backtop


Print 48 comment(s) - last by tng.. on Mar 30 at 5:59 PM


  (Source: img.wendmag.com)
Study blames human activity for climate change

NASA and international university researchers claim that humans have thrown off the balance between the Earth's rotation, surface air temperatures and movements in its molten core through our contribution of greenhouse gases.

Those included in the study were Jean Dickey and Steven Marcus from NASA's Jet Propulsion Laboratory, along with Olivier de Viron, from the Universite Paris Diderot and Institut de Physique du Globe de Paris in France.

It is well known that an Earth day consists of 24 hours, which is the time it takes for the Earth to make one full rotation. Over a year's time, seasonal changes occur due to energy exchanges between fluid motions of the Earth's atmosphere, the oceans and solid Earth itself, which changes the length of a day by about 1 millisecond. In addition, the length of a day on Earth can vary over longer timescales such as interannual timescales (two to 10 years) or decadal timescales (10 years).

But Earth’s oceans or motions of its atmosphere cannot explain the variances in the length of day over longer timescales. Instead, longer fluctuations are explained by the flow of liquid iron within Earth's outer core, which interacts with the mantle to determine Earth's rotation. This is also where the Earth's magnetic field originates, and because researchers cannot observe the flows of liquid iron directly, the magnetic field is observed at the surface.  

Studies have shown that this liquid iron "oscillates in waves of motion that last for decades," and have timescales that resemble long fluctuations in Earth's day length. At the same time, other studies have shown that long variations in Earth's day length are closely related to fluctuations in Earth's average surface air temperature. 

In this study, the NASA/university team of researchers has linked Earth's rotation, surface air temperatures and the movement in its molten core. They did this by mapping existing data on yearly length-of-day observations and fluid movements within Earth's core against "two time series of annual global average surface temperature." One dated back to 1880 from NASA's Goddard Institute of Space Studies in New York, and the other dated back to 1860 from the United Kingdom's Met Office.  

According to the study, temperature changes not only occur naturally, but are also affected by human activities. So researchers used computer climate models of Earth's oceans and atmosphere to generate changes made by humans. Then, these temperature changes caused by human activities were removed from the overall total observed temperature records. What they found was that old temperature data coordinated with data on Earth's day length and movements of its core until 1930, but after that, surface air temperatures increased without corresponding changes in movements of the core or day length. According to the study, this deviation after 1930 is linked to increased levels of the human contribution of greenhouse gases.  

But the new temperature data that the researchers generated (which subtracted human activity from the equation) had a temperature record that coordinated with Earth's core movements and day length, showing how human activity has thrown the Earth's climate off balance. 

"The solid Earth plays a role, but the ultimate solution to addressing climate change remains in our hands," said Dickey. 

Dickey is unsure as to why these three variables correlate, but hypothesized that Earth's core movements might interfere with the magnetic fielding of charged particle fluxes, which may affect cloud formation. This affects how much sunlight the Earth absorbs and how much is reflected back into space. 

"Our research demonstrates that, for the past 160 years, decadal and longer-period changes in atmospheric temperature correspond to changes in Earth's length of day if we remove the very significant effect of atmospheric warming attributed to the buildup of greenhouse gases due to mankind's enterprise," said Dickey. "Our study implies that human influences on climate during the past 80 years mask the natural balance that exists among Earth's rotation, the core's angular momentum and the temperature at Earth's surface." 

This study was published in the Journal of Climate.



Comments     Threshold


This article is over a month old, voting and posting comments is disabled

Something curious here.
By JediJeb on 3/14/2011 3:50:34 PM , Rating: 2
quote:
Scientists have long known that the length of an Earth day -- the time it takes for Earth to make one full rotation -- fluctuates around a 24-hour average. Over the course of a year, the length of a day varies by about 1 millisecond, getting longer in the winter and shorter in the summer . These seasonal changes in Earth's length of day are driven by exchanges of energy between the solid Earth and fluid motions of Earth's atmosphere (blowing winds and changes in atmospheric pressure) and its ocean. Scientists can measure these small changes in Earth's rotation using astronomical observations and very precise geodetic techniques.


