Is Dublin Missing out on Climate Change?

The concept of “global warming” or, more vaguely “climate change”, is now deeply embedded in the public’s consciousness and indeed in the economic agenda of most developed countries.  Expensive policy responses are being put in place to avert possible future environmental damage.  However, as has been pointed out by Richard Tol, “the impact of climate change on Ireland is [likely to be] moderate”, although he argues that as a constructive contribution to the global problem we should introduce a carbon tax.

This Post is prompted by my puzzlement at the contrast between predictions that our climate is heating up and the prospect of the third dismal summer in a row, coming on the heels of a severe winter and “broken” spring weather. 

Here is a summary of the evidence for warming in Ireland provided by a group studying climate change at NUIM:

The Mean annual temperatures in Ireland have risen by 0.74°C over the past 100 years (McElwain and Sweeney, 2007). This increase largely occurred in two periods, from 1910 to the 1940s and from the 1980s onwards, with a rate of warming since 1980 of 0.42°C per decade. In Ireland, 6 of the 10 warmest years have occurred since 1995 with the warmest year within this period being 1997.

From this quotation it is clear that the trend in average temperature in Ireland was quite erratic over the twentieth century.  Issues such as trend breaks, autocorrelation, and statistical significance, need to be addressed, as does the relevance of jumps in temperature early in the twentieth century for trends in the twenty-first century.

The Environmental Protection Agency’s press release (27th April 2009) based on this report states

The projections show that average temperatures will rise by 1.4°C to 1.8°C by 2050, and be in excess of 2°C relative to the 1961-1990 baseline by the end of the century.  

The basis for this fairly precise projection is unclear. Of course, a lot of very sophisticated climate change modelling is underway in Ireland and world-wide.  To give a flavour of what is involved, consider the following summary of the modelling underway at Met Éireann:

Technically, it dynamically downscales the relatively coarse-grained information produced by global models to tease out the finer details over a smaller area. This approach – regional climate dynamic modelling – is unique in Ireland. The work is done in collaboration with the Meteorology and Climate Center at UCD, and more recently, with the Irish Center for High-End Computing (ICHEC).

At a simpler level, a visit to the CSO Database under Environment, Climate opens up fifty one years of monthly data on temperature, rainfall, sunshine, and wind speeds for 15 weather stations across the Republic. This wealth of easily-accessible data could help take your mind off the banking crisis during the wet summer months. More seriously, I thought it was worth mining these series to see if the effects of climate change can be discerned in this record of the last half century of weather. 

I selected for analysis the mean monthly air temperature at Dublin Airport over the period January 1958 through April 2009 in the belief that this is a meaningful indicator of the climate affecting the largest concentration of population in Ireland.  This simple approach raised some interesting issues.

This first Chart shows the twelve-month moving average of Dublin’s temperature over the period January 1958 to April 2009. 

Even when seasonal effects are removed, the series is very erratic. Periods of cooling have been abruptly followed by warming periods. For example, temperatures fell sharply between 1983 and 1986, but then there was a period of noticeable warming from mid-1986 to late-1989.  1986 was the second coldest calendar year in the 51-year period, but 1989 was the warmest. It is especially striking that the series is very erratic and trendless over the last twenty years. The average temperature (9.4⁰ C) for the most recent twelve-month period, May 2008 to April 2009, was below the mean (9.8⁰ C) for the whole fifty-one year period and almost the same as that for the year 1958 (9.5⁰ C).  

The observations centered on 1963 reflect the exceptional winter of 1962-63.  According to one account

The winter of 1962/1963 was savage, the coldest for more than 200 years outstripping even ‘white 1947’ for bitter temperatures . . . It began freezing on Christmas Day in 1962 and barely relented until March. By early January 1963 much of Britain and the eastern part of Ireland were blanketed in snow.

This exceptionally cold period is still included in the baseline (19861-1990) for average temperatures used on the Met Éireann site. 

However, selective illustrations do not prove anything. The Chart shows the trend line through seasonally-adjusted data. The trend is positive and significant, but not impressively so. Moreover, it is not stable, as is shown in the following Chart for the 25-year period 1983-2008.  Over this period the positive trend is not significant.

To test the stability of the trend more formally, I fitted a linear trend and monthly dummies to the temperature data for the whole period and two sub-periods.  The following results were obtained:

Period

Trend 

(t-ratio) 

((upper – lower bound))

Extrapolated change in average temperature over a century

o C

Full sample: 1958-2008

.0009

(3.5)

((.0004  – .0014)) 

0.48 – 1.68

First half: 1958-1982

 .0009

(1.3)

((-.0005  – .0023)) 

-0.6 – 2.76

Second half: 1983-2008

 .0004

(0.6)

((-.0009  – .0017)) 

-1.08 – 2.04

 

These results illustrate uncertainties about global warming in the Dublin area.  While all the estimated trends are positive, they are at best weakly significant and provide a wide range of estimates of the pace of warming.  The most recent data provide the least support for the warming hypothesis.

