The science questions following a global deal on climate

There has been a huge amount of worldwide media coverage following the weekend’s announcement of a globally agreed deal to try to limit global warming to 2 °C or less. Here Professor Stephen Belcher, the Director of the Met Office’s Hadley Centre for Climate Science and Services, discusses some of the scientific questions raised by the agreement.

At the heart of the Paris agreement is the aim to hold “the increase in the global average temperature to well below 2 °C above pre-industrial levels”*. Why 2 °C? Because global governments have previously agreed this is an achievable target which could reduce some of the most dangerous impacts of climate change – such as melting of ice in places like the Greenland which would cause large scale sea level rise.

The agreement went even further, however, by saying efforts should be pursued to “limit the temperature increase to 1.5 °C”. This is a more ambitious target, especially given news from the Met Office in November that the world has reached the 1 °C above pre-industrial marker for the first time this year.

It raises some interesting questions for scientists as to how we can achieve this: how much do we need to cut global greenhouse gas emissions? How quickly do we need to make those cuts? What else might we need to do to be able to keep warming to 1.5 °C – for example, would we need to develop technologies that actually remove CO2 from the atmosphere? If temperatures overshot 1.5 °C and then reduced to 1.5 °C, would sea level also overshoot and then reduce?

To answer these questions more precisely will require scientists to get an even more detailed understanding of how sensitive our climate is to CO2 and other greenhouse gases.

Key to this will be improving understanding of what we call ‘Earth system feedbacks’. These are natural feedback processes which could either increase or decrease the amount of warming we might expect in response to a given amount of greenhouse gases. For example, we know that there are stores of greenhouse gases ‘locked away’ under frozen ground (permafrost) in some parts of the world, such as northern  Russia. If that permafrost melts due to climate change, the gases would be released – which could further increase warming.

Scientists around the world are already working on providing answers to these questions by developing a new breed of ‘Earth System Models’ (essentially complex simulations of our planet run on powerful supercomputers), which take more of these feedback processes into account, and so will help inform planning of emissions to achieve the warming targets agreed in Paris.

Whether we limit warming to 2 °C or 1.5 °C, it’s clear we can expect some further change to our global climate over the coming decades. Research shows us that this will lead to some impacts and it’s vital that we understand in more detail what this means at a regional and local level.

For example, research tells us that some parts of the world can expect more extreme weather – including heat waves and increases in extreme rainfall. For those planning everything from future homes, to flood defences, to vital infrastructure, the detail on what to expect is essential.

Again, these are questions which science is already working to answer by harnessing new research and ever more powerful supercomputing technology. At the Met Office, we’ve published papers showing that we can expect more intense summer downpours for the UK in future – which raises the risk of flash flooding. We’ve also shown how the chances of summer heatwaves in Europe have dramatically increased.

There’s still much more work to do in this area and it will be vital that the information generated by this research is presented in a way that allows everyone to make informed decisions about how we can become more resilient to our climate – whatever changes we can expect.

*There’s a lot of scientific debate about exactly what ‘pre-industrial levels’ means and how you would measure that, but here we use the average of temperatures during the period 1850-1899 as our representation.

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47 Responses to The science questions following a global deal on climate

  1. jbenton2013 says:

    Yet more spin and misinformation from the Met Office. The more accurate and reliable satellite data does not support the assertion that we have warmed by 1.0 degree centigrade from pre-industrial levels yet and may not for some decades. It’s possible that the current El Nino my have a temporary warming effect next year, but that remains to be seen.

    The references to more extreme weather resulting from AGW is not supported by empirical data and not even supported by the IPCC AR5.

    If you are referring to the BAMS report published recently it’s already clear that the best that can be said about that is that it is statistically inept, and in fact is a conglomeration of speculation modelled results masquerading as serious science.

  2. Charles Nagy says:


    Looks and sounds like you were born yesterday. 🙂

    If you believe satellite data is more accurate than actual thermometers, I have a bridge to sell you….

    • jbenton2013 says:

      The satellite datasets covers around 95% of the earth. The surface dataset only covers around 70% of the earths surface and even then very sparsely covered in many countries.

      That’s before accounting for the massive amount of adjustments to the surface datasets, many undocumented.

      Both the satellite datasets (UAH and RSS), produced using different methodologies are tracking in an almost identical manner, and are further backed up by four other empirical datasets, radiosonde etc.

      That’s the case for the prosecution, what’s the defence case.

      PS I’m sorry you are stuck with an unwanted bridge.