The quote taken from the actual NASA paper sited for the article. Winter and summer in which hemisphere? Does only one hemisphere control the variations in Earth's rotation? If summer and winter conditions cause variations in the Earth's rotation, does that mean that the two hemispheres of the planet rotate at different speeds? That would seem impossible unless the planet is shearing at the equator.

Also, the Earth's orbit is elliptical, so when are we closer to the sun, when it is winter or summer in the northern hemisphere? Could this also have some bearing on the rotational speed of the Earth? Also does the aphelion of our orbit remain the same day each year or is it shifting on a certain time cycle? Fact is it can vary by up to two and a half days from one year to the next. It also works on a 22k to 26k year cycle as the aphelion point shifts around the calendar year. Currently aphelion is in July and perihelion is in January, could that alone account for the variation in day length in summer versus winter? If it does then results of this study linking it to climate variations is moot or greatly minimized.

quote:
Since total air temperature is composed of two components -- temperature changes that occur naturally and those caused by human activities -- the researchers used results from computer climate models of Earth's atmosphere and ocean to account for temperature changes due to human activities.


This is an assumption that any warming outside of what seems to occur by the change of the length of day is human caused. Though they then go on to say:

quote:
Other possibilities are that some other core process could be having a more indirect effect on climate, or that an external (e.g. solar) process affects the core and climate simultaneously.


So something outside of human activity could also be at work here and yet the paper after making that statement follows up with this one:

quote:
Regardless of the eventual connections to be established between the solid Earth and climate , Dickey said the solid Earth's impacts on climate are still dwarfed by the much larger effects of human-produced greenhouse gases. "The solid Earth plays a role, but the ultimate solution to addressing climate change remains in our hands," she concluded.


That assumes that no matter how big any outside influence is found to be, man is still to blame for the warming of our climate. Makes me wonder if there was some far past undiscovered advanced human civilization present on Earth millions of years ago, since only man it seems can cause global warming on such a scale, and since we know the climate has been higher in the very far past, then humans must have been around to cause that also. See if you chase assumptions to their logical conclusions you can come up with some really far reaching results.

It appears many "scientists" today are putting forth assumptions as rock solid facts without ruling out any other possibilities first.




RE: Something curious here.
By kattanna on 3/14/11, Rating: 0
RE: Something curious here.
By JediJeb on 3/14/2011 5:06:52 PM , Rating: 2
I wasn't thinking so much along the lines of simply the seasons, but the fact they said it happens one way in winter and the other in summer, seeming to ignore that at any point in winter in the norther hemisphere it is also summer in the southern hemisphere and vice versa. Without defining which summer and winter you are talking about, you leave 6 months of doubt as to what you mean. Seems like a large thing to overlook in a scientific paper.


RE: Something curious here.
By FITCamaro on 3/14/2011 5:11:40 PM , Rating: 3
I think its a pretty tall order to ask scientists to be objective without thinking of their funding first.


RE: Something curious here.
By Lexda on 3/15/2011 11:54:01 AM , Rating: 2
Your disdain for the entire field is amusing. Science has never brought you anything, eh?

Sure, you run across the occasional unethical scientist, but that'll happen in any field. Unfortunately, the media and people such as yourself pick up on those few and peg them for the majority. I challenge you to pick up a recent copy of Science or Nature and show me some biased papers, and then I'll believe you.


RE: Something curious here.
By Arsynic on 3/15/2011 3:24:24 PM , Rating: 2
Science is only as objective as the ones funding it. When the Church funded it, all of the scientific proof in the world didn't convince them that the Earth was not the center of the solar system.


"Young lady, in this house we obey the laws of thermodynamics!" -- Homer Simpson














botimage
Copyright 2014 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki