Ken Fabian

After thinking about it - - that seems improbable; such a project would far exceed total turnover of a not very profitable industry (or at least of the space element of a aerospace industry), unlike F1 which uses a relatively small portion of total turnover. An attempt to get a big, enduring commitment of government support? Pavelcherepan, given that I think the viability as well as benefits of space colonisation are vastly overstated (especially with respect to the difficulties and costs) I don't think a lunar base as a training exercise is good value. I don't doubt that there are plenty of people with unbounded optimism and enthusiasm for human expansion into space here - it seems like the sort of forum that would attract them. I'm not convinced it's based on realistic assessments of those difficulties and costs.

There isn't much science to do there apart from geology (lunology?) that wouldn't be better done elsewhere. That may lead to discovery of mineral resources beyond those already known - refractory elements like magnesium, aluminium, silicon, iron and titanium mostly and mostly not in short supply plus some potential for platinum group metals - but exploiting them involves the development of entire systems of transport, construction, mining and refining that currently don't exist, for an environment more hostile than any exploited on Earth. The requirements would be somewhere beyond current cutting edge and could be presumed to be prohibitively expensive. As a PR exercise for their aerospace industry - a bit like a formula 1 car is for an automotive manufacturer - it may have some value. Some extending knowledge for it's own sake could add some more - if they can afford such extravagances.The afficionados of space tech will get thrilled, perhaps imagining this will bring their optimistic dreams of inhabiting space a bit closer. I remain very doubtful such optimism is well grounded - an abundance of resources and opportunities are one thing, exploiting them successfully is another.

I have to begin by saying I'm very doubtful of the feasibility of space based solar as any kind of, let alone an all encompassing energy solution for terrestrial use. I admit I'm even a bit doubtful of Mike Smith Cosmos' motivations for this proposition - Mike, I would say climate change is a more compelling and urgent reason for a global energy transition than the danger of running out of energy resources. Do you accept that, rather than the danger of running our energy resources dry the need to leave the greater part of fossil fuel resources in the ground is the most immediate - and unless carbon capture and storage becomes financially feasible, permanent - constraint on those resources? Although efforts towards that energy transition are a long way from adequate, as a motivation to urgently look beyond fossil fuels, climate does have strong basis in science and evidence. Much more so in my view than any hypothetical impending energy shortage. When it comes to mobilising support for seriously big, visionary projects motivation is an essential ingredient. My own view is that failure to mobilise the support - community, government and corporate - for that essential goal has been a serious constraint and impediment to the transition away from fossil fuels; a grand and visionary approach like a Space Based Solar Power System (SBPS), much like capital intensive big nuclear, is especially vulnerable to a lack of clear commitment to that fundamental goal. There have been broad, comprehensive and well credentialled studies of our energy options and space based solar hasn't emerged as the standout best option. I'm not sure it really rates as a serious option at all. I know that such an energy transition will involve significant commitments made without future certainty but Space Based Power Systems are entirely hypothetical and to be viable, look to be predicated on a pre-investment in other entirely hypothetical technologies such as space elevators or other novel and untried launch systems. I would note that I would find it disturbing to discover that the concerns people have about the climate consequences of our energy choices are being co-opted and we are misled into commitments to unproven and potentially uneconomical energy solutions by people with unbounded optimism and enthusiasm for space projects, for whom that space capability rather than energy/emissions/climate solutions, is the primary motivation. Renewable energy options down here on Earth may have their limitations, but for the most part they are not hypothetical. Importantly they can be trialled and introduced incrementally without those very large pre-investments that a space based approach requires. They are approaching or passing price points that make them viable commercial competitors to fossil fuels even without the climate consequences and costs being factored into the economics - and it doesn't look like the well of innovation is anywhere near running dry. The intermittency issues are real and challenging but I suggest they are not uncrossable barriers. As for nuclear, I have my own reservations about rapid, massive global expansion of it's use, and whilst I have no doubt it will have a significant place in a global low emissions energy mix it has some real barriers, economic as well as security and political, that put it at severe disadvantage. Later perhaps, in an appropriate thread - not here. As far as space based energy goes, it occurs to me that any feasible means of beaming energy down from orbit would have the potential to beam energy up from Earth, over and down again someplace else. Some places have energy excesses. Siting solar or wind or tidal to maximum effect would be enhanced by better transmission methods. Proponents of SBPS might took more closely at the feasibility of such technologies for a global energy transmission grid and avoid the need for launching all the other stuff. I would note that the losses from proposed microwave systems which seem to be most favoured, are still significant and transmitting energy thrice - up, over and down - would exacerbate that. Long wave radio seems to be hypothetical and being low frequency, it intrinsically carries less power and doesn't look suitable. Laser might work better in any space to space transmission with potentially lower energy losses so it might be possible to rely on microwaves only twice for up and down. However I do remain very doubtful; wind and solar may have been unrealistic as more than a niche even a decade ago but they now comprise more than half all new generation being built. Energy storage may have been solar and wind's poor relation but that is not the case any more; we are better placed than ever to develop a combination of intermittent renewables, distribution and storage systems adequate to our requirements. These are all on something of a roll and far from hitting barriers they are gaining momentum; grand, visionary - most especially the more speculative options - have a long way to go to even get any kind of foot in the door.

