In The Beginning Was The Confusion By Angelo Rubino
In the paper
Angelo Rubino, 2011: What will a new generation of world climate research and computing facilities bring to climate long-term predictions? Theoretical and Applied Climatology. DOI: 10.1007/s00704-011-0448-2Online First™
I present a critical discussion which embraces the crucial aspects of the communication between climate scientists and lay persons, of the role confusing statements may exert on possible advancements in climate research, and of scientific priorities in climate science.
I start distinguishing between different applications of climate models and identifying confusing uses of the words “prediction” and “projection” in recent discussions on climate modeling.
In my opinion, increasing model resolution and complexity, although undoubtedly helpful for many applications related to a deeper understanding of the complex climate system and to substantial improvement of short-term forecasts, is not destined…..to tackle the impossibility of predicting prominent climate forcings and to facilitate result comparisons against observations.
Finally, I discuss possible alternative resource allocations, including a different employment policy for climate scientists.
A few years ago, in an essay appeared in the BAMS, Mishchenko et al. (2007) stated that
“The analysis by Hansen et al. (2005)… indicates that the current uncertainties in the TSI and aerosol forcings are so large that they preclude meaningful climate model evaluation by comparison with observed global temperature change”.
The natural consequence of this statement should have been the (at least temporary) end of the discussion on climate projections, predictions, and the possibility of carrying out climate crucial experiments by means of numerical modelling.
Indeed, each result referring to the solution of a prognostic equation can be technically named prediction, in the sense that future values of the model variables are calculated starting from previous ones. However, as far as the specific task of numerical modeling (i.e., problem solving), but also the communication with lay persons is concerned, the word prediction possesses a particular meaning. In other words, the sense (the utility) of a prediction is to predict, verifiably, future events.
It is also obvious that, if a model is not (yet) able to perform predictions in this sense, it will be operatively useless to increase uncertainties by perturbing model conditions (obscurum per obscurium…) and hence, operatively, such perturbations should follow and not precede or substitute predictions.
Also, numerical climate simulations are and remain process studies, at least until new discoveries will definitively clarify still uncomprehended climate dynamics, clearly indicate magnitude and variability of climate forcings. and allow one to impose accurate initial conditions to the models. They are and will be important, fundamental and necessary for deepening our knowledge on the complexity of the climate system: process studies.
However, instead of disappearing from the zoo of climate nomenclature, the words “prediction”, “projection”, “forecast” etc. seem to recur with increasing frequency in the dedicated literature as well as in the media, while, as recently indicated by Bray and von Storch (2009), a considerable part of the scientists working with climate models seems not to be aware of the difference between the meaning of the word “prediction” (or “forecast”) and the word “projection”.
This is certainly to be excused. A certain touch of subjectivism seems to be inherent in the discussion since the beginning, as, for instance, the glossary of the IPCC third assessment report (2001) states that
“A climate prediction or climate forecast is the result of an attempt to produce a most likely description or estimate of the actual evolution of the climate in the future, e.g. at seasonal, interannual or long-term time scales”,
“…projections are distinguished from climate predictions in order to emphasize that climate projections depend upon the emission/concentration/radiative forcing scenario used, which are based on assumptions, concerning, e.g., future socio-economic and technological developments, that may or may not be realized, and are therefore subject to substantial uncertainty”.
The difference would be thus a matter of emphasis. Radiative forcing based on assumptions concerning human developments, which may or may not be realized, is, in the opinion of some climate scientists, substantially different from radiative forcing based on assumptions concerning volcanic eruptions or solar activity, which may or may not be realized.
