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Global temperatures - and the future

Paul Hudson | 14:08 UK time, Friday, 6 November 2009

And so to the ongoing issue of global temperatures, whether they have gone up down or flat lined and in what time period. I stated in my original article 'Whatever happened to global warming' that temperatures peaked in 1998, and have levelled out since then. I argued that it was not appropriate to take out the El Nino event from 1998 as some had suggested; for a level playing field other ocean oscillations would have to be taken out too.

However, for those that still insist that I should have not have picked on the hottest year on record, lets for argument's sake say I was wrong. With that in mind, I draw your attention to some research that is readily available on the Met Office website, in which they not only start with 1999, the year following the hottest year on record, but also strip the data of all El Nino/Southern Oscillation ocean effects to see what's happening to underlying global temperatures. (Note: Nasa GISS data is warmer; satellite data though seems on the face of it cooler than GISS so I'm sticking to the data set I know).

Take a look at the diagram below.


According to the Met Office, the least squares trend from Jan 1999 to Dec 2008 is 0.07 +/- 0.07C per decade, much lower than the 0.18C per decade from 1979 to 2005, despite steady increases in Greenhouse gases. (note the small rise is only the same as the error/noise level)

The trend in the ENSO related component (1999-2008) is 0.08 +/- 0.07C - virtually the same as the observed trend (again note clearly very close to noise levels)

Hence the trend once El Nino/SO type events are removed is 0C +/- 0.05C per decade - i.e no rise at all in underlying global temperatures.

So either from 1998, or looking at underlying temperatures 1999 onwards, then at the very least temperatures have flat lined - global warming has, at least for the time being, faltered - despite a relentless rise in C02 emissions.

Now some of you will say that the period of time is too short to draw any conclusions. But I am only trying to highlight the fact that global warming has, at least for the time being, levelled off.

The full article can be found on the Met Office website ; it explains why the Met Office believes levelling off of global temperatures is to be expected at times.

There's another element of the research which illustrates how interesting the debate is becoming.

The authors say that they have been able to simulate near zero or even negative temperature trends for intervals of a decade or less, due to the model's internal climate variability. But importantly, the simulation's rule out zero trends for intervals of 15 years or more.

And it seems that this is where the Met Office's forecast for the next five years originates from. (They say from 2010 to 2015 at least half the years will be hotter than the hottest year on record). The authors continue 'given the likelihood that internal variability contributed to the slowing of global temperature rise in the last decade, we expect that warming will resume in the next few years consistent with predictions from near term climate forecasts (source Smith et al. 2007 - note the date - we are nearly 3 years on from when this statement was made).

So, one could reasonably argue that in the next five years, we will have a far better idea about the extent to which man is warming the planet, and how much is perhaps from naturally driven mechanisms. If the Met Office is right, and temperatures rise to record levels in the next 5 five years, then the sceptics will have no-where to hide. If the Met Office is wrong, and in the next few years we have not exceeded 1998 temperature levels, then this would cause big questions to be asked - remember their simulations rule out zero trends for 15 years or more.

And talking of long term predictions, while I was away last week, Piers Corbyn from Weatheraction, held his much awaited conference. You remember I talked in my article about his theory that solar particles and their interaction with our atmosphere is the main driver of global temperature levels? My colleagues Richard Black and Roger Harribin went along. You can read Richard's account on his blog

Note once again Piers' assertion that there will be no further warming for decades, if his theory is correct.

And finally, I have also been asked to clarify Dr Latif's comments at the Geneva climate conference in September, when he talked about the possibility of no more warming for the next decade or so. Can I point you in the direction of another article from Richard , which covered the subject last year, when the research was released by Kiel University, plus an article from Tom Fielden's Radio 4 blog written following Dr Latif's comments in September of this year.


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