Question: In what capacity did the author of the book,  An Inconvenient Truth,  serve in the United States government ? 

Context:
Richard Haag
Richard Haag (born October 23, 1923) is a United States landscape architect.
 He is famous for his work on Gas Works Park in Seattle, Washington and on the Bloedel Reserve on Bainbridge Island.
 He is also noted for founding the Landscape Architecture Program at the University of Washington and for holding multiple design awards.
 His designs call to mind the current trend of being one with and improving the environment.
 Although Al Gore's "An Inconvenient Truth" is after Richard Haag's heyday, the ideals evoked from the film are shown in his designs.
 The social movement that created the hybrid car also demanded sustainable design, and Richard Haag provided it in the most distinctive and astounding ways.
 Richard Haag's modernist and minimalist ideals set the tone for northwestern landscape design and has placed the northwest on the road towards ecologically-minded design.
An Inconvenient Truth
An Inconvenient Truth is a 2006 American documentary film directed by Davis Guggenheim about former United States Vice President Al Gore's campaign to educate citizens about global warming via a comprehensive slide show that, by his own estimate made in the film, he has given more than a thousand times.
 The idea to document his efforts came from producer Laurie David, who saw his presentation at a town-hall meeting on global warming, which coincided with the opening of "The Day After Tomorrow".
 Laurie David was so inspired by Gore's slide show that she, with producer Lawrence Bender, met with Guggenheim to adapt the presentation into a film.
An Inconvenient Truth (book)
An Inconvenient Truth: The Planetary Emergency of Global Warming and What We Can Do About It is a 2006 book by Al Gore released in conjunction with the film "An Inconvenient Truth".
 It is published by Rodale Press in Emmaus, Pennsylvania, in the United States.
Yankton Treaty
The Yankton Treaty was a treaty signed in 1858 between the United States government and the Yankton Sioux (Nakota) Native American tribe, ceding most of eastern South Dakota to the United States government.
 The treaty was signed in April 1858, and ratified by the United States Congress on February 17, 1859.
 The agreement immediately opened this territory up for settlement by whites, resulting in the establishment of an unofficial local government not recognized by Washington.
 The treaty also created the 400,000 acre Yankton Sioux Reservation, located in present-day Charles Mix County in South Dakota.
Civilian Public Service
The Civilian Public Service (CPS) was a program of the United States government that provided conscientious objectors with an alternative to military service during World War II.
 From 1941 to 1947, nearly 12,000 draftees, willing to serve their country in some capacity but unwilling to perform any type of military service, accepted assignments in "work of national importance" in 152 CPS camps throughout the United States and Puerto Rico.
 Draftees from the historic peace churches and other faiths worked in areas such as soil conservation, forestry, fire fighting, agriculture, under the supervision of such agencies as the U.S. Forest Service, the Soil Conservation Service, and the National Park Service.
 Others helped provide social services and mental health services.
United States Government Manual
The United States Government Manual is the official handbook of the federal government, published annually by the Office of the Federal Register and printed and distributed by the United States Government Printing Office.
 The first edition was issued in 1935; before the 1973/74 edition it was known as the United States Government Organization Manual.
Missouri Photo Workshop
The Missouri Photo Workshop is an annual week-long photojournalism school based in Lee Hills Hall at the Missouri School of Journalism in Columbia, Missouri.
 Founded in 1949 by the "Father of Photojournalism" Cliff Edom along with American economist, federal government official, and photographer Roy Stryker and photographer Russell Lee, the workshop originally sought to instruct others in photojournalism based on the "gritty, content-rich photographs" produced by the pre-World War II (pre-1939) Farm Security Administration, a United States government effort during the Great Depression to combat American rural poverty.
 Following Edom's credo - "Show truth with a camera.
 Ideally truth is a matter of personal integrity.
 In no circumstances will a posed or faked photograph be tolerated."
 - each workshop originates in a different small town in Missouri, which is used as a backdrop for attendees from the United States and other countries to work on photograph storytelling methods such as research, observation, and timing.
 Missouri Photo Workshop faculty members have included the White House's first photo editor and NPPA Picture Editor of the Year Sandra Eisert and other prominent photojournalists.
Al Gore
Albert Arnold Gore Jr. (born March 31, 1948) is an American politician and environmentalist who served as the 45th Vice President of the United States from 1993 to 2001.
 Gore was Bill Clinton's running mate in their successful campaign in 1992, and the pair were re-elected in 1996.
 Near the end of President Clinton's second term, Gore was selected as the Democratic nominee for the 2000 presidential election but did not win the election.
 After his term as vice-president ended in 2001, Gore remained prominent as an author and environmental activist, whose work in climate change activism earned him (jointly with the IPCC) the Nobel Peace Prize in 2007.
An Inconvenient Sequel: Truth to Power
An Inconvenient Sequel: Truth to Power is a 2017 American documentary film directed by Bonni Cohen and Jon Shenk about former United States Vice President Al Gore's continuing mission to battle climate change.
 The sequel to "An Inconvenient Truth" (2006), the film addresses the progress made to tackle the problem and Gore's global efforts to persuade governmental leaders to invest in renewable energy, culminating in the landmark signing of 2016's Paris Agreement.
 The film was released on July 28, 2017, by Paramount Pictures.
Laurie David
Laurie Ellen David (née Lennard; born March 22, 1958) is an American environmental activist.
 She produced the Academy Award-winning "An Inconvenient Truth" and, most recently, teamed up with Katie Couric to executive produce "Fed Up", a film about the causes of obesity in the United States.
 She serves as a trustee on the Natural Resources Defense Council and a member of the Advisory Board of the Children's Nature Institute and is a contributing blogger to "The Huffington Post".

Answer: Vice President