The papers in this volume discuss projections of climate change impacts upon humans and ecosystems under a global mean temperature rise of 4°C above preindustrial levels. Like most studies, they are ...mainly single-sector or single-region-based assessments. Even the multi-sector or multi-region approaches generally consider impacts in sectors and regions independently, ignoring interactions. Extreme weather and adaptation processes are often poorly represented and losses of ecosystem services induced by climate change or human adaptation are generally omitted. This paper addresses this gap by reviewing some potential interactions in a 4°C world, and also makes a comparison with a 2°C world. In a 4°C world, major shifts in agricultural land use and increased drought are projected, and an increased human population might increasingly be concentrated in areas remaining wet enough for economic prosperity. Ecosystem services that enable prosperity would be declining, with carbon cycle feedbacks and fire causing forest losses. There is an urgent need for integrated assessments considering the synergy of impacts and limits to adaptation in multiple sectors and regions in a 4°C world. By contrast, a 2°C world is projected to experience about one-half of the climate change impacts, with concomitantly smaller challenges for adaptation. Ecosystem services, including the carbon sink provided by the Earth's forests, would be expected to be largely preserved, with much less potential for interaction processes to increase challenges to adaptation. However, demands for land and water for biofuel cropping could reduce the availability of these resources for agricultural and natural systems. Hence, a whole system approach to mitigation and adaptation, considering interactions, potential human and species migration, allocation of land and water resources and ecosystem services, will be important in either a 2°C or a 4°C world.
Extreme heat stress during the crop reproductive period can be critical for crop productivity. Projected changes in the frequency and severity of extreme climatic events are expected to negatively ...impact crop yields and global food production. This study applies the global crop model PEGASUS to quantify, for the first time at the global scale, impacts of extreme heat stress on maize, spring wheat and soybean yields resulting from 72 climate change scenarios for the 21st century. Our results project maize to face progressively worse impacts under a range of RCPs but spring wheat and soybean to improve globally through to the 2080s due to CO2 fertilization effects, even though parts of the tropic and sub-tropic regions could face substantial yield declines. We find extreme heat stress at anthesis (HSA) by the 2080s (relative to the 1980s) under RCP 8.5, taking into account CO2 fertilization effects, could double global losses of maize yield (ΔY = −12.8 ± 6.7% versus − 7.0 ± 5.3% without HSA), reduce projected gains in spring wheat yield by half (ΔY = 34.3 ± 13.5% versus 72.0 ± 10.9% without HSA) and in soybean yield by a quarter (ΔY = 15.3 ± 26.5% versus 20.4 ± 22.1% without HSA). The range reflects uncertainty due to differences between climate model scenarios; soybean exhibits both positive and negative impacts, maize is generally negative and spring wheat generally positive. Furthermore, when assuming CO2 fertilization effects to be negligible, we observe drastic climate mitigation policy as in RCP 2.6 could avoid more than 80% of the global average yield losses otherwise expected by the 2080s under RCP 8.5. We show large disparities in climate impacts across regions and find extreme heat stress adversely affects major producing regions and lower income countries.
Climate change is projected to have significant effects on the distribution of species globally, but research into the implications in parts of Africa has been limited. Using species distribution ...modelling, this study models climate change-related risks to the terrestrial biodiversity (birds, mammals, reptiles, amphibians and plants) of Kenya’s economically-important and ecologically diverse Tana River Basin. Large reductions in species richness are projected with just 2°C warming (relative to preindustrial levels) with birds and plants seeing the greatest impact. Potential climate refugia for biodiversity are identified within the basin, but often overlap with areas already converted to agriculture or set aside for agricultural expansion, and the majority are outside protected areas. Similarly, some protected areas contain no projected refugia at higher levels of global warming, showing they may be insufficient to protect the basin’s biodiversity as climate changes. However, risks to biodiversity are much smaller if the Paris Agreement’s goal of limiting global warming to ‘well below 2°C’ warming, rather than 2°C only, is met. The potential for refugia for plants and animals decreases strongly with warming. For example, 82% of the basin remaining climatically suitable for at least 75% of the plants currently present at 1.5°C warming, as compared with 23% at 2°C and 3% at 4.5°C. This research provides the first assessment of the combined effects of development plans and climate change on biodiversity of the Tana River Basin, including identifying potential areas for restoration, and contributes to a greater understanding of biodiversity protection and adaptation options in Kenya.
