Satellites Show That Earth Has a Fever

Roland Piquepaille writes "A recent study from NASA says that satellites are acting as thermometers in space. Contrary to meteorological ground stations which measure the air temperature around two meters above the ground, satellites can accurately measure the temperature of the Earth's skin. And this new study, which covers the 18-year period going from 1981 to 1998, shows that the Earth's temperature is rising 0.43C per decade instead of the O.34C found by previous methods. Unfortunately for us, if satellites can more precisely measure this rise of the Earth's temperature, they cannot cure this fever. This overview contains more details and a spectacular image showing the European heat wave of the summer of 2003."

Comments

Satellites Show That Earth Has a Fever...

[the Man in Black]

....and the only PRESCRIPTION...is more COWBELL.

What? I'm the only one that thought that?

Come on already

[Anonymous Coward]

The one thing I've noticed about Slashdot is that a huge number of users seem dead set against the idea of global warming. Am I the only one who thinks that regardless of the exact status of global warming its reasonable to take steps to reduce emissions and so on?
Assume global warming is real, and then enviromentally friendly policies are needed.
Then assume it isn't. Its not like enviromentally friendly policies require you to sacrifice your first born son. We enact them, maybe have fewer SUV's, and live in a slightly cleaner world.
You don't stand to lose anything by assuming global warming is real and going from there. You stand to lose a lot by ignoring it and having it turn out to be real.

Re:So?

[U.I.D 754625]

The study is important and needs to continue, but you can't assume a rise in temperature over 2 decades means something bad is happening. I don't think we'll ever have enough data to prove whether we are right or wrong until the damage has been done (or apparently not done).

Re:So?

[LS]

I smell a troll.

I see that you admit at least there is a global warming phenomena. Most scientists finally agree with that. But you question two things:

1. Whether humans are causing global warming
2. Whether global warming is a bad thing

Let's address these two issues:

1. Do humans cause global warming?

1600 scientists, include over 100 NOBEL LAUREATES, agree that human activity is causing global warming. I trust them FAR MORE than you:

http://dieoff.org/page123.htm

It's obvious that climate has changed on Earth with or without humans, but it's also a known fact that human activity is accelerating climate change in a way different from natural causes

2. Is global warming a bad thing?

Here's where the troll part comes in. Do you actually believe the only consequence of global warming is rolling up our pants and walking inland a couple feet? The economy falls apart when the prices go up on oil. What do you think will happen when we are asked to MOVE LOS ANGELES AND NEW YORK INLAND??? What happens when the phytoplankton are no longer able to survive in the ocean water with low salinity? Well, let me tell you that phytoplankton produce most of the oxygen you breath...

LS

LS

Re:Not really correct

[maxpublic]

Maybe the scientists do know, and this is just a case of bad reporting...

It's a case of bad reporting. The loss of ice in both the poles and Greenland is well-documented and goes back more than two decades, with some pretty spectacular and sudden melts or glacier break-aways occuring within the last half-dozen years.

However, as a number of people have pointed out, there's absolutely zero evidence that this is due to human activity. It could very well be natural, as was the case in human history for both the 'little ice age' and period of abnormal warming during the previous millennium which allowed the Norse to colonize the southern tip of Greenland. Both of these changes were more extreme than the changes we're currently seeing.

Hell, it could just be due to a tiny increase in our sun's thermal output. Most people don't know that our sun is a VARIABLE star, which means that it's energy output changes on an irregular, unpredictable basis. If the solar output were to increase by less than 1/10th of 1 percent over a sustained period of time, you'd get much the same thing we're seeing today - and since the alteration itself would've happened a couple of centuries back (it takes awhile for minute changes to broad impacts) we wouldn't know about it today, since two centuries ago there was no reliable way to accurately measure solar energy output.

Max

Well, actually,

[Space cowboy]

Quite apart from the fact that sometimes life didn't go on (which ought to be enough to concern anyone), if you look at how these phenomena manifest, you'll see that it's typically not a linear process. There's normally a critical point over which X happens and below which Y happens. If X is lethal to human life (snowball earth, greenhouse earth) then we'd damn well better hope we stick with Y.

A case in point is the atlantic conveyer (the 'Gulf Stream' to us Brits). If the conveyer stops, an absolutely massive amount of energy will cease to be delivered to where it currently is. The knock-on effects aren't really model-able, we just don't have the knowledge, but since staggeringly enormous amounts of warmth would cease to be delivered to the UK coastline, you could assume it will get colder, even if you don't know quite how much. To give some perspective, it generates a difference of approximately 20 degrees celcius between points at the same latitude. 20 degrees of delta-T over several hundred billion tons of water is a lot of energy to be dependent on far-easier-to-change salinity level.

