Sunday, August 24, 2014

No global warming since 1999?

Time to take a break from mind-games and revisit what scientists are learning about our global heat distribution engine.

One of the favorite diversionary ploys amongst climate science 'skeptics' is to claim that the past few decades hasn't seen any warming because 'global' surface temperature measurements have sort of plateaued... not really, you see the data being used did not include most of the polar regions of our planet, the areas of most warming, along with other issues.  The MetOffice has addressed this claim with a series of reports.  Here's their introduction.

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The recent pause in warming

Climate projections over the globe
July 2013 - Global mean surface temperatures rose rapidly from the 1970s, but have been relatively flat over the most recent 15 years to 2013. This has prompted speculation that human induced global warming is no longer happening, or at least will be much smaller than predicted. Others maintain that this is a temporary pause and that temperatures will again rise at rates seen previously.

The Met Office Hadley Centre has written three reports that address the recent pause in global warming and seek to answer the following questions:
  • What have been the recent trends in other indicators of climate over this period?
  • What are the potential drivers of the current pause?
  • How does the recent pause affect our projections of future climate?
The first paper shows that a wide range of observed climate indicators continue to show changes that are consistent with a globally warming world, and our understanding of how the climate system works.

The second suggests that it is not possible to explain the recent lack of surface warming solely by reductions in the total energy received by the planet, i.e. the balance between the total solar energy entering the system and the thermal energy leaving it. Changes in the exchange of heat between the upper and deep ocean appear to have caused at least part of the pause in surface warming, and observations suggest that the Pacific Ocean may play a key role.

The final paper shows that the recent pause in global surface temperature rise does not materially alter the risks of substantial warming of the Earth by the end of this century. Nor does it invalidate the fundamental physics of global warming, the scientific basis of climate models and their estimates of climate sensitivity.

Links to each of the three papers are below.

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Then there's this recent information regarding ocean current, atmosphere interaction and it's influence on glacial cycles that has implications for understanding some of the geophysical processes involved in the recent surface temperature "hiatus":

Ancient ocean currents may have changed pace and intensity of ice ages

Posted on 22 August 2014 by Guest Author

Climate scientists have long tried to explain why ice-age cycles became longer and more intense some 900,000 years ago, switching from 41,000-year cycles to 100,000-year cycles.
In a paper published this week in the journal Science Express, researchers report that the deep ocean currents that move heat around the globe stalled or may have stopped at that time, possibly due to expanding ice cover in the Northern Hemisphere.
"The research is a breakthrough in understanding a major change in the rhythm of Earth'sclimate, and shows that the ocean played a central role," says Candace Major, program director in the National Science Foundation (NSF)'s Division of Ocean Sciences, which funded the research.
The slowing currents increased carbon dioxide (CO2) storage in the oceans, leaving less CO2 in the atmosphere. That kept temperatures cold and kicked the climate system into a new phase of colder, but less frequent, ice ages, the scientists believe.
"The oceans started storing more carbon dioxide for a longer period of time," says Leopoldo Pena, the paper's lead author and a paleoceanographer at Columbia University's Lamont-Doherty Earth Observatory (LDEO). "Our evidence shows that the oceans played a major role in slowing the pace of the ice ages and making them more severe."
The researchers reconstructed the past strength of Earth's system of ocean currents by sampling deep-sea sediments off the coast of South Africa, where powerful currents originating in the North Atlantic Ocean pass on their way to Antarctica.
How vigorously those currents moved can be inferred by how much North Atlantic water made it that far, as measured by isotope ratios of the element neodymium bearing the signature of North Atlantic seawater. … [for the rest of the story]
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Also see 

Did global warming stop in 1998199520022007, 2010?
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The 'pause' in global warming is not even a thing
All signs point to an acceleration of human-caused climate change.  
So why all this talk of a pause?

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