Changes in summer and winter weather are probably more economically significant than changes during the transitional seasons of autumn and spring, so it is worth looking at the evidence by season.

Dublin readers may take little convincing that our summers have not been getting much warmer.  The graph shows that the city has not experienced a really warm summer since 1983. The time series show that while over the 51-year period 1958-2008  there has been a small positive trend, it is  not statistically significant (R2=.068, P=.0648). If we confine our attention to the second half of the period – 1983-2008 – the trend is negative (but not statistically significant).

Climate change is often said to be about extremes, rather than averages. The CSO site gives a time series on the maximum temperature recorded each month. This series behaves like that for average summer temperatures, exhibiting a weak upward trend over the whole period and a weak downward trend for the past 25 years.  (The highest temperature recorded at Dublin Airport over the last half century was 28.7o C in August 1990, whilst the highest recorded in 2008 was only 22.3o C.)

A common perception is that our winters have been getting milder, but it is possible that we are still influenced by memories – or accounts – of the exceptionally severe winters of 1947-8 and 1962-3. The statistical evidence for milder Dublin winters is weak.  While over the 51-year period there is an upward trend, but its statistical significance is low (R2 = 0.0462, P=0.14). Over the second half of the period, the trend is negative, but the R2 is a non-significant 0.0001. 


Well, perhaps we are enjoying warmer /mellower autumns?  Not significantly. With R2s of  0.0096 and 0.03, the trends in autumn temperatures over the 51-year period and the second 25-year period are not significantly different from zero.

Warmer /earlier springs, perhaps?  Maybe. The trend coefficient for the full 51-year period is almost significant at the 0.05 level, implying an increase of about 1.2⁰ C a century in Dublin’s average spring temperature.  However, the trend over the second 25-year period, 1983-2008, is not statistically significant (the R2 falls to 0.0445).

Overall, then, the data for Dublin’s temperatures suggest some weak evidence of a slow upward trend over the 51-year period 1958-2008, but none over the 25-year period 1983-2008.  There has been no warming in summer or winter, but perhaps during the transitional seasons.

Of course, temperature is only one dimension of climate and change may be occurring on other dimensions.  The most frequently mentioned possibility is that the warmer Atlantic Ocean will lead to stormier and wetter weather across Ireland.  However, the evidence for Dublin does not support this view – although very variable, Dublin’s rainfall shows no trend over the last half century. 

As mentioned above, extremes are important in the climate change literature.  However, extremes – especially of rainfall and wind speed  – can be very local.   The heaviest downpours tend to be produced by thunder storms confined to small areas. The highest rainfall recorded over a 24-hour period (184 mm) in Ireland was measured during a thunderstorm in Mount Merrion, County Dublin, on 11th June 1963. (For this and other nuggets see The Climate of Ireland by P. K. Rohan, The Stationery Office, Dublin, 1975).  

The series on the CSO website for “Most Rain in a Day” provides rainfall extremes for the 15 weather stations. Over the the 1958-2008 period the evidence for Dublin is of considerable variability but no trend.  The wettest day in the whole period at Dublin Airport was in June 1993, when 82.3 mm were recorded. But wettest day in the following year, 1994, had only 21.8 mm of rainfall.   (The only month over the half century in which no rain was recorded was April 2005).  

Of course, the Dublin area could be affected by warming occurring elsewhere in the world, most importantly by the impact of the widely-predicted rise in sea levels, which would presumably increase the incidence of coastal flooding.   Here is Met Éireann’s take on this topic:

Estimates of sea level rise from satellite observations around Ireland are consistent with the global picture: increases of 2.3 to 4.7 mm/year since 1993. At current rates of change, mean sea levels in Dublin, Sligo Bay and Slea Head will be 25, 44 and 40 cm respectively, above present day levels by the end of the century.

In light of what seems like an estimated 45 mm rise in sea levels over the last 15 years, it is strange that there does not seem to have been much reporting of increased coastal flooding over recent years.

This note is about the Dublin area.  There is considerable variation in climate – and possibly in climate change – within relatively small geographical areas.  There certainly is a lot of variation in the weather across Ireland – for example, summer 2007 was quite good in the West but terrible in Dublin. A sampling of data from other Irish weather stations provides stronger evidence for warming – with much higher correlations and more consistently significant positive trends.  However, even in the south and west the estimates of trends are quite unstable.  For example, the data for Shannon Airport show a strong positive trend in temperature over the 51-year period 1958-2008, but no significant trend for the most recent 20-year period and a negative (and significant) trend over the past 10-year period.  There is not much support for the view that things have been getting stormier – in Belmullet there has been no trend in maximum wind gusts since 1958 and no trend in rainfall over the past twenty years.

