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Scientists admit major error in key global temperature data

November 26th, 2010 · 3 Comments


Anthony Watts
(Watt’s Up With That) and others have long argued that there are quite serious problems with temperature records, problems that are so serious that they call into question what science is / scientists are telling us is happening in our planetary climate system due to human influence (through greenhouse gas (GHG) emissions, but also land use practices and other actions). They have, among other things, argued that climate scientists are exaggerating the situation.

Let me be the first to write this: according to recent reporting, Watts and his compatriots look to have been absolutely right.

There has been, over the last decade or so, a systemic bias in a critical global temperature system that has created a serious error in reporting that has not been understood by scientists until quite recently.

A shift from ship-based to buoy-based sea surface temperature measurements evidently occurred without any reconciling the data between these two systems. This matters because ship-based and buoy-based temperature readings of water that is, in the natural state, the same temperature will not produce the same result.

Watts, et al, have been absolutely right. There has been a systematic bias in reporting that has been skewing our understanding of ongoing events.

You see, the buoy-based temperature recordings skew cooler than ship-based temperature recording. (Actually, the buoy data is more accurate with the water (slightly) warming when brought aboard ship.) While the pace of increased warming has slowed over the past decade, this data collection error roughly doubled how much warming might have been slower for the past decade.

As the New Scientist reported, Ships and buoys made global warming look slower

Since the 1970s average global temperatures have risen by 0.16 °C per decade, but over the past decade they seemed to rise by only 0.09 °C, an apparent slowdown of 0.07 °C. John Kennedy and colleagues at the UK Met Office have now found that the real slowdown was smaller.

Over the past decade, sea-surface temperature has mostly been measured by thermometers on buoys, whereas previously it was measured aboard ships. Ship measurements tend to be too high because the water warms up as it is taken on board.

So although the newer buoy measurements are more accurate, the switch in method has erroneously shown sea-surface temperatures appearing to level off.

“Compared with ships, buoys show cooler temperatures,” says Vicky Pope at the Met Office. “You have to be careful of false signals.”

The correction of the data make it likely that 2010 will top 2005 and 1998, which are currently the warmest and second warmest years on record in modern times. (And, well, do remember that all 10 of the hottest years have occurred from 1998 to the present, the past decade is the hottest decade on record, etc … sure, ‘warming’ might have slowed (in a pausing fashion) the pace of increase but we certainly aren’t seeing any ‘cooling’ despite what anti-science syndrome sufferers think and proclaim.)

Re Anthony Watts and his claims on temperature records, this video is recommended:


ADDITIONAL RELEVANT MATERIAL
:

1. This is far from the first case where we have found that temperature measurements have understated climate change/global warming. Last year, for example, Finally, the truth about the Hadley/CRU data: “The global temperature rise calculated by the Met Office’s HadCRUT record is at the lower end of likely warming.”.

2. There are reasons why scientific processes / consensus lead to understanding climate change. See Optimists or pessimists: What is it with those IPCC types?

3. UPDATE: On this, see Romm at Climate Progress with: The deniers were half right: The Met Office Hadley Centre had flawed data — but it led them to UNDERestimate the rate of recent global warming

Tags: Global Warming · climate change

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