LOS ANGELES, CA: We can see the snow from the trailhead – scattered patches a few thousand feet above that beckon us as we tie on our hiking boots. On the heels of one of the driest winters in California’s history, the spots of white seem like a small miracle to me. This will be the last snow I see for a long time.

As we hike toward the snow, I worry. I worry about snow – not so much here, in the mountains that encircle Los Angeles, but in the Sierra Nevada, where its absence has forced Governor Jerry Brown to implement extreme, statewide cuts in water use. Can California’s farmers survive this drought? Will they change their crop choices? Before or after they pump our groundwater stores dry? I worry, also, about my grandparents, down in the valley below, with their patch of lawn and fruit trees and swimming pool.

I worry about the many dry years that are likely to follow this one. I worry about whether this is a sign of climate change and all the many ways that climate change will affect California. How will we cope? Will we succeed in reducing our greenhouse gas emissions? Will we even try? I worry about how we can possibly support our planet’s population without using fossil fuels, and I worry about the inevitability of needing to do so when the age of cheap fossil fuel ends.

Surrounded by all this worry, it’s easy to lose hope. It seems impossible to envision a world in which even a fraction of these problems are solved. The more knowledge I gain, and the more columns I write, the less faith I have that humanity will find a way to sustainably manage the planet for our own survival, much less preserve a substantial fraction of the other life that surrounds us.

And yet, here we are. During the five hours I spend on this hike, 75,000 new people will be born, and 99.9 percent of Earth’s known species will continue to survive.

Last month, I read an article about moving forward with optimism in the face of climate change.

The author, Rebecca Solnit, emphasizes the frequency with which the course of history changes in unpredictable ways. She describes about-faces in United States social and political views, the modern drop in birth rates that’s slowed population growth and the remarkable emergence of a reformed Germany as a global leader.

History tells us that the future will surprise us. Just as the world today was unimaginable to our grandparents, the world in 50 years will almost certainly look nothing like our expectations.

Today, thousands of innovators are working on hundreds of piecemeal solutions from backyard wind turbines to revolutionary crop systems. Only time will tell which of these will prove successful and what new strategies will emerge. What cocktail of renewable energy sources will replace fossil fuels? Which carbon scrubbing technologies will clear our atmosphere of greenhouse gases?

We won’t know until we get there – but to get there, we have to try. So, Solnit argues, the most important thing we can do to address climate change is to accept this uncertainty and use it as motivation to try.

The day before our hiking adventure, I drove up the 405 to visit my grandparents and, unsurprisingly, mired myself thoroughly in Los Angeles traffic. Even the carpool lane – a permanent, heavily enforced fixture far more codified than its Bay Area cousin – was at a standstill. We were all waiting in our wheeled tin cans, eager to move forward, but unable to do so.

It struck me, in those long highway moments, how stuck we all were – in traffic, in our routines, in our myriad worries. Some days, it’s difficult to summon the energy to simply persist – much less invent and reroute to a new course.

But we have both necessity and hope to motivate us.

We are surrounded by signs that we need to make changes. California’s water crisis demands immediate attention. Oil spills, train fires and terrorism highlight the increasingly fragile nature of our energy supply. Evidence of warming temperatures, rising seas and acidifying oceans is scientifically – if not politically – indisputable.

Now, we have a unique opportunity as human beings: We can interpret these warning signs and make long-term plans for the future. We can begin today to prepare a gift for our own future and for the future of our descendants. At the very least, we can leave the promise of hope and the courage to try.

Eventually, our long uphill climb leads us, many water bottle and photo breaks later, to the snowline. Chris scrapes a handful of snow out from under the shade of a manzanita bush and tosses it across the trail. Sonny, the dog, chases it down and gobbles it up. I tell him that he has eaten the last snowball in California.

Two days later, 500 miles to the north, it snows in Lassen National Park.

Contact Holly Moeller at at hollyvm ‘at’ alumni.stanford.edu.