To conclude: The implications of climate change – and of our reaction to the fear of climate change – are too important to be ignored by economists.  In the face of uncertainty there is a strong argument for erring on the side of caution, so that even weak evidence of warming might be justification for strong policy responses. But reliable estimates of past trends are nonetheless essential for the projections of future trends on which these responses should be based. 

50 thoughts on “Is Dublin Missing out on Climate Change?”

  1. I am dismayed that an economist has taken it upon himself to come to the conlusion that there is weak evidence of climate change.

    Whilst economists cannot ignore climate change, it would probably be best if they left the analysis of what are the likely physical consequences of climate change to climatologists!!!

    I would further point out that national economists need to look at the global effects of climate change (as predicted by climatologists) in assessing the impact on Ireland. For instance, if Ireland is less harmed by climate change than other countries but the capacity of the globe to support humans is reduced to approx 1 billion people, as predicted by James Lovelock, then soggy summers and sea defences will be the very least of our worries.

  2. @Zhou
    Data are data, and the average economist knows more about statistical analysis than the average meteorologist.

    @Brendan
    The effects of climate change manifest themselves quicker over land than over sea because of the greater heat capacity of water. As Ireland is in the middle of the ocean, you would expect our climate trends to lag behind the global trends. We’ll catch up, but that’ll take centuries.

    On the lousy summers of recent years, besides the secular trend of the enhanced greenhouse effect, there short- and long-term pseudo-periodic cycles mostly caused by non-linear dynamics in the oceans. One of more pronounced ones is a 70-year cycle. We’re approaching the bottom of that cycle, and this is now strong enough to offset the global warming trend.

    Medium-term climate forecasts predict that lousy summers will be with us until 2020. After that, cycle and trend will work in the same direction and you can expect some spectacularly rapid warming. (This will be a nice empirical test for the models that predict mayhem because of warming.)

    Environmentalists are in a bit of a panic over this. We are supposed to agree on drastic emission reduction lest the world melts. and now warming has stopped and may even reverse!

  3. @richard
    “Medium-term climate forecasts predict that lousy summers will be with us until 2020. ”
    Thanks….and they wonder why we are called “dismal”….im off to Italy.

  4. I’d be more comfortable with projections for the impact of climate change on Ireland if there were more of them, conducted independently of each other. The credibility of climate change models comes mainly from the fact that many modellers have come to roughly the same high level conclusion, using different models with different assumptions, and often emphasising different data. There is a good deal of diversity in their predictions at a detailed level.

    While I don’t think we have much choice but to respond to the global greenhouse gas issue, I also don’t think we should rush to rebuild our infrastructure to respond to specific predictions of future Irish temperature and rainfall patterns. There is still sense in planning for rising sea levels and more frequent and severe flooding, as these are fairly universal predictions.

  5. @Brian Lucey: “Thanks….and they wonder why we are called “dismal”….im off to Italy.”

    By bicycle, I hope, to avoid intensifying global warming.

  6. Solar activity is more likely the cause of the warming trend that has since reversed itself, in 1998 and is now a cooling trend.

    Examine the “Maunder minimum” Google etc, for the consequences of a much cooler world, when there are no sunspots for decades. Let us hope that the IPCC was correct. There are many scientists who doubt it.

    After all, Al Gore the man who conceded, unnecessarily, to George W, would never lie to us.

  7. Not content with getting it all wrong about the trend in the worlds economy,Our motley crew of social philosophers(I refuse to use the word scientists in relation to economic theorists)turn their short sighted gaze at something they know even less about,namely the real as opposed to economic climate.Climate change is a GLOBAL PROBLEM and Ireland has a global responsability as its actions impact on the overall global situation.This post reminds me of why the scientific community resisted the businness worlds Demand for a Nobel prize in Economics “SCIENCE” god help us all!

  8. Pat kenny was going on about sunspots and such like with David Bellamy,who was booted out of the BBC for incompetence,and in his radio show the morning after stoked up the auld denier fires again but this time with the chief UN scientist in charge of studys into climate change.It was a pleasure to hear such a learned man speak demolishing one by one Bellamys arguments with erudition and logic backed up by all the latest findings.As for sunspots, they cannot explain the increases in temperature period and Mr donnelly is incorrect .I would advise bloggers to look for the real facts before consulting this “IRISH ECONOMY” finance site

  9. @Richard – I disagree. Also, there is a difference between meteorologist and climatologists. Comparing economists to ‘meteorologists’ is a dismal start to begin with.

