Variability of the Atlantic thermohaline circulation described by three-dimensional empirical orthogonal functions

We describe the use of bivariate 3d empirical orthogonal functions (EOFs) in characterising low frequency variability of the Atlantic thermohaline circulation (THC) in the Hadley Centre global climate model, HadCM3. We find that the leading two modes are well correlated with an index of the meridional overturning circulation (MOC) on decadal timescales, with the leading mode alone accounting for 54% of the decadal variance. Episodes of coherent oscillations in the sub-space of the leading EOFs are identified; these episodes are of great interest for the predictability of the THC, and could indicate the existence of different regimes of natural variability. The mechanism identified for the multi-decadal variability is an internal ocean mode, dominated by changes in convection in the Nordic Seas, which lead the changes in the MOC by a few years. Variations in salinity transports from the Arctic and from the North Atlantic are the main feedbacks which control the oscillation. This mode has a weak feedback onto the atmosphere and hence a surface climatic influence. Interestingly, some of these climate impacts lead the changes in the overturning. There are also similarities to observed multi-decadal climate variability

Sexuality and Development Programme: An Annotated Bibliography

The IDS Sexuality and Development Programme is a reaction to the inadequate manner in which sexuality is approached by the development sector. Sexuality is not taken seriously: it is considered a frivolous, trivial issue that doesn’t relate to the more important aspects of development such as poverty. This is something that needs to change. This eclectic bibliography reflects global thinking on sexuality, bringing together texts on poverty, pleasure, gender, heteronormativity, rights, and a lot more! The ideas it contains will inspire you to think differently about sexuality and development whether you are an activist, academic, practitioner, policymaker, or something else entirely.DFID, Sid

Connecting climate model projections of global temperature change with the real world

Current state-of-the-art global climate models produce different values for Earth’s mean temperature. When comparing simulations with each other and with observations it is standard practice to compare temperature anomalies with respect to a reference period. It is not always appreciated that the choice of reference period can affect conclusions, both about the skill of simulations of past climate, and about the magnitude of expected future changes in climate. For example, observed global temperatures over the past decade are towards the lower end of the range of CMIP5 simulations irrespective of what reference period is used, but exactly where they lie in the model distribution varies with the choice of reference period. Additionally, we demonstrate that projections of when particular temperature levels are reached, for example 2K above ‘pre-industrial’, change by up to a decade depending on the choice of reference period. In this article we discuss some of the key issues that arise when using anomalies relative to a reference period to generate climate projections. We highlight that there is no perfect choice of reference period. When evaluating models against observations, a long reference period should generally be used, but how long depends on the quality of the observations available. The IPCC AR5 choice to use a 1986-2005 reference period for future global temperature projections was reasonable, but a case-by-case approach is needed for different purposes and when assessing projections of different climate variables. Finally, we recommend that any studies that involve the use of a reference period should explicitly examine the robustness of the conclusions to alternative choices

ESD Ideas: global climate response scenarios for IPCC assessments

IPCC Working Group I has long employed socioeconomic scenarios, based on discrete storylines, to sample the uncertainty in future forcing of the climate system, but analogous scenarios to sample the uncertainty in the global climate response have not been employed. Here, we argue that to enable development of robust climate policies this gap should be addressed, and we propose a simple methodology

Digitizing observations from the Met Office Daily Weather Reports for 1900–1910 using citizen scientist volunteers

We describe the digitization of 1.8 million sub‐daily and daily weather observations which were recorded in the UK Met Office Daily Weather Reports during the 1900–1910 period. The data were rescued from scanned images of the original documents by 2,148 volunteer citizen scientists using the weatherrescue.org website. The rescued observations include dry and wet bulb temperatures, daily maximum and minimum temperatures, daily rainfall amounts and sub‐daily sea‐level pressure from 72 different locations across western Europe. These observations will be used to fill gaps in existing pressure, temperature and rainfall records and are one of the largest recoveries of weather data by citizen scientists. The value of these additional observations is highlighted by comparing the pressure observations to the Twentieth Century Reanalysis version 3 ensemble for some specific case studies

