## How do we calculate sea level?

If you aren’t sure how sea level is calculated then read NASA’s Sea Level 101: What determines the Level of the Sea? by Alan Buis (6/3/2020) . Here is one factor:

If our ocean had no tides or currents, the sea surface would assume the shape of the geoid. These “gravity anomaly” maps, based on data from the U.S./German Gravity Recovery and Climate Experiment (GRACE) mission, show where Earth’s gravity field differs from a simplified Earth model that is perfectly smooth and featureless. Areas colored yellow, orange or red are areas where the actual gravity field is large, such as the Himalayan Mountains in Central Asia (top left of the left-hand globe). The progressively darker shades of blue indicate places where the gravity field is smaller, such as the area around Hudson Bay in Canada (top center of right-hand globe). Credit: NASA/JPL-Caltech

If you are going to teach about climate change and related ramifications such as sea levels rising, then reading articles such as this one provides helpful background knowledge. Also, it’s just real interesting.

## How do I teach about climate change when I know so little?

If you would like to incorporate climate change in your math class, by say using the calculus or statistics project here, but you don’t feel like you know enough, then you need an overview for teachers. The Paleontological Research Institute has a teacher-friendly guide to climate change. The audience for the book, free in pdf form, is high school earth science  and environmental science teachers, but it also works as a primer for those looking to add climate issues to their math class. There are useful graph and tidbits, such as FAQ 11 in Chapter 12 (see the graph copied here):

A second method that uses real data in order to create a false impression is manipulation of the scale on a graph. As discussed in the “warming hiatus” question above (Question 6), showing data over a very short time frame can be misleading. Similarly, using a vertical scale to either magnify or suppress a trend can also be misleading. For example, the temperature data plotted on the two graphs in Figure 12.2 is exactly the same (the same data from Question 5), but the scale has been expanded in the right-hand graph to compress the data and make the temperature increase appear non-existent. This procedure has been used by some who deny the existence or significance of climate change
to give an impression of “no problem.”

Chapter 6 in the text provides information specific to different regions in the U.S., which helps provide local background related to climate. All in all an excellent resource, especially if you want to know the basics so that you are comfortable raising climate issues in a math classroom.

## Is there a relationship between education level and marriage?

The U.S. Bureau of Labor Statistics post 60 percent of college graduates born from 1980 to 1984 were married at age 33 (6/30/2020) provides the chart copied here.

At age 33, people with higher levels of education were more likely to be married and less likely to be cohabiting than those with lower levels of education. At the time of their 33rd birthday, 32 percent of high school dropouts, 42 percent of high school graduates with no college, 49 percent of people with some college or an associate degree, and 60 percent of college graduates were married. Twenty-eight percent of those with less than a high school diploma were cohabiting, compared with only 13 percent of those with a bachelor’s degree and higher.

For related data, see the Census Bureau Educational Attainment in the United States: 2019 Table 2.  For people 25 years and over no more than 53% of those that didn’t complete at least an Associates degree here married. For those that have a Bachelor’s degree, Master’s degree, Professional degree, and Doctoral degree the percentage are 63%, 68%, 71%, and 73% respectively.

## Is the racial wealth gap evenly distributed by class?

The article The Racial Wealth Gap is About the Upper Classes by Matt Bruenig (6/29/2020) on the People’s Policy Project explains. First the racial wealth gap is large:

If you take the net worth of all white households and divide it by the number of white households, you get \$900,600. If you do the same thing for black households, you get \$140,000. The difference between these figures — \$770,600 — is the best representation of the overall racial wealth gap.

The graphs here from the article show that the wealth in both groups is largely concentrated in the top 10%.

What this means is that the overall racial wealth disparity is being driven almost entirely by the disparity between the wealthiest 10 percent of white people and the wealthiest 10 percent of black people.

Overall,

This means that even after you have completely closed the racial wealth gap between the bottom 90 percent of each race, 77.5 percent of the overall racial wealth gap still remains, which is to say that the disparity between the top deciles in each race drives over three-fourths of the racial wealth gap.

Further,

What this shows is that 97 percent of the overall racial wealth gap is driven by households above the median of each racial group.

