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Regional Climate Projections

Filed under: — rasmus @ 27 August 2007

Regional Climate Projections in the IPCC AR4

glasses How does anthropogenic global warming (AGW) affect me? The answer to this question will perhaps be one of the most relevant concerns in the future, and is discussed in chapter 11 of the IPCC assessment report 4 (AR4) working group 1 (WG1) (the chapter also has some supplementary material). The problem of obtaining regional information from GCMs is not trivial, and has been discussed in a previous post here at RC and the IPCC third assessment report (TAR) also provided a good background on this topic.

The climate projections presented in the IPCC AR4 are from the latest set of coordinated GCM simulations, archived at the Program for Climate Model Diagnosis and Intercomparison (PCMDI). This is the most important new information that AR4 contains concerning the future projections. These climate model simulations (the multi-model data set, or just ‘MMD’) are often referred to as the AR4 simulations, but they are now officially being referred to as CMIP3.

One of the most challenging and uncertain aspects of present-day climate research is associated with the prediction of a regional response to a global forcing. Although the science of regional climate projections has progressed significantly since last IPCC report, slight displacement in circulation characteristics, systematic errors in energy/moisture transport, coarse representation of ocean currents/processes, crude parameterisation of sub-grid- and land surface processes, and overly simplified topography used in present-day climate models, make accurate and detailed analysis difficult.

I think that the authors of chapter 11 over-all have done a very thorough job, although there are a few points which I believe could be improved. Chapter 11 of the IPCC AR4 working group I (WGI) divides the world into different continents or types of regions (e.g. ‘Small islands’ and ‘Polar regions’), and then discusses these separately. It provides a nice overview of the key climate characteristics for each region. Each section also provides a short round up of the evaluations of the performance of the climate models, discussing their weaknesses in terms of reproducing regional and local climate characteristics.

Africa Evaluations of the GCMs show that they still have significant systematic errors in and around Africa, with excessive rainfall in the south, a spurious southward displacement of the Atlantic inter-tropical convergence zone (ITCZ), and insufficient upwelling in the seas off the western coast.

The report asserts that the extent to which regional models can represent the local climate is unclear and that the limitation of empirical downscaling is not fully understood. It is nevertheless believed that land surface feedbacks have a strong effect on the regional climate characteristics.

For the future scenarios, the median value of the MMD GCM simulations (SRES A1b) yields a warming of 3-4C between 1980-1999 and 2080-2099 for the four different seasons (~1.5 times the global mean response). The GCMs project an increase in the precipitation in the tropics (ITCZ)/East Africa and a decrease in north and south (subtropics).

Europe and the Mediterranean.
Europe In general, chapter 11 states that the most rapid warming is expected during winter in Northern Europe and during summer in southern Europe. The projections also suggest that the mean precipitation will also increase in the north, but decrease in the south. The inter-annual temperature variations is expected to increase as well.

A more detailed picture was drawn on the results from a research project called PRUDENCE, which represents a small number of TAR GCMs. The time was too short for finishing new dynamical downscaling on the MMD.

The PRUDENCE results, however, are more appropriate for exploring uncertainties associated with the regionalisation, rather than providing new scenarios for the future, since the downscaled results was based on a small selection of the GCMs from TAR.

Therefore, I was surprised to see such an extensive representation of the PRUDENCE project in this chapter, compared to other projects such as STARDEX and ENSEMBLES. (One explanation could be that the STARDEX results are used more in WGII, although apparently not cited. The results from ENSEMBLES are not yet published, and besides STARDEX is mentioned twice in section 11.10.)

Glomfjord precipitation

There are some results for Europe presented in chapter 11 of IPCC AR4 which I find strange: In Figure 11.6 the RCAO/ECHAM4 from the PRUDENCE project yields an increase in precipitation up to 70%(!) along the west coast of mid-Norway. Much of this is probably due to an enhanced on-shore wind due to a systematic lowering of the sea level pressure in the Barents Sea, and an associated orographic forcing of rain.

The 1961-90 annual total precipitation measured at the rain gauge at Glomfjord (66.8100N/13.9813E; 39 m.a.s.l.) is 2069 mm/year, and a 70% increase will therefore imply an increase to 3500mm/year (Left figure) which in my opinion is unrealistic . Apart from a sudden jump in the early part of the Glomfjord record, there are no clear and prominent trends in the historical time series (Figure left). The low values in the early part are questionable as the neighbouring station series do not exhibit similar jumps/breaks and is probably a result of a relocation of the rain gauges.

An increase of annual rainfall exceeding 1000mm would imply either that evaporation from the Norwegian Sea area must increase dramatically, or the moisture convergence must increase significantly since the water must come from somewhere. However, the whole region is already a wet region (as indicated by the annual rainfall totals) in the way of the storm tracks.

There are large local variations here (see grey curves in left Figure for nearby stations) and Glomfjord is a locations with high annual rainfall compared to other sites in the same area, but even a 70% increase of the rainfall with annual totals exceeding 1000mm at nearby sites (adjacent valleys etc) is quite substantial.

However, one may ask whether the rainfall at Glomfjord may change at a different rate to that of its surroundings. This question can only be addressed with empirical-statistical downscaling (ESD) at present, as RCMs clearly cannot resolve the spatial scales required.

To be fair, another PRUDENCE scenario presented in the same figure, but based on the HadAM3H model rather than the ECHAM4, suggests an upper limit for precipitation increase over northern Europe of 20% over northern Sweden.

Asia One of the key climate characteristics of Asia is the southeast Monsoon system. Chapter 11 suggest that the circulation associated with the Monsoon may slow down, but the moisture in the air may increase. However, while the general seasonal migration of rain is simulated by most climate models, the representation of the observed monsoon maximum rainfall along the west coast of India, northern parts of Bay of Bengal and north India is poor in many models (probably because of too coarse spatial resolution in GCMs).