    • groanranger says:

      Don’t worry Charles, Benton is like a broken record replying to virtually every post on here with ‘the satellites are more accurate and they don’t show warming’. He is wrong of course. If you think that putting together a surface global record is hard, then a satellite record of temperatures away from the surface is fiendishly difficult (see below). Notwithstanding that they don’t even measure the same thing, there is no sense in which satellites provide something ‘more accurate’. And anyway, the global temperature rise over the last 50 years is actually very similar in both surface and satellite data.

      It should also be obvious that Benton did not think this particular meme up. It has become one of the pillars of climate denial through continuous repetition by people like him who want it to be true and don’t know enough to question it. Its originators would have known that its a good lie since although it has no scientific merit it might be believable to the uninitiated. This ‘credibility’ relies on the fact that most people are aware that global temperatures are primarily monitored by thermometers (at weather stations on land and ships at sea), so will be surprised to learn that there is an ‘alternative’ measure that is rarely mentioned. Further, it can be spun that this alternative is obtained from satellites (=high tech) not thermometers (=low tech) suggesting it is more modern, and therefore better. Something like a Blu-Ray compared to a grainy VHS recording. If you then suggest this other record shows something different from what we are continually told then the fib is complete.

      In fact, despite satellites seeming like a ‘high tech’ solution they have many drawbacks. They don’t measure what we want to know, i.e. temperature, but typically things like radiances (the infra red light coming up from the atmosphere). You then have to work out how to translate this into temperature, and this can be difficult. For one, the radiance the instrument on the satellite sees is emitted at a range of heights in the atmosphere, so getting the temperature for one specific height is uncertain. Often, what you end up with is something that represents a layer of the atmosphere centred on a particular height. The final temperature can also depend somewhat on a number of assumptions about the vertical profile of conditions in the part of the atmosphere being looked at. Furthermore, if we want to know about trends we have to think about how the satellite changes with time. This can be through changes in the instrument (sensors can become decalibrated when exposed to prolonged periods in space), or through shifts in the satellite’s orbit, which change the sampling of the local time-of-day of each overpass (and hence average temperature). Then for longer trends you have to worry about how to combine the data obtained from the current satellite/instrument combination with those from multiple previous missions, which may have had substantially different characteristics.

      The satellite datasets that have been made are therefore considerable achievements but not without uncertainties. In many ways, in collecting thermometer data there is less to go wrong. Even if a small minority of stations are whacky it won’t affect the result too much. But the number of satellite instruments is sufficiently small that if 1-2 start doing something subtly wrong it could substantially affect the whole global record. That is why if you take surface measurements from around the world and average them without any processing whatsoever you still get trends that are roughly similar to the post-processed best estimate. If you try to do that to the satellite data you get a mess. There is more interpretation and correction that needs to be done for the satellites.

      • jbenton2013 says:

        So much nonsense in one comment. Firstly how can the “global temperature rise” over “the last 50 years” between satellite and thermometer records be similar when the satellite record only began 37 years ago.

        You make the claim that the satellite record is less reliable, but have failed to point out that there are two independent satellite records (UAH and RSS) which are tracking in an almost identical fashion. Furthermore these satellite datasets which cover around 95% of the earth are confirmed by four other empirical datasets, radiosonde etc.

        By contrast the surface dataset covers only around 70% of the earth’s surface, and in many countries very sparsely. The surface records have suffered from many contaminating factors such as UHI effect, and that’s even before we begin to consider the huge number of ‘adjustments’ undertaken to ‘homogenise’ the results, many of which are undocumented. In contrast, all the processing of the satellite data is well documented and archived.

        No one suggested that it is not a considerable achievement, or a great deal of work to produce the satellite temperature datasets, and had there been one single one available then your criticism may have had some credibility, however the fact that there are two independent datasets producing almost identical results offers considerable safety in the event of system failure, which would be easily identified.

      • groanranger says:

        Good of you to summarise your post in the first sentence Benton. Saves people having to read it.

        For anyone who has gone through it, the points he is missing are:

        1. The agreement between the satellite datasets is encouraging, but no different to the agreement between the half-dozen-or-so surface datasets. The datasets in each case share the same primary source data by and large (more or less the same thermometers in the surface case, more or less the same satellite instruments in the tropospheric case).

        2. If the satellites are backed up by weather balloon measurements, there is also consistency at the surface: you have the record from land stations, and quite independently ships and buoys at sea. These track each other well. Add to that sea surface temperatures, which are a third, completely independent, set of measurements.

        3. The most important thing of all though is that all the records – satellite, balloons, ships, buoys, ocean depth profiles etc etc agree with each other on long-term warming. This shows that all the objections about the surface record above, the 70% coverage and urban influences, as well as baseless prejudice about the methods, actually amount to very little. You get basically the same answer whatever way you look at it.

