Table of Contents
Characteristics of The Atmosphere
How to Read Weather Maps (5:15)
Weather Forecasting: Air Masses and Fronts (12:33)
The Hydrological Cycle
The Köppen Climate Classification System
Heating and Cooling
Localized Wind Systems
The Global Climate
Global Warming and The Greenhouse Effect
The National Climate Assessment
Periodic warming of the Pacific Ocean has occurred for thousands of years but only recently have scientists come to appreciate its global reach. In its simplest sense, El Nino's effects are like placing a large stone in a shallow river. It causes ripples that run far downstream. Normally, the hottest ocean surface temperatures on the planet are found in the western Pacific, near Indonesia. During an El Nino, however, these warm, rain-generating waters slide east, creating conditions for large storms. This can also alter the path of powerful jet stream currents high above the Earth, disrupting seasonal weather patterns in profound ways. In parts of North and South America, a succession of pounding storms can roll over the landscape, as if delivered by an atmospheric conveyor belt. Seasonal rains can fail to arrive in parts of India, Africa and Southeast Asia, killing crops and stoking wildfires.
Drought causes other dangers as well. In Indonesia, slash-and-burn clearing of agricultural land has given rise to rampant forest fires. These massive fires, which have occurred during every El Nino since 1982, sicken hundreds of thousands of people. The smoke, which often spreads to Malaysia, Singapore, the Philippines and Thailand, also releases enormous quantities of the greenhouse gas carbon dioxide. El Nino-inspired drought or flooding can have other health effects: Outbreaks of cholera, typhoid and other diarrheal diseases occur in areas where flood waters have been contaminated by human or animal feces.
Warming Pacific waters can generate an increase in hurricanes and El Nino was cited as a possible factor in the creation of Hurricane Patricia, one of the strongest hurricanes ever recorded. Warm water is kind of rocket fuel for hurricanes. Similarly, researchers cite the warming effects of El Nino as a factor in recently declared global coral bleaching events. Temperature change is one of several factors that can cause coral reefs to lose their coating of algae, turning them white and endangering their survival. El Nino's effect on fisheries gave it its unique name. Before it was understood to be a global event, fishermen in Peru and Ecuador used the term to describe the warm currents that sometimes arrived around Christmas time and seemed to drive fish away. El Nino, Spanish for "the child," was a reference to the birth of Christ.
Normally, trade winds that blow from east to west cause an upwelling of deep, cold, nutrient-rich water along the coast of South America. This cool water sustains fish like anchovies, which are used internationally to feed livestock. During El Nino, however, the trade winds slow, or collapse entirely, putting an end to the upwelling — and the anchovy fisheries. This not only affects Peruvian fishermen but also sends shock waves through the commodities market as the price for soybeans — another source of livestock feed — rises. It starts a chain reaction around the globe.
In the central Pacific, a record 14 named tropical storms or hurricanes have spun through the region in the 2015 season. Fortunately, as is the case with most Pacific hurricanes, few have hit land.
El Niño, a natural warming of tropical Pacific Ocean waters, has provided fuel for the storms, which usually need warm water of at least 80º to form. Ocean temperatures near Hawaii are at record highs. El Niño also reduces the winds that tend to tear hurricanes and typhoons apart.
Other than Hurricane Joaquin, the Atlantic hurricane season has been mostly a dud, as predicted and as is typical during El Niño. Only three hurricanes have formed, according to the National Hurricane Center.
As for global warming, would warmer oceans would mean that stronger, more frequent hurricanes like Patricia are possible? The jury is still out on that one. It is premature to conclude that human activities — and particularly the greenhouse gas emissions that cause global warming — have already had a detectable impact on Atlantic hurricane or global tropical cyclone activity. (Tropical cyclones are all tropical storms, hurricanes and typhoons.)
However, looking ahead, warming by the end of the 21st century will likely cause tropical cyclones globally to be more intense on average. Scientists are always clear to point out that no one storm can be blamed on or caused by man-made climate change. All weather events are due to many causes, such as El Niño.
Global Climate Change
a change in the statistical distribution of weather patterns when that change lasts for an extended period of time (i.e., decades to millions of years)
Watch the Last 28 Years of Arctic Ice Melt