Satellite view of the Himalayas The GCMs also most likely have significant problems describing the precipitation over Tibet, due to large small-scale spatial geographical features and distorted albedo feedbacks. The net effect may therefore be an increase in the rainfall associated with the Monsoon.

The Asian climate is also influenced by ENSO, but uncertainties in how ENSO will be affected by AGW cascades to the Asian climate.

There are, however, indications that heat waves will become more frequent and more intense. Furthermore, the MMD models suggest a decrease in the December-February precipitation and an increase in the remaining months. The models also project more intense rainfall over large areas in the future.

North America.
North America The general picture is that the GCMs provide realistic representation of the mean SLP and T(2m) over North America, but that they tend to over-estimate the rainfall over the western and northern parts.

The MMD results project strongest winter-time warming in the north and summer-time warming in the southwest USA. The annual mean precipitation is, according to AR4, likely to increase in the north and decrease in southwest.

A stronger warming over land than over sea may possibly affect the sub-tropical high-pressure system off the west coast, but there are large knowledge gaps associated with this aspect.

The projections are associated with a number of uncertainties concerning dynamical features such as ENSO, the storm track system (the GCMs indicate a pole-ward shift, an increase in the number of strong cyclones and a reduction in the medium strength storms poleward of 70N & Canada), the polar vortex (the GCMs suggest an intensification), the Great Plains low-level jet, the North American Monsoon system, ocean circulation and the future evolution in the snow-extent and sea-ice. Some of these phenomena are not well-represented by the GCMs, as their spatial resolution is too coarse. The same goes for tropical cyclones (hurricanes), for which the frequency, intensity and track-statistics remain uncertain.

A number of RCM-based studies provide further regional details (North American Regional Climate Change Assessment Program). Despite improvements, AR4 also states that RCM simulations are sensitive to the choice of domain, the parameterisation of moist convection processes (representation of clouds and precipitation), and that there are biases in the RCM results when GCM are provided as boundary conditions rather than re-analyses.

Furthermore, most RCM simulations have been made for time slices that are too short to provide a proper statistical sample for studying natural variability. There are no references to ESD for North America in the AR4 chapter except for in the discussion on the projections for the snow.

Latin America.
Latin America AR4 states that the annual precipitation is likely to decrease in most of Central America and southern Andes. However, there may be pronounced local effects from the mountains, and changes in the atmospheric circulation may result in large local variations.

The projections of the seasonal mean rainfall statistics for eg the Amazon forest are highly uncertain. One of the greatest sources of uncertainty is associated with how the character of ENSO may change, and there are large inter-model differences within the MMD as to how ENSO will be affected by AGW. Furthermore, most GCMs have small signal-to-noise ratio over most of Amazonia. Feedbacks from land use and land cover (including carbon cycle and dynamic vegetation) are not well-represented in most of the models.

Tropical cyclones also increase the uncertainty for Central America, and in some regions the tropical storms can contribute a significant fraction to the rainfall statistics. However, there has been little research on climate extremes and projection of these in Latin America.

According to AR4, deficiencies in the MMD models have a serious impact on the representation of local low-latitude climates, and the models tend to simulate ITCZs which are too weak and displaced too far to the south. Hence the rainfall over the Amazon basin tends to be under-estimated in the GCMs, and conversely over-estimated along the Andes and northeastern Brazil.

There are few RCM-simulations for Latin America, and those which have been performed have been constrained by short simulation lengths. The RCM results tend to be degraded when the boundary conditions are taken from GCMs rather than re-analyses. There is, surprisingly, no reference to ESD-based studies from Latin America, despite ESD being much cheaper to carry out and length of time interval being not an issue (I’ll comment on this below).

Australia & New Zealand.
Australia The projections for Australia and New Zealand suggest weaker warming in the south and increased frequency of high daily temperatures. The precipitations will, according to MMD, decrease in most of Australia, and it is likely that there will be more drought conditions in southern Australia in the future as a result of a poleward shift in the westerlies and storm track.

The MMD projections for the monsoon rainfall show large inter-model differences, and the model projections for the future rainfall over northern Australia are therefore considered to be very uncertain.

Little has been done to asses the MMD skill over Australia and New Zealand, although analysis suggest that the MMD models in general have a systematic low-pressure bias near 50S (hence a southward displacement of the mid-latitude westerlies). The simulated seas around Australia has a slight warm bias too, and most models simulate too much rainfall in the north and too little on the east coast of Australia.

The quality of the simulated variability is also reported to be strongly affected by the choice of land-surface model.

The projections of changes is the extreme temperatures for Australia and New Zealand has followed a simple approach where the range of variations has been assumed to be constant while the mean has been adjusted according the the GCMs, thus shifting the entire statistical distribution. The justification for this approach is that the effect on changes in the range of short-term variations has been found to be small compared with changes in the mean.

Analysis for rainfall extremes suggest that the return period for extreme rainfall episodes may halve in late 21st century, even where the average level to some extent is diminishing. AR4 anticipates an increase in the tropical cyclone (TC) intensities, although there is no clear trends in frequency or location.

Furthermore, TCs are influenced by ENSO, for which there are no clear indications for the future behaviour. AR4 also states that there may be up to 10% increases in the wind over northern Australia.

AR4 states that downscaled MMD-based projections are not yet available for New Zealand, but such results are very much in need because of strong effects from the mountains on the local climate. High-resolution regional modeling for Australia is also based on TAR or ‘recent ‘runs with the global CSIRO glimate model. A few ESD studies by Timbal and others suggest good performance at representing climatic means, variability and extremes of station temperature and rainfall.

Polar regions.
The Arctic The Arctic is very likely to warm at a higher rate than the global mean (Polar amplification), and the precipitation is expected to increase while the sea-ice will be reduced. The Antarctic is also expected to become warmer albeit more moderate, and the precipitation is projected to increase too.

However, the understanding of the polar climate is still incomplete, and large endeavors such as the IPY hope to address issues such as lack of decent observations, clouds, boundary layer processes, ocean currents, and sea ice.

