Elaine Meinel Supkis
Scientists note that the cyclonic wind cycle in the Pacific that controls the El Nino/La Nina cycles as well as the monsoon/drought cycle in Asia is significantly weakening. This has been an ongoing process for the last 100 years, not a cyclic situation.
AP:blockquote>By MALCOLM RITTER, AP Science Writer 39 minutes ago
NEW YORK - An important wind circulation pattern over the Pacific Ocean has begun to weaken because of global warming caused by human activity, something that could alter climate and the marine food chain in the region, new research suggests.
It's not clear what climate changes might arise in the area or possibly beyond, but the long-term effect might resemble some aspects of an El Nino event, a study author said.
El Ninos boost rainfall in the southern United States and western South America and bring dry weather or even drought to Indonesia, Malaysia and elsewhere in the western Pacific.
As for the Pacific food chain near the equator, the slowdown might reduce populations of tiny plants and animals up through the fish that eat them, because of reduced nutrition welling up from the deep, said the author, Gabriel Vecchi.
Vecchi, a visiting scientist at a National Oceanic and Atmospheric Administration lab in Princeton, N.J., and colleagues present their results in Thursday's issue of the journal Nature.
The slowdown was detected in shipboard and land-based data going back to the mid-1800s. It matches an effect predicted by computer climate simulations that trace global warming to a build-up of heat-trapping greenhouse gases, the researchers report. But simulations that consider only natural influences fail to produce the observed slowdown, Vecchi said.
The shifting of the techonic plates changes not only ocean currents but also air currents. The uplifting of the Tibetean plateau, the uptilt of the North American continent as well as the twisted rise of the Andean mountain range all change the natural flows of winds around a planet. If one looks at the great gas giants like Jupiter or Saturn, one can see how bands of weather flow in various directions with turbulence on the edges and sometimes tremendous storms like the Great Eye on Jupiter that has lasted for hundred of thousands if not millions of years. Thanks to the ocean/mountain complex on earth, we have complex weather systems.
And whether or not continents are shoved against each other or are all on one side of the planet or evenly spaced out as they are today, makes a huge difference on what sort of ecosystem can exist, what sort of weather. I would guess, the storms during the time much of the continents were in a mega-glop were tremendous since there was no landmass for half of the planet to break them up.
The Walker circulation is caused by the pressure gradient force that results from a high pressure system over the eastern pacific ocean, and a low pressure system over Indonesia. When the Walker circulation weakens or reverses, an El Niño results, causing the ocean surface to be warmer than average, as upwelling of cold water occurs less or not at all. An especially strong Walker circulation causes a La Niña, resulting in cooler ocean temperatures due to increased upwelling.
The upwelling of water from the depths is an important part of the marine ecosystem since the krill and other infitestimally small creatures breed down in the colder, darker parts of the ocean. Stagnating ocean waters is bad for the present ecosystem. We have persistent bad "dead zones" at the mouths of many of our rivers today thanks to fertilizer and over fishing as well as petroleum pumping. Maine has just called for a ban on shellfish and it is only early May, due to red tides developing.
Last summer, the Gulf of Mexico was devasted by such problems and it was cooler than this year. One of the oddities of the Atlantic/Pacific cyclonic cycles is that when there is little wind in the Pacific, this enables hurricanes in the Atlantic to swell greatly in size. Their heads aren't reduced by upper atmospheric winds.
The Age of Ships which began when the Portugese and then the Spaniards set out across the oceans blue was also the Little Ice Age and this meant violent cycles of hurricanes and typhoons were at a low ebb and the trade winds were vigorous, enabling swift sailing.
There are two belts of latitude where winds are light and the weather is hot and dry. They are located mostly over the oceans, at about 30° lat. in each hemisphere, and have a north-south range of about 5° as they follow the seasonal migration of the sun. The horse latitudes are associated with the subtropical anticyclone and the large-scale descent of air from high-altitude currents moving toward the poles. After reaching the earth’s surface, this air spreads toward the equator as part of the prevailing trade winds or toward the poles as part of the westerlies. The belt in the Northern Hemisphere is sometimes called the “calms of Cancer” and that in the Southern Hemisphere the “calms of Capricorn.” The term horse latitudes supposedly originates from the days when Spanish sailing vessels transported horses to the West Indies. Ships would often become becalmed in mid-ocean in this latitude, thus severely prolonging the voyage; the resulting water shortages would make it necessary for crews to throw their horses overboard.
My horse, Sparky, would be very offended by this information. Snort.
If ships were becalmed constantly, international invasions of many lands would have had to been cancelled. But the winds blew with vigor and wooden ships merrily traversed the planet and even in the Little Ice Age, many a fleet went down due to violent storms or languished in dead air cycles. The system is now more dynamic. This also means the vacillations between strong winds and no winds is greater. I notice here, our weather cycle is way off. For the first time in many months, for example, we had an Atlantic storm system, the classic "April showers" that happens when a storm moves "backwards" coming from the middle Atlantic and backing into the continent. These are the multi-day, gentle rain cycles that nourish the land. It was tremendously dry here in the Northeast, we had fire alarms all spring long! Insane!
Now, the grass is growing and my horse is happy. But we can now go an entire spring without these storms. Just as Indonesia, Malaysia and the other islands have to worry about losing their monsoon season.