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Cold waves that bring unexpected freezes and frosts during the growing season in mid-latitude zones can kill plants during the early and most vulnerable stages of growth. This results in crop failure as plants are killed before they can be [[harvest]]ed economically. Such cold waves have caused [[famine]]s. Cold waves can also cause soil particles to harden and freeze, making it harder for plants and vegetation to grow within these areas. One extreme was the so-called [[Year Without a Summer]] of 1816, one of several years during the 1810s in which numerous crops failed during freakish summer cold snaps after [[volcanic eruption]]s reduced incoming sunlight.
Cold waves that bring unexpected freezes and frosts during the growing season in mid-latitude zones can kill plants during the early and most vulnerable stages of growth. This results in crop failure as plants are killed before they can be [[harvest]]ed economically. Such cold waves have caused [[famine]]s. Cold waves can also cause soil particles to harden and freeze, making it harder for plants and vegetation to grow within these areas. One extreme was the so-called [[Year Without a Summer]] of 1816, one of several years during the 1810s in which numerous crops failed during freakish summer cold snaps after [[volcanic eruption]]s reduced incoming sunlight.

== Climate change==
{{See also|Effects of global warming#Extreme weather}}
In general climate models and observed trends show that with climate change, the planet will experience more extreme weather.<ref>{{cite web|title=More Extreme Weather Events Forecast|accessdate= June 15, 2014|url=http://www.nasa.gov/centers/langley/science/climate_assessment_2012.html|author=NASA}}</ref> In particular temperature record highs outpace record lows and some types of extreme weather such as extreme heat, intense precipitation, and drought have become more frequent and severe in recent decades.<ref>{{cite web|title=Current Extreme Weather & Climate Change|accessdate= June 15, 2014|url=http://www.climatecommunication.org/new/articles/extreme-weather/overview/}}</ref> Some studies assert a connection between rapidly warming arctic temperatures and thus a vanishing [[cryosphere]] to extreme weather in mid-latitudes.<ref>{{cite journal | last1 = | first1 = | year = 2012 | title = Evidence linking Arctic amplification to extreme weather in mid-latitudes | journal = [[Geophysical Research Letters]] | volume = 39 | issue = | page = | doi = 10.1029/2012GL051000 | bibcode=2012GeoRL..39.6801F}}</ref><ref>{{cite journal
| author = Vladimir Petoukhov and Vladimir A. Semenov
|date=November 2010
| title = A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents
| journal = Journal of Geophysical Research: Atmospheres (1984–2012)
| volume = 115
| issue = 21
| doi = 10.1029/2009JD013568
| url = http://onlinelibrary.wiley.com/doi/10.1029/2009JD013568/abstract
| bibcode=2010JGRD..11521111P
}}</ref><ref name="Screen 2013">{{cite journal
| author = J A Screen
|date=November 2013
| title = Influence of Arctic sea ice on European summer precipitation
| journal = Environmental Research Letter
| volume = 8
| issue = 4
| doi = 10.1088/1748-9326/8/4/044015
| url = http://iopscience.iop.org/1748-9326/8/4/044015
}}</ref><ref>{{cite journal
| author = Qiuhong Tang, Xuejun Zhang and Jennifer A. Francis
|date=December 2013
| title = Extreme summer weather in northern mid-latitudes linked to a vanishing cryosphere
| journal = Nature Climate Change
| volume = 4
| pages = 45–50
| doi = 10.1038/nclimate2065
| url = http://iopscience.iop.org/1748-9326/8/4/044015
}}</ref>

=== Heat stress ===
The upper limit for [[heat stress]] humans can adapt to is called into question with a 7&nbsp;°C temperature rise, quantified by the [[wet-bulb temperature]], regions of Earth would lose their habitability.<ref>{{cite journal
| author = Steven C. Sherwood and Matthew Huber
|date=November 19, 2009
| title = An adaptability limit to climate change due to heat stress
| journal = PNAS
| volume = 107
| pages = 9552–9555
| doi = 10.1073/pnas.0913352107
| url = http://www.pnas.org/content/107/21/9552.long
| issue=21
}}</ref>

