When is seeing not believing?
A couple years ago, my friend sent me this photo from Ürümqi, which is the capital of Xinjiang province in northwest China.
On this particular day, she couldn't believe her eyes.
Checking the quality of the air outside using this app on her iPad, the numbers were telling her the air quality was good, one on a scale of 500.
But when she looked outside, she saw something much different.
Yes, those are buildings in the background.
(Laughter) But the data were simply not telling the truth of what people were seeing and breathing, and it's because they were failing to measure PM2.5, or fine particulate pollution.
When PM2.5 levels went off the charts in 2012, or "crazy bad," as the US Embassy once described it in a tweet, Chinese denizens took to social media and they started to question why it was that they were seeing this disconnect between official air quality statistics and what they were seeing and breathing for themselves.
Now, this questioning has led to an environmental awakening of sorts in China, forcing China's government to tackle its pollution problems.
Now China has the opportunity to become a global environmental leader.
But the picture that I'll paint for you today is one that's mixed.
There are some signs that are very promising, and there are other trends that are more troubling that warrant closer attention.
But now let's go back to the jfox@example.org.
I started to witness the beginnings of China's green evolution when I was a PhD student conducting fieldwork in China in 2011.
I traveled all across the country seeking answers to the question that I often got myself from the skeptical outsider: What, you mean China is doing something on the environment?
They have environmental policies?
What policies?
At that time, PM2.5 data was considered too politically sensitive and so the government was keeping it secret, but citizens were becoming aware of its harmful human health effects, and they were demanding greater transparency on the part of the government.
I actually started to see some of this growing evolution and awareness myself cropping up all over China.
Department stores, for example, started to market these air purifiers that could filter out harmful PM2.5.
Citizens were also adopting PM2.5 as the title of musical festivals.
(Laughter) And then I went to a golf course in Shenzhen, which is in southern China, and you can see from this banner, they're advertising a retreat from PM2.5.
Golf sub-par, but don't breathe sub-par air.
And then Shanghai's Environmental Protection Bureau decided to create a mascot named after the air quality index to better communicate the air quality data to its people.
I call her AQI Girl, and her expression and hair color changes depending on the quality of air outside.
Five years later and she's still the mostly smiling face of Shanghai's air quality.
And then in 2015, former CCTV reporter Chai Jing created this documentary called "Under the Dome."
It would be likened to Rachel Carson's "Silent Spring."
And much like Rachel Carson brought to attention the fact that pesticides were harming human health, "Under the Dome" stamped into the popular consciousness that air pollution was leading to one million premature deaths every year in China alone.
This video garnered more than a hundred million views in a single weekend before China's government, fearing that it might incite some type of social unrest, pulled it from the internet.
But the damage had already been done.
Public outcry over air pollution galvanized China's government, perhaps in an act of self-preservation, to think big and decisively about how it could tackle the root of its air pollution and many of its other environmental problems: its energy system.
For you see, in China, about two thirds of its electricity comes from coal.
China has more coal-fired power plants than any other country in the world, about 40 percent of the global total, and it's because of this fact that China's government has decided since 2014 to wage a war on coal, shutting down small coal mines, setting limits on coal consumption, even canceling an Australia's worth of coal-fired power plants.
They've also been making enormous investments when it comes to clean and renewable energy, like hydropower, wind and solar, and the pace and the scale of this transformation has been absolutely mind-blowing.
Let me give you a couple of statistics to show you what I mean.
China leads the world when it comes to hydropower, with a third of total capacity.
There's enough for every Chinese citizen to power two homes in a single year from hydropower alone.
You may have heard of the Three Gorges Dam, pictured here, which is the largest power station in the world, and it's powered by water.
In terms of wind power, China has a third of the global capacity.
This makes it the number one leader by far.
When we look at solar, China's also leading.
In fact, they crushed their 2020 target of installing 105 gigawatts of solar power.
This is after the government already revised upwards several times its solar energy target between 2009 and 2015.
Last year, in seven months alone, China was able to install a whopping 35 gigawatts of solar power.
This is more than half of what the US has combined in total and China did this in just seven months alone.
We can verify this remarkable growth in solar power from space, like the startup SpaceKnow has done in this slide.
