### Simple Math with Oil Spills

A blast from the past! Oil spills and unit conversations, a middle school Practical Uses of Math and Science (PUMAS) example published in 1999.

The short story: On February 4, 1999, the 639-foot freighter New Carissa became grounded near Coos Bay on the Oregon coast. Aboard the ship were 400,000 gallons of bunker fuel, threatening to leak from the fractured hull and damage the state’s fragile beach habitats. With an approaching storm increasing the chances of a disastrous spill, authorities decided to set the ship afire, a choice not without controversy and risks of its own. What would be the potential scale of the disaster if that much oil did spill? 400,000 gallons is equivalent to 400,000 milk jugs –- a lot of milk. But how much space does 400,000 gallons really take up? Some simple arithmetic can help put the quantity in perspective.

### Melting Snow and Rising Rivers

This map of snow water equivalent shows the amount of water contained in the snowpack–essentially, the depth of water released if the entire snowpack was melted instantaneously.

The map comes from the National Operational Hydrologic Remote Sensing Center, which also provides information about snow depth and other snow-related variables.

Snow water equivalent provides useful information for water supply (and things like soil moisture for agriculture and other land uses) as well as for flood forecasting. It’s an important number to watch during the spring months, particularly along the Nebraska-Iowa and North Dakota/South Dakota-Minnesota borders.

In these areas, the snow is melting (at last!). But there’s been a lot of snow over much of the upper midwest this winter, and it’s melting quickly. That can mean lots of surface runoff, especially in areas of deep frost, which can cause localized flooding. Eventually, this runoff makes it into the rivers, where high water levels and potential ice jamming can lead to rivers spilling over banks and levees, resulting in property damage, and in some cases, potential loss of life.

The National Weather Service has a flood safety website to help you learn about the flood danger in your particular area and review safety tips. Understanding the danger as well as the actions you can take will help you be better prepared if or when flooding does occur.

### Earthquake Education

First, if you’re inspired to help those in Haiti, please see this list of organizations compiled by CBS News. This tragedy teaches us lots of things, about life, and the human condition, and vulnerability, especially as it relates to this planet on which we live. And sticking with the idea of linking teachable moments with topics on this site, today let’s consider plate tectonics and its relation to where and how people live.

Plate tectonics refers to the movement of Earth’s crustal plates. Earth’s surface, or lithosphere, is composed of about 12 of these plates, which can move next to, over, under, toward, and away from each other.

All of these tectonic movements can cause earthquakes or volcanoes, and the infamous Ring of Fire is marked by the boundaries of the Pacific Plate with the North American, Nazca, Australian, Philippine, and Eurasian plates.

The January 12, 2010, earthquake in Haiti resulted from a break on the southern fault zone between the Caribbean plate and the Gonave microplate. While this area is not one of the more active earthquake zones on the planet, major earthquakes have occurred, often with devastating results. The January 12 event occurred on a “strike-slip” fault—one in which adjacent plates are moving against each other. Strike-slip events tend to be shallow and can therefore produce violent shaking over a sizeable area. According to the U.S. Geologic Survey (USGS), the magnitude 7.0 earthquake caused strong and very strong shaking in Haiti, with moderate shaking in the Dominican Republic and weak or light shaking as far away as the Bahamas.

Tuesday’s earthquake reminds us of something we sometimes forget: that oftentimes the regions we don’t consider vulnerable to earthquakes are indeed places where major destruction and loss of life can occur. Where could the next big one happen? Scientists have identified several places where geology and population combine with potentially dangerous results. A few of them are viewable here.

This is weather.

This is climate.

They are not the same thing. The American Meteorological Society’s Glossary of Weather and Climate (AMS, 1996) defines weather as the state of the atmosphere at a particular time. Weather consists of the short-term variations of the atmosphere, on timescales of minutes to weeks. Climate, by contrast, is the total of all statistical weather information for a given place over a specified interval of time. Climate is a “synthesis” of weather, averaged over time periods of months to decades.

In the first figure above, air and dewpoint temperatures are plotted using hourly observations over a 72-hour period. In the second figure, the monthly-averaged maximum and minimum temperatures are shown based on data from 1978-2005. Individual weather events do not and cannot give information about the climate of the area, because weather is short term and climate is long term. People (even, unfortunately, some in the scientific community) often use the terms interchangeably, and in discussions of climate change, this carelessness with words provides a disservice.

A particularly warm or cold week in your hometown does not mean that climate change is or is not happening. It means that the weather that week was anomalously warm or anomalously cool compared to the long-term climatological average. And all averages also have a variability associated with them. We’ll go back to the AMS Glossary, in which climate variability “denotes deviations of climate statistics over a given period of time (e.g., a month, season, or year) from the long-term climate statistics relating to the corresponding calendar interval.” Variability is an inherent characteristic of the climate system: we know that even on average, no month or year is likely to behave exactly like the previous month or year.

Climate change, on the other hand, is “a significant change in the climatic state of a locale or large area, typically evident with a significant change in the mean (or average) values of a weather element.” A cold week or large precipitation event does not indicate climate change: we know from the definitions above that those are weather events. However, if the average temperature for July is significantly warmer than the average for all previous Julys on record, and this pattern happens for say three (or eight, or fifteen) Julys in a row, then by the definition what has been observed is a *change* in climate.

Most often, scientists refer to climate change on a global scale. But people care most about their locality, so here are temperature records for two continental U.S. locations. On the first figure, the temperature data themselves are plotted. The second figure shows the anomalies from the long-term average, along with global temperature anomalies and linear fits to both. Do the plots correspond to weather or climate? Do you see climate variability? What about climate change?

Click image to view original data plot. Source: C. Fisk; Minnesota Climatology Working Group

Click image to view original data plot and summary. Source: State Climate Office of North Carolina