Category Archives: Definition of Climate

Follow Up On The AMS Statement On “Climate Change’

In response to my post

Contradictory Statements By The American Meteorological Society – Comments On The New Statement Titled “Climate Change”

I communicated to the Committee members of our Statements on Weather Modification (of which I am a member and in which Danny Rosenfeld is the Chair).  With their permissions, I have reproduced our e-mail exchanges below with several members of the Committee (with their permission). These colleagues are each internationally well-respected scientists:

1. Danny Rosenfeld of the University in Jerusalem

2. Alan Robock of Rutgers University

3.  Bob Bornstein of San Jose State University

The bottom line conclusion by Danny in his last e-mail fits with my view of this subject.

My Initial E-Mail To Danny

Hi Danny

In your request for input you asked whether we should consider revising any of the policy statements. The release today of the AMS Statement on Climate Change clearly ignores what we concluded in our Statement on Inadvertant Weather Modification. Thus I recommend consideration of a revision that corrects their excessively narrow view on how humans are altering the climate and the impact of natural variations in climate such as reported, for example, in Shaun Lovejoy’s new paper

“The Climate Is Not What You Expect” By S. Lovejoy and D. Schertzer 2012 [submitted to BAMS]

that I posted on in

Excellent New Paper “The Climate Is Not What You Expect” By Lovejoy and Schertzer 2012

I have posted today on the conflict between the two AMS Statements (the new one on Climate Change and ours on Inadvertant Weather Modification) in my post

Contradictory Statements By The American Meteorological Society – Comments On The New Statement Titled “Climate Change”

I would, based on their new Statement, be interested in addressing this issue in a revised Statement on Inadvertant Weather Modification. .

Best Regards

Roger

Danny’s Reply

Hi Roger,

It seems to me that the new AMS statement on climate change does recognize the roles of aerosols, land use changes and other factors apart from CO2. See the quote below.

“Human activity also affects climate through changes in the number and physical properties of tiny solid particles and liquid droplets in the atmosphere, known collectively as atmospheric aerosols. Examples of aerosols include dust, sea salt, and sulfates from air pollution. Aerosols have a variety of climate effects. They absorb and redirect solar energy from the sun and thermal energy emitted by Earth, emit energy themselves, and modify the ability of clouds to reflect sunlight and to produce precipitation. Aerosols can both strengthen and weaken greenhouse warming, depending on their characteristics. Most aerosols originating from human activity act to cool the planet and so partly counteract greenhouse gas warming effects. Aerosols lofted into the stratosphere [between about 13 km (8 miles) and 50 km (30 miles) altitude above the surface] by occasional large sulfur-rich volcanic eruptions can reduce global surface temperature for several years. By contrast, carbon soot from incomplete combustion of fossil fuels warms the planet, so that decreases in soot would reduce warming. Aerosols have lifetimes in the troposphere [at altitudes up to approximately 13 km (8 miles) from the surface in the middle latitudes] on the order of one week, much shorter than that of most greenhouse gases, and their prevalence and properties can vary widely by region.

Land surface changes can also affect the surface exchanges of water and energy with the atmosphere. Humans alter land surface characteristics by carrying out irrigation, removing and introducing forests, changing vegetative land cover through agriculture, and building cities and reservoirs. These changes can have significant effects on local-to-regional climate patterns, which adds up to a small impact on the global energy balance as well.”

Changes in aerosols and land use are major components in the anthropogenic-forced changes of Earth energy budget, and we cant get both weather and climate right without quantifying their effects, and much less the climate change.

But I would defend the emphasis on the greenhouse gases as being pointed out in the new statement as the dominant cause for warming trend in the last half century. While aerosols have not risen systematically during that period (re global deeming and brightening), CO2 and other GHGs did.

What do I miss here?

Best regards,
Danny

My Follow-Up

Hi Danny

Thank you for the quick reply. The paragraph that I highlighted in my post

“It is clear from extensive scientific evidence that the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases, including carbon dioxide (CO2), chlorofluorocarbons, methane, and nitrous oxide. The most important of these over the long term is CO2, whose concentration in the atmosphere is rising principally as a result of fossil-fuel combustion and deforestation.”

conflicts with our Statement and a wide range of other findings reported in the literature. Their statement of hindcast model quality of climate change can easily be shown to be false.

Best Regards

My Further Comment

P.S. The AMS Statement itself contradicts itself. It writes

“Land surface changes can also affect the surface exchanges of water and energy with the atmosphere. Humans alter land surface characteristics by carrying out irrigation, removing and introducing forests, changing vegetative land cover through agriculture, and building cities and reservoirs. These changes can have significant effects on local-to-regional climate patterns, which adds up to a small impact on the global energy balance as well.”

yet earlier highlights that

“…the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases, including carbon dioxide (CO2), chlorofluorocarbons, methane, and nitrous oxide. The most important of these over the long term is CO2..”

It is clear the Statement was not even probably vetted for internal inconsistencies. If they write

‘the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases”

and later write

“Humans alter land surface characteristics by carrying out irrigation, removing and introducing forests, changing vegetative land cover through agriculture, and building cities and reservoirs. These changes can have significant effects on local-to-regional climate patterns’

yet dismiss their importance because they add “up to a small impact on the global energy balance ….”

trivialize, as I read the Statement, their role in climate change.

Roger

Bob Bornstein’s Comment

Hi all

I agree with Danny that aerosols are acknowledged as a source of change, but we could further discuss a possible revised statement (if the AMS is willing to accept one from us at this time) at our Jan committee meeting.

My Reply to Bob

Hi Bob.  Acknowledging aerosols as a source of change is not the issue. It is their identification of CO2 and a few other greenhouse gases as the dominant climate forcing. It is just one of a suite of first order human climate forcings, in my view.  If we share that view, then the AMS Statement is not accurate.

Best Regards

Roger

Alan Robock’s Comment

Dear All,

I see no conflict between the two AMS statements. The new one addresses global climate, and recognizes regional impacts of aerosols and land surface changes, which is what the older statement says. What is the problem? Blog posts and submitted papers are not sufficient evidence to do anything. I don’t understand what changes would be made in the Statement on Inadvertant Weather Modification. Anyway, it addresses weather and not climate.

My Reply to Alan

Hi Alan

I list peer reviewed papers that conflict with the AMS Statement. These are not submitted papers. The blog posts are just used to communicate these papers and the NRC assessment to others. Also we discuss climate in our Inadvertent Weather Modification Statement.