    Analysis of the last 50 years will not necessarily help us predict the next 50 years. I am no climate expert but it is clear the above analysis does not take account of:
    1. The acidification of the oceans and the possible catastrophic effects on microrganisms which consume CO2 and are essential to keeping the oceans alive.
    2. The effects of the hugely accelerating melting of glaciers and ice caps which appear to have passed a tipping point.
    3. The release of CO2 from the Tundra which also appears to have gone past a tipping point.
    4. The fact that in some catastrophic climate change models Ireland may get colder.
    5. The effect of climate change on the rest of the world, especially the further desertification of Africa and southern Europe.
    6. The dramatic changes in temprtatures in the troposphere.

    I wonder are increases in human ignorance and misunderstanding directly proportionate to increases in the complexity of life and, ironically, increases in specialised education? Or putting it the old way: “a little knowledge is a dangerous thing”.

  10. @ Brian Goggin
    No, the largest fastest jet I can find. Then rent a car. Villa with heated pool, aircon, LOTS of lights for the nighttime. Not a green in sight….bliss

  11. @zhou
    I do not understand why you are dismayed at Brendan’s work. The most compelling assessment on how to respond to the risks of global climate change came from an economist – Nicholas Stern

    @Richard
    “Data are data, and the average economist knows more about statistical analysis than the average meteorologist.”
    What is the basis for this statement? Or is more facetiousness that I do not recognise?

    Do I detect some territory marking? How does this help deal in scoping an issue, outlining approaches to dealing with it and then managing it?

  12. @ zhou

    Try reading the piece again. He doesn’t deny that global warming is happening. He simply points out that weather data from Dublin airport doesn’t show any evidence of adverse effects here yet. He draws the conclusion that global warming appears (thus far) not to be affecting Ireland in any way observable in available statistics.

  13. @Donal

    A bit of overkill on my part, I admit. Economists are key to addressing the problems.

    I believe Nicholas Stern explained why it was economically necessary to respond to climate. That is somewhat different to B. Walsh’s opening post which appears to assess the physical occurences which will occur as a result of climate change.

    Whilst economists may have great expertise in statistical analysis, it does not justify economists making projections of how climate will change. Others are better trained and more qualified to do that. No doubt economists can be of valuable assistance to scientists, but if an analysis seeks to predict climate change then that analysis should be led by an scientists with expertise in climate change.

  14. @Marcus

    Noted, but the report does conclude that action should be based on projections which are in turn based on past trends: “But reliable estimates of past trends are nonetheless essential for the projections of future trends on which these responses should be based.”

    The logic is attractive but nevertheless false if one takes it to mean that one should project from the past trends referred to in the report.

    My alternative conlcusion would be that responses to climate change should be based on the best projections of the most qualified climatologists. Obviously one would need economists to assess what the economic imapact of these changes would be. However, one should not base one’s policy on the physical changes as projected by an economist based on meteorological records!

  15. @Donal
    Nick Stern is a clown and a charlatan.

    I’ve worked in the field of statistical climatology since 1991. I’ve been a professor in the Department of GeoSciences since 2000. Meteorologists and other geoscientists do not recieve much training in statistical analysis, and their textbooks are outdated. Statistical analyses that are published in geophysical journals are fairly poor. Although there are a few exceptions (Hans von Storch, Carl Wunsch, Frances Zwiers), most geoscientists have a rudimentary understanding of statistical analysis.

    If you don’t believe me, just ask one of them about multicollinearity, cointegration, or conditional heteroskedasticity.

  16. It is great to read something on Climate change that is not distorted by bias as so much of the items published are. Also many of the cliamate models used are based on poor information and if you put in crap, crap is what the computer will give back. Alot more of this type of analysis is need and the main stream media need to start giving balance to the hype.

  17. @Brian Lucey: “No, the largest fastest jet I can find. Then rent a car. Villa with heated pool, aircon, LOTS of lights for the nighttime. Not a green in sight….bliss”

    You’ll burn in … er. Italy for this …. But of course there won’t be any greens: it will all be a sort of umber, I should think.

    You forgot the patio heater.

    bjg

  18. @Richard
    I thought you would respond by flaming Nicholas Stern.

    That said, I believe that there is enough evidence of climate change arising from human activity.
    Whatever about the weather in Dublin (which is what Brendan wrote most about, although he has clearly looked at data for other parts of Ireland), the issue of climate change remains. What consequences will climate change have for hydrology cycles? How do we manage the impact on humans of changes in the availability of fresh water?

    If Stern and meterologists are out, can you point out where else I should look for some enlightenment on these issues?

    My question on dealing with the issue remains, even if you consider that answering it is beyond the scope of this forum.

  19. @Donal
    Meteorologists are fine scientists. Statistics is but one avenue of investigation.

