Friday, June 05, 2015

Ya gotta laugh at the latest excitement from NOAA

Big news: NOAA has used newly fiddled data from many locations to row back what they told the IPCC -- so they can now claim that there has been no warming slowdown in recent years.  But they might as well not have bothered. I quote:

"For the full period of record (1880–present), the new global analysis has essentially the same rate of warming as the previous analysis (0.068°C dec−1 and 0.065°C dec−1 respectively)"

So the warming per century still comes out at only two thirds of one degree Celsius.  If that continues for another century, who is going to be bothered?

A few comments anyway:  The big change they made was extensive "corrections" to the sea-surface temperature data, which is pretty haphazard data at the best of times and hence not much to be relied on.  And guess what? I quote:

"the new analysis exhibits more than twice as much warming as the old analysis at the global scale... This is clearly attributable to the new SST analysis".

The new conclusions rely, in other words on "adjustments" and the adjustments are to what is in any case a very shaky dataset.  Not a lot to hang your hat on there, is there?

And, don't laugh:  The revised temperature rise shown for the early 21st century (2000-2014) is 0.116°C -- which is just a touch over one tenth of one degree.  That's 8 THOUSANDTHS of a degree per year or eight tenths of a degree per century: Totally trivial.  When you have to express your findings about change in tenths of one degree over a 14 year period, you might as well say "no change", might you not?  Very pesky of me to go back to the actual numbers, isn't it?  I have always found that an amusing thing to do when dealing with ideologues.

And, finally, they get statistical significance for their new trend only by accepting a 10% probability of error  -- versus the usual scientific standard of 5%.  In other words, by normal scientific criteria, there has STILL been no significant warming this century.  What an anticlimax to their big fiddle!

The sad thing is that these galoots probably do really believe that they have found something important

A new study published online today in the journal Science finds that the rate of global warming during the last 15 years has been as fast as or faster than that seen during the latter half of the 20th Century. The study refutes the notion that there has been a slowdown or "hiatus" in the rate of global warming in recent years.

The study is the work of a team of scientists from the National Oceanic and Atmospheric Administration's (NOAA) National Centers for Environmental Information* (NCEI) using the latest global surface temperature data.

"Adding in the last two years of global surface temperature data and other improvements in the quality of the observed record provide evidence that contradict the notion of a hiatus in recent global warming trends," said Thomas R. Karl, L.H.D., Director, NOAA's National Centers for Environmental Information. "Our new analysis suggests that the apparent hiatus may have been largely the result of limitations in past datasets, and that the rate of warming over the first 15 years of this century has, in fact, been as fast or faster than that seen over the last half of the 20th century."

The apparent observed slowing or decrease in the upward rate of global surface temperature warming has been nicknamed the "hiatus." The Intergovernmental Panel on Climate Change's (IPCC) Fifth Assessment Report, released in stages between September 2013 and November 2014, concluded that the upward global surface temperature trend from 1998­­-2012 was markedly lower than the trend from 1951-2012.

Since the release of the IPCC report, NOAA scientists have made significant improvements in the calculation of trends and now use a global surface temperature record that includes the most recent two years of data, 2013 and 2014--the hottest year on record. The calculations also use improved versions of both sea surface temperature and land surface air temperature datasets. One of the most substantial improvements is a correction that accounts for the difference in data collected from buoys and ship-based data.

Prior to the mid-1970s, ships were the predominant way to measure sea surface temperatures, and since then buoys have been used in increasing numbers. Compared to ships, buoys provide measurements of significantly greater accuracy. "In regards to sea surface temperature, scientists have shown that across the board, data collected from buoys are cooler than ship-based data," said Dr. Thomas C. Peterson, principal scientist at NOAA's National Centers for Environmental Information and one of the study's authors. "In order to accurately compare ship measurements and buoy measurements over the long-term, they need to be compatible. Scientists have developed a method to correct the difference between ship and buoy measurements, and we are using this in our trend analysis."

In addition, more detailed information has been obtained regarding each ship's observation method. This information was also used to provide improved corrections for changes in the mix of observing methods.

New analyses with these data demonstrate that incomplete spatial coverage also led to underestimates of the true global temperature change previously reported in the 2013 IPCC report. The integration of dozens of data sets has improved spatial coverage over many areas, including the Arctic, where temperatures have been rapidly increasing in recent decades. For example, the release of the International Surface Temperature Initiative databank, integrated with NOAA's Global Historical Climatology Network-Daily dataset and forty additional historical data sources, has more than doubled the number of weather stations available for analysis.

Lastly, the incorporation of additional years of data, 2013 and 2014, with 2014 being the warmest year on record, has had a notable impact on the temperature assessment. As stated by the IPCC, the "hiatus" period 1998-2012 is short and began with an unusually warm El NiƱo year. However, over the full period of record, from 1880 to present, the newly calculated warming trend is not substantially different than reported previously (0.68°C / Century (new) vs 0.65°C / Century (old)), reinforcing that the new corrections mainly have in impact in recent decades.


Possible artifacts of data biases in the recent global surface warming hiatus

Thomas R. Karl et al.


Much study has been devoted to the possible causes of an apparent decrease in the upward trend of global surface temperatures since 1998, a phenomenon that has been dubbed the global warming “hiatus.” Here we present an updated global surface temperature analysis that reveals that global trends are higher than reported by the IPCC, especially in recent decades, and that the central estimate for the rate of warming during the first 15 years of the 21st century is at least as great as the last half of the 20th century. These results do not support the notion of a “slowdown” in the increase of global surface temperature.


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