NOTE: The following report has many embedded LINKS. For getting to all the links, click on http://www.guardian.co.uk/environment/blog/2013/jan/09/global-warming-met-office-paused/print ONLY a few links are embeddded in this blogpost.
LiveThe Met Office has revised downwards a forecast for the rise in average global temperature by 2017. Has global warming, as some say, 'plateaued'? Leo Hickman, with your help, investigates. Post your views below, email leo.hickman@guardian.co.uk or tweet @LeoHickman
Leo Hickman
guardian.co.uk, Wednesday 9 January 2013 14.23 GMT
Sydneysiders and tourists flock to the popular Bondi beach in Sydney, Australia, during the on-going heatwave. Photograph: Manan Vatsyayana/AFP/Getty ImagesLive
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2.23pm GMT
Greenpeace's Graham Thompson has published a blog post in response to "this new climate controversy":
[It] is actually the same old controversy described here, here and here and debunked here, here and here...
Basically, you can’t see a long-term trend by looking at the short term. When you’re measuring changes over brief stretches of time, you can find periods where the Dow Jones seems to show the collapse of capitalism, the climate appears to be cooling, or QPR look likely to win the Premiership. But take a step back, and things look very different.
So, no, sadly, global warming has neither stopped nor paused, when you look at climatic trends rather than weather patterns.
2.01pm GMT
Fred Pearce in the New Scientist has just posted an article "looking at the facts" on whether global warming has "stopped". He begins by highlighting the "big error bar" in the new forecast:
Atmospheric warming has certainly slowed greatly in the past decade. The Met Office says this appears to be due to natural cycles that are counteracting the warming effect of greenhouse gases. After incorporating new analysis of natural cycles into its latest model of atmospheric and ocean circulation, it has concluded that we are in for a few more years of little change.
Having calculated annual global temperatures for the next five years, its best guess is that they will be, on average, 0.43 °C higher than the average for 1970 to 2000. That's down from its previous prediction of a 0.54 °C rise. If the new prediction proves right, then 2017 will barely be warmer than most years in the past decade.
The forecast comes with a big error bar, however. The average warming for the next five years could be as much as 0.59 °C, or as little as 0.28 °C.
Pearce goes on to highlight how "oceans are the sleeping giant of climate change":
They act as a huge heat sink: 90 per cent of the heat generated by accumulating greenhouse gases is absorbed by the oceans. How fast this happens is variable, depending on ocean currents and other fluctuations.
Scientists have known for a long time that in El Niño years, when warm water spreads out across the equatorial Pacific, heat leaves the ocean for the atmosphere. But there are also longer-term cycles. The biggest cycles are known as the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. Recently, both have been causing the oceans to absorb more heat, shutting off atmospheric warming...
He concludes:
So press reports that global warming is at a standstill are not true, even in the short term. Right now the oceans are taking up almost all the extra heat. That is most unlikely to persist.
1.49pm GMT
Richard Betts, head of the climate impacts strategic area at the Met Office Hadley Centre, has posted a comment below to help clear up any possible confusion caused by the BBC article I quoted at the beginning of this Eco Audit:
Please note that, as @bbcbias correctly states, the 0.43C warming is relative to 1971-2000, *not* this year. Also, the 0.43C is the average over 2013-2017.
1.00pm GMT
A thoughtful comment posted below by AlexLawrie, suggesting that this episode highlights the problem in the way climate science is both communicated and reported:
I think the story here is one of failed science communication. Media outlets around the world have conflated 'surface temperatures' and 'global warming'. The fact is that heat that goes into melting ice, or the thermal expansion of the oceans, is as much a factor in climate change and a threat to our lives as heat going into raised surface temperatures. A pause in the latter means a surge in the former, as the earth's energy balance (heat received minus heat radiated) is still way too high, and getting higher.
It is certainly true that climate scientists are having real difficulty predicting where heat is going to go - underestimating the amount being soaked up by the arctic icecap, overestimating the amount going into atmospheric warming. If there was rational coverage of the issue, this wouldn't cause any upset - the error bars were always there, and the firm predictions have been fulfilled (even though surface temperatures have sprung some surprises, the Met Office's expectation of two record breaking years between 2010 and 2015 is still well on course.