Alan’s Reply

Dear Roger,

Yes, you can post my comments as long as you include this one:

Clearly regional climate change is affected by land use and aerosols. But for the global average climate, the dominant forcing is the increase of anthropogenic greenhouse gases. Global warming is reduced by the net effect of tropospheric aerosols, but it continues because the greenhouse gas emissions and current concentrations still produce a net positive radiative forcing.

Your claims seem to imply that greenhouse gas emissions are not a serious environmental hazard. Don’t you think that global warming is dangerous and that continued greenhouse gas emissions, particularly carbon dioxide, should be reduced as soon as we can? Or are you against mitigation?

My Reply to Alan

Hi Alan

Thank you for your permission. I will certainly include what you wrote.

In terms of your question, I agree with you that the continued elevation of atmospheric concentrations of CO2 is a major concern. We are entering uncharted territory, and the less regrets approach must be to seek effective ways to limit this increase in CO2.

My even greater concern, however, with respect to CO2 is in its biogeochemical effect (to the biosphere). Even if there were only a relatively small contribution to global warming from CO2, the effect on plant diversity (e.g. genetic response), plant function, etc could be very significant, and we do not understand the risks that society and the environment face from this biogeochemical effect.

Progress to develop effective mitigation and adaptation policies are being significantly hampered, in my view, by

i) the assumption that the multi-decadal global models are providing us with skillful predictions for the coming decades(and skillful hindcast attribution simulations); the are not – e.g. see

CMIP5 Climate Model Runs – A Scientifically Flawed Approach

where peer reviewed papers indicate that this assumption has failed so far

and

ii) that a focus on global warming when we communicate to policymakers, rather than on all of the climate forcings and feedbacks, is one reason that action on mitigating climate risks (including from added CO2) has been so ineffective. We need a more inclusive approach; win-win policies; e.g. see

A Win-Win Solution to Environmental Problems

to build consensus has to how to move forward [I subscribe to the approach my son advocates in his book "the Climate Fix" with respect to how to deal with the CO2 part of climate].

I hope this clarifies my perspective. In terms of the new AMS Statement on Climate Change, they fail, in my view, to accurately present the issue of climate.

Best Regards

Roger

Danny’s Further Comment

Hi Roger,

I don’t really see the problem with the AMS statement on climate change.

It does not undervalue the role of aerosols and land use in altering the climate. It merely states that the trend in the anthropogenic climate forcing was dominated by increasing GHG (while other components of the forcing had not such a clear rising trend during the last 50 years). Then it makes the connection between the trends in rising GHG and global temperatures.

Otherwise, your reservations might come across as if you dispute the notion that increasing GHG is causing increasing global temperatures. Did you really mean that?

Best regards,
Danny

My Reply to Danny

Hi Danny

I disagree with this claim

“the anthropogenic climate forcing was dominated by increasing GHG”.

This claim is clearly inaccurate. I am surprised that you accept this as your work shows that aerosols from human activities have altered CCN concentrations globally.

Flood or Drought: How Do Aerosols Affect Precipitation? by Daniel Rosenfeld, Ulrike Lohmann, Graciela B. Raga, Colin D. O’Dowd, Markku Kulmala, Sandro Fuzzi, Anni Reissell, Meinrat O. Andreae, Science 5 September 2008: Vol. 321. no. 5894, pp. 1309 – 1313 DOI: 10.1126/science.1160606.

In that paper you wrote

“….before humankind started to change the environment, aerosol concentrations were not much greater (up to double) over land than over the oceans… “

In the paper

Andreae and Rosenfeld, 2008: Aerosol–cloud–precipitation interactions. Part 1. The nature and sources of cloud-active aerosols. Earth System Reviews.

you wrote

“There is now clear and rapidly growing evidence that atmospheric aerosols have profound impacts on the thermodynamic and radiative energy budgets of the Earth…”

“Model calculations and observations in remote continental regions consistently suggest that CCN concentrations over the pristine continents were similar to those now prevailing over the remote oceans, suggesting that human activities have modified cloud microphysics more than what is reflected in conventional wisdom.”

I could list similar findings with respect to LULCC.

The increasing GHG did not dominate anthropogenic climate forcing over the last decades. Unfortunately, the human effects are more serious than that.

With respect to your question as to whether I dispute the notion that increasing GHGs is causing increasing global temperatures, clearly added CO2 and other greenhouse gases is a first-order positive radiative forcing. Clearly, I agree that increasing GHGs are contributing to an increase.

Its relative contribution to the observed global warming (which is best diagnosed by changes in upper ocean heat content), however, is still uncertain due to

i) aerosol effects; where you wrote in your June 2, 2006 Science Perspective article on the role of aerosols entitled “Aerosols, Clouds, and Climate

“These aerosol effects are poorly quantified and represent the greatest uncertainty in our understanding of the climate system.”

ii) solar effects – e.g. see

Lean, J. L., and D. H. Rind (2009): How Will Earth’s Surface Temperature Change in Future Decades?,
Geophys. Res. Lett., doi:10.1029/2009GL038932, in press. (accepted 9 July 2009).

iii) natural variations – e.g. see

“The Climate Is Not What You Expect” By S. Lovejoy and D. Schertzer 2012 [submitted to BAMS]

iv) land use/land cover effects – which in a global average change in heat content seem to average out, but have large regional effects on climate and the resultant effect on cloud cover is not known; e.g.

Pielke Sr., R.A., A. Pitman, D. Niyogi, R. Mahmood, C. McAlpine, F. Hossain, K. Goldewijk, U. Nair, R. Betts, S. Fall, M. Reichstein, P. Kabat, and N. de Noblet-Ducoudré, 2011: Land use/land cover changes and climate: Modeling analysis and observational evidence. WIREs Clim Change 2011, 2:828–850. doi: 10.1002/wcc.144.

Finally, it seems that we have a disagreement as to what is meant by anthropogenic climate forcing. In my view, it is much more than a change in the global average temperature (or global average TOA radiative imbalance).

Global scale effects on climate can occur due to alterations in regional atmospheric and ocean circulations due to regionally heterogeneous human-caused aerosol and land use/land cover changes, even if the global average radiative imbalance was not changed. In my view, this is the more serious issue, as droughts, floods, hurricane tracks, etc are associated with regional circulations patterns (including the NAO, PDO, ENSO etc), with a global average increase in average temperature only a relatively small contributor; e.g. see John Neilsen-Gammon’s analysis

http://blog.chron.com/climateabyss/2012/07/twenty-times-more-likely-not-the-science/

I wrote on the misleading use of the term “climate change” in my post

The Need For Precise Definitions In Climate Science – The Misuse Of The Terminology “Climate Change”

where I propose these two definitions

Global Warming is an increase in the global annual average heat content measured in Joules.

