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Cold periods had fewer storms, natural ocean cycles the largest cause of hurricane variability.

I've always been skeptical of the view that global warming leads to stronger hurricanes. The argument behind it seems overly simplistic -- hurricanes feed off warm water, so warmer sea surface temperatures will lead to more frequent and powerful storms.

Elsewhere in our solar system, the exact opposite seems true. Blisteringly hot Venus, for instance, seems to have extremely weak storm activity, whereas icy Jupiter has massive hurricanes that last centuries, large enough to swallow the entire earth several times over. This is only suggestive rather than conclusive, but clearly there's more to storm activity than just raw temperature.

Basic thermodynamics helps to explain why. Storms are essentially large heat engines. It's not temperature that drives a heat engine, but differences in temperature. Global warming, which warms the poles more than the equator, would seem to decrease the latitude-based differential that helps drive a hurricane's rotational energy.

So went my pet theory, at least— but no hard data supported it.

However, the other side had no hard data either. While climate modelers claimed global warming might strengthen storms, actual hurricanologists were adamant that no actual evidence existed. Some pointed to research on wind shear, which suggested that a warmer climate would reduce the conditions that allow hurricanes to form, despite warmer surface water.

In 2005, one hurricanologist, Emmanuel Kerry, broke ranks and claimed to have actual proof that global warming increased hurricanes. For this, Time Magazine quickly named him "Man of the Year". However, last year Kerry publicly recanted his view, admitting that his earlier work was flawed.

With Kerry's renunciation, hurricane scientists were unanimous in their view that global warming wouldn't lead to measurably stronger storms.

But could it do the reverse? Could global warming actually reduce hurricane activity? A pair of Chinese researchers now says this very well may be true, at least for some parts of the earth.

The researchers, using a new branch of science they call "paleotempestology", looked backwards through several thousand years of the earth's history. Using sedimentary deposits, core samples from caves, and other geological proxies, along with documented historical records of hurricane landfalls, they built the longest record of hurricane activity ever constructed. They then correlated it to the varying temperature at each period..

On the global level, the researchers found no link between climate and hurricane activity. Surprisingly, though, cold periods such as the Little Ice Age had the most hurricanes, at least in some regions, a result the team said "begs adequate explanation".

However, the study found a strong link between natural patterns such as El Nino and hurricanes, a clear pattern of rising and falling activity on decadal time scales. These oscillations, known as "ENSO", tended to suppress and enhance hurricanes on a regular cycle, with the cooler "la Nina" years having the most activity.

The research was published in the Chinese Science Bulletin, and can be viewed here.



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icy Jupiter...?
By wordsworm on 1/14/2009 10:28:14 PM , Rating: 2
Jupiter is a hot: "The temperature at the top of Jupiter's clouds is about -230 degrees F (-145 degrees C). Measurements made by ground instruments and spacecraft show that Jupiter's temperature increases with depth below the clouds. The temperature reaches 70 degrees F (21 degrees C) -- "room temperature" -- at a level where the atmospheric pressure is about 10 times as great as it is on Earth....

Near the planet's center, the temperature is much higher. The core temperature may be about 43,000 degrees F (24,000 degrees C) -- hotter than the surface of the sun."

From http://www.nasa.gov/worldbook/jupiter_worldbook.ht...

In any case, Jupiter should not be referred to as an icy planet. As far as I know, at its core, there is no other planet quite as hot (in our solar system).




RE: icy Jupiter...?
By masher2 (blog) on 1/14/2009 11:16:48 PM , Rating: 2
Most planets have a hot core, regardless of how much ice they may have at the surface.

Jupiter doesn't have a surface per se, but in its atmosphere where the majority of its weather takes place, it is indeed very icy. The Great Red Spot itself, for instance, has temperatures in the -260F to -230F range.


RE: icy Jupiter...?
By BigT383 on 1/15/2009 1:07:36 AM , Rating: 2
Not that this has anything to do with Jupiter, but the cloud tops of very powerful storms on earth can soar to such heights as to be in the -130F range.

Just an interesting tidbit.


RE: icy Jupiter...?
By juuvan on 1/15/2009 7:27:36 AM , Rating: 1
earth has a hot core too, but where can you find -260F temperatures inside the sun? I though it's nearly impossible to even observe the sun directly, due to the huge electro-magnetic interference.


RE: icy Jupiter...?
By wordsworm on 1/15/2009 11:07:55 AM , Rating: 2
Earth has a hot core (7,200K) but it is a fraction of what Jupiter (20,000K)reaches. I didn't check all the planets, but I believe that it is the hottest. (Remember that the sun is not a planet)


RE: icy Jupiter...?
By wordsworm on 1/15/2009 10:58:48 AM , Rating: 2
quote:
Most planets have a hot core, regardless of how much ice they may have at the surface.


No planet has a hotter core than Jupiter. As to the eye of Jupiter, perhaps the outer area of the storm is very icy, but the further down the storm you go the warmer it's going to get. In the end, saying that Jupiter is icy based on the outermost part of its atmosphere would require you, for consistency, to refer to Venus as an icy planet since its atmosphere has also been said to reach 100K (-279F) which is roughly the same temperature as the outer area of Jupiter's atmosphere. http://www.agu.org/pubs/crossref/1980/JA085iA13p08...


RE: icy Jupiter...?
By masher2 (blog) on 1/15/2009 11:11:21 AM , Rating: 2
I'm calling Jupiter icy because where its cyclones -- and the vast majority of its weather patterns -- occur, the temperatures are indeed icy.

For planets that actually have a surface, defining the surface temperature is straightfoward, but for a gas giant, the situation is trickier. Since we're discussing weather, the zone in which weather occurs seems to be most relevant.

Core temperatures are moot in any case. The earth had a core of molten iron, even during the Deep Cryogenian, when ice covered nearly the entire surface of the planet.


RE: icy Jupiter...?
By wordsworm on 1/16/2009 9:21:13 AM , Rating: 2
According to Nasa, you wouldn't have to go all that deep before you found temperatures which are adequate for life. Of course, the pressure would kill us. It's only on the uppermost parts of the clouds that you find these extremes of cold. Unfortunately, it doesn't mention how deep you'd need to go before you reach warm temperatures. I've found not so reputable websites that suggest that we have seen temperatures of around 17C under the cloud cover: http://www.geocities.com/CapeCanaveral/Lab/8108/pl...

So, the clouds which we see swirling around Jupiter are indeed extremely cold at the outer fringes, the lower parts have been recorded at 17C, which isn't freezing. I don't think Jupiter can be out of hand referred to as a freezing planet. In some ways, if you go deep enough, it's the hottest planet.


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