But we urgently need the media to get these subtleties right in order to allow scientists to be straight with us, and not muttering and mumbling as they hear the lynch mob gathering.
12.47pm GMT
On the same day that the Met Office confirmed it had adjusted its forecast, the National Climatic Data Center in the US confirmed that 2012 had been the hottest year on record across the 48 contiguous states - a full degree Fahrenheit hotter than the 1998 record.
Here's Suzanne Goldenberg's news story for the Guardian.
And here's a state-by-state map showing the temperature records in more detail.
12.41pm GMT
An interesting update has just been added to Roz Pidcock's post at Carbon Brief:
A sentence in the Met Office's revised global temperature forecast reads "The warmest year in the 160-year Met Office Hadley Centre global temperature record in 1998, with a temperature of 0.40°C above long-term average". This was quoted by several newspapers.
We queried this with the Met Office, as according to a separate Met Office statement released in December last year, the latest HadCrut4 temperature dataset puts 2010 as the warmest year, followed by 2005, then 1998.
The Met Office told us that the 0.40 degrees figure is "based on a 12-month period which isn't synchronised with the calendar year - in which case 1998 is the warmest on record". But they do allow that this isn't particularly clear, and the reference is apparently going to be updated to be in line with the HadCRUT4 records.
It's worth noting that the temperature averages in the 2013 Met Office annual forecast and the figures in the revised decadal forecast are comparisons with different long term averages (1961 to 1990 and 1971 to 2000, respectively) - which adds an extra level of complication to comparisons.
12.32pm GMT
The Met Office confirmed yesterday that its latest forecast was created using the new modelling system known as HadGEM3:
The 2012 prediction is the first to use the Met Office's latest experimental decadal prediction system, based on HadGEM3. This includes a comprehensive set of improvements based on the latest scientific understanding.
HadGEM3 has been thoroughly tested and has more accurately reproduced temperature variations over the past few decades, suggesting it shows greater skill than was available from previous decadal forecast systems.
An older Met Office webpage has some more detail about HadGEM3:
HadGEM3 stands for the Hadley Centre Global Environment Model version 3. The HadGEM3 family of models comprises a range of specific model configurations incorporating different levels of complexity but with a common physical framework. The HadGEM3 family includes a coupled atmosphere-ocean configuration, with or without a vertical extension in the atmosphere to include a well-resolved stratosphere, and an Earth-System configuration which includes dynamic vegetation, ocean biology and atmospheric chemistry.
One of the main changes in the HadGEM3 family of models compared with previous versions is the inclusion of the NEMO ocean modelling framework, which is also used in the Met Office's ocean forecasting system, and CICE, the Los Alamos sea ice model. These are coupled to the atmospheric model through the OASIS coupler developed at CERFACS in France.
12.08pm GMT
In the comments underneath, Ed Hawkins, a climate scientist working at the University of Reading, has posted a response:
This experimental forecast must be viewed in the context of the worldwide efforts of many groups who are making predictions for the coming few years.
For example, this recent paper (open access, with a Met Office lead author) summarises the range of predictions (note Fig. 8 in particular):
http://link.springer.com/article/10.1007/s00382-012-1600-0
with all the different centres predicting a warming, but differing in the magnitude. The Met Office should be applauded for making these predictions public, so that they can be tested properly. Quotes from the abstract: "Moreover, it is important to publish forecasts to enable open evaluation", and "We stress that the forecast is experimental, since the skill of the multi-model system is as yet unknown."
Finally, note the range of predicted outcomes - the new forecast is well within the range of the forecast made last year. Also, note that the new forecast is only for 5 years.
12.02pm GMT Reaction from scientists
Yesterday, the Science Media Centre published a summary of reaction it had received from scientists...
Dr Richard Allan, reader in Climate Science at the University of Reading: Global warming is not ‘at a standstill’ but does seem to have slowed down since 2000 in comparison to the rapid warming of the world since the 1970s. In fact, consistent with rising greenhouse gases, heat is continuing to build up beneath the ocean surface:
http://www.ncas.ac.uk/index.php/en/climate-science-highlights/284-warming-over-the-last-decade-hidden-below-ocean-surface
This indicates that changes in ocean circulation are in part responsible for the recent slower rate of surface warming. The way the ocean distributes the extra energy trapped by rising greenhouse gases is critical in determining the new Met Office forecasts of global surface temperature over the coming decade and is an area of active research.
