Two years mild, then: hot

So say the folks at the British Meteorological Office’s Hadley Centre in Exeter:

Using powerful computer models, scientists at the British meteorological service’s Hadley Center predict that at least half of the years after 2009 will exceed temperatures during 1998, the warmest year currently on record.

The year 2014 is likely to be 0.3° Celsius (.5° Fahrenheit) warmer than 2004, the Met Office scientists predict.

This forecast means that while it has taken a century for the global temperature to rise 0.8°C (1.44°F) it will take only 10 years for the planet to heat up half again as much.

The paper is in today’s Science (Improved Surface Temperature Prediction for the Coming Decade from a Global Climate Model).

When I wrote about this yesterday (climate change), apropos a story in Newsweek, a commentor who I’m sure was doing the WordPress rounds mentioned recent corrections to past estimates – using American data, which I criticised in turn, in my response. I believe the historical high temperature – globally – may still be 1998. It really doesn’t matter – arguing over when a historical high may have occurred is more than a bit of a furphy, these days. But whatever the sweaty optimists think will help their non-cause is fine, I guess.

The authors’ abstract:

Previous climate model projections of climate change accounted for external forcing from natural and anthropogenic sources but did not attempt to predict internally generated natural variability. We present a new modeling system that predicts both internal variability and externally forced changes and hence forecasts surface temperature with substantially improved skill throughout a decade, both globally and in many regions.

Our system predicts that internal variability will partially offset the anthropogenic global warming signal for the next few years. However, climate will continue to warm, with at least half of the years after 2009 predicted to exceed the warmest year currently on record.

The “at least half” comes from a year-on-year probability of around-to-over 50% that any given year will be a record breaker, relative to the – global – record from 1998.

They also used a word – “hindcast” – that I’d not, previously, seen. What a great word. Their model, through a combination of shorter-lead forecasts (less room for error) and better modelling/initial conditions, seems to map historical trends (out-of-sample) very accurately. Making their immediate forecasts for the next few years fairly reliable. The error on their hindcasts was within a degree or so, Centigrade.

Remember, surface temperatures refers to Oceans, not some uniform increase for the globe (I feel obliged, now, to add that caveat. You know, just in case).

From the paper, itself (subscription required, non-academics. Unless you know an academic, who can email you a copy…):

It is very likely that the climate will warm over the coming century in response to changes in radiative forcing arising from anthropogenic emissions of greenhouse gases and aerosols (1). There is, however, particular interest in the coming decade, which represents a key planning horizon for infrastructure upgrades, insurance, energy policy, and business development.

On this time scale, climate could be dominated by internal variability (2) arising from unforced natural changes in the climate system such as El Niño, fluctuations in the thermohaline circulation, and anomalies of ocean heat content. This could lead to short-term changes, especially regionally, that are quite different from the mean warming (3–5) expected over the next century in response to anthropogenic forcing. Idealized studies (6–12) show that some aspects of internal variability could be predictable several years in advance, but actual predictive skill assessed against real observations has not previously been reported beyond a few seasons (13).

Global climate models have been used to make predictions of climate change on decadal (14, 15) or longer time scales (4, 5, 16), but these only accounted for projections of external forcing, neglecting initial condition information needed to predict internal variability. We examined the potential skill of decadal predictions using the newly developed Decadal Climate Prediction System (DePreSys), based on the Hadley Centre Coupled Model, version 3 (HadCM3) (17), a dynamical global climate model (GCM). DePreSys (18) takes into account the observed state of the atmosphere and ocean in order to predict internal variability, together with plausible changes in anthropogenic sources of greenhouse gases and aerosol concentrations (19) and projected changes in solar irradiance and volcanic aerosol (20).

Those numbers, for the non-Academics, are references that I did not remove – that’s 20 references in what was originally a single paragraph. Bloody scientist show-offs.

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5 comments so far

  1. typingisnotactivism on

    Looks like the mild theory is heading out the window already.
    http://typingisnotactivism.wordpress.com/2007/08/19/global-warning-arctic-meltdown-aussie-apathy/
    At least Orwell can be closed and put down on a table to come back to by choice. The climate change sceptics are just set to IngSoc 24-7. First global warming didn’t exist, then it couldn’t exist without proof, then forecasts didn’t come true the year that they were made which relegated it to non-existent, then it was happening but not because of human impacts, and now we can expect screams to be levelled at scientists who have so allowed their projections to be conservatised that reality is hitting the accepted consensus modelling out of the park. Let’s build dykes out of Inhofes and Moncktons.

  2. zooeygoethe on

    I saw (on your blog, as a matter of fact. I was thinking about posting about it later. I guess I don’t need to, now).

    I mean at some point to go looking for any studies done on the marginal effect of Ice shrinkage. We are told already the effects of increasing Carbon Dioxide in terms of parts per million and degree increases – I would like to know what replacing a hectare of ice with one of sea will do to surface temperatures.

    It’s probably because I’m a sad economist.

  3. typingisnotactivism on

    Hey – don’t worry. If you’re a sad economist, that’s a good sign. You have understanding of the status quo as reflected by yr emotional state. If you were a happy economist it would mean that you don’t understand your area of specialty, or you do but you don’t care, or perhaps are just an eeeevil bastard!

    I don’t have the link but Monbiot has recently been spruiking the new worst case scenario which does include the albedo effect. Thing is, in my opinion, the modelling on the interaction of these self-reinforcing mechanisms is essentially very high-end grabbing at straws. I think the things to take from current knowledge are that the people who have questioned the science for being too hysterical and then challenged it for being conservative and therefore worthless need to be shown the door right now unless they’re genuine get-on-board types. Naff quarter-measures which don’t really exist (clean coal et al) need to be treated as the sideshow rather than the main event, and self-reinforcing corrective measures such as agrichar, GreenFuel (algae that feeds on industrial emissions to reduce grrenhouse and produce cleaner fuel), and radical solar technologies which build solar cells into standard building materials and generate energy even in low non-direct light (therefore turning each building into a potentially self-sufficient zero-emission power cell), etc. MUST take centre stage. So too must a rapid about face from governments that have been permitted to leave this to individual efforts. If you’re Russia and Chernobyl’s just happened, you don’t leave the cleanup to farmers with gumboots, buckets and raincoats – but that is largely the state of the global government-level response to the reality of global warming.

    To be fair – I think Germany is really leading the way and I know that many governments, China especially, are punching above their weight. Perhaps living in Australia and hearing our bullshit-peddlers each day reinforces the hopelessness of current action. Still, it is brutal. That is the reality. And I think that many of the individuals most devoted to saving the planet as we know it probably also know well enough to be prepared for a global disaster which seems so much more inevitable than the necessary global revolution. . . at this point anyway.

  4. zooeygoethe on

    The Monbiot article is here:

    http://www.monbiot.com/archives/2007/07/03/a-sudden-change-of-state/

    I also moaned about it – with pictures! – at the time:

    https://economicobjectorvism.wordpress.com/2007/07/03/if-god-hadnt-promised-no-more-floods-would-we-take-climate-change-more-seriously/

    I still think that’s a valid question, too. I notice you’re at Sydney Uni, my almer mater (twice removed, now. I got my first degree there). I get an outside insider’s perspective, I suppose, on Australia, in this regard. As I begin my 5th year living away.

    ‘The Media’ is easier to avoid in the US, surprisingly: don’t watch television, avoid the New York Times, and you’re mostly protected.

  5. Joseph on

    I have a simple hindcast of my own, spreadsheet included. It only considers CO2, so it cannot predict local variability, but it seems to do well with the long term trend. At a later time I’ll do a forecast based on the same model.


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