Wednesday, June 15, 2016

Open Session 9-10am June 20th to open the 9th ACRE conference

ICARUS and Maynooth University shall be hosting the 9th Meeting of the Atmospheric Circulation Reconstructions over the Earth project next week (20th-24th June). The opening session will be open to the public and media and be held in Renehan Hall on the South Campus from 9 to 10am.

The Session shall be chaired by Dr. Kate Willett of the UK Met Office who has created numerous datasets and edited for the past several years the annual State of the Climate Series in the Bullettin of the American Meteorological Society.

Seamus Walsh the Head of Climatology and Observations Division at Met Eireann shall welcome attendees to Ireland and provide a high level overview of the importance of data rescue and analysis to their mission.

Dr. Philip Brohan of the UK Met Office and Dr. Gil Compo of the Cooperative Institute for Environmental Sciences shall provide a talk on data rescue using citizen science and its application to historical renalayses products.

Finally, Dr. Conor Murphy of ICARUS shall provide an overview of several recent pieces of research on long-term changes in Irish climate including, droughts, floods, storminess and temperature.

All are welcome to attend and seating is on a first come first served basis. Renehan Hall is a ten minute walk from both the bus stop and the train station. For those driving onto campus the parking restrictions are lifted presently.

Details on the remainder of the program can be made available on request and a small number of seats may be available for some sessions.

Wednesday, May 25, 2016

Re-examining changes in Diurnal Temperature Ranges

This is a repost for the International Surface Temperature Initiative blog

A recently published pair of papers in JGR ($, sorry) reassessing changes in observed Diurnal Temperature Range changes has been recently highlighted in EOS and Nature Climate Change.

The analyses have been extremely long in the making. They started out back in 2010 as 'hobby' papers and never got explicit funding so trundled along very very slowly indeed. The release of the ISTI databank provided an opportunity to create a new estimate of DTR changes and compare it to several pre-existing estimates.

The first paper details the construction of the new dataset of DTR changes. This takes the version 1 release of the ISTI databank and applies the pairwise homogenisation algorithm (PHA) used by NOAA NCEI to these holdings. The paper deals with the homogenisation processing, analyses the resulting dataset estimates and discusses aspects of the underlying metrology (not a typo). Below are the gridded trends over 1951-2012 and the global timeseries. The 'raw' data is the basic data held in the databank. Directly adjusted is where the DTR series were presented to the PHA algorithm. Indirectly adjusted is where, instead, the adjustments to Tmin and Tmax are used.

We found that more breaks are returned for DTR than is the case for Tmax or Tmin, for which more breaks are returned again than Tmean. This has potential implications for future homogenisation strategies in that searching for breaks in Tmean appears sub-optimal. Potential reasons for this were detailed in a prior ISTI blogpost and are further elucidated upon in the paper itself.

The second paper takes the new analysis and compares it to several pre-existing analysis and then attempts to reformulate the findings on DTR from the IPCC Fifth Assessment Report (which assessed only medium confidence). The new analyses provide considerable confidence in a finding that DTR has decreased globally since the mid-twentieth Century, with most of that decrease occuring prior to 1980. Data are too sparse and uncertain to make meaningful conclusions about DTR changes prior to the mid-twentieth Century, at least globally. The compared datasets show very distinct coverage and somewhat divergent trends since the mid-twentieth Century:

Much of the divergence between estimates results from the disparate approaches taken to accounting for incomplete sampling by the underlying data through interolating (or not) into data sparse regions. Using the native coverage (top) or the estimates restricted to common coverage (bottom) greatly alters the perceived degree of agreement between the independently produced products from various groups:
The conclusion of the second paper was as follows:

The driving rationale behind this work was the lack of explicit progress in the literature in assessing DTR changes between the fourth and fifth assessment reports of the IPCC. Based upon the findings herein, where a new assessment to be performed by IPCC of the observational DTR record at this time the text might read as follows (use of IPCC carefully calibrated uncertainty language and italicization [Mastrandrea et al., 2010] is intended).

