Three out of four U.S. Millennials, young adults who are between 18 and 29 years old, oppose the use of hydraulic fracturing (fracking), according to a new poll by Harvard University’s Institute of Politics (IOP).

The biannual “Survey of Young Americans’ Attitudes Toward Policies and Public Service” was published on Wednesday. The group of young adults, surveyed between March 18 and April 1, is split on their views of the Keystone XL oil pipeline, which would carry crude oil from Canada to the Gulf Coast. Overwhelmingly, Millennials believe global warming is a proven fact.

“The Institute of Politics has been polling America’s Millennials, the largest generation in our nation’s history, for 15 years,” said IOP Director Maggie Williams. “Our spring poll shows there are millions of 18- to 29-year-olds who remain hopeful about our nation’s future. They are ready to engage in the 2016 election — from voting to volunteering — if political leaders build trust not only as candidates but also in the political process itself.”

The KnowledgePanel survey of 3,034 U.S. citizens was conducted with the Government and Academic Research team at GfK. The survey has a margin of error of plus/minus 2.4%, or a 95% confidence level.

“Based on what you know at this time, do you support or oppose the use of fracking in America?” the survey asked. Fifty-eight percent of those queried opposed fracking, while 40% said they supported it.

Support for the Keystone pipeline was split, with 50% in favor and 48% opposed to transporting Canadian heavy oil to Gulf Coast refineries.

The biggest response came in statements concerning views about global warming, with 75% of those surveyed agreeing it is occurring.

Of three statements offered asking respondents to choose the sentence they mostly represented their views, 55% said they believe “global warming is a proven fact and is mostly caused by emissions from cars and industrial facilities such as power plants and factories.” Another 20% said, “global warming is a proven fact and is mostly caused by natural changes that have nothing to do with emissions from cars and industrial facilities.” Only 20% said it “is a theory that has not yet been proven.”

In other findings, the poll found a solid majority — 55% — would prefer a Democrat winning the 2016 presidential campaign, while 40% would prefer a Republican. Minorities were strongly in favor of a Democrat retaining control, while a majority of white adults, 53% to 41%, prefer GOP control.

There also are “hints of optimism” emerging as trust in institutions begins to improve, but there are low levels of trust persisting for federal government and Congress. President Obama’s approval ratings also have increased across the board, especially by Hispanics. Among the Millennials surveyed, Obama’s job performance improved by 7% over the past six months to 50% from 43% last October. “Tracking with the president, job approval of Democrats in Congress improved five percentage points” to 40% from 35%, while approval of Republicans in Congress remained at 23% for the third straight poll.

The goal of the project was to collect 3,000 completed interviews, with a small pretest conducted prior to the main survey to examine the accuracy of the data and the length of the interview. There were 6,075 KnowledgePanel members assigned to the study, with a cooperation rate of 51.3%, which resulted in 3,034 completed interviews. Of those surveyed, 116 were conducted in Spanish.