        The bottom line is that the satellite data are no better (and no worse) for assessing global changes than surface data. Each measures a somewhat different thing, each has specific challenges in transforming raw measurements into usable datasets, and each paints a very similar picture of climate warming.

      • jbenton2013 says:


        I would have expected you to be aware that the RSS and UAH datasets are NOT produced using the same instruments or methodology but clearly that has escaped you. The fact that the data is providing extraordinary confirmation is a bit more than “encouraging”, I would say it’s pretty convincing, particularly since it’s also backed up by solid empirical data from completely unconnected sources.

        You also appear to be completely unaware that the surface datasets are all produced from the identical source data, the only difference being the slightly different processing methodology. Unfortunately there is nothing available to provide any support for accuracy or otherwise of the surface dataset, and since it has been at variance with all the other satellite and empirical temperature reconstructions it has to be considered an outlier, particularly given the dubious and undocumented nature of many of the adjustments.

  3. PS That Met Office press release link ‘2016 global mean temperature forecast’ is now kaput (I read it earlier before it went haywire).

  4. “I’ve no idea what you’re talking about Haworth-Roberts.
    If you are not familiar what the IPCC AR5 says about attribution of greater extremes of weather to anthropogenic CO2 then I suggest you read it again.”

    I haven’t read it. I never claimed to have read it. I asked you a question about it. Which you have ducked. The person who started talking about IPCC AR5 was YOU. Not me,

    Yet again you make claims – and then fail to back them up with evidence.

  5. Charles Nagy says:

    Groanranger & Jsam,

    I have this “satellites are more accurate” argument with deniers all the time. Most of them have not a clue as to how satellite temperature measurements work, and they don’t appreciate that this data needs far more analysis than ground temperature data which use actual thermometers. Many think that satellites provide surface temperature data (really!), whereas they just measure microwave intensity, at around 12,000 feet altitude (correlating that with temperature), and last time I looked, there weren’t a hell of a lot of people living up there.

    For general accuracy of satellite data you can’t go much further than the horses mouth, Dr Carl Mears who produces the RSS dataset:

    “A similar, but stronger case can be made using surface temperature datasets, which I consider to be more reliable than satellite datasets (they certainly agree with each other better than the various satellite datasets do!).”

    I might add that Benton is wrong about satellite data agreeing with each other, RSS & UAH have been diverging since 2000, as Dr Mears has pointed out.

    However, since “The Pause” bit the dust, this really is, all deniers have now. Satellites are the only datasets that aren’t obviously trending upwards at the same rate as ground based observations.

    Consider the following indications of Global Warming:

    Inexorable increase in all major ground based temperature datasets
    Majority of glaciers in retreat around the globe
    Sea temperature increase
    Sea level rise
    Sea acidity going up (by just the right amount given qty of CO2 absorbed)
    80% Arctic ice loss by volume in the last 30 years
    Overall ice loss (by volume) in the Antarctic (Confirmed by satellites!)
    Species migration
    Permafrost melt
    Massive increase in summer Polar region wildfires

    Need I go on? For this, the denial community, has only very weak explanations. “it’s natural variation”, so how come it always seems to vary upwards?, or “it’s the sun”, when solar activity has been quiescent for the past 15 years. Lastly, “it’s all a hoax”, the last refuge of the conspiracy theorist. These scientists must really be smart though, thousands & thousands of them, all working together, all over the globe, over a 30+ year period, managing to artificially tweak all these datasets just the right amount so that they all agree with each other. Come on, you would have to be down to your last functioning neuron to believe that upper air satellite temperatures (even if they were accurate, a very big if!), could, on their own, disprove Global Warming.

    • jbenton2013 says:

      It appears the only “denier” is yourself.

      It would be curious indeed, and not a little inconvenient also, if the earth had not been experiencing some warming over the last 200 – 300 years since otherwise we would all still be in the grip of the Little Ice Age. I’m assuming you have heard of this worldwide phenomena, you know the one where they held ice fairs on the frozen Thames.

      It is for that reason that most glaciers have been retreating for at least 250 years, but rather inconveniently for you that the greatest rates of retreat was seen before any large scale fossil fuel use. Consequently the sea level has been rising over the same period (in fact since the end of the last ice age), although again inconveniently for you not at an accelerating rate since the widespread use of fossil fuel.

      I’m sure you’re really just being facetious in your comment because you probably know already that the sea is not acidic, it is alkaline, albeit slightly less alkaline than 60 – 70 years ago, but nothing to be concerned about.