Climate Change is any multi-decadal or longer alteration in one or more physical, chemical and/or biological components of the climate system.

The National Research Council report

National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties.Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington,D.C., 208 pp

reinforces the need for this broader view.

In terms of seeking to mitigate and adapt to the effect of humans on the climate system, I have concluded that the focus on CO2 and a few other greenhouse gases as the dominate concern is not only inaccurate, but will lead to poor policy decisions.

Finally, do I have your permission (and Alan yours too) to post our e-mail exchanges on my weblog?

Best regards

Roger

Danny’s Comment [my highlight added]

Hi Roger,

Thanks for your elaboration and clarifications. I agree that my statement to which you did not agree:

“the anthropogenic climate forcing was dominated by increasing GHG”.

should be qualified to the climate scale.

Here we need indeed to separate the effects on regional and weather scales from the global and climate scales, as Lovejoy has now so nicely defined.

The amounts of anthropogenic aerosols on a global scale probably have already peaked. But the GHG concentrations keep accelerating. This means that the GHG dominate the trend of the globally averaged long term trend of the temperature, but at the regional scale other effects may dominate the trends of temperature and other parameters.

The meaning of the main points that I have been making in the publications that you have referenced are:

1. On a regional scale, the aerosols can be the dominant anthropogenic climate forcing.

2. On a global scale, the aerosols might be in par with the GHG. We just don’t know.

The inability to quantify the possibly large radiative forcing prevents us from quantifying adequately the climate sensitivity and hence from predicting the expected global warming due to a given added GHG-induced radiative forcing. This does not contradict the AMS statement that “the dominant cause of the rapid change in climate of the past  half century is human-induced increases in the amount of atmospheric greenhouse  gases”.

This is in fact a discussion on the boundary between weather modification and climate change. The impacts on the ecosystems certainly happen at the regional scales.

So where do we put the distinction between weather modification and climate change?

Roger, Your discussion has been very helpful to recognize this as a major question and the confusion that it incurs, which we as a committee need to address, and perhaps negotiate with the AMS committee on climate variability and change.

Thanks and best regards, Danny

My Reply to Danny

Hi Danny

Thank you for the further follow up. You raise an important issue -

What is the distinction between weather modification and climate change?

In the 2005 NRC report, we defined climate in Figure 1-1 [http://www.nap.edu/openbook.php?record_id=11175&page=12] as

“The climate system, consisting of the atmosphere, oceans, land, and cryosphere. Important state variables for each sphere of the climate system are listed in the boxes. For the purposes of this report, the Sun, volcanic emissions, and human-caused emissions of greenhouse gases and changes to the land surface are considered external to the climate system.”

It seems to me that weather is necessarily a component of the climate system. One can separate by averaging time (i.e. long term statistics), but this is clearly quite arbitrary. We often, for example,talk about the “microclimate” of a location and use this information to explain variations in local weather observations. Many use “seasonal climate predictions” when what they really mean are “season averaged weather statistics”.

On Shaun Lovejoy’s paper, he and I discussed more on the chaotic character of the climate system in a set of e-mails as reported in my post

Excellent New Paper “The Climate Is Not What You Expect” By Lovejoy and Schertzer 2012.

There does need to be a clearer (overdue in my view) definition of terminology and the AMS committees provide one effective set of venues to do this.

On your comment that the aerosol effect may have peaked, hopefully this is true. I agree it is not true for the GHGs. However, it is also not true of LULCC; e.g. see

Fragkias, F. and K.C. Seto, 2012: The rise and rise of urban expansion Urban land area has expanded globally during the past few decades – a trend that looks set to continue in the foreseeable future. IGBP Newsletter, 78. March 2012.

in my post

2012 IGBP Article “Cities Expand By Area Equal To France, Germany And Spain Combined In Less Than 20 years”

Can I post our e-mail exchanges? Alan (and Bob) have okayed his.

Best Regards

Roger

Danny’s Reply

Hi Roger,

Yes, you can post our email exchange.

Best regards, Danny

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2012 IGBP Article “Cities Expand By Area Equal To France, Germany And Spain Combined In Less Than 20 years”

There is an article in the March 2012 issue of the IGBP Newletter

Fragkias, F. and K.C. Seto, 2012: The rise and rise of urban expansion Urban land area has expanded globally during the past few decades – a trend that looks set to continue in the foreseeable future. IGBP Newsletter, 78. March 2012

that documents the dynamic character of urbanization. This land use change not only affects local and regional climate, but also results in a time varying effect on surface temperatures that have been used by the IPCC and others as the iconic metric of global warming. As we reported on in

Montandon, L.M., S. Fall, R.A. Pielke Sr., and D. Niyogi, 2011: Distribution of landscape types in the Global Historical Climatology Network. Earth Interactions, 15:6, doi: 10.1175/2010EI371

GHCNv.2 station locations are biased toward urban and cropland (>50% stations versus 18.4% of the world’s land) and past century reclaimed cropland areas (35% stations versus 3.4% land).

This bias is only going to increase in coming years as urban areas continue to expand.

The press release on the article has the title

Cities expand by area equal to France, Germany and Spain combined in less than 20 years

Text in the press release includes [highlight added]

Unless development patterns change, by 2030 humanity’s urban footprint will occupy an additional 1.5 million square kilometres – comparable to the combined territories of France, Germany and Spain, say experts at a major international science meeting underway in London.

UN estimates show human population growing from 7 billion today to 9 billion by 2050, translating into some 1 million more people expected on average each week for the next 38 years, with most of that increase anticipated in urban centres. And ongoing migration from rural to urban living could see world cities receive yet another 1 billion additional people. Total forecast urban population in 2050: 6.3 billion (up from 3.5 billion today).

Fragkias [Dr. Michail Fragkias of Arizona State University] notes that while there were fewer than 20 cities of 1 million or more a century ago, there are 450 today. While urban areas cover less than five per cent of Earth’s land surface, “the enlarged urban footprint forecast is far more significant proportionally when vast uninhabitable polar, desert and mountain regions, the world breadbasket plains and other prime agricultural land and protected areas are subtracted from the calculation.”

