Past changes in the North Atlantic storm track driven by insolation and sea-ice forcing

Changes in the location of Northern Hemisphere storm tracks may cause significant societal and economic impacts under future climate change, but projections of future changes are highly uncertain and drivers of long-term changes are poorly understood. Here we develop a late Holocene storminess reconstruction from northwest Spain and combine this with an equivalent record from the Outer Hebrides, Scotland, to measure changes in the dominant latitudinal position of the storm track. The north-south index shows that storm tracks moved from a southern position to higher latitudes over the past 4000 yr, likely driven by a change from meridional to zonal atmospheric circulation, associated with a negative to positive North Atlantic Oscillation shift. We suggest that gradual polar cooling (caused by decreasing solar insolation in summer and amplified by sea-ice feedbacks) and mid-latitude warming (caused by increasing winter insolation) drove a steepening of the winter latitudinal temperature gradient through the late Holocene, resulting in the observed change to a more northern winter storm track. Our findings provide paleoclimate support for observational and modeling studies that link changes in the latitudinal temperature gradient and sea-ice extent to the strength and shape of the circumpolar vortex. Together this evidence now suggests that North Atlantic winter storm tracks may shift southward under future warming as sea-ice extent decreases and the mid- to high-latitude temperature gradient decreases, with storms increasingly affecting southern Europe

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Sand-based storminess proxies from Pedrido Bog, Galicia, Spain

Over annual to decadal timescales changes in the storm track influences regional climate in Europe, however little is known about how the storm track varies over centennial and millennial timescales. We here present two datasets. The first is a reconstruction of storminess from northwest Spain spanning the period 4600-0 cal yrs BP, which was developed by measuring aeolian sand deposits in a peat core from Pedrido Bog, Galicia, Spain. Samples of equal volume (5 cm3) from 1 cm contiguous intervals along the core were processed using the loss-on-ignition method (Heiri et al. 2001), leaving the ignition residue, which was sieved to establish the weight of the 120-180 and >180 micron sand fractions. The ignition residue and sand fractions reflect the past amount of sand deposition, which can be used as proxies for storminess. The second dataset is a North-South storm track index reconstruction for western Europe spanning the period 3940-120 cal yrs BP. To create the storm track index, the above described storminess record from Spain was subtracted from a storminess record from Scotland, derived by averaging the results of two storminess reconstructions from the Outer Hebrides, Scotland (Orme et al., 2016). Each record was sampled to the same 20 year temporal resolution and standardised prior to this

North-south storm track index reconstruction for western Europe from Pedrido Bog, Galicia, Spain

To create the storm track index, the above described storminess record from Spain was subtracted from a storminess record from Scotland, derived by averaging the results of two storminess reconstructions from the Outer Hebrides, Scotland (Orme et al., 2016). Each record was sampled to the same 20 year temporal resolution and standardised prior to this

Reconstruction of past storminess and storm track position, evidence from Pedrido Bog, Galicia, Spain

Over annual to decadal timescales changes in the storm track influences regional climate in Europe, however little is known about how the storm track varies over centennial and millennial timescales. We here present two datasets. The first is a reconstruction of storminess from northwest Spain spanning the period 4600-0 cal yrs BP, which was developed by measuring aeolian sand deposits in a peat core from Pedrido Bog, Galicia, Spain. Samples of equal volume (5 cm3) from 1 cm contiguous intervals along the core were processed using the loss-on-ignition method (Heiri et al. 2001), leaving the ignition residue, which was sieved to establish the weight of the 120-180 and >180 micron sand fractions. The ignition residue and sand fractions reflect the past amount of sand deposition, which can be used as proxies for storminess. The second dataset is a North-South storm track index reconstruction for western Europe spanning the period 3940-120 cal yrs BP. To create the storm track index, the above described storminess record from Spain was subtracted from a storminess record from Scotland, derived by averaging the results of two storminess reconstructions from the Outer Hebrides, Scotland (Orme et al., 2016). Each record was sampled to the same 20 year temporal resolution and standardised prior to this