Thursday, November 14, 2013

Global warming since 1997 more than twice as fast as previously estimated, new study shows

http://skepticalscience.com/global-warming-since-1997-more-than-twice-as-fast.html

Posted on 13 November 2013 by dana1981, Kevin C, robert way

A new paper published in The Quarterly Journal of the Royal Meteorological Society fills in the gaps in the UK Met Office HadCRUT4 surface temperature data set, and finds that the global surface warming since 1997 has happened more than twice as fast as the HadCRUT4 estimate.

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The study, authored by Kevin Cowtan from the University of York and Robert Way from the University of Ottawa (who both also contribute to Skeptical Science), notes that the Met Office data set only covers about 84 percent of the Earth's surface. There are large gaps in its coverage, mainly in the Arctic, Antarctica, and Africa, where temperature monitoring stations are relatively scarce.

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In their paper, Cowtan & Way apply a kriging approach to fill in the gaps between surface measurements, but they do so for both land and oceans. In a second approach, they also take advantage of the near-global coverage of satellite observations, combining the University of Alabama at Huntsville (UAH) satellite temperature measurements with the available surface data to fill in the gaps with a 'hybrid' temperature data set. They found that the kriging method works best to estimate temperatures over the oceans, while the hybrid method works best over land and most importantly sea ice, which accounts for much of the unobserved region.

Both of their new surface temperature data sets show significantly more warming over the past 16 years than HadCRUT4. This is mainly due to HadCRUT4 missing accelerated Arctic warming, especially since 1997.

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These results indicate that the slowed warming of average global surface temperature is not as significant as previously believed. Surface warming has slowed somewhat, in large part due to more overall global warming being transferred to the oceans over the past decade. However, these sorts of temporary surface warming slowdowns (and speed-ups) occur on a regular basis due to short-term natural influences.

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This is of course just one study, as Dr. Cowtan is quick to note.

"No difficult scientific problem is ever solved in a single paper. I don't expect our paper to be the last word on this, but I hope we have advanced the discussion."

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Posted by Patricia at 3:25 PM
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4 comments:

Dan Pangburn said...

Average GLOBAL temperature anomalies are reported on the web by NOAA, GISS, Hadley, RSS, and UAH, all of which are government agencies. The first three all draw from the same data base of surface and near surface measurement data. The last two draw from the data base of satellite measurements. Each agency processes the data slightly differently from the others. Each believes that their way is most accurate. To avoid bias, I average all five. A graph of this (with different reference temperature) is Figure 1 in http://endofgw.blogspot.com/ . A straight line (trend line) fit to these data after 2001 has zero slope (actually slightly negative). That means that, for over a decade, average global temperature has not increased. Figure 2 in this paper shows the growing separation between the rising CO2 and not-rising temperature.

The bogus assertion that the earth is still warming happens by looking at the slope of a linear regression analysis of the last 17 years which includes earlier lower temperatures. It fails to recognize the sudden change in the slope of the trend that took place in about 2001. Measured temperatures since before 1900 are accurately (R^2 = 0.9) calculated by an equation at http://danpangburn.blogspot.com/

9:31 PM
Patricia said...

You posted your comment after it had come out that (1) the oceans have been warming quickly, (2) much of the surface warming that has been happening was missed because it occurred in areas where there was a lack of measurement, the arctic and antarctic areas.
Your ignoring of these facts, which I reported in my blog, make me wonder if you qre you one of those people who are being paid by the fossil fuel industry to plant denialist comments in places such as this.

6:52 PM
Patricia said...

Also, increasing CO2 would not be expected to end all weather fluctuations, weather & climate cycles, effects from such things as volcanic eruptions and air pollution. It's not going to stop winter from being colder than summer.
In fact, we are in a part of the climate cycle where temperatures are usually colder. Even if it were true that the temperature had not increased over the last decade, it has not decreased, which is what normally would have happened. So that would be evidence for global warming.

5:37 PM
Patricia said...

Since CO2 is a greenhouse gas, if the increase in the atmosphere was not causing increased warming, that would need to be explained. Eg., maybe by increased pollution or volcanic action. What is your suggestion for the mechanism you think is happening?

5:40 PM

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