Was it 20 posts or 30 before you can start a Politics thread? I can't find where I read that, but I'm sure I saw it somewhere. I may wait and just join in appropriate threads as they come up.

I don't mind debating some specifics of climate science, but when debating with people expressing mistrust in our institutions and practices of science and will not accept the advice from, for example, long running and respected organisations such US Academy of Sciences or Royal Society or World Meteorological Organisation or, dare I say it, the IPCC then I doubt there is much I could say that would persuade them. Whilst it's worthwhile to distinguish between the real, the perceived and the politically contrived grounds for doubt and attempt - as I and I'm sure others see it - to correct some of the more egregious misunderstandings and errors, it's not really what I wanted from this thread. I've been repeating myself with respect to my views on the appropriateness of accepting the work of professional scientists who are working within our institutions and frameworks of science - in my opinion the unfairly maligned "appeals to authority", ie deferring by those who aren't such experts to those who are. My interest has been driven in large part by my concerns over long running inadequacies in responding to the science based understanding of climate and climate change - more usually climate politics than climate science. My view is that doubt/scepticism is widely misused and misapplied and contributes a lot to Doubt, Deny, Delay climate politics, by providing a sciency sounding justification for withholding commitment and obstructing policy appropriate to the science based knowledge and advice. Given it's the road blocks at the intersections of science, politics and policy that I see as problematic for making emissions/energy/climate policy based on the science based advice I'm inclined towards taking the discussion beyond the scope of the 'hard science' section of the forum. Further discussing the use of doubt/scepticism as a tool of persuasion for undermining community trust in science, rather than as a scientific method that ought to reinforce it would take us into politics. If I understand correctly, as a relatively new participant here I would not be permitted to start a thread on climate politics in "Politics"?

