It’s hard right now to remember how hot it was last August on the long sandy beach where the Colorado river meets the Green river in southern Utah. I was a few days into a rafting trip through Cataract Canyon with a bunch of young climate activists, and one of them, Will Munger, was telling me that since his months at the Standing Rock resistance camp, he had been encountering young Native people whose experiences at the protest site had encouraged them to dream of new possibilities and take actions that might otherwise have seemed out of reach.

Wandering back and forth along the edge of the water, we began to discuss how, often, the consequences of an uprising or a movement are not linear. Success and failure are often premature measures and oversimplifications; actions, interventions and conversations change beliefs and create new values, alliances and possibilities. We’d seen this dynamic from many unanticipated uprisings and movements: the indigenous movement Idle No More, which began in Canada in 2012; Black Lives Matter; the feminist insurgencies since 2013 and the anti-gun movement in the hands of the Parkland youth.

On a cold day this January, I was thinking again about that conversation as I contemplated Alexandria Ocasio-Cortez’s decision to run for office. “I first started considering running for Congress, actually, at Standing Rock in North Dakota,” she said late last year. “It was really from that crucible of activism where I saw people putting their lives on the line … for people they’ve never met and never known. When I saw that, I knew that I had to do something more.”

In 2016, when LaDonna Brave Bull Allard and others launched the camps protesting the Dakota Access pipeline, they could not have known some of the indirect consequences of their actions – including prompting a young woman from New York City to run for office. Sometimes the results that matter are not direct or intended – though four tribes continue to litigate over the pipeline, and they had a modest court victory on 8 January.

Today, Ocasio-Cortez represents New York’s 14th district in Congress, and 45 congresspeople support the Green New Deal that she began promoting last fall. Significantly, the Green New Deal is not Ocasio-Cortez’s creation. As Standing Rock prompted her to run for office, the Sunrise Movement created the climate vision she carried into Congress. Founded in 2017, Sunrise is a youth-led movement that aims to “to stop climate change and create millions of good jobs in the process”. As the movement’s co-founder Varshini Prakash recently told the Huffington Post, Sunrise is trying to “activate the millions of Americans who are ready to fight for a Green New Deal but haven’t heard of it yet”. For me, the movement’s sudden appearance in national politics this year was even more surprising and thrilling than Ocasio-Cortez’s primary victory.

The Green New Deal is a much-needed response to what the Intergovernmental Panel on Climate Change and American scientists told us last fall: we probably have 12 years to transform the energy economy globally, or else. The proposal makes its mark by setting new goals for the nation and by reminding us that climate and jobs, ecology and economies don’t have to be opposed, while recent polls tell the congressional leadership that the majority of Americans want swift and radical action on climate.

Getting there requires understanding that the process may not be straightforward. Unsurprisingly, the Green New Deal was not immediately adopted by the Democratic leadership, and if you were to tell the story thus far in the terms that we’ve learned from action movies and sports, it’s a conflict that already has a conclusion: as the news site Politico put it: “Speaker of the House Nancy Pelosi 2, Ocasio-Cortez 0.”

But, like the Standing Rock uprising, the work of the Sunshine Movement and Ocasio-Cortez will generate other benefits and consequences; if we are going to get to the goal it will, of course, be by a more circuitous route – though it must be a speedy one. Last Wednesday, Congressmen Jimmy Gomez and Ted Lieu of California introduced a bill, the Climate Solutions Act of 2019, with similar goals – or reintroduced it, since Lieu (who’s also supporting the Green New Deal) has introduced a bill by that name twice before.

You could not possibly catalyze a movement in the Dakotas with the intention that a woman would run for Congress in New York City and then go to the Capitol to advocate on climate. You could not assume, imagine or calculate that that would be a consequence. But you can recognize how common such indirect consequences are, and how important it is to not discount them. The course of history is full of confluences and meanders, oxbows, watersheds, dams and floods, tributaries and distributaries.

Cataract Canyon is where the Colorado river pours into the reservoir of stagnant water backed up from Glen Canyon dam. When Glen Canyon dam was completed, a little more than 50 years ago, most people – whether they loved or hated this massive intervention in the wilderness – imagined that the reservoir would stand for centuries. But the dam is failing, thanks to overallocation of the river’s water and to the way climate change has reduced rainfall and snowfall in its watershed.

At the end of my journey with Will and the other climate activists, I saw over and over how the river was cutting new channels through the silt that had built up when the reservoir was higher; how what was stagnant was now active again. This was never supposed to happen, or it was supposed to happen hundreds of years hence.

“Let us never, ever, ever give up,” tweeted Ocasio-Cortez the day after her swearing-in, adding: “It wasn’t long ago that we felt our lives were over; that there were only so many do-overs until it was too late, or too much to take … I honestly thought as a 28-year-old waitress I was too late; that the train of my fulfilled potential had left the station.” Climate change tells is there is no time to waste. But history tells us that social change works in indirect and unpredictable ways, and that it’s worth pressing on for what you believe in.

• Rebecca Solnit is a Guadian US columnist and the author of Men Explain Things to Me and The Mother of All Questions