This article provides support for a statement in an earlier chapter of this IGBP Newsletter

Syvitski, J. 2012: An epoch of our makng. IGBP Newletter. 78.  March 2012.

which highlights that with respect to the human role on the environment (including climate ) that

“….the Anthropocene isn’t as well known as global warming, which two out of three people had heard of by 2008, according to a Gallop Poll (http://www.gallup.com/ poll/117772/Awareness-Opinions-Global-Warming-Vary-Worldwide.aspx). But the former is a more effective paradigm in describing the cumulative impact of civilisation, making global warming and its consequences but one of many ways in which humans have modified the Earth. Narrow focus on global warming might suggest that we simply need to stop emitting greenhouse gases and use renewable energy to abate the planet’s pressures. The human footprint is much larger than that.

This is the viewpoint that we presented in our article

Pielke Sr., R., K.  Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D.  Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E.  Philip Krider, W. K.M. Lau, J. McDonnell,  W. Rossow,  J. Schaake, J.  Smith, S. Sorooshian,  and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases.   Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American   Geophysical Union.

The new IPCC reprts should heed this growing call for a broader, more complete assessment of threats to the enviroment and society, rather than their scientifically flawed focus on the radiative effects of CO2 and a few other greenhouse gases.

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Excellent New Paper “The Climate Is Not What You Expect” By Lovejoy and Schertzer 2012

I was alerted to an informative new paper on the issue of what is climate [h/t to Philip Richens]. The paper highlights the nonstationarity of climate as we presented in the papers

Pielke, R.A., 1998: Climate prediction as an initial value problem. Bull.  Amer. Meteor. Soc., 79, 2743-2746.

As I wrote in that paper

“weather prediction is a subset of climate prediction and that both are, therefore, initial value problems in the context of nonlinear geophysical flow.’

“…..longer-term feedback and physical processes must be included. This makes climate prediction a much more difficult problem than weather prediction”.

As we wrote in

Rial, J., R.A. Pielke Sr., M. Beniston, M. Claussen, J. Canadell, P. Cox,  H. Held, N. de Noblet-Ducoudre, R. Prinn, J. Reynolds, and J.D. Salas,  2004: Nonlinearities, feedbacks and critical thresholds within the Earth’s  climate system. Climatic Change, 65, 11-38.

The Earth’s climate system is highly nonlinear: inputs and outputs are not proportional, change is often episodic and abrupt, rather than slow and gradual, and multiple equilibria are the norm.

The new paper on this subject is

The Climate Is Not What You Expect” By S. Lovejoy and D. Schertzer 2012 [submitted]

The abstract reads [highlight added]

Prevailing definitions of climate are not much different from “the climate is what you expect, the weather is what you get”. Using a variety of sources including reanalyses and paleo data, and aided by notions and analysis techniques from Nonlinear Geophysics, we argue that this dictum is fundamentally wrong. In addition to the weather and climate, there is a qualitatively distinct intermediate regime extending over a factor of ≈ 1000 in scale. For example, mean temperature fluctuations increase up to about 5 K at 10 days (the lifetime of planetary structures), then decrease to about 0.2 K at 30 years, and then increase again to about 5 K at glacial-interglacial scales. Both deterministic GCM’s with fixed forcings (“control runs”) and stochastic turbulence-based models reproduce the first two regimes, but not the third. The middle regime is thus a kind of low frequency “macroweather” not “high frequency climate”. Regimes whose fluctuations increase with scale appear unstable whereas regimes where they decrease appear stable. If we average macroweather states over periods ≈ 30 years, the results thus have low variability. In this sense, macroweather is what you expect.

We can use the critical duration of ≈ 30 years to define (fluctuating) “climate states”. As we move to even lower frequencies, these states increasingly fluctuate – appearing unstable so that the climate is not what you expect. The same methodology allows us to categorize climate forcings according to whether their fluctuations decrease or increase with scale and this has important implications for GCM’s and for climate change and climate predictions.

The conclusion reads

Contrary to [Bryson, 1997], we have argued that the climate is not accurately viewed as the statistics of fundamentally fast weather dynamics that are constrained by quasi fixed boundary conditions. The empirically substantiated picture is rather one of unstable (high frequency) weather processes tending – at scales beyond 10 days or so and primarily due to the quenching of spatial degrees of freedom – to quasi stable (intermediate frequency, low variability) macroweather processes. Climate processes only emerge from macroweather at even lower frequencies, and this thanks to new slow  internal climate processes coupled with external forcings. Their synergy yields fluctuations that on average again grow with scale and become dominant typically on time scales of 10 – 30 years up to ≈ 100 kyrs.

Looked at another way, if the climate really was what you expected, then – since one expects averages – predicting the climate would be a relatively simple matter. On the contrary, we have argued that from the stochastic point of view – and notwithstanding the vastly different time scales – that predicting natural climate change is very much like predicting the weather. This is because the climate at any time or place is the consequence of climate changes that are (qualitatively and quantitatively) unexpected in very much the same way that the weather is unexpected.

There are a series of informative comments on this paper by Judy Curry, Philip Richens, Shaun Lovejoy and others on the weblog All Models are Wrong post

Limitless Possibilities

In the insightful comment by Shaun Lovejoy on that weblog, he does write on one issue that I disagree with. Shaun writes

“….deterministic models (GCM’s) reproduce only weather and macroweather statistics (they do this quite well)”.

I agree on weather, but not on macroweather. Macroweather prediction has shown little, if any skill ; e.g. see the papers listed in my post

Kevin Trenberth Was Correct – “We Do Not Have Reliable Or Regional Predictions Of Climate”

As reported in that post, the papers reported on below document the failure to so far skillfully predict macroweather [what I refer to as climate, based on the definitions of  climate as a system in NRC 2005].

1. Fyfe, J. C., W. J. Merryfield, V. Kharin, G. J. Boer, W.-S. Lee, and K. von Salzen (2011), Skillful predictions of decadal trends in global mean surface temperature,  Geophys. Res. Lett.,38, L22801, doi:10.1029/2011GL049508

who concluded that

”….for longer term decadal hindcasts a linear trend correction may be required if the model does not reproduce long-term trends. For this reason, we correct for systematic long-term trend biases.”

2. Xu, Zhongfeng and Zong-Liang Yang, 2012: An improved dynamical downscaling method with GCM bias corrections and its validation with 30 years of climate simulations. Journal of Climate 2012 doi: http://dx.doi.org/10.1175/JCLI-D-12-00005.1

who find that without tuning from real world observations, the model predictions are in significant error. For example, they found that

”…the traditional dynamic downscaling (TDD) [i.e. without tuning) overestimates precipitation by 0.5-1.5 mm d-1…..The 2-year return level of summer daily maximum temperature simulated by the TDD is underestimated by 2-6°C over the central United States-Canada region.”

