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BRANDBESKERMINGS-VERENINGS. Agriculture. Climate Variability and Climate Change in the Agricultural Context. Presented by: Johan van den Berg 30 September 2013. Contents. Weather and Climate Systems High and Low pressure systems Cold fronts Orographic rain
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BRANDBESKERMINGS-VERENINGS Agriculture Climate Variability and Climate Change in the Agricultural Context Presented by: Johan van den Berg 30 September 2013
Contents • Weather and Climate Systems • High and Low pressure systems • Cold fronts • Orographic rain • Climate change and climate variability • Sun • Ocean • Pacific • Indian Ocean • Climate forecasts (outlooks) • Risk management
High and low pressure systems Favourable for rain Unfavourable for rain H L Heat
Hurricane Sandy: Oct 2012 http://www.telegraph.co.uk/news/worldnews/
Hurricane Sandy: Oct 2012 http://www.wxnotes.com/
Cold front and rain http://www.bishopmuseum.org
Climate Change: A change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings, or to persistent anthropogenic changes in the composition of the atmosphere or in land use. http://www.thegwpf.org/ipcc-introduces-new-climate-change-definition/
Climate variability refers to variations in the mean state and other climate statistics (standard deviations, the occurrence of extremes, etc.) on all temporal and spatial scales beyond those of individual weather events. • Climate variability is the “normal” variability around the long term average
Global temperature http://www.aip.org/history/climate/20ctrend.htm#S6
The Frozen Thames, looking Eastwards towards Old London Bridge: 1677 Credit: Museum of London
Sonvlekke en sonvleksiklus Sunspot count vs RSA drought/extreme wet spells Wet Dry Wet
Pacific (El Nino Southern Oscilation, ENSO)
El Nino Rain Rain Rain L L L H H H
La Nina Rain Rain Rain H L L H H
L H H
L H L H