AR4 states that all atmospheric models have incomplete parameterisations of polar cloud microphysics and ice crystal precipitation, however, the general improvement of the GCMs since TAR in terms of resolution, sea-ice modelling and cloud-radiation representation has provided improved simulations (assessed against re-analysis, as observations are sparse).

Part of the discussion about the Polar regions in AR4 relies on the ACIA report (see here , here and here for previous posts) in addition to the MMD results, but there are also some references to RCM studies (none to ESD-based work, although some ESD-analysis is embedded in the ACIA report). There has been done very little work on polar climate extremes and the projected changes to the cryosphere is discussed in AR4 chapter 10.

The models do in general provide a reasonable description of the temperature in the Arctic, with the exception of a 6-8C cold bias in the Barents Sea, due to the over-estimation of the sea-ice extent (the lack of sea-ice in the Barents Sea can be explained by ocean surface currents that are not well represented in GCMs). The MMD models suggest the winter-time NAO/NAM may become increasingly more positive towards the end of the century.

One burning question is whether is the response of the ice sheet will be enhanced calving/ice stream flow/basal melt. More snow will accumulate in Antarctica, as this ‘removes’ water from the oceans that otherwise would contribute to a global sea level rise. The precipitation in Antarctica, and hence snowfall, is projected to increase, thus partly offsetting the sea-level rise.

Small islands.
Islands AR4 concludes that sea levels will continue to rise, although the magnitude of the sea level rise is not expected to uniform. Furthermore, large inter-model differences make regional sea level projections more uncertain. AR4 states that the Caribbean islands in the vicinity of the Greater Antilles and Mauritius (JJA) will likely face drier summer-time conditions in the future whereas those in northern Indian Ocean are believed to become wetter.

Most GCMs do not have sufficiently high spatial resolution to represent many of the islands, therefore the GCM projections really describe changes over ocean surfaces rather than land. Very little work has been done in downscaling the GCMs for the individual islands. However, there have been some ESD work for the Caribbean islands (AIACC).

Two sentences stating that ‘The time to reach a discernible signal is relatively short (Table 11.1)’ is a bit confusing as the discussion was referring to the 2080-2099 period (southern Pacific). After having conferred with the supplementary material, I think this means that the clearest climate change signal is seen during the first months of the year. Conversely when stating ‘The time to reach a discernible signal’ for the northern Pacific, probably refers to the last months of the year.

Other challenges involve incomplete understanding of some climatic processes, such as the midsummer drought in the Caribbean and the ocean-atmosphere interaction in the Indian Ocean.

Many of the islands are affected by tropical cyclones, for which the GCMs are unable to resolve and the trends are uncertain – or at least controversial.

Empirical-statistical or Dynamical downscaling?
AR4 chapter 11 makes little reference to empirical-statistical downscaling (ESD) work in the main section concerning the future projections, but puts most of the emphasis on RCMs and GCMs. It is only in Assessment of Regional Climate Projection Methods section (11.10) which puts ESD more into focus.

I would have thought that this lack of balance may not be IPCC’s fault, as it may be an unfortunate fact that there are few ESD studies around, but according to AR4 ‘Research on [E]SD has shown an extensive growth in application…’. If it were really the case that ESD studies were scarce, then it would be somewhat surprising, as ESD is quick and cheap (here, here, and here), and could have been applied to the more recent MMD, as opposed to the RCMs forced with the older generation GCMs.

ESD provides diagnostics (R2-statistics, spatial predictor patterns, etc.) which can be used to assess both the skill of the GCMs and the downscaling. I would also have thought that ESD is an interesting climate research tool for countries with limited computer resources, and it would make sense to apply ESD to for climate research and impact studies to meet growing concerns about local impacts of an AGW.

Comparisons between RCMs and ESD tend to show that they have similar skills, and the third assessment report (TAR) stated that ‘It is concluded that statistical downscaling techniques are a viable complement to process-based dynamical modelling in many cases, and will remain so in the future.’ This is re-phrased in AR4 as ‘The conclusions of the TAR that [E]SD methods and RCMs are comparable for simulating current climate still holds’.

So why were there so few references to ESD work in AR4?

I think that one reason is that ESD often may unjustifiably be seen as inferior to RCMs. What is often forgotten is that the same warnings also go for the parameterisation schemes embedded in the GCMs and RCMs, as they too are statistical models with the same theoretical weaknesses as the ESD models. AR4 does, however, acknowledge this: ‘The main draw backs of dynamical models are … and that in future climates the parameterization schemes they use to represent sub-grid scale processes may be operating outside the range for which they were designed’. However, we may be on a slippery slope with parameterisation in RCMs and GCMs, as the errors feed back to the calculations for the whole system.

Moreover, a common statement heard even among people who do ESD, is that the dynamical downscaling is ‘dynamical consistent’ (should not be confused with ‘coherent’). I question this statement, as there are issues of gravity wave drag schemes and filtering of undesirable wave modes, parameterisation schemes (often not the same in the GCM and the RCM), discretisation of continuous functions, and the conservation associated with time stepping, or lateral and lower boundaries (many RCMs ignore air-sea coupling).

RCMs do for sure have some biases,yet they are also very useful (similar models are used for weather forecasting). The point is that there are uncertainty associated with dynamical downscaling as well as ESD. Therefore it’s so useful to have two completely independent approaches for studying regional and local climate aspects, such as ESD and RCMs. One should not lock onto only one if there are several good approaches. The two approaches should be viewed as two complementary and independent tools for research, and both ought to be used in order to get a better understanding of the uncertainties associated with the regionalisation and more firm estimates on the projected changes.

Thus, the advantage of using different methods has unfortunately not been taken advantage of in chapter 11 of AR4 WGI to the full extent, which would have made the results even stronger. When this points was brought up during the review, the response from the authors of the chapter was:

This subsection focuses on projections of climate change, not on methodologies to derive the projections. ESD results are takan into account in our assessment but most of the available studies are too site- or area-specific for a discussion within the limited space that is available.