3. van Oldenborgh, G.J., F.J. Doblas-Reyes, B. Wouters, W. Hazeleger (2012): Decadal prediction skill in a multi-model ensemble. Clim.Dyn. doi:10.1007/s00382-012-1313-4

who report quite limited predictive skill in two regions of the oceans on the decadal time period, but no regional skill elsewhere,  when they conclude that

“A 4-model 12-member ensemble of 10-yr hindcasts has been analysed for skill in SST, 2m temperature and precipitation. The main source of skill in temperature is the trend, which is primarily forced by greenhouse gases and aerosols. This trend contributes almost everywhere to the skill. Variation in the global mean temperature around the trend do not have any skill beyond the first year. However, regionally there appears to be skill beyond the trend in the two areas of well-known low-frequency variability: SST in parts of the North Atlantic and Pacific Oceans is predicted better than persistence. A comparison with the CMIP3 ensemble shows that the skill in the northern North Atlantic and eastern Pacific is most likely due to the initialisation, whereas the skill in the subtropical North Atlantic and western North Pacific are probably due to the forcing.”

4. Anagnostopoulos, G. G., Koutsoyiannis, D., Christofides, A., Efstratiadis, A. & Mamassis, N. (2010) A comparison of local and aggregated climate model outputs with observed data. Hydrol. Sci. J. 55(7), 1094–1110

who report that

“…. local projections do not correlate well with observed measurements. Furthermore, we found that the correlation at a large spatial scale, i.e. the contiguous USA, is worse than at the local scale.”

5.  Stephens, G. L., T. L’Ecuyer, R. Forbes, A. Gettlemen, J.‐C. Golaz, A. Bodas‐Salcedo, K. Suzuki, P. Gabriel, and J. Haynes (2010), Dreary state of precipitation in global models, J. Geophys. Res., 115, D24211, doi:10.1029/2010JD014532.

who wrote

“models produce precipitation approximately twice as often as that observed and make rainfall far too lightly…..The differences in the character of model precipitation are systemic and have a number of important implications for modeling the coupled Earth system …….little skill in precipitation [is] calculated at individual grid points, and thus applications involving downscaling of grid point precipitation to yet even finer‐scale resolution has little foundation and relevance to the real Earth system.”

In response to my request to post on Shaun’s paper, he and I had a valuable e-mail interaction which I am posting below with his permission.

My initial query with Shaun’s reply embedded (as in the e-mail)

Hi Shaun

I was alerted by Philip to your excellent new paper

http://www.physics.mcgill.ca/~gang/eprints/eprintLovejoy/esubmissions/climate.not.26.6.12.pdf

Do I have your permission to post on my weblog an announcement about it along with the abstract and the conclusion? I would link to your pdf above where readers can obtain the full paper.

I have thought along the same lines as you have; e.g. see

Pielke, R.A., 1998: Climate prediction as an initial value problem. Bull. Amer. Meteor. Soc., 79, 2743-2746. http://pielkeclimatesci.files.wordpress.com/2009/10/r-210.pdf

Rial, J., R.A. Pielke Sr., M. Beniston, M. Claussen, J. Canadell, P. Cox, H. Held, N. de Noblet-Ducoudre, R. Prinn, J. Reynolds, and J.D. Salas, 2004: Nonlinearities, feedbacks and critical thresholds within the Earth’s climate system. Climatic Change, 65, 11-38. http://pielkeclimatesci.files.wordpress.com/2009/10/r-260.pdf

Pielke, R.A. and X. Zeng, 1994: Long-term variability of climate. J. Atmos. Sci., 51, 155-159. http://pielkeclimatesci.files.wordpress.com/2009/09/r-120.pdf

Pielke Sr., R.A., R. Wilby, D. Niyogi, F. Hossain, K. Dairuku, J. Adegoke, G. Kallos, T. Seastedt, and K. Suding, 2012: Dealing with complexity and extreme events using a bottom-up, resource-based vulnerability perspective. AGU Monograph on Complexity and Extreme Events in Geosciences, in press. http://pielkeclimatesci.files.wordpress.com/2011/05/r-365.pdf

If you approve, I plan to post for tomorrow.

Best Regards

Roger

P.S. Hi again Shaun

I was just alerted by Philip of your post on Tamsin Edward’s blog

http://allmodelsarewrong.com/limitless-possibilities/#comment-1397

and that of Judy Curry

http://allmodelsarewrong.com/limitless-possibilities/#comment-1238

and

http://allmodelsarewrong.com/limitless-possibilities/#comment-1257

On your comments, there is one I disagree with. You wrote

“….deterministic models (GCM’s) reproduce only weather and macroweather statistics (they do this quite well)”.

I agree on weather, but not on macroweather; eg. see the papers listed in

http://pielkeclimatesci.wordpress.com/2012/05/08/kevin-trenberth-is-correct-we-do-not-have-reliable-or-regional-predictions-of-climate/

Shaun’s response

You’ve sent me links to a lot of new material, it will take me time to digest it and I apologize for not having cited your material, this can be corrected in the papers still in the submission process.

Let me make the above point clear.  The statement  “….deterministic models (GCM’s) reproduce only weather and macroweather statistics (they do this quite well)” only applies to control runs of GCM’s and to their statistics (e.g. spectra), and this out to about 10 year or so.   I’m not sure if this is our point of disagreement, but this in no way implies that they give correct forecasts (or hind casts) – only that the broad type of variability (as characterized by statistical exponents such as spectral exponents) is not too different from the observations.  Do you still disagree?

Since your submission is already available, I assume it is okay to post on your paper, but please let me know if otherwise. If you disagree with the perspective I have provided on macroweather prediction.

Shaun’s response

I’m not sure exactly which perspective you mean? are you referring to your criticism of decadal climate forecasts?  If so, then I could somewhat modify the point I made above, I think that we would likely be  in agreement.

Pease e-mail me why and I can post on my weblog too.

Shaun’s response

Yes, go ahead and post it if you like.

My further e-mail

Hi Shaun

This comment of mine in BAMS and associated weblog post might also be of interest to you

Pielke Sr., R.A., 2010: Comments on .A Unified Modeling Approach to Climate System Prediction.. Bull. Amer. Meteor. Soc., 91, 1699.1701, DOI:10.1175/2010BAMS2975.1, http://pielkeclimatesci.files.wordpress.com/2011/03/r-360.pdf

http://pielkeclimatesci.wordpress.com/2011/01/25/publication-of-comments-on-a-unified-modeling-approach-to-climate-system-by-r-a-pielke-sr-and-reply-by-hurrell-et-al-2010/

Roger

Shaun’s reply

Thanks Roger.  Go ahead and cite all the stuff you want from our exchanges.  I’ll take a look at your papers, and maybe then the exchanges will be a bit more precise!  Thanks!