## What’s New at sustainabilitymath?

The data sets for the calculus and statistics projects have all been updated. Along with the traditional Excel file each tile now has a csv file with the data used to create the graphs. The associated R file now pulls the data directly from the csv file. Of course you can use other programs and import the data directly.

The graph here is from the Ozone Hole project on the Calculus page. This provides an example that when the world cooperates things can improve.

## What is the relationship between class, race, and police killings?

The People’s Policy Project reports on their recent research paper in the post Class and Racial Inequalities in Police Killings (6/23/2020). The full paper, Police Killings in the U.S. is by Justin Feldman, ScD. In general,

The highest-poverty areas have a police killing rate of 6.4 per million while the lowest-poverty areas have a police killing rate of 1.8 per million, a 3.5-fold difference.

The differences in killing rate have the same pattern when viewed by Black, Hispanic, and White populations. Differences by class among Hispanics is the least. Further,

He finds that class differences account for more than 100 percent of the difference between white and Latino police killing rates, meaning that, after adjusting for socioeconomic differences, Latinos have a lower police killing rate than whites. Class differences account for 28 percent of the difference between black and white police killing rates.

There are three other graphs in the post.

## What are Warming Stripes?

The image here from ShowYourStripes has a vertical strip representing global average temperature anomalies from 1850 to 2019 where darker blue is cooler and darker red is warmer. This graphic style, warming stripes, is credited to Ed Hawkins. The ShowYourStripes page has similar graphics for different regions.

On the Climate Central page 2020 Mets Unite (6/17/2020) there are warming stripes for states and slected cities that can be downloaded.

## How has Black educational attainment changed?

The Census Bureau post Black High School Attainment Nearly on Par with National Average  by Jennifer Cheeseman Day (6/10/2020) notes:

In 1940, when the U.S. Census Bureau started asking about educational attainment, only 7% of Blacks had a high school education, compared with 24% for the nation as a whole.

In recent years, Black educational attainment has been much closer to the national average and today, 88% of Blacks or African Americans have a high school diploma, just shy of the national average, according to census data released last month from the Current Population Survey.

Related to the graph copied here:

The national average dropout rate declined from 19% in 1968 to about 6% in 2018. The Black dropout rate fell more steeply from 33% to 5%, bringing it in line with the national average.

Average enrollment for young adults increased from 26% to 41%. At the same time, the proportion of Black young adults in college more than doubled, rising from 15% to 38%.

The article contains five other graphs and links to the Census Bureau data sources.

## How hot was May 2020?

The global land and ocean surface temperature for May 2020 tied with 2016 as the highest in the 141-year record at 0.95°C (1.71°F) above the 20th century average of 14.8°C (58.6°F). The 10 warmest Mays have all occurred since 1998; however, the 2014–2020 Mays are the seven warmest in the 141-year record. May 2020 also marked the 44th consecutive May and the 425th consecutive month with temperatures, at least nominally, above the 20th century average.

The global land-only surface temperature for May 2020 was also the highest on record at 1.39°C (2.50°F) above the 20th century average of 11.1°C (52.0°F). This was 0.04°C (0.07°F) above the previous record set in 2012. The 10 highest May global land-only surface temperature departures have occurred since 2010.

The May 2020 global ocean-only surface temperature was near-record warm at 0.79°C (1.42°F) above average. This value was only 0.01°C (0.02°F) shy of tying the record warm May of 2016.

May time series data here. Climate.gov provides a summary of May 2020 in their post Was May 2020 warm and dry or cool and wet across the U.S.? It depends… by Rebecca Lindsey (6/9/2020)

## What is the connection between crime and lead?

Kevin Drum asks a good question in his post How Many Cops Does New York City Need?  First note that violent crime has been dropping since around 1990 (see his graph copied here for examples). In particular for NYC:

The per capita number of police officers increased by about 10 percent through 2000 and then declined by about 20 percent through 2018. That’s nearly flat over the entire period. Violent crime, by contrast, plummeted 60 percent from its peak in 1990 through 2000 and then declined another 40 percent through 2018. That’s a total decrease of nearly 80 percent between 1990 and 2018.

Violent  crime has decreased even though the per capita number of cops has been nearly flat. So, why did crime decrease? There is overwhelming evidence that removing lead emissions from cars is the main driver of crime decline. I strongly encourage you to read Drum’s 2018 summary of the evidence.