Willie71 @80 said - Except perhaps me? Although I wouldn't state it quite like that; there are some caveats. Expert advice, professionally given by appropriate experts may be open to question but not by anyone and everyone. In some cases to fail to accept it can constitute professional negligence. I think for most people there is no reasonable option but to accept appropriate expert advice. Not because authorities are beyond question, but because most people lack the necessary competencies for questioning to effectively to resolve doubts and distinguish between those with a sound basis and those arising from inadequate understanding. Accepting expert advice is a practical - and responsible - way to deal rationally with issues raised by 'authorities'. Whilst it's certainly reasonable and for those within a professional field - even necessary - to question and confirm what's valid, I question the extent to which those outside it can question effectively without impeding their capacity to deal rationally and effectively with issues raised. And I question whether, when the issues raised are directly relevant to lives and economies, any 'right' let alone obligation exists for those in positions of trust and responsibility, who are required to make decisions relevant to those issues, lives and economies, to question appropriate expert advice from scientific 'authorities'. As I've said there is legal precedent and potential for legal actions over negligence for failure to pay attention to expert advice, but whilst it's not yet become explicit with respect to climate science, I think the ethical basis for legal precedents involving other kinds of expert advice is there. From outside we can determine a lot - for example whether what one authority says is consistent with that of his/her peers or if there is ongoing uncertainty over specific issues and find what has stood up to repeated expert review and questioning. We can learn what is a matter of ongoing investigation and debate within a specialty and why. From outside it is even possible that real issues that are overlooked can be brought to light but unless it's addressed to those within it or with oversight, like professional publications or ethical and professional standards committees, boards of review or the like it's going to get intermixed with the mess that is political and partisan debate and influencing of public opinion. To doubt the integrity of climate scientists, their methods and of the systems of oversight as a rule of thumb is likewise something that I think inappropriate for most people. Personally I think our institutions and practices of science have well and truly earned respect and trust. Because of the culture of keeping records and having those openly available, open to review any ongoing errors, misunderstandings and failures of standards will be difficult to sustain and therefore there is a sound basis for extending such trust. And I would be very surprise if Presidents and Prime Ministers and the like, who have often publicly exhibited their doubts and held partisan political positions on climate policy haven't asked, via the investigative authorities and powers at their disposal, if any entrenched misconducts or failures of professional standards, or conspiracies have been going on within our institutions and practices of science in order to expose them. And make ongoing political use of such evidence. I see plenty of accusations but I don't see little if any such evidence. On the contrary.

Tantalus, if you won't accept that climate modelling is a valid way to figure the possible and likely consequence of emissions, how do you think we should make some kind of judgement and proceed? From my perspective I see pretty much every major study or report, from every institution that studies climate, every peak science body and every Academy of Sciences saying it's real, it's serious and it's urgent. There are also a lot of uncertainties that are not, in my view, glossed over. They include the possibility that impacts may be less severe than some kind of average of models and projections. But I think uncertainty leaves open the possibility that they may be much more severe. Taking no actions until we know better is in reality continuing to take strong actions - gigatonnes a year of fossil fuel burning - on the basis that we just don't know. Yet claiming we just don't know looks like a choice, one that involves withholding acceptance of the validity of the body of knowledge science has accumulated so far. For those not working professionally it's a free choice; only those bound by professional codes of conduct have any obligations that preclude believing and saying whatever they want. To what extent should your personal doubts be grounds for withholding acceptance of the professional work of others - work that National Academies and Meteorological organistions consider valid? And to what extent should that withheld acceptance be the basis in turn of political opposition to policy that treats the mainstream advice as valid?

Whilst I think it's unrealistic for individuals to do a competent and complete review of a multi-faceted field like climate science I think that mistakes, misunderstanding and misrepresentations can be usually be recognised easily enough. I have tried to be reasonably well informed, whilst not claiming any status as expert. I think the use of doubt, misapplied and not accompanied by adequate competent investigation is inappropriate and as likely to lead to error as not. Tantalus I think any suggestion that computer modelling should line up within timescales of 15 years and are failures if they don't is a misunderstanding or, when from people who know better, a misrepresentation. They have never been claimed (except by people who want to criticise them for doing something they were never intended or expected to do) to predict internal climate variability on that scale by those developing and using them. It's a bit like claiming that modelling of temperature changes through Spring, based on the axial tilt theory of seasons, that shows that on average each Spring day will be warmer than the one before, is wrong if each and every day is not warmer, and further, that the whole axial tilt theory must be wrong if there is a couple of weeks of cooler than average Spring temperatures. Sorry but I'm not impressed so far with your ability to evaluate the validity of climate modelling if you don't see that natural variability from ocean oscillations means trends averaged from many model runs will never - and should never be expected to - line up with temperature records over short time scales like 15years. The process of averaging... smooths the trend line, but each model run has ups, downs, pauses, accelerations of global average temperature, very often exceeding those of the past 15 years. Failing to look at the natural variations, principally the ocean oscillations and their phases, that underpin shorter term variability, when evaluating how well models performed, ie comparing the averages of many models with phases averaging to flat, rather than those that had those phases closest to what actually occurred, is not evidence of failure of modelling but of failures of competent and honest evaluation of them. Natural variation from just one climate variable alone - ENSO - can shift the global average temperature more than 10 years worth of global warming between one year and the next and even one or two more el Nino years than la Nina or vise versa within such a 15 year period will skew a trend up or down from any longer term average. ENSO resists prediction much beyond the following year. They appear in models and model runs in different sequences and strengths, yet looking back at the model runs that chanced to put the phases for ENSO nearest to what actually occurred, showed global warming close to what actually occurred. ie the modelling did not fail at all. From Abstract for Nature paper "Well-estimated global surface warming in climate projections selected for ENSO phase" (paywalled unfortunately but a news article discusses it here) The authors' conclusion? It's certainly possible to reference work we aren't personally able to verify and understand why some doubts are not well founded in fact. It does rely on my trusting that the Nature paper is accurately published, was peer reviewed by people with relevant skills and does not misrepresent the models that it references.