If one looks at the spectra of the NAO, the PDO or the Southern Oscillation Index, they don’t actually show a very big deviations from scaling behaviour, so that the ability or inability of the models to capture these process (which I admit are in the “macro weather” regime) will not affect very much this more fundamental question of the overall low unforced frequency behaviour (essentially the low frequency limiting behaviour of unforced GCM’s).

-Shaun

The new Lovejoy and Schertzer 2012, is a very important research contribution with major implications for the current IPCC assessment.  While it could be used to infer too positive a statement about the skill of predicting macroweather (i.e. climate on multi-decadal time scales as I have defined it),  it clearly documents the nonlinearity of the climate system and that weather, macroweather and climate (as defined in their paper) are initial value problems.

Their research also shows that there is a large over confidence in assessment reports, such as the IPCC, in being able to skillfully predict the human role in altering macroweather and longer term climate.

Shaun has also informed us that he will be publishing a book at Cambridge University Press with Daniel Schertzer this Fall titled “The Westher and Climate – Emergent Laws and Multifractal Cascades” that promises to be a very important much needed contribution to climate science.  I look forward to learning from it!

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Research Paper “Discursive Stability Meets Climate Instability: A Critical Exploration Of The Concept Of ‘Climate Stabilization’ In Contemporary Climate Policy” By Boykoff Et Al 2010

In response to the post

The Need For Precise Definitions In Climate Science – The Misuse Of The Terminology “Climate Change”

I was alerted to a paper on climate stabilization which adds significant insight into this subject. The paper is

Boykoff, M. T., D. Frame, and S. Randalls, 2010. Discursive stability meets climate instability: A critical exploration of the concept of ‘climate stabilization’ in contemporary climate policy, Global Environmental Change, Vol. 20, pp. 53-64.

The abstract reads [highlight added]

The goals and objectives of ‘climate stabilization’ feature heavily in contemporary environmental policy and in this paper we trace the factors that have contributed to the rise of this concept and the scientific ideas behind it. In particular, we explore how the stabilization-based discourse has become dominant through developments in climate science, environmental economics and policymaking. That this discourse is tethered to contemporary policy proposals is unsurprising; but that it has remained relatively free of critical scrutiny can be associated with fears of unsettling often-tenuous political processes taking place at multiple scales. Nonetheless, we posit that the fundamental premises behind stabilization targets are badly matched to the actual problem of the intergenerational management of climate change, scientifically and politically, and destined to fail. By extension, we argue that policy proposals for climate stabilization are problematic, infeasible, and hence impede more productive policy action on climate change. There are gains associated with an expansion and reconsideration of the range of possible policy framings of the problem, which are likely to help us to more capably and dynamically achieve goals of decarbonizing and modernizing the energy system, as well as diminishing anthropogenic contributions to climate change.

The conclusion reads

In this paper we have argued that the elegant attraction of ‘climate stabilization’ discourses has culminated in a focus on long term mitigation targets and a cost-effective climate policy that does not address broader political and ethical questions about the timescale, actors and costs involved. It seems appropriate, scientifically, historically and socially, to question this discursive hegemony and open up debates on more productive and effective framings of climate policy. This paper therefore argues that while the climate stabilization discourse (and associated ways of thinking/proposing/acting) has been valuable in drawing greater attention to human influences on the global climate, it is time to explicitly move to more productive ways of considering minimizing detrimental impacts from human contributions to climate change.

The perspective of “it is time to explicitly move to more productive ways of considering minimizing detrimental impacts from human contributions to climate change” fits with the view we express in our paper below, however, in my view, we  need to broaden the recommended viewpoint so that

More productive ways of considering minimizing detrimental impacts from human contributions to climate (and not just a change part), as well as from all other environmental and social threats.

In our paper

Pielke Sr., R.A., R. Wilby, D. Niyogi, F. Hossain, K. Dairuku, J. Adegoke, G. Kallos, T. Seastedt, and K. Suding, 2011: Dealing with complexity and extreme events using a bottom-up, resource-based vulnerability perspective. AGU Monograph on Complexity and Extreme Events in Geosciences, in press.

we write in the abstract

We discuss the adoption of a bottom-up, resource–based vulnerability approach in evaluating the effect of climate and other environmental and societal threats to societally critical resources. This vulnerability concept requires the determination of the major threats to local and regional water, food, energy, human health, and ecosystem function resources from extreme events including climate, but also from other social and environmental issues. After these threats are identified for each resource, then the relative risks can be compared with other risks in order to adopt optimal preferred mitigation/adaptation strategies.

This is a more inclusive way of assessing risks, including from climate variability and climate change than using the outcome vulnerability approach adopted by the IPCC. A contextual vulnerability assessment, using the bottom-up, resource-based framework is a more inclusive approach for policymakers to adopt effective mitigation and adaptation methodologies to deal with the complexity of the spectrum of social and environmental extreme events that will occur in the coming decades, as the range of threats are assessed, beyond just the focus on CO2 and a few other greenhouse gases as emphasized in the IPCC assessments.

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Climate Includes Extreme Events – A Forecast Extreme New Zealand Weather Cold and Snow Event

While it is common to state that weather is not climatology, the reality is that climatalogy is composed of a collection of weather events over some time period. 30-year average temperatures and precipitation, for example, are two examples.  NCDC has recently released its new climatological averages; e.g. see

Anthony Arguez, Russell S. Vose, 2011: The Definition of the Standard WMO Climate Normal: The Key to Deriving Alternative Climate Normals Bulletin of the American Meteorological Society Volume 92, Issue 6 (June 2011) pp. 699-704. doi: 10.1175/2010BAMS2955.1

It is also important to recognize, however, that extreme weather events are themselves part of climatology. It is such occurrences that often cause the most significant societal events.  It is also useful to identify thes extreme events as there are often claims that extreme events, such as drought and heat waves, will become more common (e.g. see), or less common such as snowstorms (e.g. see).

The extreme snow event in New Zealand that is forecast this weekend is noteworthy in the context of climatology since, according to the IPCC-type predictions, such events should be becoming less common.  The forecasts for this event are quite serious. The news agency TVNZ just released the article

Much of NZ braced for a polar blast

The text reads

Snow to sea level and blizzard conditions are set to hit New Zealand’s deep south, with snowfalls also spreading north.

MetService is warning of a polar outbreak in the deep south overnight tonight and tomorrow morning.