It is virtually certain that globally averaged DTR has significantly decreased since 1950. This reduction in DTR is robust to both choice of data set and to reasonable variations in station selection and gridding methodology. However, differences between available estimates mean that there is only medium confidence in the magnitude of the DTR reductions. It is likely that most of the global-mean decrease occurred between 1960 and 1980 and that since then globally averaged DTR has exhibited little change. Because of current data sparsity in the digitized records, there is low confidence in trends and multidecadal variability in DTR prior to the middle twentieth century. It is likely that considerable pre-1950 data exist that could be shared and/or rescued and used in future analyses. All assessed estimates of global DTR changes are substantially smaller than the concurrently observed increases in mean and maximum and minimum temperatures (high confidence, virtually certain).

The datasets and code used are available via

Monday, April 11, 2016

ICARUS researchers give public lecture last month in Customs House , Dublin.

Recent Flooding in Ireland: Hydro-Climatic aspects and associated impacts

Darren Clarke and myself Simon Noone gave a recent talk to the Irish Meteorological Society (IMS) in the Customs House, Dublin. The public lecture gave some insights into the causes and effects of the recent widespread flooding by looking through the lens of each of their areas of expertise. There was a good attendance of about 40 people from Met Éireann staff, engineers and even pilots to climate enthusiasts. After the talk we both responded to some interesting comments and received very positive feedback. We would like to thank Paul Halton and his colleagues at the IMS for inviting us and for their hospitality. For the lecture Darren focused on the social impacts of flooding and asked whether the current national approach to managing flood risks is fit for purpose. Darren is examining how societies adapt to climate change, specifically focusing on community adaptation to flood risk management strategies in Ireland.  I discussed the flooding in the context of the long-term hydrological cycle, how recent events fit into the historical record and what, if any, trends are emerging.  The recent rainfall extremes of late 2013/14 and 2015 were put into context over the longer term, using the recently updated Island of Ireland Precipitation (IIP) series 1850-2015.

 Key hydro-climatic results presented:
      Results indicate statistically significant increasing trends in winter and decreasing trends in summer precipitation.
      Across 13 IIP stations (mainly in west) so far 2014 was the wettest winter (Dec 2014, Jan/ Feb 2015) in Ireland over the past 165 years (see table 1).
      2015 has seen the wettest December at 16 IIP stations over the past 165 years and 2015 ranked either 2nd or 3rd for the other 9 IIP stations (see table 2).
      However, December 1978 was the wettest across eastern IIP stations (see table 2).

Table 1. Presents the wettest and driest seasons from 1850-2015 using the IIP series.

Table 2.  Presents the wettest December from 1850-2015 and corresponding standardized monthly anomaly for each of the IIP stations.

Key results on social impacts presented:
·         The economic impacts of flooding currently dominate policy, political and media debates at the expense of social costs such as physical and mental well-being. However, understanding the social impacts of flooding is crucial as the effects last long after a flood has receded
·         Greater attention to non-engineered flood defences will be needed in the coming decades if flood risks are to be managed sustainably and fairly.
·         The provision of flood insurance is likely to remain a contentious issue for those unable to avail of flood insurance nationally. The implementation of a flood re-insurance scheme as exists in the UK and France may be difficult to implement in Ireland for social, political and economic reasons.
·         Understanding of the local context in which new flood defences are to be located and the value of community input will be crucial if flood authorities are to be considered as legitimate both now and in the future.

Friday, March 25, 2016

On Hansen et al

By Peter Thorne

As I am getting dribs and drabs of queries from several angles on the Hansen et al paper that appeared this week in final form I thought I'd write a post (possibly against my better judgement). I was an invited reviewer and my initial and second reviews are available online. I stand by those. The whole paper has been a highly unusual experience to be part of the review process of, and not because its in the EGU Open Access journals. I have reviewed many times for EGU journals articles that have proceeded by a more traditional route. In this blog post I shall try to reflect upon the process, the potential issues that remain, and its reception. Much more can be found in my reviews which will likely help if you have issues with falling to sleep at night.

Before getting into the nitty gritty let me be clear on several points:
  • There is value in exploring possibilities of future behaviour of the climate system. We have not observed it long enough or well enough, and we do not (yet) have powerful enough and complete enough models, to absolutely rule out 'nasty surprises'. 

