Some features of scenario development and application that are now well established and tested include continued development of global and regional databases for defining baseline conditions, widespread use of incremental scenarios to explore system sensitivity prior to application of model-based scenarios, improved availability and wider application of estimates of long-term mean global changes on the basis of projections produced by specialized international organizations or the use of simple models, and a growing volume of accessible information that enables construction of regional scenarios for some aspects of global change. [3.9.1]
There also are numerous shortcomings of current scenario development, many of which are being actively investigated. These investigations include efforts to properly represent socioeconomic, land-use, and environmental changes in scenarios; to obtain scenarios at higher resolution (in time and space); and to incorporate changes in variability as well as mean conditions in scenarios. Increasing attention is required on construction of scenarios that address policy-related issues such as stabilization of GHG concentrations or adaptation, as well as improving the representation of uncertainties in projections, possibly within a risk assessment framework. [3.9.2]
Table TS-2: Examples of impacts resulting from projected changes in extreme climate events. | |
Projected Changes during the 21st Century in Extreme Climate Phenomena and their Likelihooda | Representative Examples of Projected Impactsb (all high confidence of occurrence in some areasc) |
Simple Extremes | |
Higher maximum temperatures; more hot days and heat wavesd over nearly all land areas (Very Likelya) |
|
Higher (increasing) minimum temperatures; fewer cold days, frost days,
and cold wavesd over nearly all land areas (Very Likelya) |
|
More intense precipitation events (Very Likelya over many areas) |
|
Complex Extremes | |
Increased summer drying over most mid-latitude continental interiors and associated risk of drought (Likelya) |
|
Increase in tropical cyclone peak wind intensities, mean and peak precipitation intensities (Likelya over some areas)e |
|
Intensified droughts and floods associated with El Niño events
in many different regions (Likelya) (see also under droughts and intense precipitation events) |
|
Increased Asian summer monsoon precipitation variability (Likelya) |
|
Increased intensity of mid-latitude storms (little agreement between current models)d |
|
a Likelihood refers
to judgmental estimates of confidence used by TAR WGI:
very likely (90-99% chance); likely (66-90% chance).
Unless otherwise stated, information on climate phenomena is taken from
the Summary for Policymakers, TAR
WGI. b These impacts can be lessened by appropriate response measures. c Based on information from chapters in this report; high confidence refers to probabilities between 67 and 95% as described in Footnote 6 of TAR WGII, Summary for Policymakers. d Information from TAR WGI, Technical Summary, Section F.5. e Changes in regional distribution of tropical cyclones are possible but have not been established. |
Other reports in this collection |