===Tropical cyclones===
[[File:Hurricane Katrina (short film by NASA).ogv|thumb|thumbtime=28|right|[[NASA]] film ''In Katrina's Wake'', covering the impacts from [[Hurricane Katrina]].]]
There has been long ongoing debate about a possible increase of [[tropical cyclone]]s as an effect of [[global warming]].<ref>{{cite web|last=Redfern |first=Simon |url=http://theconversation.com/super-typhoon-haiyan-hits-philippines-with-devastating-force-20016 |title=Super Typhoon Haiyan hits Philippines with devastating force |publisher=Theconversation.com |date=November 8, 2013 |accessdate=2014-08-25}}</ref> However, as of March 2012, the latest [[IPCC]] report on extreme events SREX states that "there is low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e., intensity, frequency, duration), after accounting for past changes in observing capabilities." <ref>IPCC Special Report on Climate Extremes. [http://www.ipcc-wg2.gov/SREX/images/uploads/SREX-All_FINAL.pdf "IPCC Special Report on Climate Extremes"] Retrieved on 01 April 2012.</ref>
Increases in [[population]] densities increase the number of people affected and damage caused by an event of given severity. The [[World Meteorological Organization]]<ref>Commondreams.org News Center. [http://www.commondreams.org/headlines03/0703-05.htm Extreme Weather Prompts Unprecedented Global Warming Alert.] Retrieved on 13 April 2007.</ref> and the [[U.S. Environmental Protection Agency]]<ref>U. S. [[Environmental Protection Agency]]. [http://yosemite.epa.gov/OAR/globalwarming.nsf/webprintview/ActionsIndustryInsurance.html Global Warming.] Retrieved on 13 April 2007.</ref> have in the past linked increasing extreme weather events to [[global warming]], as have Hoyos ''et al.'' (2006), writing that the increasing number of category 4 and 5 hurricanes is directly linked to increasing temperatures.<ref>Carlos D. Hoyos, Paula A. Agudelo, Peter J. Webster, Judith A. Curry. [http://www.sciencemag.org/cgi/content/abstract/1123560v1 Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity.] Retrieved on 13 April 2007.</ref> Similarly, [[Kerry Emanuel]] in ''[[Nature (journal)|Nature]]'' writes that hurricane power dissipation is highly correlated with temperature, reflecting [[global warming]].<ref>Emanuel, K.A. (2005): [ftp://texmex.mit.edu/pub/emanuel/PAPERS/NATURE03906.pdf "Increasing destructiveness of tropical cyclones over the past 30 years"]. ''Nature''</ref>

Hurricane modeling has produced similar results, finding that hurricanes, simulated under warmer, high CO<sub>2</sub> conditions, are more intense than under present-day conditions. [[Thomas Knutson]] and Robert E. Tuleya of the [[NOAA]] stated in 2004 that warming induced by [[greenhouse gas]] may lead to increasing occurrence of highly destructive category-5 storms.<ref>Thomas R. Knutson, ''et al.'', [[Journal of Climate]], [http://www.gfdl.noaa.gov/reference/bibliography/2004/tk0401.pdf ''Impact of CO<sub>2</sub>-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Parameterization''], 15 Sept. 2004. Retrieved March 4, 2007.</ref> Vecchi and Soden find that [[wind shear]], the increase of which acts to inhibit [[tropical cyclones]], also changes in model-projections of global warming. There are projected increases of [[wind shear]] in the tropical Atlantic and East Pacific associated with the deceleration of the [[Walker circulation]], as well as decreases of wind shear in the western and central Pacific.<ref>{{cite web|url=http://www.gfdl.noaa.gov/~gav/ipcc_shears.html |title=Geophysical Fluid Dynamics Laboratory - Global Warming and 21st Century Hurricanes |publisher=Gfdl.noaa.gov |date=2014-08-04 |accessdate=2014-08-25}}</ref> The study does not make claims about the net effect on Atlantic and East Pacific hurricanes of the warming and moistening atmospheres, and the model-projected increases in Atlantic wind shear.<ref>{{cite journal |last= Vecchi |first= Gabriel A. |author2=Brian J. Soden |date= 18 April 2007 |title= Increased tropical Atlantic wind shear in model projections of global warming |journal= [[Geophysical Research Letters]] |volume= 34 |issue= L08702 |pages= 1–5 |doi= 10.1029/2006GL028905 |url= http://www.gfdl.noaa.gov/reference/bibliography/2007/gav0701.pdf |format= PDF |accessdate= 21 April 2007 |bibcode=2007GeoRL..3408702V}}</ref>


== Referencias ==
== Referencias ==

Revisión del 02:00 20 may 2015

Un tornado que golpeó Anadarko (Oklahoma) durante un estallido de tornado en 1999