  • We are undertaking an unintended geoengineering project that is pushing the climate system away from what has been a remarkably (in geological terms) stable climate that has allowed agricultural, then industrial revolutions and modern society to develop. Married to other ongoing large perturbations to aspects of the Earth System such as ecosystem disturbance on an unprecedented scale we truly are entering uncharted territory. From a purely scientific perspective, the precautionary principle of reducing our environmental footprint should be pursued strongly.

  • It is the absolute right of the journal and its editors to publish any piece using their best judgement upon completion of a proper peer review process. I would strongly support any editor and any journal in the right to publish what they view as fit so long as the paper has undergone rigorous peer-review.

Peer-review process observations

The whole process was as if we had fallen through Alice's looking glass. The paper was trumpeted at a major news conference several days before the discussion paper was even published online and available for review. Many media outlets, completely incorrectly, reported this as a new paper. Discussion papers on EGU journal sites are not peer reviewed articles and do not therefore constitute scientific papers. Coincidentally, since then EGU now no longer typeset the discussion papers so that it is now more obvious whether the paper is a submitted manuscript or the final real deal. I have no idea whether these issues are linked.

This deliberate publicity surrounding a discussion paper (which to my knowledge is unique) led to unprecedented interest in the paper. By the time the comment period was closed there were over three times as many reviews as to the next most commented discussion paper in the journal's history. This included many off-topic comments including a long thread on the existence of the greenhouse effect. Ironically, this was one of the better responded to comments by the authors (more later ...).

Amongst the greenhouse effect deniers and other off-topic comments were unsolicited reviews from a large number of very well respected scientists expert in many fields pertinent to the paper including several colleagues who were (Coordinating) Lead Authors in the Fifth Assessment Report of IPCC or who have contributed to major works such as the annual state of the climate series. These reviews highlighted very many salient issues that the official reviewers failed to spot, and hence added substantial value.

In my view the responses from the paper author team to very many of the comments they received were inappropriate. Scientific peer review has a set of norms that you respond to the issues raised in a calm and measured manner including point-by-point responses that detail whether changes were made, what these were, and why. Instead, the authors chose to respond in many cases by writing discursive policy pieces that were too often non-responsive and often verged on playing the man and not the ball.

The reviewers (invited or otherwise) all donated the precious gifts of their time and their expertise to the peer review process. Their contributions both required and deserved scientifically substantive responses. Sadly, in many cases this is not what they received. The most egrerious example is the Drijfhout et al comment and its response. The reader should consider whether the response is polite and addresses the substantive points raised by the reviewers in a measured manner. In my judgement it does not. This is but the most obvious example of a systemic issue in how the reviews were dealt with by the authors during the public review segment of the process.

It is beholden upon senior members of the community to set an exemplar of expected behaviour. They are role models and they rightly or wrongly set or modify expectations of cultural norms, be that in climate science or elsewhere. My view is that the authors treated many of the reviews as a nuisance and did not provide the response that was justified to them that allowed the reviewers to fully understand how each of their review comments was dealt with. This included the public version response to my own invited review. It was not the behviour I would expect from such senior colleagues.

Science and content

Peer-review is a necessary but grossly insufficient condition for eventual acceptance of a new hypothesis as a scientific theory. Its a very weak and imperfect filter. So, publication is the first step on a long road to eventual either acceptance or rejection of the hypothesis. I'll briefly highlight here some of the open issues as I see it that lead me personally to put a very low prior on the work being correct. There are many more open issues detailed in mine and others' reviews at

The sea-level rise is prescribed and not predicted

The authors prescribe an extreme freshwater hosing (pumping of fresh water) into the sub-polar oceans. Hence the extreme short-term sea-level rise is not a prediction arising from the model at all, and assertions to the contrary are patently false. The authors basically give up on ice-sheet processes in climate models or even ice sheet models and decide to play what-if with some, in my view, poorly physically justified assumptions.

It is important to stress that there is therefore no rigourosly physically justified mecanism or basis underlying the posited multi-metre sea-level rise. They basically assume you start off adding one olympic swimming pool today, two tomorrow, four the next day etc. then when they determine they have added enough swimming pools of water they switch it off.

