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Global Warming - From Inside the Globe
Bill Kendrick writes "The National Post reports that a team of American and Canadian researchers has found evidence of real global warming: the temperature of the Earth's crust is increasing at a remarkable rate. What's really interesting is that heat absorbed by rocks slowly permeates into the earth. By boring holes in the ground, they can tell how hot the earth was years ago, in a 'reading tree rings' fashion."
Can we all just please realize that humans have been on the earth such a short period of time that we really have no idea how global climate is over a long period of time, so we have no real reference to figure out if humans are the cause of this "global warming"
To some extent that is true, post hoc ergo propter hoc and all that. But if you look at the article more closely, they mention that, and I quote..
"...The warming is most pronounced in northern latitudes, Dr. Beltrami says. On Ellesmere Island and in Alaska, ground temperatures are four to five degrees higher than they were in 1500. The rise is having a significant effect on permafrost, turning some northern areas that were once perpetually frozen into "several metres of muck," he says...."
Surely, this can't all be entirely due to the slow seething disturbances down below. I think humanity, especially post-Industrial Revolution generations have to take some quarter of the blame. It may of course be, that since the earth isn't entirely spherical and the poles are closer to the centre, they tend to get warmer "faster".
higher than they were in 1500
Well, duh, ever hear of the Little Ice Age? Circa 1400 to 1800, give or take a half century. Prior to that (about 1000 to 1300), temperatures were warmer than they are today. In England farmers raised wine grapes, the Norse had dairy farms in Greenland.
Climate change happens. Ten thousand years ago a good part of North America (and Europe) was under a mile of ice. I suppose humans take the blame for melting that?
Get a grip.
-- Alastair
PK
Also from the article:
"Dr. Beltrami and his colleagues from the University of Michigan found that more than half of the land's heat gain over the past 500 years came during the 20th century, and 30% since 1950."
Try to keep an open mind.
Well, since you're apparently too lazy to use Google, I found this one from NASA for you.
In it you'll see that they mentioned the greatest affect on temperature changes seem to have been El Niño.
Anyway, read, learn, enjoy.
Therefore unless if we can know the temperature of the surface of the earth in the past, there is no way of knowing the temperature of the surface of the earth in the past. Am I the only one who thinks this is weird science?
(It's been ten years since I took a PDE course, so parts of this could be slightly off.)
The heat equation looks like this:
du/dt = A * (d/dx)^2 u
where u is temperature, and the partial derivative with respect to time is proportional to the second partial derivative with respect to space (depth). (A is a constant determined by the thermal conductivity of the material.)
To use the heat equation to solve for u(x,t), you need boundary conditions surrounding a two-dimensional domain (space and time). Time here runs from 1500 AD to 2000 AD, and space runs from 0 meters at the surface to 1000 meters at the bottom of the hole. So there are four boundary functions along the extremes of both dimensions:
1. u(0 meters, t)
2. u(1000 meters, t)
3. u(x, 2000 AD)
4. u(x, 1500 AD)
The first one is the function they're trying to get- it's their unknown. The second they have to assume is constant, because there is no way to directly measure it. But since temperature perturbations at the surface of the earth won't have penetrated that deep over the time scale they're looking at, and most of the variability will originate at the surface, this is a fairly safe assumption. The third just requires them to drop a thermometer down the hole, as they have done. The fourth is what you're worrying about, but they don't need it because they have 2. and 3. and can use the heat equation to extrapolate over the rest of the domain.
A problem arises because the left side of the heat equation is a first derivative in time. As time progresses, features in the temperature profile u(x) degrade. (Partial differential equations that have second derivatives on both sides, like the wave equation, don't have this problem.) What you don't want to find, when you measure the temperature down one of these holes, is that the temperature increases uniformly with depth. That means you've waited too long, everything has equilibrated, and both sides of the heat equation are now zero, which prevents you from extrapolating backward. Apparently they must have found some curvature in u(x), or we wouldn't be seeing this article posted.
There are other complications. The thermal conductivity constant won't be uniform with depth, for example. What that means is they need computers to solve for u(x,t) numerically. Partial differential equations can almost never be solved symbolically anyway, so this isn't much of an issue.
I realize that confusing all this theology with some science is the kind of thing that gets one flamed, if not burned at the stake, but the Belltrami's own web site is here. Both cites for papers published elsewhere and some online papers are available.
Duh ! What is this silly nonsense? Do you think heat is some kind of liquid that is affected by gravity and slowly soaks down through the rocks? Heat flows in all directions.
I don't think you understand something. Nowhere in the article did it say heat was "affected by gravity". Heat does show limited properties of signal propagation, because it flows at a finite rate along a gradient of decreasing temperature and is always conserved. (Meaning, because of the First and Second Laws of Thermodynamics.)
And measuring temperature alone provides little useful information, you also need to know the thermal conductivity and specific heat of the medium(rocks), which is highly non-uniform.
This just requires extra data on rock composition, which is well known and easily accounted for in any computational heat equation model.
Old boreholes? Give me a break. The air convection in the hole will effect the measured temperature.
Air convection is unlikely to be much of a problem at all. Air is a good insulator and a borehole of air has low thermal mass. Water convection is a much larger problem. This is from their web site, explaining how they get rid of environmental interference:
Temperature perturbations in boreholes are produced by several processes. For climate reconstruction it is important to distinguish between a changing temperature through time at the Earth?s surface and other sources of temperature perturbations.
Geologic conditions and processes, other than climate change, that produce curvature in temperature-depth profiles include the following: (1) systematic variation of thermal conductivity with depth, (2) radioactive heat generation in rocks, (3) topography, (4) lateral variation of surface temperature caused by surface orientation, changing vegetation, or variable snow cover, (5) uplift and erosion or subsidence and burial at the site, and (6) vertical percolation of groundwater.
Several approaches are taken to isolate and correct for temperature anomalies from these sources. Available topographic and geological information available at each borehole site allows one to compute the magnitude and expected shape of temperature perturbations from each source. Sites can be discarded if the geologic disturbances are too large, otherwise corrections can be made. It is also possible to combine or stack temperature anomalies from several nearby drillholes. As geologic, topographic, and hydrologic conditions at each hole are unlikely to be identical, spurious temperature anomalies are likely to cancel. If each hole has experienced a similar climatic thermal signal, the climatically induced temperature anomalies will constructively interfere in the stacked temperature profiles.
There is one very efficient method of isolating climate change effects in borehole temperatures but the method requires patience. All of the non-climate sources of temperature anomalies are steady state, or quasi steady state relative to the time scale of climate change. Thus curvature in temperature profiles from these sources is stationary in time. By measuring and remeasuring borehole temperatures after an appropriate time lapse, changes in temperature with time can safely be ascribed to climatic sources. Several monitoring experiments are in progress. With present technology available to measure temperatures in boreholes to better than 10 mK accuracy, the repeat time to isolate climate-change signals is about 5 years.
So it appears they have thought of some of these things.
I for one don't believe any such thermal signal more than a few years old can exceed the noise threshold.
It's clear you haven't read the paper, but I guess I'll take your word for it. You should know.