In comparing the observed temperature changes to the model simulations, they suggest that the recent
surface warming slowdown is due to a large natural flucuation, and / or that some source of bias in climate models is making it difficult for them to simulate it.
What do you think of the suggestion from parts of the media that it will signal the end of the so - called
surface warming slowdown?
The researchers hope that the new study will lay the foundation for future research in the global change field, suggesting that the climate community replaces the term «global warming hiatus» with «global
surface warming slowdown» to avoid confusion.
To begin, they suggest the climate community replace the term «global warming hiatus» with «global
surface warming slowdown» to eliminate confusion.
Reuters didn't connect the dots between these two articles, telling us one week that oceans help explain
the surface warming slowdown, and the next week claiming the slowdown is puzzling climate scientists.
The question remains how much other factors have contributed to
the surface warming slowdown.
Not exact matches
While it is still possible that other factors, such as heat storage in other oceans or an increase in aerosols, have led to cooling at the Earth's
surface, this research is yet another piece of evidence that strongly points to the Pacific Ocean as the reason behind a
slowdown in
warming.
Gerald Meehl, a climate scientist at the National Center for Atmospheric Research who was also an author on the paper, said this research expanded on past work, including his own research, that pointed to the Interdecadal Pacific Oscillation as a factor in a
warming slowdown by finding a mechanism behind how the Pacific Ocean was able to store enough heat to produce a pause in
surface warming.
When ocean cycle shifts, globe is likely to
warm up When climate models were run that included the stronger winds, they were able to reproduce the
slowdown in
surface temperatures.
The results show that even though there has been a
slowdown in the
warming of the global average temperatures on the
surface of Earth, the
warming has continued strongly throughout the troposphere except for a very thin layer at around 14 - 15 km above the
surface of Earth where it has
warmed slightly less.
«Such a
slowdown is consistent with the projected effects of anthropogenic climate change, where
warming and freshening of the
surface ocean from melting ice caps leads to weaker overturning circulation,» DeVries explained.
The growing body of scientific evidence indicates that this negative phase has played a heavy role in driving an approximately 15 - year old
slowdown in worldwide
surface warming.
An analysis using updated global
surface temperature data disputes the existence of a 21st century global
warming slowdown described in studies including the latest Intergovernmental Panel on Climate Change (IPCC) assessment.
The research, published last June in the journal Science, concluded that an improved record of
surface temperatures no longer shows evidence of a
slowdown in global
warming.
If this rapid
warming continues, it could mean the end of the so - called
slowdown — the period over the past decade or so when global
surface temperatures increased less rapidly than before.
If the recent intensification of the cool spot were caused by a recent AMOC
slowdown you would expect to see
warming of intermediate waters under a cool fresh water
surface layer.
They suggest this «pause» in the acceleration of carbon dioxide concentrations was, in part, due to the effect of the temporary
slowdown in global average
surface warming during that same period on respiration, the process by which plants and soils release CO2.
If the recent «
slowdown» in global
surface warming is reversing, the stronger land carbon sink seen in recent years may weaken again, and the rise in CO2 may quicken again.
While the planet's
surface temperatures over the past century have risen to unprecedented levels, records have shown a
slowdown in the pace of
warming over the past 15 years.
«It has been claimed that the early - 2000s global
warming slowdown or hiatus, characterized by a reduced rate of global
surface warming, has been overstated, lacks sound scientific basis, or is unsupported by observations.
This was one of the motivations for our study out this week in Nature Climate Change (England et al., 2014) With the global - average
surface air temperature (SAT) more - or-less steady since 2001, scientists have been seeking to explain the climate mechanics of the
slowdown in
warming seen in the observations during 2001 - 2013.
... a pronounced strengthening in Pacific trade winds over the past two decades — unprecedented in observations / reanalysis data and not captured by climate models — is sufficient to account for the cooling of the tropical Pacific and a substantial
slowdown in
surface warming through increased subsurface ocean heat uptake.
A variety of mechanisms have been proposed to account for this
slowdown in
surface warming.
http://climate.nasa.gov/news/1141/: «Norman Loeb, an atmospheric scientist at NASA's Langley Research Center, recently gave a talk on the «global
warming hiatus,» a
slowdown in the rise of the global mean
surface air temperature.