Overtone, I think there is no reasonable option except to trust in our institutions of science. Not out of faith, but as something earned. Expert 'opinion' from working scientists comes with obligations for relevance, honesty and accuracy. For those who hold public - or corporate - office, there are similar obligations around responsibility and trust. Popular opinion, or that of self appointed 'experts', which have no such obligations, simply aren't good enough. Tantalus, I'm glad I managed to not misrepresent your views. Just to be clear I think the risks of failure to adequately reduce emissions in a timely manner look to be greater than the foregone economic growth from doing so. More importantly that appears to be consistent with the expert advice commissioned by and for governments. Doing and not doing, action and inaction can be inverted in these discussions. We are taking 'strong' actions in burning fossil fuels at multi- gigatonne per annum rates and dumping the combustion products into the atmosphere without restraint. There really isn't any default 'no action' position that has no consequences and no risk. We can argue the level of confidence in understanding the consequences and we can argue about the risks, but whatever we 'do' - and we will be doing something - will be on the basis of imperfect knowledge. Yet this is an issue where the mainstream scientific advice has been broadly consistent in the face of decades of exceptional scrutiny so I'm doubtful of claims that the fundamental basis is seriously in doubt. Given that emissions are ongoing, and the advice that the climate impacts are cumulative and effectively irreversible, delaying and deferring policy for better, more perfect knowledge comes with significant risk. Personally I'm not sure 'risk' (like 'scepticism') has the broad acceptable meaning that is appropriate when the consensus of experts is that it's something that is happening rather than something that might happen. Scientific inquiry going back more than a century has revealed a physical basis for climate consequences to raising atmospheric CO2 levels. Given the widespread use of fossil fuels, scientists and scientific institutions are being called upon to investigate and advise on the consequences for global climate for a variety of future scenarios. Sometimes scientific inquires can be implicit - scientists working within a field where better understanding of climate processes is intrinsic to what they do - or it can be explicit - a Prime Minister or President or Parliament or Congress requesting answers to questions or information or an overview or reports from an agency like the US National Academy of Sciences. Or a group of governments can use an international body like the UN to set up a specific agency like the IPCC to review, summarise and advise. I have serious reservations about the capability of self appointed individuals to do it better than organisations like The Royal Society or National Academy of Sciences or the IPCC and whilst I think it's certainly an individual's right to believe and express whatever he/she wants, i don't think policymaking should defer to them. So, Tantalus, I can't accept that where your confidence in climate science differs from that within the reports by such agencies, that policy should be influenced in any way by your judgement. When people hold positions of trust and responsibility that 'right' to believe whatever you like and withhold acceptance for the expertise of others becomes constrained. In reality and unlike areas like medicine and engineering, responsibility for basing decisions on expert advise with respect to climate responsibility has not yet been made explicit. But it is heading towards being legally recognised, at least in limited ways - a court decision in the Netherlands for example requiring government policy on emissions reductions to have goals in line with the mainstream science. As a scientific principle, properly applied, doubt may serve well, but misused as a means to justify deferring and delaying appropriate policy, it's not serving us well in this time of need.