By 2020, China is on track to generate Germany's entire electricity consumption from just wind and solar power alone.
It's pretty darn remarkable.
And we see some evidence now that China's efforts on clean energy is actually having an effect, not just on air pollution reduction, but also on global climate change, where China has the world's largest carbon footprint.
If we look at some of the data, we can see that China's coal consumption may have already reached a peak as early as 2013.
This is a major reason why China's government announced that actually they've already achieved their 2020 carbon reduction pledge ahead of schedule.
This reduction in coal consumption is also directly driving improvements in air quality across the country, as I've shown here in blue.
In most major Chinese cities, air pollution has fallen by as much as 30 percent.
And this reduction in air pollution is actually leading people to live longer lives in China, on average two and a half years more than they would have in 2013.
In yellow, we can see the cities that have experienced the greatest improvements in air quality.
But of course, as I mentioned at the beginning of this talk, we have to temper some of this optimism with a healthy dose of caution, and that's largely because the data are still being determined.
At the end of last year, after roughly three years of pretty steady global carbon emissions, scientific projections suggest that global emissions may be on the rise again and that could be due to increases in China's fossil fuel consumptions, so they may not have reached that peak that I showed earlier.
But of course, the statistics and the data are still murky and that's because China regularly revises its coal statistics after the fact.
Actually, it's funny, since I've been here I've been having a debate on Twitter with other climate modelers, trying to figure out whether China's carbon emissions have gone up, gone down or whether they're staying relatively stable.
And of course, China is still a rapidly developing country.
It's still experimenting with a range of policies, like dockless bike sharing, which has been hailed as a possible sustainable transport solution.
But then we have images of this bicycle graveyard that tell a more cautionary tale.
Sometimes, solutions can move too fast and outpace demand.
And of course, coal is still king in China, at least for now.
So why should we care about what China is doing on the environment?
Well, what China does at home on the environment can have global implications for the rest of us.
To borrow a line from Chai Jing, we're all under the same dome, and air pollution that originates in China can travel beyond its borders and affect populations as far away as those in North America.
China's not only exporting air pollution, but they're also exporting aid, infrastructure, technology abroad.
President Xi Jinping in 2013 announced the One Belt, One Road Initiative, a massive, one-trillion-US-dollar infrastructure investment project in more than 60 other countries.
And historically, when we've seen that China has made these infrastructure investments abroad, they haven't always been clean.
The Global Environment Institute, a Chinese civil society group, found that in the last 15 years, China has invested in more than 240 coal-fired power plants in more than 68 countries affiliated with the One Belt, One Road Initiative.
That's more than a quarter of China's own domestic coal-fired capacity that is exported abroad.
So we can see that even though China is cleaning up at home, it's exporting some of that pollution to other countries, and greenhouse gas emissions simply don't have a passport.
So when we're trying to evaluate this question of whether or not China is actually leading, we can see it's still very much an open debate.
But time is running out.
I've studied the climate models, and the outlook is not good.
We still have a gap between current policies and what needs to happen if we want to avoid dangerous climate change.
Leadership is what we desperately need, but it's not coming from the US, for example.
The US administration last June announced its intent to withdraw from the Paris Climate Agreement, so now people are looking towards China to fill that leadership void.
So China is very much in the driver's seat determining our global environmental future.
What they do on carbon trading, on clean energy, on air pollution, we can learn many lessons.
One of those lessons is that clean energy is not just good for the environment, it can save lives by reducing air pollution.
It's also good for the economy.
We can see that last year, China was responsible for 30 percent of the global growth in green jobs.
The US?
Only six.
So the picture that I just painted for you hopefully seems much different from those murky, foggy air quality statistics to a much clearer picture of China's clean energy.
And even though China is headed in the right direction, we know that there's still a very long road ahead.
So let me ask you once more: Is seeing believing?
Can we trust the data and the statistics that show that China's air quality is coming down and that its war on coal is actually having an effect?
Well, let's take a look at some of the latest satellite images of China's solar power installations.
I want you to look very closely at this image.
Can you see?
The proof may just be in the pandas.
Thank you so much.
(Applause)