The Rate of Change: July 1, 2019

This graph shows us our past, and two possible futures.

Each thin vertical stripe represents the average global temperature in a single year (reds = warmer, blues = cooler). On the far left is our past, stretching back to the year 1850. We’re in the middle. On the right, the path forks into two possible futures, ending in the year 2200. One future is warm, and the other is much warmer.

Here’s a version of the graph that shows four possible futures.

These brilliant visualizations are brought to us by Alexander Radtke. He took the Warming Stripes idea developed by Ed Hawkins, and extended it forward in time, using the four major paths to the future adopted by the Intergovernmental Panel on Climate Change.

You can find these graphs on his website, Warning Stripes, as well as more details on how they were created. Here’s an annotated version (click to enlarge):

The lowest road, known as RCP 8.5, is widely considered to be a terrifying worst-case scenario. The highest road, known as RCP 2.6, is a best-case scenario, describing a world where we limit warming to under 2 degrees Celsius.

Which road are we on? At the moment we appear to be headed somewhere between the bottom two paths. To limit global warming to 1.5 degrees Celsius, we’ll need emissions to peak in the next few years, and shrink in half by 2030. However, carbon emissions are still rising, as you can see for yourself in the graph below (and you can dig into the data here).

According to the most recent BP annual review of global energy use, 2018 saw a 2% rise in carbon dioxide emissions, the largest rise in seven years, driven by an uptick in global energy consumption. The chief economist behind the BP report described this rise in carbon emissions as “roughly equivalent to [..] increasing the number of passenger cars on the planet by a third.” And that’s just 2018.

To me, Radtke’s Warning Stripes graphic makes it vividly clear that warming is real, that it’s happening in our lifetime, and that no matter what, the future is going to be very different from the past. It also impresses on me the urgent need for climate action (indicated by the arrow pointing upwards). Every decade is a branching point between possible futures. We need to throw every available resource into taking the highest road possible.

If you’re interested in learning about how bad things can get on the lower roads, I recommend reading The Uninhabitable Earth, by David Wallace-Wells. It’s an extremely vivid and alarming look at what three degrees (or more) of warming portends.

If you’d prefer to dive into the numbers, this in-depth summary by Carbon Brief compiles statistics from ~70 peer-reviewed climate studies on how warming will impact the globe.

Two Roads Diverging in the US

In the New York Times, Brad Plumer takes a look at the differences in how US states are tackling climate change.

First, the good news.

Over the past year, Democratic majorities in California, Colorado, Maine, Nevada, New Mexico, New York and Washington have all passed bills aimed at getting 100 percent of their state’s electricity from carbon-free sources like wind, solar or nuclear power by midcentury

And, on the other side of the coin:

But these laws are passing almost exclusively in states controlled by Democrats, while Republican-led states have largely resisted enacting aggressive new climate policies in recent years. [..]

“What we’re seeing is a tale of two climate nations,” said Barry Rabe, a professor of public policy at the University of Michigan. “The split has become much more pronounced in recent years.”

Read more, by Brad Plumer in The New York Times.

How Politics and Carbon Align in the US

I found this remark in Plumer’s piece particularly interesting (emphasis mine):

How heavily a state relies on fossil fuels is increasingly becoming a good predictor of how it leans in national politics. In the 2016 election, the 14 states with the least carbon-intensive economies voted for Hillary Clinton, while 26 of the 27 most carbon-intensive states voted for Donald Trump, who vowed to promote oil, gas and coal production.

Happily, he includes a link to the data. So, being somewhat of a data nerd, I decided to dive into the numbers, and take a closer look at how a state’s ‘carbon intensity’ related to how it voted in 2016.

But first, what exactly is “carbon intensity”? It turns out that there are two ways this term is used, so let’s start by disentangling these.

The carbon intensity of an energy source measures the emissions released for every unit of energy produced. It’s measured in grams of carbon dioxide released per kiloWatt hour (or gCO2/kWh for short). You can calculate this for a fuel source, like coal or natural gas. Or, you could calculate this for the electricity that flows into your home, which comes from a mix of different energy sources. For example, here’s a real-time map of the carbon intensity of the electricity supply in New York state.

(If the energy source releases a mixture of greenhouse gases, you measure it in grams of carbon dioxide equivalent / kWh. A kWh or kiloWatt hour is just the standard albeit-awkwardly-named unit in which electricity is measured and billed. For comparison, a 40 Watt light bulb uses about a kWh of energy in a day.)

Meanwhile, the carbon intensity of an economy is the carbon dioxide emitted by an economy divided by its gross domestic product (GDP). This tells you about how much an economy relies on fossil fuels. Personally, I think a better name for this quantity might be carbon reliance, but sadly I don’t get to name these things.