      You appear to be rather behind the times regarding your knowledge of the Antarctic. I suggest you read the latest papers on the subject, starting perhaps with Zwally et al 2015 which confirms that the Antarctic is gaining both mass and sea ice area, in fact it has been gaining sea ice area consistently since satellite measurements began thirty years ago. You also appear to be unaware that the Arctic sea ice area has been increasing since 2008 both in thickness and area. I assume your claim of less Arctic sea ice is measured from 1979, a cherry picked year. When measured against 1974 there has been a considerable increase, or perhaps you would prefer an even earlier year.

      Your claim that the UAH and RSS datasets are not tracking in an almost identical fashion is complete nonsense that anyone can check for themselves. Both are freely available on the internet.

      The only thing which is likely to happen over the next year or so is a slight warming from the El Nino we are currently experiencing but that is very likely to be only a temporary respite from the flood of inconvenient data currently debunking the alarmist propaganda. At present the ‘pause’ is still very much with us.

      So in answer to your question, Yes it appears you do need to “go on”, because all you have provided so far is a list of cherry picked claims which do not stand up to scrutiny.

  6. I would be grateful if the Met Office could PUBLISH my response to Benton’s reply to me dated 18 December.

  7. Apologies. My reply to Benton HAS been published (but nowhere near his comment within the thread).


    Oh, and Hartnett believes Earth is just 6,000 years old, that a worldwide hill-covering flood a la Genesis occurred less than 5,000 years ago, and that evolution is a lie. (He also frequently censors my attempted comments under his blogs.)

  9. Charles Nagy says:

    For Benton re “However you may like to explain to a non religious person like myself why approximately 45% of the warming since the end of the little Ice Age had occurred BEFORE the substantial burning of fossil fuels by man?”

    Here is an explanation:

    I might add that it seems that Benton gets his disinformation from various right wing blog sites, none of which have any scientific credibility, and none of which are managed by people with any scientific expertise. If I may give an analogy:

    Suppose that Roger Federer offered to give you free instruction in tennis but instead you chose to go and get instruction from some guys you know at the local tennis club, most of whom were not even accredited tennis coaches, Even the actual local coach had never played professional tennis, You would have to be crazy to spurn coaching from one of the top experts in tennis! Similarly, it just doesn’t make sense to take your climate advice from people who have no expertise in climate science.

    For example, one of the top climate contrarian sites is WhatsUpWithThat, run by an ex TV meteorologist. On paper, this sounds good, but when you realise this guy does not possess any qualifications in Meteorology, and in fact, doesn’t possess ANY University qualifications in anything at all, having spent 7 years at university without graduating at all, surely this should raise alarm bells?

    • jbenton2013 says:

      LOL. On the contrary I get my information from published scientific papers. You have linked to a spoof climate website above.

      • Charles Nagy says:

        Cripes! If Carbonbrief is a spoof website, what does that make WUWT?
        It would appear that climate deniers lack some sort of irony gene, (along with a common sense and objectivity gene). Benton, after claiming he only gets his information from scientific papers comes right back with stuff that he could only have got from sites like WUWT. Even if true, he very clearly has omitted reading the thousands upon thousands of climate papers that agree AGW is happening. Feel like picking any cherries anyone?

        There is a saying that “Nature bats last”. After the hottest year on record, and in NH summer, with large parts of the Northern Tundra burning, along with huge chunks of Canada & the US, plus the drought in California; and now the historic winter warmth warmth along the North Eastern US seaboard; then several, once in a thousand year floods in the UK, plus rainfall for the first time ever in mid winter at the North Pole (where the temperature is set for + 2 degrees C this coming weekend); the deniers are still bleating “but the satellites say no warming”, preferring microwave intensity measurements taken at 12,000 ft over the actual temperature at the surface where most of us live.

        Anyhow, I am not prepared to waste any more time arguing with such recalcitrance, impervious to objectivity and logic. It is already blindingly obvious that our planet is warming, and the serious consequences have already started. Within the next few years, even the most hardened deniers are going to get mugged by reality. I really wish it weren’t so, and though I will get some satisfaction in telling them “I told you so”, I will take no pleasure in the disastrous consequences.

      • jbenton2013 says:

        Your problem Charles is that you appear to be lacking in any historical perspective, quite apart from not recognising that climate and weather are two completely different things.

        The warm weather in the eastern US and the current drought in southern California are weather events, which even since you wrote your comment two days ago have changed considerably. The eastern US has seen some record snow over the last couple of days and the rain and snow has been falling on California, very possibly as a result partly from the effects of the current El Nino. Nothing whatsoever to do with additional CO2.

