ABSTRACT
Among the most urgent challenges in future climate change scenarios is accurately predicting the magnitude to which precipitation extremes will intensify. Analogous changes have been reported for an episode of millennial-scale 5 °C warming, termed the Palaeocene-Eocene Thermal Maximum (PETM; 56 Ma), providing independent constraints on hydrological response to global warming. However, quantifying hydrologic extremes during geologic global warming analogs has proven difficult. Here we show that water discharge increased by at least 1.35 and potentially up to 14 times during the early phase of the PETM in northern Spain. We base these estimates on analyses of channel dimensions, sediment grain size, and palaeochannel gradients across the early PETM, which is regionally marked by an abrupt transition from overbank palaeosol deposits to conglomeratic fluvial sequences. We infer that extreme floods and channel mobility quickly denuded surrounding soil-mantled landscapes, plausibly enhanced by regional vegetation decline, and exported enormous quantities of terrigenous material towards the ocean. These results support hypotheses that extreme rainfall events and associated risks of flooding increase with global warming at similar, but potentially at much higher, magnitudes than currently predicted.
ABSTRACT
OBJECTIVE: To determine whether blood pressure control in a general practice setting is influenced by the presence of additional risk factors, and to analyse the role of antihypertensive therapy in this relationship. DESIGN: A cross-sectional study was conducted with a sample of 3153 general practitioners. SETTING: Primary care. PARTICIPANTS: The first five hypertensive patients presenting at the practitioner's office were included. MAIN OUTCOME MEASURES: Cardiovascular risk factors, antihypertensive drugs and cardiovascular history were reported. Blood pressure was measured. The analysis was conducted in treated patients who were divided in three groups: no other risk factors (group I); 1-2 risk factors (group II); 3 or more risk factors or target-organ damage or diabetes or associated cardiovascular disease (group III). RESULTS: Data were available for all variables in the 14 066 treated hypertensive individuals who form the basis of this report. Blood pressure control had been achieved in a lower percentage of individuals in group III (27%) than in group I (42.9%). To control hypertension, combination therapies were more frequently required in group III (55.8%) than in group II (43.5%) or group I (34.2%). Among individuals with uncontrolled hypertension, about 39% of patients in group III were receiving monotherapy and the percentage receiving two-drug treatments identified as effective in the 1999 WHO guidelines was significantly lower in group III. CONCLUSION: The study shows that, in general practice, control of blood pressure decreases as the number of risk factors present increases. An underuse of combination therapy, especially effective two-drug treatment in patients with several risk factors, may account for this finding.
