Geoscience Reference
In-Depth Information
specific, short and near-term activities are envisioned that will enable progress on this
Grand Challenge. Key areas of development include
1. Utilization of the new global and regional datasets outlined above and from improved
data assessment (within the GEWEX Data and Assessments Panel) to better characterize
extremes on different spatial scales and, with the WCRP Modeling Council, promote
evaluations of model results, potentially with one or more workshops in 2014-15.
2. Ensure strong involvement in the Global Drought Information System. This focuses on
one particular type of extreme but the effort may also act as a prototype for dealing
with all types of extremes in the future. In particular, GEWEX and CLIVAR will
develop trackable actions on monitoring and quantification of the global distribution of
droughts and their trends using observational information, model development, land
area factors governing drought and societal interactions.
3. Facilitate a number of inter-comparison projects aimed at comparison of character-
istics of extremes in different data sets (in situ, reanalyses and satellites), and revealed
by different models.
4. Initiate a parallel activity centered on capabilities of statistical methodologies to deal
with the complexity of extremes, including their clustering in space and time and with
sparse and regionally unevenly distributed data.
5. Initiate multi-methods activities and encourage documentation and data inventory
centered on a few mega-extreme events (for example, catastrophic flooding, droughts,
unusual storm patterns) to enable further analysis with observations and models,
ensure that all their aspects are comprehensively addressed, and with special attention
on assessing their likelihood in the future. This activity may be facilitated by bringing
teams together and should build in flexibility with adaptable approaches as one learns
by doing. It has the advantage that the results are immediately relevant.
6. Examine cold season extremes such as snowstorms, rain-on-snow episodes, freezing
precipitation and prolonged cold weather events with CliC and other international and
national research programs/projects.
There are multiple benefits, and the results are important for society. Drought has
devastating consequences whenever and wherever it occurs. Water resources can be
strained, and adverse effects occur in agriculture. Heat waves are often but not always
linked with drought. Health effects can be profound. Prolonged cold weather episodes are a
critical feature of mid- and sub-polar latitudes in winter. They are disruptive and costly.
Isolated extreme rainfalls as well as continuous periods of heavy and moderate precipi-
tation occur everywhere with numerous impacts including flooding, devastation of eco-
systems and havoc in urban regions. Storms in different parts of the world are the means by
which precipitation, often linked with strong winds, occurs, and changes in their paths,
intensity and frequency have enormous consequences, sometimes devastating. Warming
conditions imply that regions accustomed to receiving snow should experience more rain,
and changing times of runoff and peak stream flow, with large consequences for ecosys-
tems, hydrological risks and water resources.
These examples highlight the importance of progress in the area of climate extremes,
both in terms of their observations and analysis, and in terms of improved modeling and
prediction. In summary, WCRP through GEWEX, CLIVAR and CliC and its seamless
modeling framework across space and time scales (e.g., Working Groups on Coupled
Modeling and Numerical Experimentation (WGCM and WGNE)) will focus great attention
on extremes, including research on detection and attributions of causes and consequences
of such events over the next 5-10 years. By doing so, it will be carrying out its very natural
