### Earth Day 2007

Earth Day is on April 22nd. The first Earth Day was in 1970, which was the same year President Nixon created the EPA (Environmental Protection Agency).

The Earth Day 2007 environmental tip of the day was: "Celebrate Earth Day - Change a light, Change the world! Buy or switch to energy efficient lighting fixtures and bulbs. Look for the Energy Star label."

GDT used the Earth Day Footprint Calculator at FootprintNetwork.org to find the following.

```   CATEGORY          ACRES
======================
FOOD               5.4
MOBILITY           3.7
SHELTER            7.9
GOODS/SERVICES    10.6
TOTAL FOOTPRINT   28      <-- note how this is rounded

In comparison, the average ecological footprint in your country
is 24 acres per person.  Worldwide, there exist 4.5 biologically
productive acres per person.  If everyone lived like you, we would
need 6.2 planets.
```

The following was copied from the Ecological Footpring FAQ.

```   "Today, the biosphere has 26.7 billion acres (or 10.8 billion
hectares) of biologically productive space corresponding to
less than one-quarter of the planet's surface. These 26.7 billion
acres (10.8 billion hectares) include 5.7 billion acres (2.3 billion
hectares) of productive ocean and 21 billion acres (8.5 billion
hectares) of productive land."
```

Note: hect- is a metric prefix denoting `100` and an are is a unit of area equal to `100 square meters`. There are `640 acres` in one square mile.

##### Exercises
1. One acre is equal to `__________ hectare`. [record to nearest thousandth]

2. Compared to other residents in the U.S.A., GDT's total ecological footprint is `________%` higher than average.

3. Explain why we would need `6.2 planets` if everybody lived like GDT.

Creator: Gerald D. Thurman [gthurman@gmail.com]
Created: 22 April 2007