Can someone clarify what the time limit is for editing? I've managed to put a 'not' in the wrong place, inverting the meaning but was absent for a time and didn't notice - but found the edit option expired when I went to change it. I'm sure most people will realise from context but I would have liked to fix it. My own habit is to put an edit postcript saying what if any substantial changes were made, and for minor ones too unless the edit was immediate or within a very short time.

ere the work of others is held to be in doubt until personally satisfied otherwise - to what extent is personal support withheld in turn for policy that is based on the expert advice being sound? I doubt it is unaffected. Ophiolite suggests that, on the basis of risk assessment, policy based on the presumption of mainstream advice being valid would have his support during the period his judgement is held in abeyance. But, whilst he insists that withholding acceptance of the work of others is a scientist's obligation, supporting policy based upon it, on the basis of risk assessment isn't presented as an obligation. I don't doubt that it's possible that the issue of holding the science to be in doubt won't affect support for policy based on it being valid, but I seriously doubt it. Tantalus points out that it involves significant decisions - ... if some of the worst case scenarios of the IPCC are correct, then we need to take drastic actions, these actions could potentially cost the world's economy a lot of money and slow growth. It doesn't sound like Tantalus feels such an obligation. Sounds like the risks of excessive costs of action impeding economic growth are ones we should be hesitant to take. I don't know what efforts Tantalus makes to validate such assessments, or what he does to address his doubts of climate science. Or if that is a legitimate and productive use of his time and effort. I would say that if he held some kind of relevant public office he would be negligent to ignore the expert advice. Is every 'scientist' even capable of personally validating a body of knowledge as large and complex as climate science? Is there a time limit for doing so or a point at which holding the work of others in doubt should revert to holding one's own ability to properly validate it to be in doubt? Holding to high principles can also be impractical, unrealistic and disabling. Now, my own understanding is that the climate problem is one where the consequences are decades to centuries delayed between cause and effect, the effects are cumulative and are effectively irreversible, so the risk assessment criteria are there for justifying strong policy with minimum delay. ie deferring commitment to action until doubts are answered has significant consequences. I also have a lot of trust in the institutions, the methods and processes of science and I don't believe it is misplaced or inappropriate. The US Academy of Sciences or UK's Royal Society for example have earned their places as expert advisors to governments and communities, through attracting and engaging the most capable scientists and through a history of probity and service to the community. Even if I were a working scientist, it would be wholly appropriate to treat the advice they give as trustworthy, whether I've personally validated it or not.

As a cornerstone of science I suggest scepticism is applied individually to the specific but collectively to the whole. I disagree that AGW is as simple as risk assessment when doubt holds you back from accepting that the work of others is not valid until personally confirmed - it requires some level of confidence that the work of others will be valid. I believe there are sound reasons to trust that the work of others - within fields of science where trustworthy methods and processes and oversight are in use - without personally validating them.

Ophiolite - withholding acceptance of the work of others as valid during the interim between a starting point of doubt and any conclusion of your investigations will leave you in don't-know limbo and incapable of action based on the expertise of others. I disagree that science must work as you claim. I can see where doubt is the appropriate starting point, such as in reviewing newly submitted and published papers, novel hypotheses or where significant data that is inconsistent comes to light but as a general rule applied to existing bodies of knowledge I think trust in the methods and processes, and of institutions providing oversight are valid and serve well. I think doubt is something to be applied selectively rather than as an all encompassing prerequisite to acceptance of science based conclusions as valid. All encompassing doubt will ultimately fail for all but the most extraordinary intellects and I suspect the overall body of knowledge of a multifaceted area of study such as climate science may be beyond even the extraordinary. Trust in the methods, processes and institutions that built and oversee a specialised body of knowledge, as well as much of the consensus knowledge itself is valid and reasonable. For those aiming for expertise it's reasonable to begin from acknowledging ignorance and commitment to learning, including learning past and current methods and processes, which will, of course, include the application of sceptism. ie they will have a sound basis for trust in the reliability of the knowledge base they hope to build upon even where unable to confirm it's validity personally.