These decadal forecasts are very much experimental – they are at the cutting edge of the science and are technically very challenging. The Met Office are being open and transparent by making the forecasts available to allow a proper validation to occur. The Met Office is one of about 10 groups performing these type of forecasts worldwide and all predict a warming over the coming decade. Nothing in their data leads me to think that global warming due to human influence has stopped, or is irrelevant. It hasn’t, and it isn't.
Prof Myles Allen, head of the climate dynamics group at the University of Oxford: Comparing the expected temperature for 2013-2017 with a single exceptionally warm year (1998), as some reports have done, is just daft. 1998 was around 0.2 degrees warmer than the 1996-2000 average, largely thanks to a massive, once-a-century El Nino event. The IPCC predicted a warming of 0.1-0.2 degrees per decade due to human influence back in 2000. That means the one-off impact of that El Nino event was equivalent to about 20 years of the expected background warming trend So, unsurprisingly, 20 years later, expected temperatures have risen so that an average year is now as warm as that exceptionally hot year.
That said, a lot of people (not the IPCC) were claiming, in the run-up to the Copenhagen 2009 conference, that ‘warming was accelerating and it is all worse than we thought’. What has happened since then has demonstrated that it is foolish to extrapolate short-term climate trends. We did see unexpectedly fast warming from the mid-1990s to the early-2000s, but the IPCC, quite correctly, did not suggest this was evidence for acceleration.
While every new year brings in welcome new data to help us rule out the more extreme (good and bad) scenarios for the future, it would be equally silly to interpret what has happened since the early-2000s as evidence that the warming has stopped.
Prof Sir Brian Hoskins, director, Grantham Institute for Climate Change at Imperial College London: The current news item that the Met Office now predicts no global warming in the period up to 2017 is based on the latest 5-year forecast run with their new climate model. Such forecasts are at the frontiers of the subject and form part of a research programme in this area in the Met Office and elsewhere, but should not be considered to be predictions.
One interpretation of the forecasts is for little warming from 1998 until 2017. This is consistent with a multi-decadal fluctuation in temperature that presently opposes the continued upward trend. However the two supported one another during the rapid warming in the 1990s and can be expected to do this again in the future, leading to another period of rapid warming. The forecast results also suggest that half the years in the period to 2017 would be expected to give new record global temperatures.
Prof Chris Rapley, professor of climate science at University College London: I despair of the way data such as this is translated as ‘global warming has stopped’! Global mean temperatures - whether measured or predicted - are not the issue. What matters is the energy balance of the planet and the changes that an energy imbalance will drive in the climate system - as well as the consequences for humans.
90% of the energy imbalance enters the ocean and is not visible to the global mean surface temperature value. The continuing rise in sea level demonstrates ongoing energy accumulation in the ocean (as well as a contribution from melting land ice).
Even if the global mean temperature were to remain unchanged, if the geographic patterns of temperature and rainfall change, the consequences will still be potentially severe. We only need to look at what is going on in Australia at this very moment.
11.53am GMT Comment
Here's a snapshot of some of the commentary that has been published...
Mark Lynas in the Times (and reposted on his blog):
This was the story that the scientists “tried to bury”; yet more evidence that global warming is at a standstill — or so it seemed to climate sceptics.
The reality about the Met Office’s new decadal forecast is more prosaic, and also more complicated: it has indeed issued some predictions for how global temperatures might change between now and 2017, but these are not like long-range weather forecasts. They are experimental projections assessing the probabilities of different temperature outcomes averaged out over the whole globe.
Nor is it true that these show a downgrading of global warming. Although five years is a short time period for assessing a changing climate, it is still likely that the planet will continue to warm and that new temperature records will be set. The Met Office also make clear that warming is driven by increasing levels of atmospheric greenhouse gases, not natural fluctuations.
David Whitehouse on the Global Warming Policy Foundation website:
If the latest Met Office prediction is correct, and it accords far more closely with the observed data than previous predictions, then it will prove to be a lesson in humility. It will show that the previous predictions that were given so confidently as advice to the UK government and so unquestioningly accepted by the media, were wrong, and that the so-called sceptics who were derided for questioning them were actually on the right track.
