Ilissa Ocko

Environmental Defense Fund · Global Climate

Food consumption is a major source of greenhouse gas (GHG) emissions, and evaluating its future warming impact is crucial for guiding climate mitigation action. However, the lack of granularity in reporting food item emissions and the widespread use of oversimplified metrics such as CO2 equivalents have complicated interpretation. We resolve these...

Food consumption is a major source of greenhouse gases emissions, and evaluating its future warming impact is crucial for guiding climate mitigation action. However, the lack of granularity in reporting greenhouse gas emissions from food items and widespread use of oversimplified metrics such as CO 2 -equivalence has made this difficult. We resolve...

Given the urgency to decarbonize global energy systems, governments and industry are moving ahead with efforts to increase deployment of hydrogen technologies, infrastructure, and applications at an unprecedented pace, including USD billions in national incentives and direct investments. While zero- and low-carbon hydrogen hold great promise to hel...

A growing body of literature has identified methane mitigation as a key component of limiting the rate and extent of global warming. However, little is known about how methane mitigation can benefit other critical aspects of the climate system. This study explores the value of early methane mitigation in addition to carbon dioxide mitigation in hel...

Hydrogen is quickly gaining attention as a “clean” fuel that can support a transition to a decarbonized energy system. Given the urgency to decarbonize global energy systems, governments and industry are moving ahead with efforts to increase hydrogen technologies, infrastructure, and applications at an unprecedented pace, including billions in nati...

Net zero greenhouse gas targets have become a central element for climate action. However, most company and government pledges focus on the year that net zero is reached, with limited awareness of how critical the emissions pathway is in determining the climate outcome in both the near- and long-term. Here we show that different pathways of carbon...

Methane mitigation is essential for addressing climate change, but the value of rapidly implementing available mitigation measures is not well understood. In this paper, we analyze the climate benefits of fast action to reduce methane emissions as compared to slower and delayed mitigation timelines. We find that the scale up and deployment of great...

While individual countries work to achieve and strengthen their nationally determined contributions (NDCs) to the Paris Agreement, the growing emissions from two economic sectors remain largely outside most countries' NDCs: international shipping and international aviation. Reducing emissions from these sectors is particularly challenging because t...

To stabilize the climate, we must rapidly displace fossil fuels with clean energy technologies. Currently hydropower dominates renewable electricity generation, accounting for two-thirds globally, and is expected to grow by at least 45% by 2040. While it is broadly assumed that hydropower facilities emit greenhouse gases on par with wind, there is...

While individual countries work to achieve and strengthen their nationally determined contributions to the Paris Agreement, the growing emissions from two economic sectors remain outside the bounds of national jurisdictions: international shipping and aviation. Reducing emissions from these sectors is particularly challenging because adoption of an...

KEY FINDINGS 1. In 2013, primary energy use in North America exceeded 125 exajoules,1 of which Canada was responsible for 11.9%, Mexico 6.5%, and the United States 81.6%. Of total primary energy sources, approximately 81% was from fossil fuels, which contributed to carbon dioxide equivalent (CO2e)2 emissions levels, exceeding 1.76 petagrams of carb...

It is clear that the most effective way to limit global temperature rise and associated impacts is to reduce human emissions of greenhouse gases, including methane. However, quantification of the climate benefits of mitigation options are complicated by the contrast in the timescales at which short-lived climate pollutants, such as methane, persist...

It is clear that the most effective way to limit global temperature rise and associated impacts is to reduce human emissions of greenhouse gases, including methane. However, quantification of the climate benefits of mitigation options are complicated by the contrast in the timescales at which short-lived climate pollutants, such as methane, persist...

Global warming potentials (GWPs) have become an essential element of climate policy and are built into legal structures that regulate greenhouse gas emissions. This is in spite of a well-known shortcoming: GWP hides trade-offs between short- and long-term policy objectives inside a single time scale of 100 or 20 years ( 1 ). The most common form, G...

Anthropogenic aerosols are a key factor governing Earth's climate and play a central role in human-caused climate change. However, because of aerosols' complex physical, optical, and dynamical properties, aerosols are one of the most uncertain aspects of climate modeling. Fortunately, aerosol measurement networks over the past few decades have led...

Anthropogenic aerosols are a key factor governing Earth’s climate, and play a central role in human-caused climate change. However, because of aerosols’ complex physical, optical, and dynamical properties, aerosols are one of the most uncertain aspects of climate modeling. Fortunately, aerosol measurement networks over the past few decades have led...

Anthropogenic aerosols comprise optically scattering and absorbing particles, with the principal concentrations being in the Northern Hemisphere, yielding negative and positive global mean radiative forcings, respectively. Aerosols also influence cloud albedo, yielding additional negative radiative forcings. Climate responses to a comprehensive set...

The direct radiative forcing of the climate system includes effects due to scattering and absorbing aerosols. This study explores how important physical climate characteristics contribute to the magnitudes of the direct radiative forcings (DRF) from anthropogenic sulfate, black carbon, and organic carbon. For this purpose, we employ the GFDL CM2.1...

Mann offers a personal account of the acrimonious attacks on climate change science.

Measurements of ozone (O3) and carbon monoxide (CO) have been made above a Mixed Hardwood Forest in northern Michigan as part of the Program for Research on Oxidants: PHotochemistry, Emissions, and Transport (PROPHET) since 1997. Back trajectories calculated using the NOAA HYSPLIT Model have been used to classify air masses reaching the site into f...

Several intensive campaigns have recently focused on the transformation and transport of pollutants to the Arctic. During the International Polar Year large-scale coordinated aircraft campaigns will be conducted throughout the circum-Arctic as a part of the POLARCAT project. Additionally, measurements at surface based sites in the IASOA network wil...

The purpose of this study is to better understand the typical air flow regime and environmental conditions of the University of Michigan Biological Station (UMBS), and determine the seasonal and year-to-year variability from 1999-2005. Calculating back-trajectories of air parcels arriving at the station exposes the history of the air mass flow, whi...