Los fenómenos meteorológicos extremos incluyen fenómenos inusuales, severo o impropio de la estación; tiempo en los extremos de la distribución histórica (el rango observado en el pasado).[1]​ A menudo los acontecimientos extremos están basados en el registro meteorológico de una localización como ubicado en diez por ciento más inusual.[2]​ En años recientes algunos eventos extremos han sido atribuidos al calentamiento global antropogénico, con estudios que indican una amenaza creciente de fenómenos extremos en el futuro.[3]​[4]​[5]​

Costos

De acuerdo con estimaciones del IPCC (2011) de las pérdidas anuales han variado desde 1980 desde unos pocos millardos y arriba de US$200 millardos (en dólares de 2010), con el mayor valor para 2005 (el año del Huracán Katrina).[6]​ Las pérdidas globales de desastres meteorológicos informado en las últimas décadas reflejan mayormante los daños directos calculados a bienes inmuebles y están distribuidos desigualmente. El límite inferior de las estimaciones de pérdidas está subvalorado debido a que muchos impactos, tales como la pérdida de vidas humanas, el patrimonio culturas y servicios ambientales, son difíciles de evaluar y valorizar y por lo tanto están pobremente reflejados en las estimaciones de pérdidas.[7]​[8]​

Temperaturas extremas

Olas de calor

Ola europea de calor 2003
Artículo principal: Ola de calor

Una ola de calor es un periodo de temperaturas secas y temperaturas bochornas anormalmente altas. Sus definiciones varían debido a las variaciones térmicas en las diversas ubicaciones geográficas.[9]​ El calor excesivo a menudo está acompañado por altos niveles de humedad, pero también pueden ser catastróficamente secas.[10]​ Debido a que las olas de calor no son visibles como otras formas de fenómenos severos, como los huracanes, los tornadas y tormentas, son uno de las formas menos conocidas de fenómenos extremos.[11]​ Olas de calor severas pueden dañar las poblaciones y cultivos debido a su potencial de deshidratación e hipertermia, calambre térmicos, dilatación térmica e infarto de calor. La tierra seca es más susceptible a la erosión, lo que disminuye el suelo disponible para la agricultura. Los brotes de incendios forestales aumentan en frecuencia ya que la vegetación seca es más susceptible a la ignición. La evaporación de los cuerpos de agua pueden ser devastador para las poblaciones marinas, lo que disminuye el tamaño de los hábitats disponibles además de la cantidad de alimento presente en las aguas. También puede disminuir el ganado y otras poblaciones animales.

Durante el calor excesivo las plantas cierran los poros de sus hojas (estomas), un mecanismo protector para conservar el agua pero también limita la capacidad de absorción. De este modo dejan más polución y ozono en el aire, lo que lleva a una mayor mortalidad en la población. Se ha estimado que la polución durante el verano caluroso de 2006 en Reino Unido, costó 460 vidas.[12]​ Se estima que las olas de calor del verano europeo de 2003 causaron 30 000 muertes adicionales, debido al estrés térmico y la polución aérea.[13]​

En áreas afectadas por olas de calor también pueden sufrir apagones debido al aumento en la demanda de electricidad (por ejemplo, por el uso de aire acondicionado)[14]​ El efecto de isla de calor pueden incrementar las temperaturas, especialmente durante la noche.[15]​

Olas de frío

Cold wave in continental North America since Dec-03 to Dec-10, 2013. Red color means above mean temperature; blue represents below normal temperature.
Artículo principal: Cold wave

A cold wave is a weather phenomenon that is distinguished by a cooling of the air. Specifically, as used by the U.S. National Weather Service, a cold wave is a rapid fall in temperature within a 24-hour period requiring substantially increased protection to agriculture, industry, commerce, and social activities. The precise criterion for a cold wave is determined by the rate at which the temperature falls, and the minimum to which it falls. This minimum temperature is dependent on the geographical region and time of year.[16]​ Cold waves generally are capable of occurring any geological location and are formed by large cool air masses that accumulate over certain regions, caused by movements of air streams.[9]​

A cold wave can cause death and injury to livestock and wildlife. Exposure to cold mandates greater caloric intake for all animals, including humans, and if a cold wave is accompanied by heavy and persistent snow, grazing animals may be unable to reach necessary food and water, and die of hypothermia or starvation. Cold waves often necessitate the purchase of fodder for livestock at considerable cost to farmers.[9]​ Human populations can be inflicted with frostbites when exposed for extended periods of time to cold and may result in the loss of limbs or damage to internal organs.