Roz Pidcock on the Carbon Brief website:
To put the new forecast in context with current global temperatures, 1998 was the warmest year on record - according to the Met Office Hadley Centre global temperature record, with a global temperature of 0.40 degrees above the long term average. This is 0.03 degrees lower than the best estimate for temperature rise by 2017 given in the new forecast.
Paul Hudson, a BBC weather presenter, on his blog:
The new projection, if correct, would mean there will have been little additional warming for two decades despite rising greenhouse gases. It's bound to raise questions about the robustness and reliability of computer simulations that governments around the world are using in order to determine policies aimed at combating global warming.
The Met Office says natural cycles have caused the recent slowdown in warming, including perhaps changes in the suns activity, and ocean currents. And mainstream climate scientists, who are in a majority, say that when the natural cooling factors change again, temperatures will be driven up further by greenhouse gases.
But climate sceptics, who have long argued that natural processes are either underestimated, or not properly understood, will not be surprised at this scaling back of expected warming.
11.36am GMT Media coverage
Various outlets have reported on the Met Office's announcement. Here's a round-up...
Daily Telegraph: "Global warming at a standstill, new Met Office figures show"
Daily Mail: "Global warming has STALLED since 1998: Met Office admits Earth's temperature is rising slower than first thought"
Daily Express: "Surprise Surprise... Global warming has stalled, admits Met Office"
Canada's National Post: "Global warming hasn’t stopped, but it has stalled, says new prediction from British national weather service"
Scotsman: "New warming model from Met Office"
Times (subscription): "Global warming is over for five years, says Met Office"
Channel 4: "Met Office: global warming predictions revised down"
Energy and Environmental Management: "Met Office affirms its position on long-term global warming"
Updated at 12.13pm GMT
11.19am GMT
These two graphs show the adjustment made by the Met Office. The first image was published in December 2011. (Here's a Wayback Machine capture.)
Met Office's global annual temperature decadal forecast. Published December, 2011 Photograph: Met Office
The second graph is the latest forecast published on 24 December, 2012...
Met Office's global annual temperature decadal forecast, December 2012 Photograph: Met Office
And as highlighted in the comments below by harhar120, a blogger called Bob Tisdale has produced an animated gif blending the two graphs together.
10.59am GMT Welcome to the Eco Audit
Yesterday, the Met Office published a press release confirming that it had recently revised downwards a decadal global temperature prediction for the period up to 2017. It said it had been prompted into issuing the release following "media coverage" of the adjustment, something it had published without fanfare on its website on 24 December.
The adjustment was first spotted on 5 January by a poster called "Duwayne" on the SolarCycle24.com web forum. Climate sceptic bloggers soon picked it up and on 7 January Roger Harrabin, the BBC's environment analyst, tweeted that the Met Office had confirmed to him that it had cut its warming projection for the period up to 2017 by 20%. He followed it up yesterday with a brief item on the BBC Radio 4's Today programme, which, in turn, was later fleshed out by David Shukman, the BBC's science editor, in an article on the BBC News website:
The UK Met Office has revised one of its forecasts for how much the world may warm in the next few years. It says that the average temperature is likely to rise by 0.43 C by 2017 - as opposed to an earlier forecast that suggested a warming of 0.54C.
The explanation is that a new kind of computer model using different parameters has been used. The Met Office stresses that the work is experimental and that it still stands by its longer-term projections. These forecast significant warming over the course of this century.
The forecasts are all based on a comparison with the average global temperature over the period 1971-2000. The earlier model had projected that the period 2012-16 would be 0.54C above that long-term average - within a range of uncertainty from 0.36-0.72C. By contrast the new model, known as HadGEM3, gives a rise about one-fifth lower than that of 0.43C - within a range of 0.28-0.59.
The news has been seized upon by climate sceptics who were already arguing that global warming had "stopped" since the record breaking year of 1998 and that this new development further undermines both climate science itself as well as any policy response to rising temperatures. Climate scientists have responded saying that to draw such a conclusion is misleading.
Please leave your own thoughts below. If you are quoting figures or studies, please provide a link through to the original source. I will also be inviting various interested parties to join the debate, too. And later on today, I will return with my own verdict.