This is meant to approximate large-scale ice-sheet disintegration of Antarctic and Greenland ice sheets that are posited to add a huge volume of water on a short multi-decadal period. Such pulses have occured in the past, but primarily to my knowledge when transitioning from glacial to interglacial and presumably associated with the disintegration of the much more unstable Laurentide and Eurasian ice sheets. Antarctica and Greenland have remained ice caps whilst these other giant ice sheets have come and gone. There is therefore evidence the present ice sheets are much more stable. You'd have to look to colleagues who provided comments for further clarification though.

That said, West Antarctic is unstable, and we almost certainly have passed a tipping point that will see eventual c.8m rise but the scientific literature generally suggests this shall be a multi-century process. East Antarcic and Greenland have a few retrograde bedding outlet glaciers that with water intrusion could surge in the short term. But they are a bit like funnels draining huge areas and therefore the potential rate of addition will quickly become constricted as a result. A short term acceleration would not likely be a precursor to continued acceleration posited by the authors based upon current understanding of ice sheet dynamics. Reviewers more expert than I pointed these issues (and the lack of perceived realism) out but to my judgement were never adequately addressed.

I therefore see the claimed multi-metre sea-level rise as not a prediction and their characterisation as such is at best unfortunate. The fresh water injection is simply a prescribed forcing of the model system. The authors have no robust basis and ample comments on the record associated with the review calling into considerable doubt the verity of the underlying assumptions. So, the central headline of multi-metre sea-level is probably best considered an assumption instead of a prediction.

The hosing experiments also have an issue that the water is injected into the Oceans at -15C, which you can do in a model. I could inject water at absolute zero if I wished (although the model might, admittedly, crash). But in the real-world the water will be added at or close to -1.8C or higher. It is an open question whether this step is valid to approximate ice calving effect, and how it impacts the model predictions (more, again, on that later).

The Boulder deposit is at least as plausibly tsunami-mediated

One of the most eye-catching aspects of the paper was the apparently storm tossed relic boulders atop a current day cliff that was used to support an assertion of increased storminess in the Eemian. There is little doubting the boulder deposit was wave mediated and whilst there is some uncertainty inherent in dating it was at or around the late Eemian maximum. What is highly uncertain is that the waves were storm driven. These boulders were likely well in excess of 1,000 tonnes and i) dislodged from the sea-floor then ii) raised 20 metres. The amount of energy required to do this is tremendous. There are likely only a few places in the world where meteorologically driven waves get large enough to do this and in the modern climate the location is definitively not one of these. Wave power is a function of windspeed, fetch and duration. It is only really in mid-latitude locations, such as the west coast of Ireland, where such waves can plausibly occur. In the tropical locations although wind speed can be considerably higher fetch and duration are both limited. A local point tsunami which may have also led to local uplift (hence reducing the work required) as mentioned by expert reviewers is at least as likely.

The largest impacts go almost unmentioned

From an impacts perspective the biggest impact is not the sea-level rise at all. The model runs show very large perturbations to, in particular, northern hemisphere climate in the mid-21st Century. Basically many areas in Europe in particular enter a period at least as cold if not colder than the little ice age. The associated rainfall changes are equally as impressive. This would lead to large-scale challenges around provision of food, services etc. for global society and large-scale disruption of ecosystems. It is also entirely opposite to the direction of climate change that policy makers are currently planning for on this timescale. If (and in case you haven't twigged this yet that is an extremely big if in my expert judgement) the paper hypothesis were to eventuate, we'd have made massively incorrect adaptation decisions and investments and it would have large-scale implications for society.

