LIVERMORE, Calif. — The rain in Spain may lie mainly on the plain, but the location and intensity of that rain is changing not only in Spain but around the globe.
A new study by Lawrence Livermore National Laboratory scientists shows that observed changes in global (ocean and land) precipitation are directly affected by human activities and cannot be explained by natural variability alone. The research appears in the Nov. 11 online edition of the Proceedings of the National Academy of Sciences.
Emissions of heat-trapping and ozone-depleting gases affect the distribution of precipitation through two mechanisms. Increasing temperatures are expected to make wet regions wetter and dry regions drier (thermodynamic changes); and changes in atmospheric circulation patterns will push storm tracks and subtropical dry zones toward the poles.
“Both these changes are occurring simultaneously in global precipitation and this behavior cannot be explained by natural variability alone,” said LLNL’s lead author Kate Marvel. “External influences such as the increase in greenhouse gases are responsible for the changes.”
The team compared climate model predications with the Global Precipitation Climatology Project’s global observations, which span from 1979-2012, and found that natural variability (such as El Niños and La Niñas) does not account for the changes in global precipitation patterns. While natural fluctuations in climate can lead to either intensification or poleward shifts in precipitation, it is very rare for the two effects to occur together naturally.
“In combination, manmade increases in greenhouse gases and stratospheric ozone depletion are expected to lead to both an intensification and redistribution of global precipitation,” said Céline Bonfils, the other LLNL author. “The fact that we see both of these effects simultaneously in the observations is strong evidence that humans are affecting global precipitation.”
Marvel and Bonfils identified a fingerprint pattern that characterizes the simultaneous response of precipitation location and intensity to external forcing.
“Most previous work has focused on either thermodynamic or dynamic changes in isolation. By looking at both, we were able to identify a pattern of precipitation change that fits with what is expected from human-caused climate change,” Marvel said.
By focusing on the underlying mechanisms that drive changes in global precipitation and by restricting the analysis to the large scales where there is confidence in the models’ ability to reproduce the current climate, “we have shown that the changes observed in the satellite era are externally forced and likely to be from man,” Bonfils said.
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Identifying external influences on global precipitation
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Edited by Kerry A. Emanuel, Massachusetts Institute of Technology, Cambridge, MA, and approved October 18, 2013 (received for review July 30, 2013)
Significance
This study provides evidence that human activities are affecting precipitation over land and oceans. Anthropogenic increases in greenhouse gases and stratospheric ozone depletion are expected to lead to a latitudinal intensification and redistribution of global precipitation. However, detecting these mechanisms in the observational record is complicated by strong climate noise and model errors. We establish that the changes in land and ocean precipitation predicted by theory are indeed present in the observational record, that these changes are unlikely to arise purely due to natural climate variability, and that external influences, probably anthropogenic in origin, are responsible.
Abstract
Changes in global (ocean and land) precipitation are among the most important and least well-understood consequences of climate change. Increasing greenhouse gas concentrations are thought to affect the zonal-mean distribution of precipitation through two basic mechanisms. First, increasing temperatures will lead to an intensification of the hydrological cycle (“thermodynamic” changes). Second, changes in atmospheric circulation patterns will lead to poleward displacement of the storm tracks and subtropical dry zones and to a widening of the tropical belt (“dynamic” changes). We demonstrate that both these changes are occurring simultaneously in global precipitation, that this behavior cannot be explained by internal variability alone, and that external influences are responsible for the observed precipitation changes. Whereas existing model experiments are not of sufficient length to differentiate between natural and anthropogenic forcing terms at the 95% confidence level, we present evidence that the observed trends result from human activities.
paper: http://www.pnas.org/content/early/2013/11/05/1314382110.full.pdf
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“Both these changes are occurring simultaneously in global precipitation and this behavior cannot be explained by natural variability alone,” said LLNL’s lead author Kate Marvel.
But they can clearly assign it to humans…
The team compared climate model predications..
Ok, read enough now.
‘it is very rare for the two effects to occur together naturally.”
‘ said Céline Bonfils, the other LLNL author. “The fact that we see both of these effects simultaneously in the observations is strong evidence that humans are affecting global precipitation.” ‘
So it is rare for the two effects to act together, ( meaning it must have happened in the past); but that it is happening now is evidence of man’s mighty hand upon the tiller of Climate Change.
The circulation hasn’t been moving towards the poles since around 2000 as I have tirelessly been pointing out.
Indeed the average net position looks like it is the process of moving equatorward.