Extreme winter cold often causes poorly insulated water pipes to freeze. Even some poorly protected indoor plumbing may rupture as frozen water expands within them, causing property damage. Fires, paradoxically, become more hazardous during extreme cold. Water mains may break and water supplies may become unreliable, making firefighting more difficult.[9]​

Cold waves that bring unexpected freezes and frosts during the growing season in mid-latitude zones can kill plants during the early and most vulnerable stages of growth. This results in crop failure as plants are killed before they can be harvested economically. Such cold waves have caused famines. Cold waves can also cause soil particles to harden and freeze, making it harder for plants and vegetation to grow within these areas. One extreme was the so-called Year Without a Summer of 1816, one of several years during the 1810s in which numerous crops failed during freakish summer cold snaps after volcanic eruptions reduced incoming sunlight.

Climate change

Véase también: Effects of global warming#Extreme weather

In general climate models and observed trends show that with climate change, the planet will experience more extreme weather.[17]​ In particular temperature record highs outpace record lows and some types of extreme weather such as extreme heat, intense precipitation, and drought have become more frequent and severe in recent decades.[18]​ Some studies assert a connection between rapidly warming arctic temperatures and thus a vanishing cryosphere to extreme weather in mid-latitudes.[19]​[20]​[21]​[22]​

Heat stress

The upper limit for heat stress humans can adapt to is called into question with a 7 °C temperature rise, quantified by the wet-bulb temperature, regions of Earth would lose their habitability.[23]​

Tropical cyclones

NASA film In Katrina's Wake, covering the impacts from Hurricane Katrina.

There has been long ongoing debate about a possible increase of tropical cyclones as an effect of global warming.[24]​ However, as of March 2012, the latest IPCC report on extreme events SREX states that "there is low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e., intensity, frequency, duration), after accounting for past changes in observing capabilities." [25]​ Increases in population densities increase the number of people affected and damage caused by an event of given severity. The World Meteorological Organization[26]​ and the U.S. Environmental Protection Agency[27]​ have in the past linked increasing extreme weather events to global warming, as have Hoyos et al. (2006), writing that the increasing number of category 4 and 5 hurricanes is directly linked to increasing temperatures.[28]​ Similarly, Kerry Emanuel in Nature writes that hurricane power dissipation is highly correlated with temperature, reflecting global warming.[29]​

Hurricane modeling has produced similar results, finding that hurricanes, simulated under warmer, high CO2 conditions, are more intense than under present-day conditions. Thomas Knutson and Robert E. Tuleya of the NOAA stated in 2004 that warming induced by greenhouse gas may lead to increasing occurrence of highly destructive category-5 storms.[30]​ Vecchi and Soden find that wind shear, the increase of which acts to inhibit tropical cyclones, also changes in model-projections of global warming. There are projected increases of wind shear in the tropical Atlantic and East Pacific associated with the deceleration of the Walker circulation, as well as decreases of wind shear in the western and central Pacific.[31]​ The study does not make claims about the net effect on Atlantic and East Pacific hurricanes of the warming and moistening atmospheres, and the model-projected increases in Atlantic wind shear.[32]​