So perhaps there should be more coordinated ESD efforts for the future?

On a different note, the fact that the comments and the response are available on-line demonstrates that IPCC process is transparent indeed, showing that, on the whole, the authors have done a very decent job. The IPCC AR4 is the state-of-the-art consensus on climate change. One thing which could improve the process could also be to initiate more real-time dialog and discussion between the reviewers and the authors, in additional to the adopted one-way approach comment feed.

One section in IPCC AR4 chapter 11 is devoted to a discussion on uncertainties, ranging from how to estimate the probability distributions to the introduction of additional uncertainties through downscaling. For instance, different sets of solutions are obtained for the temperature change statistics, depending on the approach chosen. The AR4 seems to convey the message that approaches based on the performance in reproducing past trends may introduce further uncertainties associated with (a) models not able to reproduce the historical (linear) evolution, and (b) the relationship between the observed and predicted trend rates may change in the future.

Sometimes the uncertainty has been dealt with by weighting different models according to their biases and convergence to the projected ensemble mean. The latter seems to focus more on the ‘mainstream’ runs.

AR4 stresses that multi-model ensembles only explore a limited range of the uncertainty. This is an important reminder for those interpreting the results. Furthermore, it is acknowledged that trends in large-area and grid-box projections are often very different from local trends within the area.

262 Responses to “Regional Climate Projections”

  1. 201
    Nick Gotts says:

    Re #185 Michael: [My arguments here are an exercise in logic, based on personal experience, my observances of human nature, and common sense.]

    Well, given your earlier failure to distinguish (for example) total population from population density, and total GHG emissions from per capita GHG emissions, I’m somewhat sceptical of your logical credentials: if you want to undertake an “exercise in logic”, a key requirement is to be clear about what conclusions you are claiming to have reached from what premises. As for “personal experience, my observances of human nature, and common sense”, if, as appears to be the case, others have had different experiences, have made different observations of human nature, and differ about what constitutes “common sense”, where does that leave the argument? So far as I can see, it means we have to go to the trouble of looking at “statistics, studies or data”, rather than asserting that our own beliefs should simply be accepted.

  2. 202
    Ray Ladbury says:

    My comment was not an attack on the grid. The grid is indeed a tremendous friend–where it is available. What I realized in traveling in rural Brazil, is that gridding an entire country is prohibitively expensive for many developing nations–in part because the resources needed to do so have increased in price significantly. Moreover, solar, wind and other renewables are most competitive where the grid does not reach–especially if energy storage issues can be resolved. Batteries are not a particularly good solution in the tropics, since they are expensive and high humidity and heat shorten their life. If we can resolve this issue before developing countries start extending the grid to remote villages, then renewables become the best energy solution for these populations and we have a chance to reduce future ghg emissions as well as reliance on nuclear power.

  3. 203
    SecularAnimist says:

    Michael wrote: “My arguments here are an exercise in logic, based on personal experience, my observances of human nature, and common sense. If you want statistics, studies or data, do your own legwork. If your arguments can’t stand on their own, there is no sense in engaging me.”

    With all due respect, there is no sense engaging with “arguments” that “stand on their own” without any factual basis in statistics, studies or data.

    Such highly subjective things as “personal experience, observances of human nature, and common sense” do not provide an adequate basis for such a sweeping, categorical proclamation as “Reducing emissions will not make a bit of difference” which is contrary to everything that science has to tell us about anthropogenic global warming, namely that large (80 to 90 percent) and rapid (within a decade or so) reductions in GHG emissions can significantly reduce future warming and may prevent the worst-case outcomes of climate change.

    Now, if you were to say that your “personal experience, observances of human nature, and common sense” have convinced you that humanity is unlikely to actually reduce emissions sufficiently, and soon enough, to make a bit of difference, that would be a statement of what you think people are likely to do, and unfortunately it is an opinion that I tend to share.

  4. 204
    Dave Rado says:

    Re. grid vs. renewables see also the article: “Nigeria Launches Solar Electrification Project”, which states:
    “The event … marked the kick-off of a rural electrification project by the country’s Lagos State government that will provide solar installations to a total of nineteen villages previously without power … It costs about 150 million naira (around 1.2 million dollars) to connect each village to the national grid, while the solar energy project costs only about 10 million naira (around 83,000 dollars) per village.”

  5. 205
    SecularAnimist says:

    Ray Ladbury wrote: “Batteries are not a particularly good solution in the tropics, since they are expensive and high humidity and heat shorten their life. If we can resolve this issue before developing countries start extending the grid to remote villages …”

    Two comments.

    First, from what I have read recently about deployment of solar photovoltaic systems to remote rural villages in India — villages that have never had any form of electricity at all — even with very limited storage capacity, comparable to a car battery, the electricity provided by these systems makes an immediate and huge improvement in the quality of life for the people there. So deployment of these systems and the improvements in human well-being they provide need not wait for the development of better electrical storage solutions, which can be retrofitted later as they become available.

    Second, one electrical storage technology that I think has great promise but is seldom discussed is flywheel systems. Modern, high-tech flywheels offer excellent storage capacity at low cost — particularly for fixed systems where compact size and very low weight is not as critical as it is with vehicular storage. Flywheels also don’t have many of the drawbacks of batteries and fuel cells — no toxic chemicals as with batteries, no need for hydrogen fuel as with fuel cells. A sealed, “turnkey” flywheel device requires little or no maintenance and would tend to have a longer service life than a battery. I think they deserve a lot more attention.

  6. 206
    David B. Benson says:

    I suggest an electric generator powered by a biodiesel. Simple, reliable, and the biofuel can be produced locally.

  7. 207
    Hank Roberts says:

    David, you’re very big on biodiesel, but you’re aware that we’re currently using more than a complete year’s photosynthesis budget for energy — plant-based energy is a nice additive but it’s not the only answer worth encouraging. It’s certainly not as efficient a way of _storing_ energy as a modern flywheel system promises to be.

