period records. "

    I take it that by that you mean the 5 year moving average?

    If so, you seem to be deviating from your usual stance that 30 years is the minimum period over which to look as far as temperatures are concerned?

    The reason that the 5 year average has increased this year is that this year's temperatures are replacing those of 2008 in the average, and UAH temperatures were particularly low in 2008, i.e. monthly anomalies were mostly negative until August, and -0.009c for the year, compared to +0.2c for 2007, +0.189c for 2006, +0,21c for 2009 and +0.4c for 2010.

 

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Hello, I’m Paul Hudson, weather presenter and climate correspondent for BBC Look North in Yorkshire and Lincolnshire. 

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I worked as a forecaster with the Met Office for nearly 15 years locally and at the international unit, after graduating with first class honours in Geophysics and Planetary physics at the University of Newcastle upon Tyne in 1992. I then joined the BBC in October 2007, where I divide my time between forecasting and reporting on stories about climate change and its implications for people's everyday lives.

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