Call for standard indices to measure droughts
Can
we tell if there are more or fewer droughts as a result of climate
change? How does one compare the intensity, duration and spatial
coverage of agricultural droughts in countries?
These
were some of the questions raised at the recent International Workshop
on Drought and Extreme Temperatures, organized jointly by the World
Meteorological Organization (WMO) and the China Meteorological
Administration (CMA), which pondered ways to cope with the unwelcome
impact of droughts and extreme temperatures on agriculture, rangelands
and forestry.
The
problem is that there are at least 20 kinds of drought indices -
numerical scales based on data such as rainfall and temperature - used
to measure three types of droughts: meteorological, agricultural and
hydrological.
"Many a time, appropriate indices are not
used, as there are no standards or guidelines for the use of drought
indices," said Robert Stefanski, a WMO scientific officer who works on
weather and climate issues related to agriculture. The workshop has
asked the WMO to develop standards for agricultural drought indices.
"Many agricultural drought indices are country- and sometimes even
crop-specific, and are used as an early warning for decision-makers
(governments and farmers)," said Stefanski. "The standards would
address the appropriate use of an index for a particular type of
drought (meteorological, agricultural, and hydrological)".
The
standards would address the appropriate use of an index for a
particular type of drought (meteorological, agricultural, and
hydrological)
Prompted by the need to measure drought intensity and duration for
climate-change studies, participants also called for a unified and
standardized drought index.
Stefanski
pointed out that the Intergovernmental Panel on Climate Change (IPCC)
had used one drought index, the Palmer Index, "which was originally
derived for the USA, and these kinds of indices need to be adapted and
modified for the whole world."
"Standardizing and
establishing guidelines for the use of indices will help such studies,"
he said, but developing a unified and standardized drought index would
be "more difficult".
He said several ideas that combined two or three drought indices into a
single one were presented at the workshop, "but this concept needs to
be tested over different climates. This is why there needs to be
further research into this issue."
For more information on the different types of drought see: www.wamis.org
Contact information | n/a |
---|---|
News type | Inbrief |
File link |
http://www.wamis.org/agm/pubs/brochures/WMO1006e.pdf |
Source of information | Irin News - © IRIN 2009. |
Keyword(s) | drought |
Subject(s) | METHTODOLOGY - STATISTICS - DECISION AID , RISKS AND CLIMATOLOGY |
Relation | http://www.wamis.org |
Geographical coverage | International |
News date | 17/03/2009 |
Working language(s) | ENGLISH |