The United Nations' Paris Agreement includes the aim of pursuing efforts to limit global warming to only 1.5 °C above pre-industrial levels. However, it is not clear what the resulting climate would ...look like across the globe and over time. Here we show that trajectories towards a '1.5 °C warmer world' may result in vastly different outcomes at regional scales, owing to variations in the pace and location of climate change and their interactions with society's mitigation, adaptation and vulnerabilities to climate change. Pursuing policies that are considered to be consistent with the 1.5 °C aim will not completely remove the risk of global temperatures being much higher or of some regional extremes reaching dangerous levels for ecosystems and societies over the coming decades.
Scoping reviews are used to identify knowledge gaps, set research agendas, and identify implications for decision-making. The conduct and reporting of scoping reviews is inconsistent in the ...literature. We conducted a scoping review to identify: papers that utilized and/or described scoping review methods; guidelines for reporting scoping reviews; and studies that assessed the quality of reporting of scoping reviews.
We searched nine electronic databases for published and unpublished literature scoping review papers, scoping review methodology, and reporting guidance for scoping reviews. Two independent reviewers screened citations for inclusion. Data abstraction was performed by one reviewer and verified by a second reviewer. Quantitative (e.g. frequencies of methods) and qualitative (i.e. content analysis of the methods) syntheses were conducted.
After searching 1525 citations and 874 full-text papers, 516 articles were included, of which 494 were scoping reviews. The 494 scoping reviews were disseminated between 1999 and 2014, with 45% published after 2012. Most of the scoping reviews were conducted in North America (53%) or Europe (38%), and reported a public source of funding (64%). The number of studies included in the scoping reviews ranged from 1 to 2600 (mean of 118). Using the Joanna Briggs Institute methodology guidance for scoping reviews, only 13% of the scoping reviews reported the use of a protocol, 36% used two reviewers for selecting citations for inclusion, 29% used two reviewers for full-text screening, 30% used two reviewers for data charting, and 43% used a pre-defined charting form. In most cases, the results of the scoping review were used to identify evidence gaps (85%), provide recommendations for future research (84%), or identify strengths and limitations (69%). We did not identify any guidelines for reporting scoping reviews or studies that assessed the quality of scoping review reporting.
The number of scoping reviews conducted per year has steadily increased since 2012. Scoping reviews are used to inform research agendas and identify implications for policy or practice. As such, improvements in reporting and conduct are imperative. Further research on scoping review methodology is warranted, and in particular, there is need for a guideline to standardize reporting.
The systematic review on which this paper is based provided evidence for the Canadian Task Force on Preventive Health Care to update their guideline regarding screening for cervical cancer. In this ...article we highlight three questions covered in the full review that pertain to the effectiveness of screening for reducing cervical cancer mortality and incidence as well as optimal timing and frequency of screening.
We searched MEDLINE, Embase and Cochrane Central from 1995 to 2012 for relevant randomized controlled trials and observational studies with comparison groups. Eligible studies included women aged 15 to 70 years who were screened using conventional cytology, liquid-based cytology or human papillomavirus DNA tests. Relevance screening, data extraction, risk of bias analyses and quality assessments were performed in duplicate. We conducted a meta-analysis using a random-effects model on the one body of evidence that could be pooled.
From the 15,145 screened citations, 27 papers (24 studies) were included; five older studies located in a United States Preventive Services Task Force review were also included. A randomized controlled trial in India showed even a single lifetime screening test significantly decreased the risk of mortality from and incidence of advanced cervical cancer compared to no screening (mortality: risk ratio 0.65, 95% confidence interval 0.47, 0.90; incidence: relative risk 0.56, 95% confidence interval 0.42, 0.75). Cytology screening was shown to be beneficial in a cohort study that found testing significantly reduced the risk of being diagnosed with invasive cervical cancer compared to no screening (risk ratio 0.38; 95% confidence interval 0.23, 0.63). Pooled evidence from a dozen case-control studies also indicated a significant protective effect of cytology screening (odds ratio 0.35; 95% confidence interval 0.30, 0.41). This review found no conclusive evidence for establishing optimal ages to start and stop cervical screening, or to determine how often to screen; however the available data suggests substantial protective effects for screening women 30 years and older and for intervals of up to five years.