  8. 208
    David B. Benson says:

    Hank Roberts(207) — No, I wasn’t aware of that claim, which is in direct contradiction to Biopact’s statement on the matter, and on the face of it, improbable.

    I’ve nothing against flywheels, but for applications in remote villages I suspect that the lower the tech, the better. Primarily it is due to cost and reliability.

    As for storing energy, I suspect that nothing matches the efficiency of biocoal when environmental, production and maintainance costs are included.

  9. 209
    Michael says:

    My argument is: Reducing emissions will not make a bit of difference.
    My argument is not: Reducing emissions is a bad idea, reducing emissions never helps…

    Reducing emissions is a good idea. It is a good idea to take care of our environment, it is a good idea to stop pumping CO2 into the atmosphere, it is a good idea for us to be an example to the world (especially if we want to lead by example). Reducing emissions helps. If you modify your lifestyle to cut your emissions by half, there is no arguing that you have helped the overall picture by reducing your emissions.
    Reducing emissions will not make a bit of difference in the same way that your odds buying ten lotto tickets instead of one is still next to nothing if your overall odds are 1 in 80 million. Your chances are so small you could say buying ten instead of one won’t make a bit of difference.

    The main reason is humans rarely do what they are supposed to do; they do what they want to do. The world has had ample opportunity and ample warning, but the graph is ever increasing, and not making the sharp right turn we need to “cap emissions by 2020”. There is a tangible change in general attitudes, but it is gradual. This, I believe goes back to human nature, and hundreds of millions of people, some who just don’t care, and others in poverty wanting heated houses and upgrades to the pack mule.

    Please address me on the human nature point, because it is the basis for my argument.
    I have been to third world countries, but there are many with more experience, and a wider perspective such as Ray Ladbury. That is why I am here. I would like someone with experience tell me they have seen pockets of people on this planet where human nature is different from what I’ve seen in large enough numbers to turn the tide and mobilize 6 billion people by 2020.

  10. 210
    Rod B says:

    re 197 Jim Eager, “Sorry, I see no point in tilting at your catch 22 conundrum. I don’t know about where you live, but where I live climate change consistently tops the polls of public concern; etc; etc; etc; etc….

    Admittedly a little orthogonal to the main point and maybe picky, but your citing all of the mass reaction (hysteria, maybe) as proof per se of global warming is akin to citing Chicken Little. When people act as a mass, even in a local situation or environment, it’s hardly ever because they know what’s going on. Credible “expert” witnesses they ain’t.

  11. 211
    Hank Roberts says:

    David, the flywheel reference discusses storage in New York, as part of the national electric grid.

  12. 212
    Holly Stick says:

    Michael, nobody is interested in some vague logical fiddling and twiddling when we have a real world to deal with. You know, a really good way to get people to do things is by example. You act to reduce your emissions, and your friends will start thinking that maybe they should try that too. Act on your own understanding, and you’ll begin to meet people who have come to the same conclusions and are acting on them. Don’t sit around waiting for someone to lead you.

  13. 213
    Hank Roberts says:

    David, here’s one of many references on overshooting primary productivity, you’ll recognize the authors’ names:

    10.1073/pnas.142033699 PNAS July 9, 2002, vol.99 no.14 9266-9271
    Tracking the ecological overshoot of the human economy
    “… According to this preliminary and exploratory assessment, humanity’s load corresponded to 70% of the capacity of the global biosphere in 1961, and grew to 120% in 1999.”
    Articles citing that one track the idea forward in research work.

    Thoughtful, recent essay on the implications here:

  14. 214
    J.S. McIntyre says:

    re 209.

    Okay, so we agree GHG reduction is a good idea.

    And we agree re your OPINION that human nature will likely prevent a timely reduction of those GHGs.

    Thing is, you still haven’t addressed my question to you re explain the difference between the two statements.

    “My argument is: Reducing emissions will not make a bit of difference.
    My argument is not: Reducing emissions is a bad idea, reducing emissions never helps…”

    Still waiting.

    Elsewhere, you have said 1) GHG reductions is not the answer and 2) there must be some other answer and you want to hear it.

    Here’s the inevitable truth: at the end of the day, nothing is going to fix this short of GHG reduction. Nothing. Expressing the opinion GHG reduction can’t be done is a non sequitur. It doesn’t MATTER that it can’t be done; what matters is that it is the only likely answer, the only way to get it done!

    Your opinions of the human animal and its behaviors are really not a new concept by any stretch of the imagination. Constantly spinning your figurative wheels regurgitating a view that pretty much everyone here already agrees with to vatying degrees and has expressed to one extent or another – the idea that getting the human animal to react to a crisis before it has a chance to do serious damage is an at best difficult proposition – is getting you nowhere and, frankly, rather tiresome.

  15. 215
    ray ladbury says:

    Michael, Have you ever read “The Plague” by Albert Camus? It represents the most advanced statement of his views on human nature. In the book, plague breaks out in an Algerian city and the city is quarantined. People respond in various ways: 1)Some attack the problem. 2)Some minister to the dying out of sympathy. 3)Some try to profit. 4)Some try to flee. And so on. Ultimately, however, enough people realize that their survival depends on cooperation and collective struggle, and at great cost, they bring the disease under control. No one would deny that shortsightedness, complacency, self-delusion and cowardice are all part of the human character. However, humans can and do transcend that character, and literature provides us with many authors with keen insight into this ability to transcend. I could have equally cited Shakespeare, Victor Hugo Karl Hiassen or even Michael Moore (author of “Bloodsucking Fiends–a Love Story”–great, funny book).