The changes in trend appear to be solar induced.
So many papers now coming out covering aspects that I have been going on about since at least 2007 yet all being distorted to prop up the failed hypothesis rather than using the new information to provide a fresh start such as mine.
Quoting models that can’t even predict today’s reality is pretty dumb even for PhD people.
This at least seems to be a scientific statement. It can be supported or refuted by observational data. Climate science is still alive at some locals it seems. Further they are aware of the unfavourable signal to noise ratio.
As a somewhat naive layman (!) I still have this minor problem with scientific pronouncements of this sort. Is the world’s weather REALLY capable of differentiating between 14.1C and 14.8C?
What utter rubbish.
Friends:
It is reported that
Marvel did that with Bonfils?
I thought Marvel produces comics which provide stories about people having supernatural powers to overcome the laws of nature.
Oh! Wait …
Richard
Phew. We are saved then. The world stopped warming last century.
Don’t panic.
Perhaps the researchers did not go back far enough to track the numerous changes in precipitation intensity and location over the ages.
Starting with the formerly green Sahara desert might help.
tonyb
“Both these changes are occurring simultaneously in global precipitation and this behavior cannot be explained by natural variability alone,” said LLNL’s lead author Kate Marvel. “External influences such as the increase in greenhouse gases are responsible for the changes.”
A couple o tiny wee, wee points. The first is that there is only 33 years of GPCP’s observational data being used, the Earth is 4.5 billion years old. I would have preferred to see a little more observational data in play. Secondly, can anybody PURLEEEEZE tell me & everyone else what is Natural Variability!!!! To date warmists have repeatedly stated that this or that perceived/observed abnormality cannot be explained by Natural Variability (NV) alone, yet they fail to explain beyond a reasonable doubt what NV is! It truly seems that we have plummeted to the depths of “cry witch” about every sunny/wet/windy/cold/hot/stormy weather event that occurs around the planet! The give away of course is obvious, relating these events to reference points in history. The worst storm for 50/30/40/20/100/50 (pick a number) years! With respect, I fail to see how Kate is that much of a Marvel!
Bully…we can now look forward to an exclusively human caused apocalypse. Thank heavens these rocket scientists at LNL have found this.
Must be good. They can work around the 95% confidence level.
As solar activity declines and the earth’s magnetic field continues to weaken, cloud formation increases and with it rain. Well researched and documented. (www.co2science.org/subject/e/summaries/extraterrestrial.php covers much of the research)
If these researchers looked outside of their chosen ‘co2’ mechanism they would be aware of these but I guess there would be no grant money for them to do that. Maybe they a simply trying to look ahead at the likely increase in cloud formation from known natural causes and trying to pull it under the co2 umbrella to keep the fiction going.
If you start from the premise that human CO2 emissions are causing the majority of warming in the recent temperature record, then this warming will cause the climate to change to an extent, and so it is easy to attribute any observed changes to CO2. It is another thing altogether if you start with different assumptions, or compare modeled output to real life measurement. Yet again we seem to have pseudo-science masquerading as real science. Or am I being harsh?
If the Earth continues to be warm but then starts to cool, at some likely predictable point the photosynthetic sequestering sinks will saturate (so that their increasing capacity to sink CO2 will quit increasing; and then for the same continued cooling causes, these sinks will subsequently and rapidly reverse to a decreasing capacity to absorb CO2; while the emission sources more slowly respond; and the oceans, in particular, fail to respond for many decades).
Then very steep atmospheric spiking will ensue just as it so often has in the past. It is very likely that photosynthetic sequestering (biological response) provides an enormous (geologically real-time) negative feedback to additional atmospheric CO2 until such time as it saturates. This predicted saturation event is not likely very near if the planet continues to slide sideways on temperature. However, a near-term solar-driven mini ice age may likely accelerate this predictable spiking event into the near term (i.e. atmospheric CO2 will likely increase sharply quite geologically soon).
AGW will then morph to AGC (anthropogenic global cooling). And it will be said that Mother Nature can no longer choke down 1/2 our poisonous anthropogenic CO2 emission.
How do people get away with this kind of junk. They reviewed 33 years of GPCP’s observational data, smoothed it with statistical processes, did a fit for the CMIP3/5 junk models and did model runs for precipitation and called that evidence that natural variability couldn’t be responsible for the 33 years of observational data. This from a model that has significant problems predicting/projecting anything more than a few days out with any kind of accuracy, and has known problems with aerosols/ghg forcings that they are trying to fingerprint!
v/r
David Riser
And we must therefore through ourselves onto our own swords even sooner and harder than these rocket scientists had ever thought.