Abstract:... Here we show that a pronounced strengthening in Pacific trade winds over the past two decades — unprecedented in observations / reanalysis data and not captured by climate models — is sufficient to account for the cooling of the tropical Pacific and a substantial
slowdown in
surface warming through increased subsurface ocean heat uptake.
A recent
slowdown in global
warming has led some skeptics to renew their claims that industrial carbon emissions are not causing a century - long rise in Earth's
surface temperatures.
Although there have been many suggestions for possible contributions to the
slowdown of the recent
warming rate, a reduced
warming rate of the Pacific sea
surface temperature seems to be a significant factor.
In regards to your question, if you mean how robust is the «
slowdown» in global
surface warming, the answer is it just probably just barely statistically significant.
Some question remains as to how much of the temporary
slowdown in
surface warming is due to human aerosol emissions, how much due to ENSO, how much due to heat being transferred to the deep oceans, and so forth.
The sheaf of explanations for the apparent slight
slowdown of
surface warming since 1998, relative to the previous two decades, all help to reduce «noise» by assigning explicit mechanisms to previously - unexplained variation.
That would help explain the
slowdown in
surface warming but would also suggest that the pause may be only temporary and brief.»
Professor Adam Scaife, the head of monthly to decadal prediction at the Met Office Hadley Centre, said: «The end of the recent
slowdown in global
warming is due to a flip in Pacific sea -
surface temperatures.
«Although the forecast generally indicates that global temperatures will remain high, it is not yet possible to predict exactly when the
slowdown in
surface warming will end.»
A separate study in August (2014) in the journal Science said the apparent
slowdown in the Earth's
surface warming in the last 15 years could be due to that heat being trapped in the deep Atlantic and Southern Ocean.
Temporary
slowdown in global average
surface temperature
warming observed between 1998 and 2013 represented a redistribution of energy within the Earth system, new research shows.
Last year he said the 5 - year mean was weak evidence of a
slowdown of global
warming, by which he means the
surface air temperature, which should be clear to anybody who reads Hansen.
A new study of the temporary
slowdown in the global average
surface temperature
warming trend observed between 1998 and 2013 concludes the phenomenon represented a redistribution of energy within the Earth system, with Earth's ocean absorbing the extra heat.
Personally I think that recent research (including several studies discussed in the above post, published after the IPCC AR5 cutoff date) make a strong case that internal variability (ocean cycles) are responsible for more of the
slowdown in
surface warming than changes in external forcings, but there's not a consensus about that yet.
So, as I understand it, there hasn't been a
slowdown in global
warming, only a
slowdown in the * rate * of
surface warming.
Any of these factors may contribute to a
slowdown in
surface warming over the past 16 years.
Because the latter has an uninterrupted positive trend, there would have been no
slowdown of the
warming of the
surface or the upper layers.
The
slowdown or «hiatus» in
warming refers to the period since 2001, when despite ongoing increases in atmospheric greenhouse gases, Earth's global average
surface air temperature has remained more or less steady,
warming by only around 0.1 C.
These salinity shifts correspond well in timing to the OHC shifts, which are also coincident with
surface transitions from global -
warming slowdown to rapid
warming and then to the current
slowdown, with intervals between shifts lasting about three decades.
Many contrarians claim it's because of the
slowdown in
surface warming in the past 15 years or so.
«The end of the recent
slowdown in global
warming is due to a flip in Pacific sea -
surface temperatures,» says Adam Scaife, who heads monthly - to - decadal prediction for the Met Office.
That the
slowdown in
surface warming has been concentrated in the ocean -
surface (and shallow - ocean) temperatures has led a number of scientists (including the Met Office) to posit that the pause in ocean
surface warming may be driven in part by increased heat uptake in the deep ocean.
Much of the recent discussion of climate sensitivity in online forums and in peer - reviewed literature focuses on two areas: cutting off the so - called «long tail» of low probability \ high climate sensitivities (e.g., above 6 C or so), and reconciling the recent
slowdown in observed
surface warming with predictions from global climate models.
(That
warming is mostly due to a
slowdown in exchange of cold deep water with
surface water.)
The updated data shows a statistically significant global
warming trend over the 1998 - 2012 period and the authors note that their results «do not support the notion of a «
slowdown» in the increase of global
surface temperature.»
When corrected, the range of likely
warming based on
surface temperature observations is in line with earlier estimates, despite the recent
slowdown.