Kisai - It's not doubt that's the fine state of mind, it's the commitment to becoming well informed that doubt can lead to. If it's not a process that includes that follow through action - the prying open of textbooks - doubt is a disabling state of mind that impedes rational decision making. Whether that follow through occurs or not, if it comes with provisional withholding of acceptance that the work of others is valid it is disabling. We can hope that for those identifying as scientists doubt is motivating rather than disabling. I still believe that scientists should provisionally accept the body of work of other scientists as valid, whether they carry through with scepticism as a process or not. This should be explicit when urging the use of sceptical inquiry as a scientific method. My own view is because withholding acceptance that climate science as valid is widely taken to be a correct response to doubt, that state of mind and the very term 'sceptic/skeptic' has become something to be identified with and held to for climate action obstructionists. It becomes an opportunity to put open alternative 'textbooks' of their choosing in front of people as well as a 'legitimate' reason to oppose, delay and impede prompt action.

To be fair to Ophiolite this was included - - which could equate to the provisionally treating the consensus of experts as true that I think is most appropriate. If, as a scientist, you feel you should confirm it for yourself and then find something that is in error, then point it out - journals accept and publish criticisms as long as there are valid grounds and there are other channels. Standards and Ethics committees or similar are there if malpractice is found; absolutely fraud or other malpractice should be reported and investigated. Ten Oz - I certainly notice fallacies from focus too narrow - local or regional rather than global, one or few indicative measures out of many and too short time scales. And focus too broad - looking at very long time scales that can make current climate change appear trivial.

Ophiolite and I had an exchange in the "Who here is a global warming skeptic?" thread. I did want to continue but the thread was locked (for being overlong) before I could do so. Hope I'm not stepping on toes by starting this thread. Ophiolite asked for responses to this - My own reply was that it is not an appropriate default position to take because most people do not have the ability to evaluate complex science and accepting what the overwhelming majority of experts in a field tell us is not just appropriate, for those who hold positions of trust and responsibility it could be considered negligence for them to fail to do so. Ophiolite replied that many participants here are scientists and it is a correct position for scientists to take but agreed that, for those without the requisite skills, deferring to experts is more appropriate. I still find myself disagreeing. Ophiolite - It may be a matter of semantics - just what you mean by "doubt" in this context - but I think a default position of doubt suggests, intentionally or not, that you won't accept the validity of climate change science (or any other science) until personally satisfied, through personal investigation. That may not be what you mean but I think it requires clarification. My own view is that, even for scientists, treating the work of other scientists as valid should be the default position. It's not a matter of tribal loyalty or science as faith but of trust in the institutions and practices of science. We can quibble - there are some areas of science that I personally think need to lift their game - but climate science is, in it's fundamentals, about maths, physics and chemistry. It's based on the 'hard' sciences rather than the 'soft', without much room for the subjective. And perhaps no area of science has been subject to as much scrutiny as modern climate science. For those involved in oversight within scientific institutions, keeping eyes open for sloppy science, bias and malpractice is good practice but not the same as doubt as the default. Perhaps, for those appointed to a panel of experts by Institutions like the National Academy of Sciences to review a field of science - as happened at President G.W. Bush's request on climate science - witholding any acceptance and doubting everything it might be appropriate but more generally even for other scientists I don't think it is. It looks most appropriate when individual science papers are submitted and published, for experts capable of competent review to provisionally withhold acceptance and begin with doubt and scepticism; in that circumstance it could be the kind of scientist's obligation suggested. For the accumulated body of knowledge within a field - the consensus if you will - an initial position of acknowledged ignorance is, I believe, more appropriate - an "I don't know" rather than "I doubt" - if only because it won't be construed to mean the work of others is provisionally rejected. I never completed undergraduate science - not qualifying as a scientist - but my impression was that students don't begin from a position of doubt but of acknowledged ignorance. Along the way they should learn how and why the widely agreed conclusions within a field have been achieved rather than presented as unassailable 'facts'- ie come to know why it's valid not simply taken on faith. And learn which conclusions are in dispute and why. The end result for a student starting from a position of doubt should be much the same; a confidence in the conclusions that merit it and awareness of the grounds for dispute for those that don't. Making the effort to understand something personally and be well informed is to be applauded and sharing your experiences, of your doubts and how you dealt with them, in places like this is worthwhile. With respect to climate change science Doubt has become a professionally crafted product by and for partisan interests for political gain - to compromise, impede and delay oppropriate and effective government policy. In a context of climate politics where concepts of doubt, scepticism and uncertainty are being misused we need to be especially careful in urging it's wide application. People who don't have the skills and competency or even a real comprehension of scientific scepticism and who may not follow through with it as a process, are being encouraged to provisionally withhold acceptance of mainstream climate change science and oppose policy based on that 'scepticism'. So I'm sceptical about urging doubt as a default place to start with climate science. (edit: last three sentences added after initial post) My own experience is that, whilst the nitty gritty of real science can often be dense and opaque and beyond the non-expert to critique, even ordinary people like myself can recognise misunderstandings, misinformation, logical fallacies, appeals to tribal loyalties, pressing of emotive buttons ie the charlatan's (or politician's or PR/advertiser's or tankthinker's or non-thinker's) tools of persuasion. Most of the commonly repeated grounds for doubt of climate change science can be examined by non-scientists and recognised as weak or invalid.