An extremely cold southerly outbreak is expected to bring snow to sea level over the south of the South Island early Sunday morning, the forecaster says.

A heavy snowfall warning has been issued for Fiordland south of Te Anau, Southland and the south and east of Otago including Dunedin.

Snow is forecast to spread to many other parts of the South Island and the lower North Island later on Sunday, it says.

Significant accumulations are likely in Fiordland south of Te Anau, Southland and the south and east of Otago.

The snow is expected to continue on Monday and into Tuesday.

The heavy snow is likely to cause major disruptions to traffic and make driving conditions very difficult, MetService warns.

Strong southerlies, gale-force on exposed coasts, with the cold temperatures will make the wind feel bitterly cold and create blizzard like conditions in some places, it says.

Farmers are being advised that stock may need shelter.

Road workers at the ready

Roading contractors are preparing to work around the clock this weekend clearing snow and laying grit.

The Transport Agency says it’s inevitable restrictions and some closures will be needed during the polar blast predicted.

Spokesman Andy Knackstedt says the number one concern is ensuring people’s safety.

He says people need to plan ahead, check the latest information, and think carefully about whether the journey is necessary or not.

This quite likely will be an historic extreme event for New Zealand, and is not in the direction of expected extreme events forecast such as presented in the news article in Cosmos by Oliver Chan titled

No snow, more drought, climate report warns

that I posted on yesterday in

Interesting Quote On Climate Model Prediction Skill By Steven Sherwood Of The University of New South Wales

source of the two images ECMWF

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A New View Of The Climate System Involving Spatio-temporal Chaos

There have been two post on Climate Etc [Judy Curry's weblog] that may change how we view the climate system. These posts under a name Tomas Milanovic  are

Chaos, ergodicity, and attractors

Spatio-temporal chaos

The text of one of the posts concludes that

“Fluid dynamics is a field theory. This means that the solutions of the Navier Stokes partial differential equations are fields – functions f(x,y,z,t) like velocity and pressure fields. The “phase space” of fluid dynamics is a Hilbert space where the elements are fields (functions). This Hilbert space is uncountably infinite dimensional (the L2 space of square integrable functions) and exactly the same as the one used to study quantum mechanics and more generally any PDE system.

This above mentioned fundamental property, which applies to the even broader climate system of which fluid dynamics is just one part,  is what makes the difference between temporal and spatio- temporal chaos.”

This view significantly broadens out the view of the climate system to include its spatial components and pattern features involving atmospheric/ocean features such as the Pacific Decadal Oscillation, ENSO, the North Atlantic Oscillation, etc.  As the text in one of the post writes

 “….the only approach that in my opinion goes in the right direction is Tsonis (see also the thread on climate shifts). If one reinterprets the Tsonis theory in the frame of a more general and correct field theory, he suggests that the climate attractor exists and is 5 dimensional. He identifies the 5 fields with 5 oceanic oscillations and quantifies every field by a single number (index). He doesn’t formulate it that way and it is extremely unlikely that a 3D field can be relevantly represented by a single number, but the paradigm is on the right track. I am convinced that this kind of approach will eventually lead to progress.”

I am privileged to be working with a Ph.d. student at the University of Colorado, Marcia Hyatt, who independently, developed an intuitive idea of what is refersed to as spatio-temporal chaos.  Marcia is working with Anastasios Tsonis and Sergev Kravtsov of the University of Wisconsin (as part of her doctoral committee) on this subject and the viewpoint expressed in the weblog posts will be  very valuable.

I look forward to posting Marcia’s research results when available.

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Missing The Major Point Of “What Is Climate Sensitivity”

There is a post by Zeke on Blackboard titled  Agreeing [See also the post on Climate Etc  Agreeing(?)].

Zeke starts the post with the text

“My personal pet peeve in the climate debate is how much time is wasted on arguments that are largely spurious, while more substantive and interesting subjects receive short shrift.”

I agree with this view, but conclude that Zeke is missing a fundamental issue. 

 Zeke writes

“Climate sensitivity is somewhere between 1.5 C and 4.5 C for a doubling of carbon dioxide, due to feedbacks (primarily water vapor) in the climate system…”

The use of the terminology “climate sensitivity” indicates an importance of the climate system to this temperature range that does not exist. The range of temperatures of  “1.5 C and 4.5 C for a doubling of carbon dioxide” refers to a global annual average surface temperature anomaly that is not even directly measurable, and its interpretation is even unclear, as we discussed in the paper

Pielke Sr., R.A., C. Davey, D. Niyogi, S. Fall, J. Steinweg-Woods, K. Hubbard, X. Lin, M. Cai, Y.-K. Lim, H. Li, J. Nielsen-Gammon, K. Gallo, R. Hale, R. Mahmood, S. Foster, R.T. McNider, and P. Blanken, 2007: Unresolved issues with the assessment of multi-decadal global land surface temperature trends. J. Geophys. Res., 112, D24S08, doi:10.1029/2006JD008229.

This view of a surface temperature anomaly expressed by “climate sensitivity” is grossly misleading the public and policymakers as to what are the actual climate metrics that matter to society and the environment. A global annual average surface temperature anomaly is almost irrelevant for any climatic feature of importance. 

Even with respect to the subset of climate effects that is referred to as global warming, the appropriate climate metric is heat changes as measured in Joules (e.g. see). The  global annual average surface temperature anomaly is only useful to the extent it correlates with the global annual average climate system heat anomaly [most of which occurs within the upper oceans].  Such heating, if it occurs, is important as it is one component (the “steric component”) of sea level rise and fall.

For other societally and environmentally important climate effects, it is the regional atmospheric and ocean circulations patterns that matter. An accurate use of the terminology “climate sensitivity” would refer to the extent that these circulation patterns are altered due to human and natural climate forcings and feedbacks. As discussed in the excellent post on Judy Curry’s weblog

Spatio-temporal chaos

finding this sensitivity is a daunting challenge.

I have proposed  definitions which  could be used to advance the discussion of what we “agree on”, in my post

The Terms “Global Warming” And “Climate Change” – What Do They Mean?

As I wrote there

Global Warming is an increase in the heat (in Joules) contained within the climate system. The majority of this accumulation of heat occurs in the upper 700m of the oceans.

Global Cooling is a decrease in the heat (in Joules) contained within the climate system. The majority of this accumulation of heat occurs in the upper 700m of the oceans.

Global warming and cooling occur within each year as shown, for example, in Figure 4 in

Ellis et al. 1978: The annual variation in the global heat balance of the Earth. J. Geophys. Res., 83, 1958-1962.

