we have all been 'had' re global warming

[howmuchdidyousay]

To think its the biggest conspiracy theory of all time ?

BTW, Bishop Hill, to whose blog cat linked, is a long-time sceptic (closely associated with the academic McIntyre whose anti-hockey stick work has been largely discredited), and he also has an anti-global warming book to sell. I'm just saying he's got an agenda.

Ok I've been able to skim the thread now.

Governments do not like to implement policies that might loose them votes. Asking people to alter their current behaviour in ways that help the planet are unpopular. Therefore politicians will only do this if the need is desperate. Therefore our government are, as usual, trying to do too little too late.

Climate change is real, man is causing part of the changes. The models aren't yet accurate enough to predict exactly what man's contribution is, what will happen or how bad it will get. But me - I have a house on a hill and I'm not about to move anywhere lower. And I'm doing my little bit to ease the strain on the planet and will go on doing so. Maybe it will buy enough time to develop a solution or perhaps it is already so bad that we can't implete solutions before many of the poor people on this planet have lost their homes. You can't separate this from the issue of poverty because many of those who will be badly affected will be the poor.

I've also tried to encourage my children to study the subjects that would allow them to work on finding solutions. We're going to need technical solutions, if we have time to develop them. Meanwhile bring on the taxes as it's the fastest way to change behaviour.

please could someone tell me what a 'hockeystick' is?

Katie - link to New Scientist explanation of the hockey stick graph

The hockey stick graph is one of the sceptics' key targets. The scientists behind the graph are the ones whose emails have recently been hacked.

I thought the hockey stick graph had been discredited as being totally made up and not based on any kind of data.

Katie, the hockey stick graph is a graph of carbon dioxide levels over time. It shows that CO2 levels were bumbling along going up a bit, down a bit throughout history. Then, suddenly it shot up out of all proportions seemingly to coincide with industrialisation and the dramatic increase in the use of fossil fuels. Unfortunately, the dates don't makee a lot of sense.

CertainAge - it hasn't been discredited at all. Have a look at the New Scientist link I posted below.

Thanks very much.

I believe in climate change. I just don't think that me changing the lightbulb in my lav or rinsing out my Marmite jars is going to save the world.

The Wiki Page is quite informative about describing the nature of the controversy.

Policy - you found the study I was considering and then did what I thought you would do - found another that showed something different. It illustrates what happens when you take different start and end points - and that is where the true problems lie because of all the variables involved.

If we are relying on 'best guesses' then have you any links whereby anyone has accurately predicted climate change say in the last ten years such that the information is useful.

Such as accurate rain fall predictions for various geographic locations? Accurate temperature predictions for a specific town? Accurate sea level predictions? Surely if anyone had produced an accurate climate model then their views may be taken a little more seriously?

I can take a guess on say the weather next weekend for my area - but actually predicting the temperature, the windspeed, the rainfall - well beyond my means. Show me a scientist able to do that for 10 years from now and maybe I will take what they are saying more seriously?

And again not so much sticking my fingers in my ears but more of what do we actually do with the information we have got? And who gets to decide what interventions should take place?

It is a very different problem to predict the rainfall in a given area in a given day - you have to model the cloud dynamics - which is very poorly understood.

It is much easier to predict the average climate in a given place at any time. Because we have much more understanding of how the large scale climate works. And in certain places it doesn't vary much (eg continental interiors). The UK happens to be on the frontline between the cold polar air and warm, wet tropical air - and is inherently volatile in much more difficult to predict.

It is more straightforward to predict large scale patterns - eg warm air moving north, or cold air moving south, and make a prediction as to what that will mean to the climate.

What we can do it look at the fact that all over the world ice areas are melting. Storms are becoming stronger, which is a function of more heat in the system, species are moving northwards. Any number of indicators that on average in most areas it is warmer than it was. This is happening faster in the polar regions - probably because the large ocean mass in the middle of the earth helps to buffer things.

What I am trying to say - don't confuse an inability to predict where a thunderstorm will be (although often that is reasonably predicted) to a longer term larger scale change.