    My take on climate change and climate policy is summarised here: http://ideas.repec.org/p/esr/wpaper/rb20090101.html

    To summarise, we should replace all domestic climate policy with a simple carbon tax that tracks the ETS permit price. This would raise taxes and cut public spending, and has the additional advantage that Ministers Gormley and Ryan will have time again to focus on their jobs (which I believe includes drinking water quality, local government, broadband, electricity, …).

  20. @Zhou

    Whilst the IPCC debate may be moving on, I think it is important to address queries raised by those not closely engaged with climate science. Brendan has provided a solid analysis of the data to hand, and in a far more balanced and logical way than many of my family and friends would when criticising the lousy summers. To their minds there is a clear absence of any indication of ‘warming’ – the current weekend excepted.

    The point, I would suggest, is that it is never a good idea to tell people to just ‘leave it to the experts’. The experts must always be willing to explain apparent anomalies – many times over – to bring the general populace along with the flow.

  21. Richard,

    Watch the hubris.

    The economic literature (or more accurately econometric literature) may be more advance on statistical issues than the field of climate science, there are pitfall for the unwary in the understanding and interpretation of data.

    For example, are you Dublin/Dublin airport data adjusted for urban heat islane affects? What about homogeneity of measurment (can you vouch for the fact that the measurement equipment has not move location, or that the location has not chaged in nature (e.g. a big tree grown over the site)?

    That nothwithstanding your points are valid, but I tihk you miss the more important area of potential economic contribution, which is in hthe area of welfare economics.

    For example, what is the Pareto comaprison of world+2 degree C compared with world climate today? That is probably fairly easy to answer, it is very most likely reduced.

    But go further and find the normative intrudes. How much welfare should Irish citizens forego for the greater good and how are you going to convince them to do so?

    It is a minfield

  22. @Tom
    My response was to Zhou, who argued that economists cannot analyse climatological data. That argument is nonsense.

    I don’t know whether the data are homogenous. Urbanisation would have implied an upward trend, while Brendan finds no trend. So, the data may have been overhomogenised and mask an upward trend, the data may have been correct homogenised and there is no trend, or the data may not have been homogenised and urbanisation masks a downward trend.

    Two degrees above today is Pareto indeterminate. Two degrees of warming is potentially Pareto superior, though.

  23. I am intrigued by the forecast that Ireland will have ‘lousy summers until 2020’. The UK Met Office recently forecast a long hot summer in 2009 and leaflets have been distributed by the authorities over there advising people what do during the expected heatwave this summer. So, why the gloom in Ireland? Is Ireland’s climate now diverging from that in the UK? Or, perhaps, George Lee is now in charge of Ireland’s Met Office?

  24. @John
    They run different models for the forecast of the century, the decade, the year, and the week.

    The 2020 forecast comes out of the decadal forecast, the summer 09 out of the annual forecast.

    Let’s hope the latter forecast is correct.

  25. I agree with Richard Tol that “data are data” and that economists’ expertise in time series analysis could be relevant to the climate change debate.
    That was really the point of my Post.
    Marcus summarizes my point well – I am not a “climate change denier”, it’s just that I am puzzled as to why the evidence for Dublin over the past 51 years is less than striking.
    @Tom: As travelers arising from warmed climes will know, Dublin Airport is a cool and breezing location. Temperatures there are consistently lower than elsewhere in the Dublin area. I notice that yesterday (May 29th) the max at Dublin Airport was only 18.4 C compared with 22.8 C at Casement Airport. But this should not affect trends.
    I hope all of you enjoy this fine Bank Holiday weekend – but don’t draw any inferences about climate change from a few fine days!

  26. It would be interesting to see the results with 1962 (the coldest year, looks like an outlier) omitted. It is a degree colder than any other year, and as its at the start of the data set will contribute more to the slope (all the other points outside the range 9-10.5 degrees bar one are in the late 1980s, the middle of the dataset, and therefore wouldnt contribute much to the trend, I think?

    As the slope is weak, it would be even weaker with that omitted. Not saying there is necessarily a strong argument for omitting outliers and shaping the dataset like that (although I wold be inclined to think so as they will contribute disproportionately to the error minimised slope), but at least would be interesting to see how much that one point contributes.

    (As a vaguely related example, recently I was looking at correlations in commodity prices; the omission of two extreme points (out of a dataset of hundreds) reduced the correlation from approx 0.4 to 0.25.)

  27. @Richard:

    “Two degrees above today is Pareto indeterminate. Two degrees of warming is potentially Pareto superior, though.”

    You are saying that nobody will be worse off with a 2 degree C increase in temp?

    But you miss the substantive point. This is ALL about welfare economics. It is welfare trade off across groups and across generations. Regardless of you views on what is happening (if anything).

    The policy prescriptions alone are already the largest influence on shifts in welfare across arbitrary groups and across time, when one looks at all the taxes, regulation, subsidy etc. associated with this issue.