    Yes, I know that it is tempting to write off humanity when you have politicians at the APEC summit adopting “aspirational goals” of reducing carbon and when Pope Benny is calling on European countries to raise their birthrates… However, we gain nothing by cynicism.
    The fact of the matter is that every gram of carbon we do not put into the atmosphere delays the day where natural CO2 and CH4 sources really kick in. It buys time for humans to develop technical and economic solutions and to mitigate the damage that will occur. In fact, one could argue that when our leaders have feet of clay, hearts of stone and brains of questionable functionality, individual and community action becomes even more important.
    One of my favorite stories from the French Revolution concerns Robespierre discussing politics with his buddies from the Directorate when a mob goes by with torches and weapons of destruction. “There goes the mob,” said Robespierre. “I am their leader. I must get in front of them.”
    If the people lead, our “leaders” will eventually follow.

  16. 216
    Jim Eager says:

    re 210 Rod B: “your citing all of the mass reaction (hysteria, maybe) as proof per se of global warming is akin to citing Chicken Little”

    Rod, if you think that my post [197] in any way cited mass reaction as proof of global warming then perhaps you need to work on your reading comprehension skills. I would think it fairly obvious that my cites were intended to prove that individuals and governments are capable of addressing energy use and climate change, not prove it’s existence.

  17. 217
    tamino says:

    Re: #215 (Ray Ladbury)

    Well said!

  18. 218
    Rod B says:

    Jim (216) says, “…my cites were intended to prove that individuals and governments are capable of addressing energy use and climate change, not prove it’s existence.”

    Fair enough, though you might also be just so slightly overestimating your writing ability. And I agree — the same mass psyche I was negatively describing above can also get the action going as you describe, once you get past a very elusive and fuzzy trigger point.

  19. 219
    Hank Roberts says:
    GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L17703, doi:10.1029/2007GL030775, 2007

    Present-day springtime high-latitude surface albedo as a predictor of simulated climate sensitivity

  20. 220
    James says:

    Re #205, Here’s a link to a recent article about high-speed flywheels:

  21. 221
    J.C.H. says:

    Jim Eager Says:

    I would think it fairly obvious that my cites were intended to prove that individuals and governments are capable of addressing energy use …

    A few years ago the EPA determined that the Houston area had failed to meet air pollution goals, and they said it was finally time to implement lower speed limits (55 mph) in Harris and surrounding counties. That the local air is polluted came as a surprise to nobody.

    The people and local politicians were angered.

    They found a scientist who claimed the proper thing to do was to raise speed limits. He reasoned that air pollution would be lessened if drivers got to their destination quicker. His scam worked a bit. They settled on lowering the speed limit to 65 mph, which will do almost nothing to help reach the required levels of pollutants.

    And just like before, everbody drives 80 if congestion allows it.

  22. 222
    Hank Roberts says:

    > a scientist … raise speed limits
    How did they decide this was a scientist? Did he know aerodynamic drag increases with the square of speed.

  23. 223
    Jim Eager says:

    Re 218 Rod B: “Fair enough, though you might also be just so slightly overestimating your writing ability.”

    Hmmm, my editors may quibble with you (two books, ~150 magazine articles). Granted, I did assume readers would have been following Michael’s posts and reader replies, and thus know what was being referred to.

    “And I agree — the same mass psyche I was negatively describing above can also get the action going as you describe, once you get past a very elusive and fuzzy trigger point.”

    So, individuals and corporate and government entities acting to reduce emissions and greenhouse gasses, and save both energy and dollars is mere mass hysteria now?

    Come on Rod, drive-bys like that are beneath you.

  24. 224
    ray ladbury says:

    On the other hand, if people have hybrid cars which alert them to how much fuel they are guzzling by doing 80 mph, they tend to slow down and maximize fuel economy. I’ve found this to be nearly universal. Without a way of alerting drivers to consequences of high speed, they tend to be aware mainly of the passage of time. Alert them and now you have competing drives–saving time (and illusion, as the drivetime depends almost exclusively on the slowest step) and savine fuel.

  25. 225
    Jim Eager says:

    Re 223 Ray Ladbry: “On the other hand, if people have hybrid cars which alert them to how much fuel they are guzzling by doing 80 mph, they tend to slow down and maximize fuel economy.”

    Ray, even some conventional cars now come with fuel consumption displays. I wonder if any non-hybrid drivers use them?

  26. 226
    Rod B says:

    JCH, and you think a 55MPH speed limit imposed by EPA is something better than assinine for reducing pollution in Houston??? What numerical effect would you (or the EPA) predict, using what magical assumptions? The others seem to be confusing CO2 emissions (directly related to fuel consumption) with pollutants that EPA is supposed to watch over which are loosely tied to consumption but also tied to engine operating and environment characteristics.

  27. 227
    J.C.H. says:

    I’ve had lots of Texans scream at me that their cars/trucks get better mileage at 80 than they do at 55.

  28. 228
    Hank Roberts says:

    > fuel gauge
    Source info:
    Circuit Cellar, the Magazine for Computer Applications. Reprinted
    by permission.

  29. 229
    ray ladbury says:

    Guys, better fuel economy at lower speed is simple physics. Drag increases as the square of the velocity. The fact that citizens of a certain state might disagree says more about the state’s educational system than it does about reality.

    As to whether drivers use fuel displays, some probably do not. Still, a visual display gives drivers something to think about other than the passage of time and the illusion that going faster on the highway will significantly impact one’s commute time.

  30. 230
    Joseph O'Sullivan says:

    Rod B. (sigh) The lowered speed limits in Houston were not done to reduce CO2 and not done by the EPA. They were done by the Texas agency the Texas Natural Resource Conservation Commission in a package of several efforts to reduce the air pollution in Houston which is undeniably a problem. Cars and trucks are more efficient at lower speeds, and more efficient means less fuel burnt per mile traveled and therefore less air pollution.

  31. 231
    J.S. McIntyre says:

    re 227

    MPG v MPH

    Secrets of Better Fuel Economy What really saves gas?

    It’s pretty conclusive…lower speeds promote savings.