It is true that we can't predict the detail of what might happen in 20 years accurately - which is why they run ensemble runs with lots of different models and look for trends - repeated patterns. As computers get more powerful the ability to run models at finer and finer scales is improving understanding of the physics/chemistry involved. These are then used to model past situations to see if they can get the right results, and if they do then that knowledge of the system is then fed into predictive models. This is improving over time.

Regardless of what sceptics say - the majority of scientists working in the field would say that most indicators are pointing to the same general trend - rapid (on a global geological scale) warming. They then produce what if scenarios to try and gauge what that means. And most of those what ifs come out with a less than desirable result for the majority.

If we can buy time by slowing it down (and that is a big if) then we should at least try, and hope we come up with some geoengineering solutions.

Linden (and throck, AceBaby and anyone else who knows more about the science than I do) - would it be right to say that we are talking about (at least) three different areas of study here:

1. whether the world, broadly speaking, is getting warmer, and at an unprecedented rate;
2. whether, if the world is warming, this is significantly affected by anthropogenic factors; and
3. what the future outcomes of such change might be.

Yes? (Possibly no )

If that summary is correct, then isn't it correct to say that 1) and 2) are the subject of much less scientific uncertainty than 3)?

Policywonk

For your questions 1 and 2, have a look at www.ipcc.ch/graphics/syr/fig2-5.jpg

This shows modelled temperature with only natural forcings (blue shaded area), observed temperature (black line) and modelled temperature with natural and anthropogenic forcings. YOu can clearly see that

1. The temperature of most continental regions is rising
2. Climate models need natural AND anthropogenic forcings to replicate the trends.
3. At this coarse scale, and for temperature, climate models don't do too bad a job of replicating the gross trends.

As for 3 "what the future outcomes of such change might be." yes this is less certain because the climate models will be operating with stronger forcings and possibly simulating very different conditions than exist now (making the models more difficult to test). Also, there is great uncertainty in how greenhouse gas concentrations will change, which is why projections are always carried out for several emissions scenarios. The results are markedly dependent on the emissions scenario used.

Hope that helps.

I will return the the thread tomorrow (I reckon this particular mumsnetting counts as work !)

Thanks very much, will have a look.

The predictions of what will happen may not be exact but the vast majority of scientists are clear that it is going to be bad, the area of uncertainty is how bad and how quickly. The worrying thing is that as the science improves they seem to be suggesting that it will happen more quickly.

Governments have plenty of ways to raise taxes with less complaint. This is not some sneaky government conspiracy it is recognition that the only way to change most people's behaviour quickly is to make it cheaper to do the right thing. The government didn't want to implete vote losing policies any more than you want to pay more for behaviour that damages the environment. They are doing so only because the need is desperate.

Those graphs were interesting - but some questions - When you take a continent how many different areas do you select to take an initial temperature? Do you use different weather research stations and how many?

Why are there dips in the graphs when the temperature went down? Surely CO2 levels were still increasing at this time so you would have expected the temperature to increase? I would agree that temperature rises would be more likely to occur in cities but why do you get such a variation in temperature say in the USA where some places have experienced temperature rise over the last 100 years and some have decreased and some have stayed roughly the same?

How accurate were the records in 1920, 1930, 1960 in comparison to taking temperature today - when we are talking about such small rises? Were all temperatures taken using the same 'standard' equipment? How about human error? Were temperatures rounded up or down? Who decided on the significant figure?

Still too many variables - and the climate models are not accurate enough - some are clearly way off the mark.

not strictly CC as such but example of loony left propaganda

seriously do you think it is all ok?

Linden - the data is based on collated and quality controlled information from thousands of stations. Of course there are still issues with data quality. For example the setting of a station can change with time and this can affect the readings (urban areas often have higher temperatures than rural areas). You can see similar trends however if you look at individual trusted stations. For western Europe and America the data from the early part of the 20th century is often of high quality, although if you go much further back, both the quality and quantity of data decline. In the developing world, the story is quite different - with there being little data in many parts of Africa for the early 20th century and observed data being patchy and of variable quality for all periods. The advent of satellite data will address this to some degree over the next decades.

I agree completely though that the importance of observed datasets cannot be overstated. Unfortunately, the difficult, routine and time intensive work that goes into maintaining/processing the data is often not appreciated by the funding councils.