    Economist need to look at this and provide information to policymakers to determine whether all this flurry of action makes any sense.

  28. @Brendan,

    Perhaps I shouldn’t be surprised that you feel the need to state that you are not a climate change ‘denier’, but in a way it highlights one of the main irritants in the public debate on climate change – anyone who raises a question about the current orthodoxy is liable to find themselves labelled a ‘denier’.

    The trouble with the climate change debate though, in Ireland as elsewhere, is that economists are too little involved in it, not too much. At either end of the spectrum of debate on this issue, there are the eco-fundamentalists for whom ‘saving the planet’ has more to do with a secular religious creed than any sober evaluation of the scientific facts and the equally vocal climate change ‘deniers’ who, not content with having stupidly used up half the world’s known reserves of fossil fuels in the past century, can’t wait to make profits squandering the remaining 50%, mainly to ensure a comfortable lifestyle for the earth’s few, irrespective of any environmental considerations.

    Small wonder then that most of the rest of us, caught in the middle, opt for the eco-fundis analysis as the less obnoxious of the two extremes. No progressive politician worth his/her salt wants to be labelled a ‘climate change denier’ either. The net result is there is a real risk of very bad decisions being made in the name of mitigating climate change, policies that will then fall prey to the law of unintended consequences, economically and ecologically – the rush to biofuels in the 1980s and 90s illustrates the point.

    At national level, for a whole host of reasons, the debate on climate change policy would benefit from a wider enagement by economists – as well as contributions from philosphers, archaeologists and historians, but we’ll leave them aside for the moment. Enthusiasts for a transition to a ‘green economy’ in Ireland have a depressing, if natural, tendency to overstate claims of what can be achieved by their policies. Even more depressingly most of what they claim goes unchallenged, in the media or by economists. Political cheerleaders of all political colours are not slow to jump on the eco-bandwagon – a few years back they were all enthusing merrily about Ireland becoming a ‘world leader’ in biofuels production and as late as Budget 2006 €260m was being set aside to subsidise the growth of noxious weeds throughout the country. Today, it’s all about our wind resources generating enough hot air to power the whole of the European Union. Our carbon free future will have us all on the pig’s back in no time at all, or so it appears.

    In Copenhagen in December, we are likely to sign up to targets of 20% reduction in carbon emissions. Unfortunately, there does not appear to have been any rigorous anlaysis of the economic impact of this target, apart from some ESRI estimates and the Irish Exporters Association claim that it will cost the Irish economy €1bn.

    December’s Budget will also see the introduction of a carbon tax – the last time this issue was examined it emerged that the emissions’ savings that could be achieved from the ‘deterrent’ effect of this form of taxation were so small as to make it hardly justifiable as an environment measure. This time around it seems no public consutlation is being conducted in advance of itnroducing this measure and because the government needs money, economists seem prepared to go along with this tax because it will raise much needed revenue. That’s not good enough!

    Then there is the huge issue of energy policy – I’ve yet to see every possible option for Ireland’s future energy resources set out in terms of a proper comparative costs/benefits analysis.

    These are all very critical issues for our economy, even in the short term. Perhaps it might be worth considering a special economics conference, along the lines of those that have already been conducted on the economic crisis, on Ireland’s policy response to climate change?

    Finally, up to recent times I was personally inclined to accept that the science on global warming was pretty much settled and that the climate models on which the IPCC base their conclusions are broadly correct. Then along came the global economic crisis. With the benefit of hindsight, most economists now agree that the financial and regulatory models of the past twenty years were flawed. It turns out that the models were wrong, or were modelling the wrong things. The LTCM debacle fo the 1990s is a typical example of what can go wrong: the celebrated geniuses involved won the Nobel Prize for economics in 1996; by 1997 their model was a busted flush because it was based on short term data rather than an appreciation of long term trends. As historian Niall Ferguson put it: “The Nobel Prize winners had known plenty of mathematics, but not enough history. They had understood the beautiful theory of Planet Finance, but overlooked the messy past of Planet Earth.”

    Perhaps unwittingly, Prof. Walsh’s exercise on the met data for Dublin Airport points to a problem that may be part of climate modelling in general : the timescales that are used. Fifty years of data is far too short a timescale to tell you anything useful about climate change – a hundred, ten thousand or 100,000 years may not be enough. We just don’t know enough about how earth cycles work over longer periods to draw any conclusions from short range climate models and in any case, our predictive capacity as human beings is inherently flawed. What climate modelling is telling us may either exaggerate global awarming effects or, worse, underestimate them. At any rate , what happened with the financial models somewhat undermines confidence.

