(CNN) If you're concerned about climate change, you're likely in full panic mode right now.

Consider three recent news items:

• US President-elect Donald Trump has called climate change a "hoax" and has suggested he might scrap many Obama-era environmental regulations, including the landmark Paris Agreement, which aims to limit warming to 2 degrees Celsius

Climate change is happening now. We're causing it. And frankly, it's terrifying.

But -- and this is a critical "but" -- there's still room for hope.

Gina McCarthy, shown in 2015.

That's the message I took from an interview Friday with the outgoing head of the Environmental Protection Agency, Gina McCarthy, who has been fighting climate change for the Obama administration.

"Whether you're a Democrat or a Republican, you're going to care about the future for your kids," she told me. "Our clean energy train has left the station and it is filled with very happy people.

"I'm pretty confident that we'll be fine."

This from a woman who may be replaced with a climate change skeptic.

I asked McCarthy a number of questions you sent in via Facebook and CNN's Two Degrees newsletter . Many of you wanted to know how rapidly she expects Trump to shred Obama-era climate goals.

Those laws -- including the Paris Agreement, the international treaty to slow warming, and the Clean Power Plan, which aimed to limit pollution from coal power -- may not matter as much as you think, McCarthy said, since markets already are heading toward wind and solar and away from dirtier energy.

"I don't think that anyone could think that getting rid of the (Clean Power Plan) or not joining the Paris Agreement ( the US already joined it , actually, as have 114 others ) is somehow going to change anything in the US," she said. "Investments are set. Five times as much investment in clean energy as there is in the rest of the economy."

"The private sector is demanding it, businesses are demanding it," she added.

Another ray of hope: Young people really care about this.

I relayed your questions about a federal court case in Oregon in which 21 young people are suing the federal government -- including McCarthy -- over relative inaction on climate change . The symbolism of the case is awesome: The kids argue on constitutional grounds that the government is failing to protect their right to property (one young plaintiff lives on the Florida coast, which is disappearing) and a livable future. Basically, they think young people are being discriminated against when it comes to climate. They have the most to lose -- since they'll live the longest, and see the most warming -- yet they can't vote.

Advocates and attorneys for the kids want the Obama administration to settle the case now, before Trump takes office. They say the courts could force the Trump administration to curb global-warming pollution.

A settlement is unlikely, McCarthy told me.

But she is encouraged young people are speaking up (even though she's named in the suit).

"Their voices need to be heard," she said. "It's about their future."

"States can take action. Local communities can take action," she said. "People should not go back into their corners or be shy. And there's no closet big enough to hold everybody who reads the climate science and understands it. We will still be able to make progress -- (but) it may not be at the federal level."

To win on climate, Trump needs to see the business case, she said.

And realize the US could fall behind in the modern economy without action.

"Are we going to be leading the worldwide effort or ceding that to another country, in particular China? Is that where we want to be?" she said. "Or do we want to be in a leadership position where we're making the jobs, we're doing the innovation, we're doing the investing, and frankly we're standing up and doing what the science tells us we have to do."

The science, by the way, tells us we need to ditch fossil fuels -- almost completely -- this century . That's to have any reasonable shot of limiting warming to 2 degrees Celsius above pre-industrial levels, the threshold world leaders have agreed is the absolute red line for climate change.

It's a harsh reality.

But, as climate activists are fond of saying, the Earth's math doesn't change because of politics.

We've already warmed the planet about 1 degree Celsius.

"I'm hoping that this next administration will not have blinders on," McCarthy said.

The same could be said of the public.