Methane Mitigation:Methods to Reduce Emissions, on the Path to the Paris Agreement

The atmospheric methane burden is increasing rapidly, contrary to pathways compatible with the goals of the 2015 United Nations Framework Convention on Climate Change Paris Agreement. Urgent action is required to bring methane back to a pathway more in line with the Paris goals. Emission reduction from “tractable” (easier to mitigate) anthropogenic sources such as the fossil fuel industries and landfills is being much facilitated by technical advances in the past decade, which have radically improved our ability to locate, identify, quantify, and reduce emissions. Measures to reduce emissions from “intractable” (harder to mitigate) anthropogenic sources such as agriculture and biomass burning have received less attention and are also becoming more feasible, including removal from elevated-methane ambient air near to sources. The wider effort to use microbiological and dietary intervention to reduce emissions from cattle (and humans) is not addressed in detail in this essentially geophysical review. Though they cannot replace the need to reach “net-zero” emissions of CO2, significant reductions in the methane burden will ease the timescales needed to reach required CO2 reduction targets for any particular future temperature limit. There is no single magic bullet, but implementation of a wide array of mitigation and emission reduction strategies could substantially cut the global methane burden, at a cost that is relatively low compared to the parallel and necessary measures to reduce CO2, and thereby reduce the atmospheric methane burden back toward pathways consistent with the goals of the Paris Agreement

Combining behavioural types with security analysis

Today's software systems are highly distributed and interconnected, and they increasingly rely on communication to achieve their goals; due to their societal importance, security and trustworthiness are crucial aspects for the correctness of these systems. Behavioural types, which extend data types by describing also the structured behaviour of programs, are a widely studied approach to the enforcement of correctness properties in communicating systems. This paper offers a unified overview of proposals based on behavioural types which are aimed at the analysis of security properties

iLeak: A Lightweight System for Detecting Inadvertent Information Leaks

Data loss incidents, where data of sensitive nature are exposed to the public, have become too frequent and have caused damages of millions of dollars to companies and other organizations. Repeatedly, information leaks occur over the Internet, and half of the time they are accidental, caused by user negligence, misconfiguration of software, or inadequate understanding of an application's functionality. This paper presents iLeak, a lightweight, modular system for detecting inadvertent information leaks. Unlike previous solutions, iLeak builds on components already present in modern computers. In particular, we employ system tracing facilities and data indexing services, and combine them in a novel way to detect data leaks. Our design consists of three components: uaudits are responsible for capturing the information that exits the system, while Inspectors use the indexing service to identify if the transmitted data belong to files that contain potentially sensitive information. The Trail Gateway handles the communication and synchronization of uaudits and Inspectors. We implemented iLeak on Mac OS X using DTrace and the Spotlight indexing service. Finally, we show that iLeak is indeed lightweight, since it only incurs 4% overhead on protected applications

Privacy in the Genomic Era

Genome sequencing technology has advanced at a rapid pace and it is now possible to generate highly-detailed genotypes inexpensively. The collection and analysis of such data has the potential to support various applications, including personalized medical services. While the benefits of the genomics revolution are trumpeted by the biomedical community, the increased availability of such data has major implications for personal privacy; notably because the genome has certain essential features, which include (but are not limited to) (i) an association with traits and certain diseases, (ii) identification capability (e.g., forensics), and (iii) revelation of family relationships. Moreover, direct-to-consumer DNA testing increases the likelihood that genome data will be made available in less regulated environments, such as the Internet and for-profit companies. The problem of genome data privacy thus resides at the crossroads of computer science, medicine, and public policy. While the computer scientists have addressed data privacy for various data types, there has been less attention dedicated to genomic data. Thus, the goal of this paper is to provide a systematization of knowledge for the computer science community. In doing so, we address some of the (sometimes erroneous) beliefs of this field and we report on a survey we conducted about genome data privacy with biomedical specialists. Then, after characterizing the genome privacy problem, we review the state-of-the-art regarding privacy attacks on genomic data and strategies for mitigating such attacks, as well as contextualizing these attacks from the perspective of medicine and public policy. This paper concludes with an enumeration of the challenges for genome data privacy and presents a framework to systematize the analysis of threats and the design of countermeasures as the field moves forward

DR.SGX: Hardening SGX Enclaves against Cache Attacks with Data Location Randomization

Recent research has demonstrated that Intel's SGX is vulnerable to various software-based side-channel attacks. In particular, attacks that monitor CPU caches shared between the victim enclave and untrusted software enable accurate leakage of secret enclave data. Known defenses assume developer assistance, require hardware changes, impose high overhead, or prevent only some of the known attacks. In this paper we propose data location randomization as a novel defensive approach to address the threat of side-channel attacks. Our main goal is to break the link between the cache observations by the privileged adversary and the actual data accesses by the victim. We design and implement a compiler-based tool called DR.SGX that instruments enclave code such that data locations are permuted at the granularity of cache lines. We realize the permutation with the CPU's cryptographic hardware-acceleration units providing secure randomization. To prevent correlation of repeated memory accesses we continuously re-randomize all enclave data during execution. Our solution effectively protects many (but not all) enclaves from cache attacks and provides a complementary enclave hardening technique that is especially useful against unpredictable information leakage

The environmental and political ecology of natural gas

Methane (CH4) is the primary constituent of natural gas and a significant contributor to global climate change, accounting for 11% of all U.S. greenhouse gas emissions. With the advent of hydraulic fracturing technology, production of natural gas from shale gas reserves has increased by 35% from 2005 to 2013. Fugitive CH4 emissions attributed to venting or leakage across the life cycle of natural gas systems have also increased, making the climate benefits ascribed to natural gas questionable when compared to oil and coal. This dissertation reports the results of three studies that improve our knowledge of the environmental and political ramifications of continued investment in and consumption of natural gas fuels. Using bottom-up flux chamber techniques we made direct measurements of CH4 emissions from 100 natural gas leaks in cast iron distribution mains within Metro Boston, MA in order to assess the nature of the distribution of gas leak size and constrain estimates of fugitive CH4 emissions across leak-prone urban distribution infrastructure. We find that the distribution of leak size is skewed, a small fraction of ‘superemitter’ leaks contribute disproportionate CH4 emissions, and CH4 flux at leak sites is not an indicator of safety. Next, we use the lens of urban natural gas infrastructure systems and apply an ecological analytical framework to identify dysfunctions in and opportunities for coordinated urban infrastructure management in Boston, MA. We find that there are real physical and fiscal constraints to retrofitting and expanding aging, urban infrastructure in U.S. cities. Achieving sustainable, resilient urban infrastructure requires active participation by all stakeholders as well as coordination within and between stakeholder groups. Finally, we introduce the term ‘unleakable carbon’ to refer to the uncombusted carbon-based gases associated with fossil fuel systems and demonstrate that in particular the unleakable carbon associated with natural gas constitutes a potentially large and heretofore unrecognized factor in estimating usable portions of Earth’s fossil fuel reserves. We demonstrate that unless unleakable carbon is curtailed, roughly 80 – 100% of our global natural gas reserves must remain underground if we hope to limit warming to 2 °C from 2010 to 2050