Of course greenhouse gas (GHG) concentrations are not the only forcing factor on temperatures. Volcanic activity, natural climate variability, decadal changes in ocean/atmosphere circulation are all superposed on the GHG increases, meaning that there is not a straight upward trend in all regions.

You are also right that there is much work left to be done for model development. The figure I linked to shows large scale temperature increases - one of the easiest things for models to simulate. Simulating smaller scale rainfall changes is still highly problematic.

However, I think that there is now sufficient scientific evidence to demonstrate a significant threat, that governments and 'ordinary people' should act to mitigate.

part of the complication is that the natural variation in the cycle is superimposed on the mad made input. It is difficult to untie them all.

For example sun spot cycles can change the amount of energy reaching the earth (I think I am right in saying the little ice-age period in the 1600s when the Thames regularly froze coincided with low sun sport activity), el nino/la nina cycles, can all raise or lower the global average temperature, or change the flow patterns over different timescales.

There is a lot of discussion about the integrity of the measurements and the siting of stations - which is why lots of different analyses are done - using selected subsets of the data to try and understand what any inherent biases may be (these types of exercises may be the type of "tricks" mentioned in some of the leaked emails). Most scientists would agree there is much we don't understand particularly in the detail. But they now think they do understand the bigger picture.

I think there is evidence to think that there is a cooling effect at present which will phase out over the next 10 years. This may be buffering the C02 temp rise - so that when it goes we might get a sudden rise.

The observationlists and the theorectical modellers are also increasingly finding evidence that the climate is capable of changing much more suddenly than previously thought. For years it has been fairly safe to think we had a long time to react to the potential problem of global warming. But lots of people are now thinking we might get sudden changes. If anything the IPCC reports underestimate this aspect - it is not main stream enough yet to be included in the accepted models.

The fear is also that you can get tipping points where you flip over into another "stable" state in the atmosphere. This has happened in the past when the earth was warmer (or colder) than it is now. The issue for all species living now is we are adapted to deal with our current climate state - and the change to another state is unlikely to be comfortable for most.

I think the inescapable fact it we have increasingly released fossilized carbon into the dynamic system. Whilst co2 is a very minor gas in terms of concentration it is very important in the way it interacts with the wider environment. The earth seems to have a buffering capacity (much of which we still don't understand) which means the effects lag the increase - with suggestions that the rise we see today results from releases in earlier decades. If that is the case then the effect could well accelerate to match the increased releases of the late 20th and early 21st century.

oops - should proof read !

man made - not mad made !

According to someone posting on a different site, the public in general has got the wrong idea about 'runaway' warming - this guy (not a sceptic but apparently a physicist of some sort) says it's never going to happen on Earth in the way it apparently happened on Venus, as it would require the oceans to boil dry.

Just thought I'd mention it on here as lots of us non-scientists (well me anyway) had got the impression that positive feedback loops and runaway warming are the same thing.

a freudian error there Throck

well there is a long way to go before we get to that state !

I guess the thing is - to most of us a 3-4*C warming doesn't sound that much - but it is actually a lot more heat in the system - making the whole thing more volatile. It may mean snow in very cold areas because there is more moisture in the air, but areas currently in equilibrium will be knocked into a different state.

one thing that bugs me - if the government really wanted to make a difference and take a lead - it could insulate every house to the most it can take (obviously some you can't do much with). It would provide work for a lot of people (good for keeping the economy chugging), make a big difference to the amount of energy used in a domestic setting, and make everyone feel better off as they spend less on heating. Win win. And they could tackle industry too - how many people work in overhot offices ? I certainly do - I only ever wear a tshirt at work - I wear a jumper at home.

There is a lot of work that could be done now that would make a difference.

Also all new building should have compulsory ground-heat exchange. Large buildings should have solar etc. We could have wind turbines along motorways (good access and already blighted for noise etc). If all these things were put in place now we could actually start to cut our reliance on oil and gas. Which politically is only a good thing - the world's reserves of those are hardly in friendly stable places are they ?

throck - I imagine that the short answer to that one is 'the Treasury says no'...