Improved Arctic sea-ice thickness projections using bias corrected CMIP5 simulations

Projections of Arctic sea ice thickness (SIT) have the potential to inform stakeholders about accessibility to the region, but are currently rather uncertain. The latest suite of CMIP5 Global Climate Models (GCMs) produce a wide range of simulated SIT in the historical period (1979–2014) and exhibit various biases when compared with the Pan-Arctic Ice Ocean Modelling and Assimilation System (PIOMAS) sea ice reanalysis. We present a new method to constrain such GCM simulations of SIT via a statistical bias correction technique. The bias correction successfully constrains the spatial SIT distribution and temporal variability in the CMIP5 projections whilst retaining the climatic fluctuations from individual ensemble members. The bias correction acts to reduce the spread in projections of SIT and reveals the significant contributions of climate internal variability in the first half of the century and of scenario uncertainty from mid-century onwards. The projected date of ice-free conditions in the Arctic under the RCP8.5 high emission scenario occurs in the 2050s, which is a decade earlier than without the bias correction, with potentially significant implications for stakeholders in the Arctic such as the shipping industry. The bias correction methodology developed could be similarly applied to other variables to reduce spread in climate projections more generally

Implications from opening Arctic sea routes

Summary for Policy Makers The Arctic is warming faster than anywhere else on Earth; satellite observations have revealed the region is losing sea ice at a dramatic rate and this decline is expected to continue. This loss of sea ice is creating opportunities for shorter global trade links between East Asia and the UK via the Arctic. The Northern Sea Route and North West Passages are seasonally open most years, although specialised vessels are currently required. The Arctic shipping season will continue to extend tripling in length by mid-century, coinciding with the opening of the trans-polar sea route across the central Arctic Ocean, although there will still be sea ice present in the Arctic winter. Typically by mid-century voyages from East Asia to the UK could save 10 – 12 days by using trans-Arctic routes instead of the Suez Canal route. These findings suggest that trans-Arctic routes may provide a useful supplement to the traditional canal routes, but they will likely not replace them. There are mixed views on whether trans-Arctic routes will become economically viable. The Russian government wishes to develop the Northern Sea Route as a commercial enterprise and offers substantial fee-based services such as ice breaking support and pilotage, which are certainly necessary for future investment and development of the route. However Arctic transport is also likely to grow due to increased destination shipping to serve natural resource extraction projects and cruise tourism. The UK is well positioned, geographically, geopolitically, and commercially, to benefit from a symbiotic relationship with increasing Arctic shipping. The UK has a prominent role in Arctic science and a world leading maritime services industry based in London, including the International Maritime Organisation (IMO), one of the world’s leading financial centres, and Europe’s largest insurance sector. Arctic economic growth is focused in four key sectors — mineral resources, fisheries, logistics, and tourism — all of which require shipping, and could generate investment reaching $100bn or more in the Arctic region over the next decade. The UK had a fundamental role in preparing the UN IMO Polar Code which came into operation in January 2017. The Polar Code is an historic milestone in addressing the specific risks faced by Arctic shipping and acts to supplement the existing SOLAS and MARPOL conventions for protecting the environment whilst ensuring safe shipping in international waters. Much of the investment into Arctic shipping projects is from China but northern European countries are also playing an increasing role. Potential opportunities for the UK include the development of UK based Arctic cruise tourism, and a UK based trans-shipment port — transferring goods from ice-classed vessels to conventional carriers. The UK has an active diplomatic role in many international organisations; this should be used to ensure that increased activity in the Arctic is accomplished in line with established UN maritime conventions, many of which were written with significant UK contributions. The UK’s leading role in Arctic science has wide reaching positive implications for international collaboration; this role requires continued investment into climate modelling centres, and science programs, that are essential to enhance predictions of the future Arctic