Whilst I understand the nuances of what you have said I suggest a default position of doubt is not an appropriate one. Most people are not capable of a genuine sceptical critique of complex science and doubting the truth of what an overwhelming majority of experts within a field say until personally satisfied otherwise is a path more likely to lead to error than not. I suggest the default position should be to take what the experts say as true unless there are legitimate grounds for doubt - such doubt then to be followed by thorough and competent investigation. Despite the refrains about falling back on appeals to authority, such deferring to experts is actually the most appropriate position for people without relevant expertise to take. More importantly failure to take the expert advice seriously is, for those in positions of trust and responsibility, potentially negligent and where the consequences can be shown to have resulted in harm to others, it could be criminally negligent. I'm fairly sure that for holders of public and corporate postions of trust, unless you have appropriate expertise yourself and have reasonable grounds to disagree with your peers, disregarding expert advice would be counted as negligent, ie that would in line with precedents of law in most jurisdictions when it comes to questions of negligence. What would make me doubt the science on climate? Were panels of independent experts within the most respected science advisory bodies like US National Academy of Sciences or UK's Royal Society to find egregious errors, inconsistencies or malpractice sufficient to call the fundamentals into question I would pay attention. Such panels have, on the contrary, found the science to be valid and consistent. Those organisations have well and truly earned their reputations for probity, excellence and community service; they deserve to be taken seriously.

No mentions of ocean acidification and how space shades/mirrors allowing CO2 emissions to continue unabated would stil leave that problem unaddressed? Whilst it's not directly a climate problem it is an excess burning of fossil carbon problem of global scale of great seriousness. I'm new here but not new to these kinds of debates. I tend to be bemused by the extraordinary optimism for some kinds of solutions that are combined with extraordinary pessimism for others. We can build a whole space launch infrastructure of types never before tried, at very large scale - some that can only be built and proven feasible at large scale, like space elevators - but better, cheaper, energy storage, that seems to me a key technology that will allow full displacement of fossil fuels by intermittent renewables is fairy dust? Harold Squared - I don't think you have offerred any substantive, feasible solutions to the climate problem - certainly not compared to the many serious studies and proposals that are already out there. I'm not entirely convinced you really accept the mainstream science on climate - but I am only going by what's written in this thread. It's a question that matters; a real depth of commitment to the fundamental goal looks to me like an absolute prerequisite for taking any solutions, let alone the speculative ones through to implementation. I wouldn't like to see people who's optimism and desire for space enterprise is boundless use the depth of concern for the climate problem to mislead the world into supporting speculative climate fixes in order to further their desired investments in expansion into space. My own view is that real depth of commitment is fundamental and essential to both effective policy and it's implementation and I think 'failures' to date are far more down to it's lack than any inadequacies or inappropriateness of the technological approaches that are available. Even now, with a global climate agreement I suspect the governments of most nations remain more concerned with avoiding the inconveniences and costs of doing the minimum necessary than doing the minimum necessary. What may trigger an avalanche of change is the continuing cost falls for renewable energy technologies taking it below that of fossil fuels; that may be as crucial to broad acceptance of the fundamental 'fix the climate problem' goal as the strength of the science on climate.