In general, the IPCC projects an increased incidence of extreme weather events.42 Droughts, flash floods, heat waves, and wildfires are all projected to become more frequent and more intense in regions where such events are already common. Intense tropical and mid-latitude storms with heavier precipitation and higher wind speeds are also projected. There is evidence that many of these events already occur more frequently and have become more intense.43 Projections indicate fewer cold spells and a decrease in the frequency of low-intensity storms. As a consequence, the total number of storms decreases globally even as the number of intense storms increases.
Extreme precipitation and drought. In general, the IPCC projects that a larger fraction of total precipitation will fall during extreme events, especially in the moist tropics and in mid- and high latitudes, where increased mean precipitation is projected. Regionally, extremes are expected to increase more than the means. Even in areas projected to become drier, the average intensity of precipitation may increase because of longer dry spells and greater accumulation of atmospheric moisture between events. This portends increased incidence and duration of drought, punctuated by extreme precipitation, which may be either rainfall or snowfall, depending on latitude and season. In general, the risk of drought is expected to increase during summers in the continental interiors.
Some tropical and subtropical regions experience monsoons, distinct rainy seasons during which prevailing winds transport atmospheric moisture from the tropical oceans. The Asian, African, and Australian monsoons are projected to bring increased rainfall to certain regions of these continents. Because this rain falls during what is already the rainy season, it may cause more flooding without bringing additional benefits. In Mexico and Central America, the monsoon is projected to bring less precipitation to the region, contributing to the increased drought generally projected for the region.
Temperature extremes. Hotter temperature extremes and more frequent, more intense, and longer-lasting heat waves are robust projections of the models examined by the IPCC, portending increased heat-related illness and mortality. Growing seasons will also become longer because of earlier spring warming and later fall cooling, but crops will face greater heat stress and associated drought during the growing season. Cold spells will become less frequent, causing fewer deaths and economic losses associated with cold weather.
Tropical and mid-latitude storms. Projected patterns of change are similar for both tropical cyclones, including typhoons and hurricanes, and extratropical cyclones (mid-latitude storms). Tropical storms may become less frequent overall, yet are expected to reach higher peak wind speeds and bring greater precipitation on average. The decrease in frequency is likely to result from fewer weak tropical storms, whereas intense tropical storms may become more frequent with warming. Similarly, mid-latitude storms may become less frequent in most regions yet more intense, with more damaging winds and greater precipitation. Intensification of winter mid-latitude storms may bring more frequent severe snowstorms, such as those experienced in the north-central United States in February and March of 2007. Near coasts, both tropical and mid-latitude storms will increase wave heights and storm surge heights, increasing the incidence of severe coastal flooding (see section on abrupt sea level rise on page 80).
Regions affected by tropical storms, including typhoons and hurricanes, include all three coasts of the United States; all of Mexico and Central America; the Caribbean islands; East, Southeast, and South Asia; and many South Pacific and Indian Ocean islands. Although tropical storms are very rare in the South Atlantic, in 2004 Hurricane Catarina became the only hurricane to strike Brazil in recorded history.44 Similarly, it is unusual for tropical storms to make landfall in Europe, yet in 2005 the remnants of Hurricane Vince became the first tropical storm on record to make landfall on the Iberian Peninsula.45 In June 2007 Cyclone Gonu, the first category 5 hurricane documented in the Arabian Sea, temporarily halted shipping through the Strait of Hormuz, the primary artery for exporting Persian Gulf oil.46 Whether such historical aberrations are related to global warming remains uncertain, but extreme weather events exceeding historical precedents should be expected as a general consequence of climate change. Hence, such events illustrate the consequences of climate change for a given region.
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Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.