I began working on climate change law and policy on January 20, 2009, the day I joined Berkeley Law, which was coincidentally Barack Obama’s Inauguration Day. So it’s been a full decade for me focusing exclusively on this subject (I focused on related land use and transit issues prior to 2009), roughly coinciding with the 2010s now coming to a close.

As we mark the end of this decade, two things stand out: remarkable progress reducing the price and deploying critical clean technologies, and dispiriting failure to reduce overall greenhouse gas emissions, with more severe climate impacts happening each year.

I noted some of these trends in a foreword to “Climate Change Law in the Asia Pacific” from Berkeley Law, which features articles from scholars in places like Japan, Korea, and Taiwan, as well as California.

To summarize the good news on clean technology:

• From 2009 to 2017, the levelized costs for utility-scale solar photovoltaic dropped 86 percent;
• Wind power levelized costs dropped 67 percent from 2009-2017; and
• Lithium ion battery prices (central to electric vehicles and grid energy storage) have dropped 85 percent from 2010 to 2018.

This progress is the key reason for optimism on climate change. With the price decreases, support for deployment has increased across the political spectrum and allowed for some remarkable success stories on emissions reductions, such as California’s ability to achieve its 2020 carbon goals four years earlier, due primarily to renewable energy deployment.

But despite the progress, we have this sobering data:

• Carbon parts per million have increased from 385 in 2009 to 411 (and counting).

And unsurprisingly, the bill is now coming due. This decade has brought some of the predicted severe climate impacts, such as unprecedented wildfires, droughts, extreme rain events and hurricanes, and warming oceans.

On the positive side, the extreme weather has helped shift public opinion in favor of climate action. But it’s come at a significant cost to human life, happiness, and ecosystems.

Hopefully in the 2020s we’ll see the widespread deployment of clean technologies and other climate-smart practices that we need to stabilize and reduce emissions. And while climate impacts will inevitably worsen, perhaps our ability to withstand them will improve, such as through electricity grid resilience in the face of wildfires and using natural infrastructure to lessen storm surges and flooding.

And to make any of these positives happen, we will need smart policies and public support and political leaders to enact them. I’ve had the good fortune to work on climate policy now for over a decade, and as the 2020s dawn, much work remains.