The available evidence supports the conclusion that cervical screening does offer protective benefits and is associated with a reduction in the incidence of invasive cervical cancer and cervical cancer mortality.
Abstract Background This report was produced for the Canadian Task Force on Preventive Health Care to provide guidelines on screening for abdominal aortic aneurysm (AAA) with ultrasound scan. Purpose ...The aim of this systematic review is to examine the evidence on benefits and harms of AAA screening. Search strategy This systematic review considered studies from the most recent United States Preventive Services Task Force review on AAA screening and passed through the screening process with citations identified in our search up to April 2015 (PROSPERO Registration #CRD42015019047). Results For benefits of one-time AAA screening in men compared with controls, pooled analyses from four randomized controlled trials with moderate quality evidence showed significant reductions in AAA-related mortality and AAA rupture rate up to 13 to 15 years of follow-up with 42% reduction (risk ratio RR, 0.58; 95% confidence interval CI, 0.39-0.88; number needed to screen = 212) and 38% reduction (RR, 0.62; 95% CI, 0.45-0.86; number needed to screen = 200), respectively. The effect of on all-cause mortality was marginally significant for longer follow-up. The Chichester trial examined the benefits of one-time AAA screening in women and found no significant differences between screening and control arms for up to 10 years of follow-up (RR, 0.88; 95% CI, 0.72-1.07). For consequences of one-time AAA screening in men compared with controls, there was a significant increase in the total number of AAA-related procedures over a follow-up of 13 to 15 years (2.16 times more likely) compared with controls. For harms of one-time AAA screening, no significant differences were observed in 30-day postoperative mortality for elective and emergency operations with compared control groups. Evidence from the Multicenter Aneurysm Screening Study trial using 13-year follow-up data showed that one-time AAA screening with ultrasound scan was potentially associated with an overdiagnosis of 45% (95% CI, 42%-47%) among screen-detected men. Conclusions Population-based screening for AAA with ultrasound scan in asymptomatic men aged 65 years and older showed statistically significant reductions in AAA-related mortality and rupture and, hence, avoids unnecessary AAA-related deaths. The current evidence showed no benefit of one-time AAA screening in woman. Limited evidence is available on the benefits of repeat AAA screening and targeted screening approaches based on risk factors for AAA. Future research should explore the differential benefits of AAA screening based on risk factors that increase risk for developing AAA.
Abstract Objective To evaluate the effectiveness of colorectal cancer (CRC) screening in asymptomatic adults. Data Sources The search was conducted in Medline, Embase and the Cochrane Library. A ...targeted search of PubMed was conducted for on topic RCTs. Results Meta-analysis across four RCTs for guaiac fecal occult blood testing (gFOBT) and flexible sigmoidoscopy (FS) screening showed a reduction of 18% RR 0.82 (95% CI 0.73-0.92) and 26% RR 0.74 (95% CI 0.67-0.83) in CRC mortality for screening group as compared to controls respectively. The number needed to screen (NNS) were 377 (95% CI 249-887) and 864 (95% CI 672-1,266) for gFOBT and FS screening respectively. A reduction of 8% and 27% in incidence of late stage CRC was also observed for gFOBT and FS screening respectively, but both had no significant effect on all-cause mortality. A single RCT found that screening with immunochemical fecal occult blood test (iFOBT) had no significant impact on CRC mortality RR 0.88 (95% CI 0.72-1.07). Screening with FS has potential harms such as perforation, both major and minor bleeding, and death from the procedure or from follow-up colonoscopy. Conclusion gFOBT and FS screening reduce CRC mortality and incidence of late stage disease. The absolute effect and NNS were much more favorable for older adults (≥ 60 years) suggesting a targeted screening approach may avoid exposing younger adults to harms of CRC screening which are unlikely to derive any significant benefit. Although there is insufficient RCT evidence on the impact of iFOBT on mortality outcomes; as compared to gFOBT, this test showed higher sensitivity and comparable specificity indicating the need to update and re-evaluate the evidence in light of future high quality research. Methods for this systematic review have been published with PROSPERO 2014: CRD42014009777.
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