The atlantic conveyer depends on salinity in different parts of the world. If it rains more (in places that it currently rains little) and rains less (in places where it currently rains significantly) the saline levels will change, and the conveyer will be affected - at the critical point, it will simply stop. There's no obvious way we could restart it either. Shifting several hundred billion tons of water is way beyond our capabilities, and restoring the initial conditions may not be sufficient.

I guess I'm sufficiently worried about the consequences (which we will not be able to counter) to pay some heed to people who try to assess risk under next-to-impossible scientific conditions. I guess, given the potential consequences, that I'm willing to listen more to those who get off their backsides and put some effort into the analysis than people who sit around saying, 'hell we've had ice ages before and we will again'.

Actually humankind hasn't had ice-ages before, and to suggest we'd just cope is hubris of the highest order. We live in a highly technological society, and yes, given an immense struggle I think we would probably cope, as in 'Western civilisation' would cope. Countless millions would die in poorer, less developed, and simply unluckily-positioned countries as weather systems went out of control. One other thought is that a highly-structured, lean-and-mean (due to commercial pressures, mainly) society is a vulnerable society. If central America were reduced to a desert (unlikely, but possible) then the food chain would break within the US, and other countries would have a hard-enough time to feed their own. 280 million people is a lot of mouths...

Simon

Re:So?

[ThosLives]

That doesn't mean that all the current changes, however, are natural.

Interesting philosophical debate: If humans are a product of nature, and humans do something, shouldn't that still be considered "natural"? If the evolution of a species such as humans is then natural, and that evolution "naturally" results in technology which stresses an ecosystem in strange ways, is that bad? Is it good?

I think this whole debate is moot until people can decide on how to determine such fundamental things. Saying stuff like "because it will cause certain species to die off" doesn't mean anything in an amoral, evolutionistic world view: is it bad for species to die off?

I also like to point out for all you who like their statistics: correlation does not imply causality. (For instance: the fact that trees always move when there is wind does not mean that the movement of trees causes wind.) I do not yet think it is possible to set up an experiment to test the relationship between millions of variables and some average global temperature reading. The inertia and chaotic nature of the terrestrial atmospheric system also makes it quite difficult to put into a control system - do you use a PID controller? H-infinity? What *should* the setpoint be? The answer to most of these is "nobody knows".

*shrug*

The technology behind these satellites...

[Van Halen]

I happen to work for a company that manufactures and sells some of these satellite-based temperature sensors to the government. I actually work on the ground processing software for one of them, which has all kinds of neat algorithms for turning raw microwave spectrum measurements into meaningful science data, including surface temperature and air temperature at several different levels of the atmosphere. If anyone is interested in the technology behind them, here are just a few of the sensors used by the US government for these purposes:

MSU - 1970s era air temperature

• http://ghrc.msfc.nasa.gov:5721/sensor_documents/ms u_instrument.html

AMSU - next generation of MSU, several are flying on US and European satellites

• http://amsu.cira.colostate.edu/
• http://aqua.nasa.gov/AMSU3.html

ATMS - next generation AMSU, scheduled for first flight in a few years

• http://www.ipo.noaa.gov/Technology/atms_summary.ht ml

SSM/T-1 - old 1970s/80s era air temperature sensor, the last one launched in 1999

• http://ghrc.nsstc.nasa.gov/uso/readme/ssmt1.html (about the only decent information that's left about it)

SSMIS - next generation SSM/T-1 that also combines functions of 2 other older sensors (atmospheric water vapor and a ton of surface data like ice concentration, sea surface wind speed, soil moisture, etc), the first of 5 launched in October of last year

• http://xenon.aerojet.com/Weapon_Systems/Earth_Sens ing/SSMIS/
• http://www.osdpd.noaa.gov/PSB/IMAGES/ssmisdoc.htm
• http://www.metoffice.com/research/interproj/nwpsaf /ssmi/ssmis_ug_moud001_v2.pdf (PDF gets pretty technical but lots of good info)

CMIS - next generation SSMIS scheduled to fly by the end of the decade

• http://www.ipo.noaa.gov/Technology/cmis_summary.ht ml

All of the above are what are known as microwave sounders or radiometers. They look at radiation in specific bands in the microwave region of the spectrum (based on oxygen absorption lines) to infer air temperatures.

It looks like the study in the article was using MODIS and TOVS data. TOVS consists of some of the above instruments - MSU and AMSU in particular for this application. MODIS is another sensor that doesn't look at the microwave region of the spectrum, so it's out of my area of expertise. Look at the website for more info on that if you're interested. :)