Referencias

  1. ↑ Intergovernmental Panel on Climate Change. 2.7 Has Climate Variability, or have Climate Extremes, Changed?
  2. ↑ NOAA. «Extreme Events». 
  3. ↑ Scientists attribute extreme weather to man-made climate change. Researchers have for the first time attributed recent floods, droughts and heat waves, to human-induced climate change. 10 July 2012 The Guardian
  4. ↑ Hansen, J; Sato, M; Ruedy, R; Lacis, A; Oinas, V (2000). «Global warming in the twenty-first century: an alternative scenario». Proceedings of the National Academy of Sciences of the United States of America 97 (18): 9875-80. Bibcode:2000PNAS...97.9875H. PMC 27611. PMID 10944197. doi:10.1073/pnas.170278997. 
  5. ↑ Extremely Bad Weather: Studies start linking climate change to current events November 17, 2012; Vol.182 #10 Science News
  6. ↑ U.S. Billion-Dollar Weather and Climate Disasters: Summary Statistics
  7. ↑ Smith A.B. and R. Katz, 2013: U.S. Billion-dollar Weather and Climate Disasters: Data sources, Trends, Accuracy and Biases. Natural Hazards, 67, 387–410, doi:10.1007/s11069-013-0566-5
  8. ↑ Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX), Summary IPCC
  9. ↑ a b c d Mogil, Micheal.H (2007). Extreme Weather. New York: Black Dog & Leventhal Publishers. pp. 210-211. ISBN 978-1-57912-743-5. 
  10. ↑ NOAA NWS. «Heat: A Major Killer». 
  11. ↑ Casey Thornbrugh, Asher Ghertner, Shannon McNeeley, Olga Wilhelmi, and Robert Harriss (2007). «Heat Wave Awareness Project». National Center for Atmospheric Research. Consultado el 18 de agosto de 2009. 
  12. ↑ «It's not just the heat – it's the ozone: Study highlights hidden dangers». University of York. 2013. 
  13. ↑ «Vulnerable populations: Lessons learnt from the summer 2003 heat waves in europe». Eurosurveillance. 2005. 
  14. ↑ Doan, Lynn; Covarrubias, Amanda (27 de julio de 2006). «Heat Eases, but Thousands of Southern Californians Still Lack Power». Los Angeles Times. Consultado el June 16, 2014. 
  15. ↑ T. R. Oke (1982). «The energetic basis of the urban heat island». Quarterly Journal of the Royal Meteorological Society 108 (455): 1-24. Bibcode:1982QJRMS.108....1O. doi:10.1002/qj.49710845502. 
  16. ↑ Glossary of Meteorology (2009). «Cold Wave». American Meteorological Society. Consultado el 18 de agosto de 2009. 
  17. ↑ NASA. «More Extreme Weather Events Forecast». Consultado el June 15, 2014. 
  18. ↑ «Current Extreme Weather & Climate Change». Consultado el June 15, 2014. 
  19. ↑ «Evidence linking Arctic amplification to extreme weather in mid-latitudes». Geophysical Research Letters 39. 2012. Bibcode:2012GeoRL..39.6801F. doi:10.1029/2012GL051000. 
  20. ↑ Vladimir Petoukhov and Vladimir A. Semenov (November 2010). «A link between reduced Barents-Kara sea ice and cold winter extremes over northern continents». Journal of Geophysical Research: Atmospheres (1984–2012) 115 (21). Bibcode:2010JGRD..11521111P. doi:10.1029/2009JD013568. 
  21. ↑ J A Screen (November 2013). «Influence of Arctic sea ice on European summer precipitation». Environmental Research Letter 8 (4). doi:10.1088/1748-9326/8/4/044015. 
  22. ↑ Qiuhong Tang, Xuejun Zhang and Jennifer A. Francis (December 2013). «Extreme summer weather in northern mid-latitudes linked to a vanishing cryosphere». Nature Climate Change 4: 45-50. doi:10.1038/nclimate2065. 
  23. ↑ Steven C. Sherwood and Matthew Huber (November 19, 2009). «An adaptability limit to climate change due to heat stress». PNAS 107 (21): 9552-9555. doi:10.1073/pnas.0913352107. 
  24. ↑ Redfern, Simon (November 8, 2013). «Super Typhoon Haiyan hits Philippines with devastating force». Theconversation.com. Consultado el 25 de agosto de 2014. 
  25. ↑ IPCC Special Report on Climate Extremes. "IPCC Special Report on Climate Extremes" Retrieved on 01 April 2012.
  26. ↑ Commondreams.org News Center. Extreme Weather Prompts Unprecedented Global Warming Alert. Retrieved on 13 April 2007.
  27. ↑ U. S. Environmental Protection Agency. Global Warming. Retrieved on 13 April 2007.
  28. ↑ Carlos D. Hoyos, Paula A. Agudelo, Peter J. Webster, Judith A. Curry. Deconvolution of the Factors Contributing to the Increase in Global Hurricane Intensity. Retrieved on 13 April 2007.
  29. ↑ Emanuel, K.A. (2005): "Increasing destructiveness of tropical cyclones over the past 30 years". Nature
  30. ↑ Thomas R. Knutson, et al., Journal of Climate, Impact of CO2-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Parameterization, 15 Sept. 2004. Retrieved March 4, 2007.
  31. ↑ «Geophysical Fluid Dynamics Laboratory - Global Warming and 21st Century Hurricanes». Gfdl.noaa.gov. 4 de agosto de 2014. Consultado el 25 de agosto de 2014. 
  32. ↑ Vecchi, Gabriel A.; Brian J. Soden (18 April 2007). «Increased tropical Atlantic wind shear in model projections of global warming» (PDF). Geophysical Research Letters 34 (L08702): 1-5. Bibcode:2007GeoRL..3408702V. doi:10.1029/2006GL028905. Consultado el 21 April 2007. 
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