Change of title

The original title was:
"Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 ◦C global warming is highly dangerous"

and became:
"Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 ◦C global warming could be dangerous"

This change has been variously discussed e.g. here amongst many others. I see no way that the original title could remain given:
  • The speculative nature of the freshwater injection (amount, rate and method)
  • Open questions over interpretation of the supporting observational and in particular palaeo-evidence and its interpretation
  • The non-deterministic nature of the climate system
  • The fact that the findings contravene accepted science based upon many decades of research and publications by many respected and established groups and individuals
The title was (and has to be) a reflection upon the paper contents and not on whether 2C does or does not reflect dangerous interference with the climate system. Those who willingly or unwittingly conflate these two issues are falling into a very obvious and dangerous (no pun intended) logic trap. The title should reflect the paper and not be a position statement upon whether some nominal departure from pre-industrial is safe or not. The two are completely seperate issues. To answer the second requires a holistic assessment of the totality of evidence for impacts of various thresholds on subcomponents of the Earth System. For that you want to wade through IPCC WG2 (book a few days out to do so) and not a single paper! The editor was entirely correct in that context to follow reviewer advice and insist on the change. To not do so would have been to discount the points raised above and have been extremely foolhardy.


Here I shall just concentrate, briefly, upon the reception to the revised paper published this week. There is an interesting twitter thread here (see also here) on how two journalists came to polar opposite views. Obviously, I agree with Seth Borenstein's position here. Indeed, possibly the worst piece of journalism on the paper that dispensed with even any pretence of scientific balance was the piece at Slate. If you have got this far firstly congratulations and secondly you should be well sensitized to the fact that peer review is an imperfect filter. Being published does not make it part of a scientific 'canon' and nor should science be conflated with religion in such a manner (actually, at all).

Elsewhere I've seen pieces in the Washington Post and several other places that provide a degree of balance. Climatehome ran a nice piece after a phone interview. The Guardian has also decided to dispense pretty much entirely with balance. Twitter has been somewhat 'fun'.

Some of the articles, discussions and discourse have shown up a small number of the people supporting the paper to be no better in terms of behaviour, conspiracy theorising or reasoned logic than those on the opposite side of the aisle. Science works by a slow, deliberative methodical process. Single papers do not overturn received wisdom. Nor do blog articles (this one included) or comments below the line in various fora. A lot more light and a lot less heat is needed.

And people wonder why many of my colleagues are in general reticent to wade into the wider public debate ...

Tuesday, March 1, 2016

The Road from Paris: Low Carbon World or Dangerous Climate Change?

On Thursday 10 March we are hosting a seminar by Prof Kevin Anderson, one of the world's leading authorities on climate change.

The Road from Paris: Low Carbon World or Dangerous Climate Change?

Professor Kevin Anderson

11am Thursday, 10th March, Hamilton Institute Seminar Room (Room 317),
3rd Floor Eolas Building,

In this presentation, Kevin Anderson will revisit the scale of the climate challenge, arguing that whilst the science of climate change has progressed, there has been no corresponding acknowledgement of the rate at which our emissions from energy need to be reduced. He will suggest that the Paris Agreement exemplifies this duality. Similarly, he will argue that the focus on green growth continues to eclipse scientific analysis which demonstrates the need for radical social as well as technical change. Prof. Anderson will develop a quantitative framing of mitigation, based on IPCC carbon budgets, before finishing with more qualitative examples of what a genuine low-carbon future may contain.

Kevin Anderson is Professor of Energy and Climate Change in the School of Mechanical, Aerospace and Civil Engineering at the University of Manchester. He is Deputy Director of the Tyndall Centre for Climate Change Research and is research active with recent publications in Royal Society journals and Nature. He engages widely across all tiers of government; from reporting on aviation-related emissions to the EU Parliament, advising the Prime Minister's office on Carbon Trading and having contributed to the development of the UK's Climate Change Act.

Professor Anderson's work on carbon budgets has been pivotal in revealing the widening gulf between political rhetoric on climate change and the reality of rapidly escalating emissions. His work makes clear that there is now little chance of maintaining the rise in global temperature at below 2C, despite repeated high-level statements to the contrary. Moreover, Kevin's research demonstrates how avoiding even a 4C rise demands a radical reframing of both the climate change agenda and the economic characterisation of contemporary society.

Professor Anderson has a decade of industrial experience, principally in the petrochemical industry. He sits as commissioner on the Welsh Government's Climate Change Commission and is a Director of Greenstone Carbon Management.

Thursday, February 25, 2016

Past and future climate change in the context of memorable seasonal extremes

A new paper by ICARUS researchers and international colleagues has been published in Climate Risk Management. The paper is Open Access.