Lets see now.
From 31 years of data 1979 to 2012, they have concluded with the help of some climate models that mankind is responsible for what can only be described as some major changes in global precipitation patterns. Those precipitation patterns would have to be major to detect any such precipitation pattern changes in that utterly miniscule period of time,
I am a seventy five year old retired Australian farmer and have been a glider and power pilot for over 50 years.
Weather is my life’s study. Rainfall made my living.
. Rainfall is our life blood on the land in the second driest continent on Earth, second only to Antarctica.
Sure I’ve seen, watched and wondered about major changes in precipitation patterns right across Australia probably about every two or three years, sometimes longer, sometimes shorter between changes but changes, big changes in precipitation patterns occurring right through out all of my 75 years.
And sure the global weather patterns and the precipitation patterns have changed, are going to change. and are going to keep right on changing.
Sure the great global weather and climate cycles and patterns are going to keep changing in ways that might never be completely predictable. And sure the precipitation patterns have and will continue to change and usually in ways we can never predict with confidence
Come back in a couple of century’s time and get a decent data bank of precipitation patterns that really does start to provide a long term, trustworthy pattern of precipitation instead of announcing all over again the end of civilization as we know it, you bloody useless climate science BS artists.
31 years of data in a world where weather and changes of the climate can be measured in millenniums or in minutes and from that it is postulated that once again we humans are somehow causing all the worlds rainfall problems! Shhhh!
And climate alarmist scientists wonder why they can’t convince an increasing number of people to believe them.
First, increasing temperatures will lead to an intensification of the hydrological cycle (“thermodynamic” changes).
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Nonsense. All engines require a temperature differential, not simply an increase in temperature. The greater the temperature difference, the greater the engine efficiency.
AGW predicts most of the increase will occur towards the poles, with less warming at the equator. This reduces the temperature difference that drives the hydrological cycle, which reduces the intensity.
You cannot make an engine run faster by increasing the temperature of the sink (poles). You need to increase the temperature of the source (equator) as compared to the sink. Otherwise you could build all sorts of fantastic machines as found between the pages of science fiction.
http://chemwiki.ucdavis.edu/Physical_Chemistry/Thermodynamics/Thermodynamisc_Cycles/Carnot_Cycle
I assume that at any given time, the precipitation patterns are intensifying or deintensifying.
And at any given time, the precipitation patterns will either be shifting poleward or toward the equator.
It seems the chance of them happening together is 1 in 4, actually 1 in 2 if you count the other combination of moving in sync, deinsifying and moving away from the poles..
Unless we understand the underlying physics, to state that something is very rare means it has occurred seldom (but has occurred for sure). Then it raises the question is our period of observation causing this rarity. It is hubris if not malpractice to believe otherwise.
Deebee,
Did you really mean to say what you just said?
@Stephen Fisher wilde
I think most of us are agreed with you.
Just for interest’s sake, I looked at precipitation in Wellington, NZ.
I found that rainfall 1930-1940 there was significantly lower, by about 14 or 15% ,when compared to 1940-2000.
Hence my prediction of the drought 2021-2028 on the great plains of N-America,
similar to the Dust Bowl droughts of 1932-1939
http://blogs.24.com/henryp/2013/04/29/the-climate-is-changing/
From now on, rainfall will progressively decrease at >[40] latitudes and increase at the lower latitudes, especially around the equator. It is simple physics: it is cooling from the top.
http://www.woodfortrees.org/plot/hadcrut4gl/from:1987/to:2014/plot/hadcrut4gl/from:2002/to:2014/trend/plot/hadcrut3gl/from:1987/to:2014/plot/hadcrut3gl/from:2002/to:2014/trend/plot/rss/from:1987/to:2014/plot/rss/from:2002/to:2014/trend/plot/hadsst2gl/from:1987/to:2014/plot/hadsst2gl/from:2002/to:2014/trend/plot/hadcrut4gl/from:1987/to:2002/trend/plot/hadcrut3gl/from:1987/to:2002/trend/plot/hadsst2gl/from:1987/to:2002/trend/plot/rss/from:1987/to:2002/trend
Observations don’t match the model output, so the difference has to be anthropogenic! It can’t be anything else because of course the model captures natural variability perfectly! :facepalm How about the man-made model is wrong?