  29. @James M
    If you omit just two observations – January and February 1963 – the R2 falls to 0.0905 and the slope flattens to 0.0007 – so these two months do have an undue influence on the whole 51-year picture. However, one must be cautious about selectively picking or omitting observations!

  30. @Richard/Brendan

    If you read my posts carefully you will see that I have not questioned economists ability to conduct statistical analysis. RT’s assertion that economits cannot analyse climate change date is nonsense is no more than an attack on a straw man.

    An interdisciplinary approach is highly desirable. A single disciplinary approach by economists is substantially less desirable. I have questioned economists’ ability to make projections based on statistical analysis without the input of climatologists/ geo-scientists/ meterologists or whatever else you want to call them.

    RT has clearly had access to many such geo-scientists and has taken time to learn about their discipline but is blase about how crucial their input is in any statistical analysis purely because they are less skilled in statistical analysis. I cannot understand this attitude.

    For clarity, my two main criticisms of the OP were as follows:

    1. It does not appear to have been done in co-operation with a geo-scientist who could point out large underlying changes in the global ecosystem which may dramatically alter the trends which are analysed. If somebody were to show you similar graphs of house prices over the 40 years to 2006 would it have revealed the credit bubble underlying international markets? Similarly for pensions.

    2. My interpretation of the piece (without re-reading it again) is that it suggests that we should base our actions and policies on how climate change will affect the climate of Ireland. I think that the economic, social and security effects of climate change in Ireland will be largely determined by how climate change affects the climates of other countries with particular emphasis on Africa and Europe. An ancillary criticism which I did not make is that Ireland has a role in determining EU policy for the good of Europe, and so we should live up to those responsibilities by looking at Europe as a whole.

    Brendan’s post has shone a light on the whole question about how analysis of climate change is conducted and gives clues as to why “experts” might differ so strongly. I welcome Brendan’s skilled efforts for that reason. On the other hand, I fear that ignorant members of the public, civil service and political classes conclude to themselves as follows: “Now I have seen some real analysis of climate change and it is clear things are not going to change so much; we really shouldn’t get so worked up over this.”

  31. Interesting article, Brendan. One massive mistake you’ve made (and seemingly implicitly acknowledged) is that you looked exclusively at Ireland for evidence of warming, which assumes that warming is somewhat uniform across the world, when it’s clearly not. Individual national changes don’t establish a warming pattern, overall global trends do.

    For example, the Earth could heat up quite significantly, causing ice to melt, dumping large amounts of cold freshwater into the North Atlantic current of the Gulf Stream. If this “shut down” the current, then we’d likely see Ireland’s average temperatures go down, not up.

    This wouldn’t be “weak evidence” or evidence against climate change, it would simply show that an overall trend of warming leads to vastly different regional effects – some warming, some cooling. What matters is the overall trend.

    Incidentally, I suspect that it is because of this that people have shifted away from the term “global warming”, since it encourages people to point to cold periods somewhat simplistically as refutations of the theory. That’s why the term “climate change” is handier.

  32. “The projections show that average temperatures will rise by 1.4°C to 1.8°C by 2050, and be in excess of 2°C relative to the 1961-1990 baseline by the end of the century.”

    Interesting quote on projections above. The problem with projections, and presumably models, surely lies in the baseline assumptions and the quality of the model in reflecting reality.

    Nassim Nicholas Taleb’s book ‘The Black Swan’ is well worth a look on this. He discusses the effects of high impact, low probability events, black swans. Direct quote (pages 160-161) on response to a lecture he gave to the Woodrow Wilson Institute:

    “One anonymous person explained to me privately after the talk that in January 2004 his department was forecasting the price of oil for twenty five years later at $27 a barrel, slightly higher than it was at the time. Six months later, after oil doubled in price, they had to revise their estimate to $54 a barrel…It did not dawn on them that it was pointless to forecast a second time”.

    In short, no one can predict the future!

  33. @Pidge
    Apparently the idea – which we all learned in school- that the Gulf Stream is responsible for our mild, temperate climate is not good science! See
    http://www.americanscientist.org/template/AssetDetail/assetid/51963?fulltext=true&print=yes
    Carl Wunsch, professor of physical oceanography at MIT, has stated that
    “. . . the notion that the Gulf Stream would or could “shut off” or that with global warming Britain would go into a “new ice age” are either scientifically impossible or so unlikely as to threaten our credibility as a scientific discipline if we proclaim their reality.”

  34. @Pidge – in a recent interview on Radio One, James Lovelock said that the Gulf Stream has already shifted westwards and that accounted for our damper summers. He posited that the negative effects would be small for Ireland. He said Ireland’s greatest challenge would be that because it would not be affected badly and is not already over-populated, it will come to be viewed as an ark and difficult decisions will have to be made as to how immigration and available resources are managed.