Multi-decadal global warming or cooling involves a long-term imbalance between the global warming and cooling that occurs each year.

Climate Change involves any alteration in the  climate system , which is schematically illustrated  in the figure below (from NRC, 2005)

which persists for an (arbitrarily defined) long enough time period.

 Shorter term climate change is referred to as climate variability.  An example of a climate change is if a growing season 20 year average  of 100 days was reduced by 10 days in the following 20 years.  Climate change includes changes in the statistics of weather (e.g. extreme events such as droughts, land falling hurricanes, etc), but also include changes in other climate system components (e.g. alterations in the pH of the oceans, changes in the spatial distribution of malaria carrying mosquitos, etc).

The recognition that climate involves much more than global warming and cooling is a very important issue. We can have climate change (as defined in this weblog post) without any long-term global warming or cooling.  Such climate change can occur both due to natural and human causes.”

It is within this framework of definitions that Zeke and Judy should solicit feedback in response to their recent posts.  I recommend a definition of “climate sensitivity” as

Climate Sensitivity is the response of the statistics of weather (e.g. extreme events such as droughts, land falling hurricanes, etc), and other climate system components (e.g. alterations in the pH of the oceans, changes in the spatial distribution of malaria carrying mosquitos, etc) to a climate forcing (e.g. added CO2, land use change, solar output changes, etc).  This more accurate definition of climate sensitivity is what should be discussed rather than the dubious use of a global annual average surface temperature anomaly for this purpose.

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The Terms “Global Warming” And “Climate Change” – What Do They Mean?

There continues to be considerable misunderstanding of the terms “global warming” and “climate change”. I have posted in previous years about these terms; e.g. see these posts in 2005;

What is Climate Change?

Is Global Warming the Same as Climate Change?

What is Climate? Why Does it Matter How We Define Climate?
 

Is Global Warming Spatially Complex?

but there continue to be misunderstandings.

I have attempted below to succinctly define these terms below:

Global Warming is an increase in the heat (in Joules) contained within the climate system. The majority of this accumulation of heat occurs in the upper 700m of the oceans.

Global Cooling is a decrease in the heat (in Joules) contained within the climate system. The majority of this accumulation of heat occurs in the upper 700m of the oceans.

Global warming and cooling occur within each year as shown, for example, in Figure 4 in

Ellis et al. 1978: The annual variation in the global heat balance of the Earth. J. Geophys. Res., 83, 1958-1962.

Multi-decadal global warming or cooling involves a long-term imbalance between the global warming and cooling that occurs each year.

Climate Change involves any alteration in the  climate system , which is schematically illustrated  in the figure below (from NRC, 2005)

which persists for an (arbitrarily defined) long enough time period.

 Shorter term climate change is referred to as climate variability.  An example of a climate change is if a growing season 20 year average  of 100 days was reduced by 10 days in the following 20 years.  Climate change includes changes in the statistics of weather (e.g. extreme events such as droughts, land falling hurricanes, etc), but also include changes in other climate system components (e.g. alterations in the pH of the oceans, changes in the spatial distribution of malaria carrying mosquitos, etc).

The recognition that climate involves much more than global warming and cooling is a very important issue. We can have climate change (as defined in this weblog post) without any long-term global warming or cooling.  Such climate change can occur both due to natural and human causes.

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Recommended Definitions of “Global Warming” And “Climate Change”

As discussed often in my posts; e.g.

What is Climate? Why Does it Matter How We Define Climate?

What is Climate Change?

Is Global Warming the Same as Climate Change?

there is lack of clarity in how these terms are defined. In today’s post, I offer the following short definitions:

Global Warming is an increase in the global annual average heat content measured in Joules.

Climate Change is any multi-decadal or longer alteration in one or more physical, chemical and/or biological components of the climate system.

The figure below (from NRC, 2005) schematically illustrates the Earth’s climate system 

 

Thus climate change includes, for example, changes in fauna and flora, snow cover, etc which persists for decades and longer. Climate variability can then be defined as changes which occur on shorter time periods.

Global warming involves the accumulation of heat in Joules within these components of the climate system, which is predominently the oceans, as shown in Table 1 in Levitis et al 2001.  The current use of the global average annual surface temperature trend to diagnose global warming involves only the two dimensional land, cryosphere and ocean surface.

As I wrote in

Pielke Sr., R.A., 2008: A broader view of the role of humans in the climate system. Physics Today, 61, Vol. 11, 54-55.

“Unlike temperature at some specific depth in the ocean or height in the atmosphere, where there is a time lag in the response to radiative forcing, no time lags are associated with heat changes, since the actual amount of heat present at any time is accounted for. Moreover, because the surface temperature is a massless two-dimensional global field while heat content involves mass, the use of surface temperature as a monitor of climate change is not accurate for evaluating heat storage changes. “

My recommendation is that the next IPCC assessment adopt these definitions for global warming and climate change.

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Weather And Climate – Well Summarized By On Tomas Milanovic On Climate Etc.

Tomas Milanovic has a accurate succinct summary of the relationship between weather and climate on the weblog post The Uncertainty Monster at Climate Etc.

The comment reads

“Weather is chaotic, nobody disputes that. The “climate” is exactly the same system, obeying to the same laws and described by the same equations like weather. The only difference being that the variables of the system “climate” are space and time averages instead of the instantaneous values. In addition for practical purposes the weather time scale is defined in days so that many slow variables are considered constant what spares computing time. However it is clear that if the system is chaotic with these constant coefficients , it will be chaotic with variable coefficients on longer time scales too.”

The issue of what is climate is discussed further in the article

Pielke, R.A., 1998: Climate prediction as an initial value problem. Bull. Amer. Meteor. Soc., 79, 2743-2746

where I wrote

“….weather prediction is a subset of climate prediction. Societally useful (i.e. reliable, accurate,etc.) requires that all of the feedbacks and other physical processes included in weather prediction be represented in the climate prediction model. In addition, longer-term feedback and physical processes must be included. This makes climate prediction a much more difficult problem than weather prediction.”

Indeed, climate models must not only be able to simulate weather features such as high and low pressure systems including tropical cyclones are well as operational numerical weather prediction models, but must be able to accurately simulate a diverse variety of physical, chemical and biological processes. Even then, nonlinear interactions between the many components of the climate system (e.g. as illustrated in Figure 1 in Rial et al 2004) can result in limiting skillful prediction decades into the future.  The Milanovic comment on Climate Etc. effectively summarizes this issue. A subject that is not properly assessed in the 2007 IPCC report.

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