    Here’s another perspective: I used to drive delivery for a living for a 4-color spearation house in the San Francisco Bay Area for a couple of years, spending a lot of time running back and forth to the shop to deliver and pick up commercial art. Often we would have a series of pieces running at the same time and would have drivers leaving within minutes of each other for the same or nearby destinations. I learned early on no matter how fast I drove, trafiic conditions invariably slowed me down so that my average time from teh shop to, say, San Francisco would very – at most – by a few minutes, and that once I hit the city streets stop lights and traffic would not let you get there any faster than anyone else by more than a minute.

    Upshot: Driving the speed limit gets you there almost as quick as playing Speed Racer, saves wear and tear on the vehicle, and ends up making the experience of driving semi-relaxing (except for all the other idiots who pretend the road is their private speedway).

    Oh, and it saves gas.

  32. 232
    J.C.H. says:

    Rod B, I’ll make you a bet. Two identical garages equipped with dynamometers; two identical cars, one in each garage; me in one car and you in the other; we’ll close the garage doors and roll down all the car windows; I go 55 and you go 80; to avoid boring the hell out of the audience, we’ll simulate climbing a hill.

    I bet one of us is going to shut up before the other.

  33. 233
    Rod B says:

    Joseph says, “…Cars and trucks are more efficient at lower speeds, and more efficient means less fuel burnt per mile traveled and therefore less air pollution.”

    O.K., I can accept that. I’m just curious how much the NOx, CO, and HC is reduced by slowing cars/trucks from, say 63MPH to 55+mph. [from an objective scientific view; I’m sure the agencies predicted jiggatons.. Though I don’t know and am asking.]

  34. 234
    James says:

    Re #229: [Guys, better fuel economy at lower speed is simple physics.]

    Perhaps too simple, though. What you may not be considering is the power/performance curves of internal combustion engines. I have one of those hybrid cars (Honda Insight) with a fuel consumption gauge, and I’ve found that when climbing hills, for instance, I generally get worse mpg at 55 than 65, and worse yet at 45, because I have to downshift to where the engine is running less efficiently.

  35. 235
    jax says:

    re: Houston air quality and MPG v MPH

    The scientist, Dr.Ken Green, said that the impact to Houston air quality would be negligible if the automobile speed limit was changed from 70 to 55 or from 55 to 70. Of course you would get better mileage at the lower speed on a highway, but around a city there are idling and congestion factors which increase at lower speeds. The difference in mpg improvement and time on the road would not impact local air quality. There was no mention of GHG differences, just local air quality. Dr. Green did convince the Texas Natural Resource Conservation Commission and the EPA. The speed limit which had been reduced to 55 with no noticeable difference in air quality from this source was increased to 65 with, again, no noticeable difference in air quality from this source. The seemingly obvious choice didn’t have the expected outcome. Dr. Green did offer suggestions to improve air quality from on road sources such as incentives for newer cars, traffic light synchronization, mass transit, etc.

  36. 236
    J.C.H. says:

    James, try this guy’s technique:

    … And it turns out that I’m not alone in this mild obsession. Almost from the day the first hybrids came off the boat from Japan, drivers have found themselves pushing to get the maximum mileage. Their crowing fills one webpage after another. John Johnson in Michigan, for instance, bought his two-seater Honda Insight not for environmental reasons but simply because it was the latest cool thing. Now he calls himself “Insightman” and his vanity plate reads IGO ECO. He reports that on those days when other cars are scarce and he can really slow down going up hills, he can break 80 miles per gallon. “On the first leg of my 82 mpg personal record fifteen-mile round trip to work,” he writes, “I achieved an amazing 91.1 mpg!” …

  37. 237
    Roy Simison says:

    I have been a truck driver for thirty five years and am not really into the scientific aspect of the issues here. My main concern is the drastic reductions of co2 emissions and the methods some people wish to use to obtain them.

    I do not need to explain how much the world depends on trucks trains ships and aircraft to deliver all the goods and sevices you all use and life depends on. I also do not need to explain that this currently all depends on fossil fuel.

    I, and I am sure the rest of the transportation idustry would love to have another choice of fuel because after all we all want clean air water and earth. How do we do that? I have seen much debate on what must be done but nothing on how and when the scientific minds will do the one thing that will cut emissions more than any other give us the fuel.

    So far I get the impression that treaties and government mandates must be made to cut Co2 to solve the problem. This scares me because if the transition to clean is not done reasonably you could destroy the economy and my job with it and you might indeed cause more suffering than you propose to fix.

    I would also like to say I am no fan of oil we are getting shafted on the prices (that get passed on to you) and dependence on foreign oil makes me sick and I cannot help but think some of the proceeds go to fund terrorism.

    Give us the clean fuel we need to keep America the best and cleanest nation on earth and you will solve your problems without the fighting that divides us.

  38. 238
    James says:

    Re #234: […on those days when other cars are scarce and he can really slow down going up hills, he can break 80 miles per gallon.]

    A piker, considering that he lives in Michigan, which is pretty flat. Much of my driving is on mountain roads, with passes over 8500 ft, and my average, for the four years I’ve owned my Insight, is 70.5 mpg. Driving into town, which is pretty flat and half freeway, I frequently get in the 90s.

  39. 239
    Patrick 027 says:

    Michigan has a few hills. (topography layer at

    Driving at high elevations should reduce the drag and increase mileage that way (assuming same wind speeds), but what might the effect of air pressure be on the engine (if any at all?)

    Ideally, energy savings going downhill would make up for the uphill effort.

  40. 240
    Ray Ladbury says:

    Patrick, altitude also decreases the amoung of oxygen to burn the fuel. Competing effects. You can tune the car to run leaner, but it’s not a complete fix.

  41. 241
    James says:

    Re #239: [Michigan has a few hills.]

    The Sierra Nevada has more :-)

    [Ideally, energy savings going downhill would make up for the uphill effort.]