In 2016, the average carbon intensity of the US economy was 309 grams of carbon dioxide per dollar of GDP (309 gCO2/$ for short). The state with the least carbon-intensive economy was New York, at 128 gCO2/$, and the state with the most carbon-intensive economy was Wyoming, at 1748 gCO2/$.

A Look At The Numbers

Now that we know what the terms mean, let’s take a look at the numbers. This reference gives us the economic carbon intensity for every US state. I also pulled up the numbers for the electoral vote margin in the 2016 election (i.e., the difference between the percent of people in each state who voted for Donald Trump and Hillary Clinton.)

Here’s what you get if you put these together in a graph. Every dot in this graph represents a US state. The red dots are the states that voted for Trump in 2016, and the blue dots voted for Clinton. The higher the dot, the more the state’s economy relies on fossil fuels, and the further to the right a dot, the more strongly that state leaned towards supporting Trump in 2016.

I thought this was pretty interesting. Here’s the data with the state names shown, and with the vertical axis re-scaled using a log scale so that the states are more spread out.

There’s a lot of overlap near the middle where many states cluster together, but the overall trend is clear. The blue states are mostly in the bottom left, the red states in the top right. There are very few states in the top left (Democrat-leaning and higher than average carbon reliance) or the bottom right (Republican-leaning and lower than average carbon reliance).

If you draw a line at 300 gCO2/$, it divides the country into two halves. Ninety percent of the states above this line (27/30) voted for Trump in 2016. Meanwhile, eighty-five percent of the states below this line (17/20) voted for Clinton. In other words, US states are almost as neatly divided along carbon lines as they are on political lines. “Two climate nations”, indeed.

Nerdy Footnotes: Here’s the Google spreadsheet I used to make these graphs. The correlation coefficient between the (log of the) carbon-intensity of a state’s economy and its vote margin in 2016 is r = 0.84. This raises many more questions. What does this graph look like for the 2008 and 2012 elections? Has the correlation gotten stronger over time? Does this pattern occur in any other countries? If you end up digging into this, I’d love to hear what you learn!

Great Reads

>> Ed Yong wrote an absolutely beautiful piece on the people who care for creatures on the border of extinction.

When animals die out, the last survivor is called an endling. It is a word of soft beauty, heartbreaking solitude, and chilling finality.

>> And in an unexpected silver lining, a tiny endangered bird known as a piping plover has been faring well in the aftermath of Hurricane Sandy in Fire Island. Annie Roth reports in NYT.

>> In more rare good news:

>> Air quality regulations in the UK between 1970 and 2010 lowered deaths due to air pollution by half, a new study argues. The research is freely accessible.

>> When quantifying air pollution, the standard unit used is called PM 2.5, which measures the concentration of airborne particles that are smaller than 2.5 microns. PM 2.5 levels are strongly linked to a host of health problems ranging from asthma to premature death. However, a commentary published in Nature argues that all PM 2.5 pollution is not the same, and its toxicity depends on the mix of chemicals that make it up. (via @AirQualityIndia)

Data source: WHO

>> CNN reports that New York City declared a climate emergency, and is the first US city with more than a million residents to do so.

>> The heat wave is Europe’s new normal

While scientists have yet to draw a firm connection between this particular heat wave and global warming, it fits a clear overall trend. As the climate changes because of greenhouse gas emissions, heat waves around the world are occurring more often, and they are hotter and last longer.

Read more in NYT

>> “It’s Getting Warmer, Wetter, Wilder”: The Arctic Town Heating Faster Than Anywhere

An excellent read in the Guardian:

In the world’s northernmost town, temperatures have risen by 4C, devastating homes, wildlife and even the cemetery. Will the rest of the planet heed its warning?


Since 1971, temperatures here have risen by 4C, five times faster than the global average. In the winter, when the changes are more marked, it has gone up by an astonishing 7C. These are increases that the rest of the world is not expected to experience until the 22nd century. They are far ahead of most computer simulations. Yet there is still more to come. On current trends, Svalbard will hit 10C of warming by 2100.


“It’s difficult to maintain the safety of people. Things are happening that are not supposed to happen,” Olsen says. “We have to adapt a whole city. It’s difficult. We do a white paper and it will be obsolete the next year.”

>> In the Atlantic, Ed Yong reports on how North Atlantic Right Whales Are Dying in Horrific Ways.

>> When Alexandria Ocasio-Cortez met Greta Thunberg: 'Hope is contagious'

GT: Before I started school striking, […] I was so depressed and I didn’t want to do anything, basically. But what I find encouraging is having all these people who are fighting on different sides in different ways, to create a better future and to make us avoid catastrophic climate breakdown.

[…] We aren’t destroying the biosphere because we are selfish. We are doing it simply because we are unaware. I think that is very hopeful, because once we know, once we realise, then we change, then we act.

Read more in the Guardian. (via @cartoonconnie)

Thanks for tuning in, and see you next week.