Under brilliant blue skies, more than 10,000 people marched to the State Capitol on Saturday in defense of science, the largest Minnesota arm of a global effort to champion independent research and scientific fact at a time when many people feel that both are under attack by those seeking political gain.

"Science is the truth — you can prove it," said a white-coat-clad Jeannine Conway, a professor at the University of Minnesota's College of Pharmacy. "Most things we do benefit everyone."

Beginning at St. Paul's Cathedral Hill Park, the Minnesota march ended a short distance away at a rally outside the Capitol that featured impassioned pro-science speakers. They argued that investing in science education, vaccinating children and taking measures to combat climate change should be collective, nonpartisan actions undertaken for the benefit of all.

An idea that first arose after the massive worldwide protests on Jan. 21 against the new Trump administration, the science march likewise attracted interest across six continents. In all, marchers in more than 600 cities marked the occasion, with notable events in London, Paris and Sydney. Washington, D.C., Chicago, New York and Los Angeles were among the largest U.S. marches, and smaller events took place across the country.

In Minnesota, 12 other rallies took place beyond the main event in St. Paul.

The St. Paul march was peaceful and upbeat, with live music along the route. Among the whimsical, mostly handmade signs were ones that read, "Defiance for science," "There is no Planet B," "Climate change is not a liberal conspiracy" and "I like big brains — I cannot lie."

Video (01:37): 10,000-plus march in name of science in St. Paul Video (01:37): 10,000-plus march in name of science in St. Paul

While organizers went out of their way to label the event nonpartisan, there was no doubt that the demonstrators' ire was squarely focused on President Donald Trump and his administration. The president, who previously dismissed climate change as a hoax, has appointed a head of the Environmental Protection Agency who wants the United States to pull out of the Paris climate accord and has proposed broad rollbacks of environmental regulations. Trump's proposed EPA budget calls for a 31 percent cut in its funding.

In an Earth Day statement hours after the marches began, Trump took what appeared to be a conciliatory tone, saying that "rigorous science depends not on ideology, but on a spirit of honest inquiry and robust debate." He called science critical to economic growth and said his administration is committed to a better understanding of environmental risks.

Many of the marchers, however, saw Trump's message as empty words.

Denis Hayes, co-founder of the first Earth Day in 1970, told demonstrators in Washington that Trump has brought a new, disturbing tone to the capital.

"America has had 45 presidents, but we have never before had a president who is completely indifferent to the truth. Donald Trump makes Richard Nixon look like Diogenes," Hayes said.

'Seekers of truth'

Climatologist Mark Seeley began the St. Paul rally with a speech urging citizens to serve as stewards of the environment and one another, and decrying attempts to mock or marginalize science.

"Some go so far now to say that scientists conspire to deceive the public," Seeley said. "Nothing could be further from the truth. Scientists are seekers of truth."

Alan Lifson, a professor of epidemiology at the University of Minnesota, told the crowd that false narratives about science are increasingly endangering public health. He cited a recent outbreak of measles among children in Minnesota's Somali immigrant community, where many people have been led to believe that crucial vaccinations are hazardous and unnecessary.

U.S. Rep. Betty McCollum, D-Minn., the rally's final speaker, declared science "under attack" by the Trump administration and urged residents to cast a vote for science in the next presidential election.

"Today is about standing united to fight the destructive political agenda that promotes ignorance, denial and dangerous alternative facts — otherwise known as lies," she said. "We cannot allow climate deniers up at Capitol Hill to undermine the pursuit of knowledge through scientific discovery."

A time 'to be engaged'

The wall of marchers eventually stretched more than five city blocks and included hundreds of retirees and parents with children. At least 60 volunteers collected litter as they walked, saying that in the spirit of Earth Day, they wanted to leave their route cleaner than they found it.

Karen Tarrant of St. Paul walked alongside her son, Patrick Raines, occasionally pausing to toss cigarette butts in a trash bag. Though one march will not change the climate, she said, nonlinear progress is sure to occur.

"This will land on the president's desk," said Tarrant, 68. "At least on the margins, he will pay attention to it. I don't know what to do other than to be here."

Raines, dressed in a white lab coat and toting a cardboard Captain America shield, said he worries that even the short-term effects of climate change will be life-changing for everyone.

People head Saturday to the Capitol in St. Paul as part of the international March for Science.

"If we don't get our act together, then I shouldn't make plans past 2050," said Raines, 28, a St. Paul resident and Boston Scientific employee.

Beth Campbell, a professor at the U's Carlson School of Management, said she has previously donated to social causes but hadn't become an activist until the Women's March in January.

Though she's long considered herself politically unaffiliated, Campbell, 33, of Minneapolis, said she now fears that American culture is moving away from "evidence-based opinions."

"It's an important time to be civically and socially engaged," she said. "At the end of the day, it's about science. But if there's a specific party that neglects and misuses science to further their platform, I won't be silent about that."

Some protesters brought along their pets, the animals acting as trotting billboards for protest signs. Joshua Davies' Briard shepherd helped build morale for the movement.

"Science and critical thinking should not be bad words," said Davies of River Falls, Wis. "It's seemingly impervious to reason that we would ignore everything in the best interest of our species."

Star Tribune wire services contributed to this report.