    But alas, we don’t live in an ideal world :-( Even though the Insight is better than most cars in this respect, it still burns fuel going downhill. Even when I’m using the MIMA system to apply full regenerative braking, it’s using about 0.2 gph according to the OBDI readout. (Which only displays one decimal place.) Then figure that on the steeper climbs you’re not running at the most efficient RPM – the Insight has a lean-burn system that allows a very efficient 22:1 air/fuel ratio, but only at lighter loads & a particular RPM range. On a flat road with a good surface and no headwinds, I can cruise at 90-100 mpg…

  42. 242
    Hank Roberts says:

    That’s 0.2 gallons per _hour_ going downhill?

    I imagine it’s fuel injected and has to keep some fuel moving through the system — but isn’t the internal combustion engine _off_ when it’s going downhill? Or does that engine run all the time on the Insight? Could it be using engine compression braking and so pulling some fuel through into the cylinders in the long downhill mode?

    The NYT today has an article on the new “sticker shock” — somewhat more realistic, lower, fuel economy ratings on most vehicles as of next year.

  43. 243
    James says:

    Re #242: [Or does that engine run all the time on the Insight?]

    Yes, the engine runs all the time (unlike the Prius system, which can run electric-only for short distances). I imagine the rationale is to keep the engine at operating temperature. The Prius has a thermos system to retain heat, but of course that adds weight & complexity. Engineering tradeoffs…

    […somewhat more realistic, lower, fuel economy ratings on most vehicles as of next year.]

    I never thought the old ones were unrealistic, as I’ve usually gotten at or above rated mpg from my cars. I suspect that, as is so often the case, the problem lies in the nut holding the steering wheel :-)

  44. 244
    Patrick 027 says:

    Re 240 – Thanks, that’s what I was wondering.

    Re 241 – help me out, how fast were you going at 0.2 gph?

    (PS setting aside the elevation affect, my point with hills was going towards the slope – you might go up some grade for a few seconds (?) in MI vs a few minutes out west, (although don’t forget the UP of MI; PS I haven’t been in MI much myself, I’m just supposing – I do recall some slopes in WI) – of course, it’s easy to build a main road around a small hill or cut through a small hill – a different matter with a mountain range …)

    (PS I’m not going to argue that our world is ideal, but there is a theoretical limit that we can try to get a little closer to.)

  45. 245
    James says:

    Re 244: On a long, comparatively straight downhill (say US 50 west of Carson City) I might be going 55-65, while on a more winding road like the upper part of Nevada 431 I’ll probably do from 45 down to maybe 30 in the curves. The 0.2 GPH downhill seems independent of speed, but of course I only have one decimal digit of accuracy, so it might vary a little. (And of course this is with no throttle applied at all.) Works out to around 200-300 mpg, sometimes more :-)

  46. 246
    James says:

    And re 244 again (I sure wish we still had the edit function): {…you might go up some grade for a few seconds (?) in MI vs a few minutes out west…]

    There’s where momentum is your friend. On a short grade, you just let the speed drop a bit as you go up, and pick it back up on the downhill side. Another place where adjusting the wheel-holding nut would help: I see a lot of people who try to maintain constant speed: step on the gas going up a slight rise, then brake on the downside.

  47. 247
    Patrick 027 says:

    Re 246 “There’s where momentum is your friend” – good point.

    Okay, if going downhill at a grade A gives X mpg and going on a flat road gives Y mpg, and going uphill at grade A gives Z mpg, then if going downhill made up for going uphill, 1/X + 1/Z = 2/Y (based on averaging gallons per mile); Z = 1/(2/Y – 1/X).

    if Y = 90 and X = 250, then Z = about 54.9 would be adequate for the uphill and downhill portions to average to flat conditions. This formulation does ignore the increased distance from point A to point B on a map that results from a slope and would only generalize to any pathway if changes in the reciprocal of mpg were linearly proportional to grade, etc… but for the case given, 54.9 – Z (or perhaps better: 1/Z – 1/54.9 ) would be one measure of the reduced performance from slopes.

  48. 248
    James says:

    I think you’re forgetting the non-linear nature of the internal combustion engine. Take a practical example: climbing Nevada 431 – IIRC about 12 miles, from 4600 ft to 8900 ft elevation). I need to be in 3rd for most of the climb, downshifting to 2nd in places. The engine is thus running at higher rpms to produce the power needed to climb the steep grade, so the VTEC system has shifted the valves into power mode & the engine management computers have presumably made similar changes… As a result, I get about 40 mpg in 3rd, 25 in 2nd – say 35 mpg overall. Assume 0 mpg for the downhill, and that’s about 70 mpg average.

    Now on a flat, smooth road I can cruise in 5th, at relatively low RPM, where I get a base 70-80 mpg. If the load’s light enough – slight downslopes, a bit of a tailwind, even a particularly smooth road surface – the lean-burn system system kicks in, pushing mpg into the 90-150 range.

  49. 249
    Patrick 027 says:

    Re 248 – well, you know more about about that than I do; but my point was about theoretical limits when technology is left unspecified.

  50. 250
    george flores says:

    hi, im just an intrigated and concerned guy on this world controled by some corrupted means of communication ´(tv means , political means, etc).I tried to mail to realclimate but i couldnt because of an internet error; so the reason i write is just to sugest an unratified and interesting topic that i really would like to be analyzed. This issue is about the controversial climate change and global warming that to me is now really confusing because of the contradictions that are now emerging; as an ussual member of the society the first time i heard about “the global warming” was from the world known documentary movie “an inconvenient truth” from Al Gore, and i think the rest of the world got the issue of global warming from al Gore too. so my question is : should i believe all that is mentioned on the movie?, is the movie based on real and true facts, scientists, theories, etc? is this documentary fiable and can i tke it as a scientific statement?

    I have no political intensions and im not trying to make any type of disorder, just want to know the truth of the global warming issues and wich theory is the right.
    if you can answer my questions ill be really satisfied and thankfull.
    thanks a lot.