  35. @Gulf Stream
    James Lovelock is a publicist. Carl Wunsch is an oceanographer at MIT. Who would you believe about ocean currents?

    The most sophisticated models that have run a scenario of a shutdown of the meridional overturning circulation (aka the Gulf Stream) suggest that the associated cooling over the British Isles is roughly equal in size to the expected warming over this century. That is, should the Gulf Stream shut down by 2100 (a very unlikely prospect), we will return to today’s climate. If the Gulf Stream would continue, we will suffer a climate in 2100 that is comparable to the one in Northern Spain today.

  36. @Gulf Stream

    The Wunsch link did not work for me. I see no reason to believe Lovelock ahead of him. Is it not the case that both say that the importance of the Gulf Stream is over-rated?

    The point of citing Lovelock is that he posits that Ireland’s problems will come from how the rest of the World is affected. An anology might be the dramatic increases in global food prices in 2007. John Beddington has said we will need to increase global food production by 50% by 2030. At the same time, global water reserves continue to decline and more of Southern Europe and and Africa are become arid due to climate change. Climate, Food, Energy, Water and Population are inextricably interlinked.

    Whether or not it gets one or two degrees hotter at Dublin Airport or whether the sea will ise by 5cm or 30cm over the next 20 years will hardly be the main factor to be taken into account in planning for climate change. If the debate were restricted solely to the expenditure on sea defences then it would be more relevant.

    @RT

    Is it correct to say that climate change models are more accurate in predicting the changes that will take place over the next 70-100 years than they are in predicting what will take place over the next 20-40 years, or has that problem been solved?

    I ask this because you have mentioned a number of times about the change which will have occurred by 2100, whereas a Government will be much more concerned about the change that will possibly have occurred by 2035. I understand that there is now widespread agreement that the rate of change will not be linear. I would of course bow to your superior knowledge on the point.

  37. @zhou @Brendan Walsh
    I don’t want to get bogged down in the specifics of the Gulf Stream – my point was a broader one. I was simply using the Gulf Stream as a well known example to illustrate it. It isn’t a good idea to test whether climate change is happening or not (or, more precisely, the extent to which it’s happening) by looking at a specific region. The overall warming is global, which results in a series of regional changes in temperature and weather pattern.

    Looking at Dublin and not seeing warming is evidence of nothing whatsoever. If Dublin shot up in temperature, or its temperature collapsed, that would not – by itself – be evidence for global warming or cooling.

  38. @Pidge

    I agree but in fairness to BW his article was restricted to the actions which the Irish Govt should take in relation to climate change. I don’t think BW made any assertions as to global climate change based on the data he analysed.

  39. @zhou_enlai & others seeking the Gulf Stream article referenced by Brendan.
    Searching in the American Scientist website for “Richard Seager” will bring the relevant pieces.

    @richard and others
    I too think that a carbon tax is the right approach, as I am still convinced that CO2 emissions arising from human activity is the major cause of climate change. So tax CO2 emissions without exception or allowances – on the simple basis that we tax things that are undesireable, collectively and individually (eg. tobacco, lead in petrol) and should not tax things that are good (eg. income). If sufficient evidence emerges that climate change is not happening or that CO2 is not a major contributor, we can change the tax measures – knowing that we are still waiting for concept of income tax to be abolished in Britain, now that Napoleonic wars are over!

    As regards the use of mathematical models in any sphere, have things moved on since Einstein observed “As far as the laws of mathematics are certain, they are not real and as far as they are real, they are not certain.”?

    Despite the weaknesses, I prefer that options for policies be drawn up and implemented based on more formal working out of options, using data, methods and models that are open to public scrutiny. That still leaves considerable room for the exercise of judgement in the political sphere. In this Republic, I consider that the Executive side of government is out of control and not subject to the kind of checks and balances that we deserve.

    You will all have your own favourite examples government by whimsy(eg. the Ahern/McCreevey/Parlon decentralisation v the National Spatial Strataegy) and/or arbitrary interference (eg. the non-connecting LUAS lines being joined by a non-connect Metro North v what the 1998 Atkins report recommended following the DTI proposals)

  40. Any treatment of warming globe ,has to be based on large convention ,especially when the phenomena is touching big areas over globe.

    What our government can do ,is to support and adopt clear and serious politics to less down the CO2 ,and in the same time balance between social and economical policies,via serious education system .

  41. We cannot blame Ireland for not going green as Ireland is unfortunately deprived of considerable amount of Solar energy unlike other countries who are not making the most out of it.

    Solar Attic Fan

  42. Any treatment of warming globe ,has to be based on large convention ,especially when the phenomena is touching big areas over globe.

    What our government can do ,is to support and adopt clear and serious politics to less down the CO2 ,and in the same time balance between social and economical policies,via serious education system .

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