Past and future climate change in the context of memorable seasonal extremes
T. Matthews, D. Mullan, R.L. Wilby, C. Broderick, C. Murphy

It is thought that direct personal experience of extreme weather events could result in greater public engagement and policy response to climate change. Based on this premise, we present a set of future climate scenarios for Ireland communicated in the context of recent, observed extremes. Specifically, we examine the changing likelihood of extreme seasonal conditions in the long-term observational record, and explore how frequently such extremes might occur in a changed Irish climate according to the latest model projections. Over the period (1900–2014) records suggest a greater than 50-fold increase in the likelihood of the warmest recorded summer (1995), whilst the likelihood of the wettest winter (1994/95) and driest summer (1995) has respectively doubled since 1850. The most severe end-of-century climate model projections suggest that summers as cool as 1995 may only occur once every ~7 years, whilst winters as wet as 1994/95 and summers as dry as 1995 may increase by factors of~8 and  ~10 respectively. Contrary to previous research, we find no evidence for increased wintertime storminess as the Irish climate warms, but caution that this conclusion may be an artefact of the metric employed. It is hoped that framing future climate scenarios in the context of extremes from living memory will help communicate the scale of the challenge climate change presents, and in so doing bridge the gap between climate scientists and wider society.

Fig. 8. Evolution of z-scores in the historical and RCP experiment calculated for centred, 30-year sliding windows. The shaded region of the CMIP5 ensemble spans 5–95th percentiles, whilst the solid lines provide the median. The discontinuity between the historical and RCP 8.5 medians is because only a subset of historical model runs continues to RCP 8.5. Note that the observed series are also displayed in each panel and the different scaling on the respective y-axes.

Thursday, February 18, 2016

Congratulations to (soon to be) Dr. Shaun Harrigan

Shaun has just successfully defended his thesis in a viva held at Maynooth. Congratulations, Shaun.

Here are details of the thesis completed under the supervision of Dr. Conor Murphy.

Exploring the Hydroclimatology of Floods: From Detection to Attribution

Uncertainties in projected future flood risk and challenges of detecting signals of change from observations highlight the need to advance process understanding through linking hydrological extremes to large-scale climate drivers. In Ireland, recent years have highlighted vulnerability to flooding yet little research has been undertaken exploring hydroclimatic signatures of change in extremes at different scales, in part due to a lack of quality assured data for relevant variables. This is an important research gap given Ireland’s sentinel position on the Atlantic margin of northwest Europe and is addressed within this thesis. The Island of Ireland (IoI) is classified into 3 Extreme Rainfall Regions (ERRs) reflecting distinct extreme precipitation climatologies, thus furthering understanding of physical flood-producing mechanisms. A comprehensive statistical trend analysis is performed on extreme precipitation and flood indices under a standard statistical framework. Results show a robust increasing trend in extreme precipitation magnitude, frequency, and intensity. Similar results are found for flood indices at longer time-scales but limited station density prohibits stronger conclusions. Atmospheric drivers of flood occurrence are reconstructed back to 1872 using an objective weather classification scheme and used to identify four flood rich periods: 1.) pre-1890s; 2.) late-1900s to mid-1930s, 3.) a short spell in the 1980s, and 4.) late-1990s onwards. The recent flood rich period is not unprecedented at the centennial time-scale. Moving towards attribution, the North Atlantic Oscillation (NAO) is found to modulate flood propensity, with strongest influence in the west and northwest. At the catchment scale the utility of an attribution framework based on the method of multiple working hypotheses is posited using the Boyne catchment as an exemplar. Results show the complexity of attributing hydroclimatic change at the catchment scale where the system is influenced by internal and external change. This work advances understanding of hydroclimatic flood processes and establishes important new datasets that together will be important for better managing current and future flood risk and open prospects for new management tools in Ireland, especially seasonal hydrological forecasting.

Total Column Water (TCW) fields (in kg m-2) at 12:00 UTC from ERA-Interim reanalysis at 0.75°  0.75° resolution on the day before, day of (08/01/2005), and day after the most widespread flooding across the Island of Ireland (almost 80 % of catchments).

We can finally also give Shaun his mail without jinxing him ...