660 Items

erosion of a dune in front of a house

AP/Virginia Mayo

Presentation - Belfer Center for Science and International Affairs, Harvard Kennedy School

Climate Change and Cape Cod: What We Know. What We Expect. What We Can Do.

| Mar. 29, 2019

Professor John P. Holdren made these remarks for the Harvard Institute for Learning in Retirement at the Marine Biological Laboratory in Woods Hole, Massachusetts, on March 29, 2019.

Earthrise over the Moon

NASA/Bill Anders

Journal Article - Nature Sustainability

Policy Design for the Anthropocene

    Authors:
  • Thomas Sterner
  • Edward B. Barbier
  • Ian Bateman
  • Inge van den Bijgaart
  • Anne-Sophie Crépin
  • Ottmar Edenhofer
  • Carolyn Fischer
  • Wolfgang Habla
  • John Hassler
  • Olof Johansson-Stenman
  • Andreas Lange
  • Stephen Polasky
  • Johan Rockström
  • Henrik G. Smith
  • Will Steffen
  • James E. Wilen
  • Francisco Alpízar
  • Christian Azar
  • Donna Carless
  • Carlos Chávez
  • Jessica Coria
  • Gustav Engström
  • Sverker C. Jagers
  • Gunnar Köhlin
  • Åsa Löfgren
  • Håkan Pleijel
  • Amanda Robinson
| 2019

The authors examine the complexities of designing policies that can keep Earth within the biophysical limits favorable to human life.

iceberg in North Star Bay

NASA/Jeremy Harbeck

Presentation - Belfer Center for Science and International Affairs, Harvard Kennedy School

International Collaboration in Arctic Science: Progress and Prospects

| Dec. 13, 2018

Professor John P. Holdren gave this presentation at the Session on 60 Years of Arctic & Antarctic Science at the American Geophysical Union Fall Meeting in Washington, D.C., on December 13, 2018.

Sunset on the Indian Ocean

NASA

Journal Article - Environmental Research Letters

Stratospheric Aerosol Injection Tactics and Costs in the First 15 Years of Deployment

| 2018

We review the capabilities and costs of various lofting methods intended to deliver sulfates into the lower stratosphere. We lay out a future solar geoengineering deployment scenario of halving the increase in anthropogenic radiative forcing beginning 15 years hence, by deploying material to altitudes as high as ~20 km. After surveying an exhaustive list of potential deployment techniques, we settle upon an aircraft-based delivery system. Unlike the one prior comprehensive study on the topic (McClellan et al 2012 Environ. Res. Lett. 7 034019), we conclude that no existing aircraft design—even with extensive modifications—can reasonably fulfill this mission. However, we also conclude that developing a new, purpose-built high-altitude tanker with substantial payload capabilities would neither be technologically difficult nor prohibitively expensive. We calculate early-year costs of ~$1500 ton−1 of material deployed, resulting in average costs of ~$2.25 billion yr−1 over the first 15 years of deployment. We further calculate the number of flights at ~4000 in year one, linearly increasing by ~4000 yr−1. We conclude by arguing that, while cheap, such an aircraft-based program would unlikely be a secret, given the need for thousands of flights annually by airliner-sized aircraft operating from an international array of bases.