A matter of taste, which seems to suggest to some climate scientists to rapidly move ahead:
“It is both necessary and possible to revolutionize climate prediction”
to meet societal needs like those aimed at achieving
“accurate and reliable estimates of changes in the probability of regional weather variations to develop science-based adaptation and mitigation strategies” (Shukla et al. 2010),
and at providing
“improved projections, predictions, and monitoring of multidecadal global to regional climate and coupled Earth system changes, including estimates of the frequency and intensity of regional extremes, their impacts and improved information on the assumptions, confidence, and uncertainty of all estimates…”
as well as
“improved early warning of famine, water shortages, pestilence, and disease in developing nations and the promotion of social and economic development in a changing climate…” (Shapiro et al. 2010).
The confusion is remarkable.
The costs of the announced revolution? Maybe a few billion $ for a 5 year project would suffice…
But is the goal to be achieved?
In point of fact, in March 2010, the UK Met Office decided to stop issuing a seasonal forecast for the UK four times a year. Instead, a monthly outlook, updated on a weekly basis, will be published. In an official note – see http://webarchive.nationalarchives.gov.uk/+/http://www.metoffice.gov.uk/corporate/pressoffice/2010/pr20100305b.html), the Met Office explained that
“…although we can identify general patterns of weather, the science does not exist to allow an exact forecast beyond five days, or to absolutely promise a certain type of weather…”
I am thus convinced that the relevance of these topics and the possible confusion deriving from rather contrasting statements (sometimes even expressed by the same scientists, maybe also depending on the different arguments to be emphasized…) and different meanings given to the same words deserve a large discussion on epistemological aspects of climate science and on resources allocations.
It is possible, in fact, that climate research will profit from the proposed institution of a few multinational, very large centres for climate prediction devoted at producing long-term forecasts. As a possible intermediate task, however, I propose to
a) Concentrate energies, using part of the supercomputer resources already available for climate simulations, on a Interdisciplinary multi-year, large, multinational pilot modelling project aimed at predicting a complete ENSO cycle (IMMENSO);
b) Reconciling in situ and remote sensing measurements by initiating a truly open source, independent, major international project for the reassessment of global temperatures;
c) Deepen our knowledge of the circulation and of the distribution and variability of abyssal as well as Arctic and Antarctic water masses;
d) Implement a new employment policy for climate scientists.
As a concluding remark I also note that
Organization is important…But, in science, organization can also easily degenerate into hierarchization and conformism if not sustained by freedom. In the past, periods of strict control on research did not always correspond to expansive phases for science, and, often, fundamental developments and new discoveries arrived from personalities who were (and felt) profoundly free.
Mishchenko MI , Cairns B, Hansen JE , Travis LD , Kopp G, Schueler CF , Fafaul BA, Hooker RJ , Maring HB , Itchkawich T (2010) Accurate Monitoring of Terrestrial Aerosols and Total Solar Irradiance: Introducing the Glory Mission Bul. Amer Meteor Soc 88: 677–691.
Bray D, von Storch H (2009) ‘Prediction’ or ‘projection’? The nomenclature of climate science. Sci Commun 30: 534–543.
Shukla J, Palmer TN, Hagedorn R, Hoskins B, Kinter J, Marotzke J, Miller M, Slingo J (2010) Climate prediction from weeks to decades in the 21st century: towards a new generation of world climate research and computing facilities for climate prediction. Bull Am Meteorol Soc 91: 1407–1412.
Shapiro MA, Shukla J, Brunet G, Nobre C, Béland M, Dole R, Trenberth K, Anthes R, Asrar G, Barrie L, Bougeault P, Brasseur G, Burridge D, Busalacchi A, Caughey J, Chen D, Church J, Enomoto T, Hoskins B, Hov Ø, Laing A, Le Treut H, Marotzke J, McBean G, Meehl G, Miller M, Mills B, Mitchell J, Moncrieff M, Nakazawa T, Olafsson H, Palmer T, Parsons D, Rogers D, Simmons A, Troccoli A, Toth Z, Uccellini L, Velden C, Wallace JM (2010) An earth-system prediction initiative for the twenty-first century. Bull Am Meteorol Soc 91: 1377–1388.