        As for your claim that the North Pole will be +2 degrees C this weekend, well according to the instruments available they are currently telling us it’s -20 degrees C as I write. I suspect you have been duped by the article in Time magazine (subsequently repeated by some unreliable sources to the great amusement of sensible people) by some silly reporter who could not tell the difference between the town of North Pole in Alaska and the actual North Pole, but that’s just another consequence of your choice of information.

        I did not say Carbon Brief was a spoof site, but their very name will leave the reader with little doubt where they are placed on the spectrum of believers. In fact their very existence depends on their belief that there is a problem.

        Perhaps you don’t appreciate that I’m not American (not all of us are) so don’t follow the sources you suggest, but you need to widen your reading to appreciate there are many opinions on the climate and what it will hold in the future.

  10. When I ask Benton for links I normally get nothing in response (and when I found one of the papers, about whether there was record rainfall or not in Cumbria around 5 December, it turned out he was ‘over-egging’ it and that the researchers’ claims about past centuries appeared speculative and were devoid of statistics).

    • Charles Nagy says:

      Yes Ashley,

      Pretty standard practice for Climate Contrarians I’m afraid. They never give links, because while they claim to only read actual scientific papers, in reality all they do is take talking points copied and pasted from the various Denier sites. They are too scientifically illiterate to understand the papers themselves and posting links would give the game away.

      Also, it is interesting to see, that the surface temperature datasets which they were happy to use to trumpet “the pause”, are now hopelessly compromised (so they say), since the surface temps blew past the 1998 high (which was of course a cherry pick anyway). Now the last remaining datasets they have which show little warming are the Satellites, so of course that is what they have circled the wagons around.

      They are impossible to argue with as they never respond to any individual criticism, but immediately change the topic or raise another completely irrelevant issue. (Witness Benton calling any link to a legitimate science site a “Spoof” site, mistakenly thinking that he has dismissed the criticism and has no need to address it further).

      And nary a word from any denier sites (as far as I know) about the revelations that Exxon’s own scientists warned about Global Warming 30 years ago, which incidentally, killed off quite a few denier memes in the process…..

      • jbenton2013 says:

        It’s always amusing to hear the Exxon claim repeated Charles.

        You’re well down the rabbit hole Charles. I think even most of the alarmists would be embarrassed by many of your statements. They’re probably more appropriate for the sites you have been frequenting.

    • jbenton2013 says:

      If you would read the papers they were referring to rather than the press report you linked to, then you may be better informed.

      • Charles Nagy says:

        So are you are you going to refute it? If so how? It would be interesting to have you actually refute something (anything, since you never post any sources), instead of posting pithy little fact free comments. If you have a link contradicting the Exxon revelations then post it, otherwise shut up.

      • jbenton2013 says:

        The comment was referring to Haworth-Roberts. I’ve got no interest whatsoever in responding to nonsense about Exxon.

      • Charles Nagy says:

        Would you care to provide a link as to why you think the Exxon revelations are nonsense? in order for your comment to have any relevance whatsoever, you would need to present some evidence which challenges those findings. Exxon hasn’t denied it. The scientific reports are now in the public domain (despite Exxon’s best efforts), and they clearly indicate that Exxon scientists thought Global Warming would be a problem. It is also clear that Exxon buried the reports and instead, decided to fund “Denier” organisations.

        Presenting your uninformed opinion is less than worthless. Put up or shut up. Either you can back up your assertions or you can’t. Your fact-free and vain pronouncements expose your general scientific illiteracy.

      • Please note sections of this have been edited in accordance with the moderation guidelines

      • jbenton2013 says:

        Your constant use of the word “denier” is clear indication that you have lost the scientific argument and must therefore resort to ad hom attacks on anyone who disagrees with your views, even if those views are not supported by the data.

        What is a “denier” supposed to be denying? Does a climate denier deny that a climate exists? I haven’t come across one of those.

        It is simply of no interest to me to respond to someone who’s only response to engage in insults instead of debating what the data tells us. As for Exxon I would imagine their lack of response, if indeed their is a lack of response since it’s not something I’m remotely interested in, is probably a result of how seriously they deem the claims.

  11. Charles Nagy says:


    You keep blathering on about the “data”, but never seem able to link to anything that supports your claims, (or in fact, to anything at all).

    Instead, you just seem intent on showing off your ignorance and stunning lack of comprehension. If you want to continue embarrassing yourself with your meaningless prattle, please go ahead; but you will have to do it by yourself.

    I for one, am not going to help you.


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