Tørt bliver ikke tørrere, vådt ikke vådere

Så kan man sige, at det ikke lige nu kan sandsynliggøres igennem antallet af orkaner, men så er tørken da til gengæld til at få øje. Det tørre bliver mere tørt, det våde bliver mere vådt.
Her i lille Danmark kan vi ikke mærke det så tydeligt på egen krop (vi ligger indtil videre heldigt geografisk placeret) - men det er der mange andre, der kan.
Fortsættes denne udvikling (og det gør den), vil dette antal fortsat stige.

In summary, the current assessment concludes that there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century due to lack of direct observations, geographical inconsistencies in the trends, and dependencies of inferred trends on the index choice. Based on updated studies, AR4 conclusions regarding global increasing trends in drought since the 1970s were probably overstated[min fremhævelse, NAN]. However, it is likely that the frequency and intensity of drought has increased in the Mediterranean and West Africa and decreased in central North America and north-west Australia since 1950

In summary, there continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale

Altså - de sidste år har givet væsentlige forbedringer i forskning omkring tørke. Alene derfor er alt hvad NA skriver baseret på forældet viden :-)

NAs postulat om, at tørre områder [ikke] bliver mere tørre og omvendt, er forkert, er som det fremgår et totalt falsum nu.
Se figur: "Paradigm of wet regions get wetter and dry regions get drier"

Substantial changes in the hydrological cycle are projected for the 21st century, but these projections are subject to major uncertainties. In this context, the "dry gets drier, wet gets wetter" (DDWW) paradigm is often used as a simplifying summary. However, recent studies cast doubt on the validity of the paradigm and also on applying the widely used P − E (precipitation − evapotranspiration) metric over global land surfaces. Here we show in a comprehensive CMIP5-based assessment that projected changes in mean annual P − E are generally not significant, except for high-latitude regions showing wetting conditions until the end of the 21st century. Significant increases in aridity do occur in many subtropical and also adjacent humid regions. However, combining both metrics still shows that approximately 70% of all land area will not experience significant changes. Based on these findings, we conclude that the DDWW paradigm is generally not confirmed for projected changes in most land areas.

Changes in the hydrological conditions of the land surface have substantial impacts on society1, 2. Yet assessments of observed continental dryness trends yield contradicting results3, 4, 5, 6, 7. The concept that dry regions dry out further, whereas wet regions become wetter as the climate warms has been proposed as a simplified summary of expected8, 9, 10 as well as observed10, 11, 12, 13, 14 changes over land, although this concept is mostly based on oceanic data8, 10. Here we present an analysis of more than 300 combinations of various hydrological data sets of historical land dryness changes covering the period from 1948 to 2005. Each combination of data sets is benchmarked against an empirical relationship between evaporation, precipitation and aridity. Those combinations that perform well are used for trend analysis. We find that over about three-quarters of the global land area, robust dryness changes cannot be detected. Only 10.8% of the global land area shows a robust 'dry gets drier, wet gets wetter' pattern, compared to 9.5% of global land area with the opposite pattern, that is, dry gets wetter, and wet gets drier. We conclude that aridity changes over land, where the potential for direct socio-economic consequences is highest, have not followed a simple intensification of existing patterns.

In short, we need to stop the simple extrapolation of results from ocean studies to the land and vice versa

Wet regions of Earth are getting wetter and dry regions are getting drier, but it is happening at a slower rate than previously thought, report investigators who, in a new report, provide robust evidence for their claim.

N A Nielsen skrev:
Paradigmet tørt bliver tørrere, vådt vådere, som på engelsk udtrykkes dry gets drier, wet gets wetter (DDWW), er ofte og som regel på meget insisterende vis blevet fremført i videnskabelige debatter som en uimodsigelig følge af en global temperaturstigning. Vi vil således ifølge paradigmet få flere, mere ekstreme tørkehændelser og flere, mere ekstreme oversvømmelser.