Sustainability movement will be defined and described. The physics part of sustainability is driven by energy use and environmental impacts. Recent data on energy and climate change will be displayed. This will be followed by back-of-the-envelope calculations, which prove the following:

• King Hubbert’s equations for oil production are modified, using supply and demand economics. The additional production from higher prices will not be sufficient to stave off the problems of “peak oil.” The impact of energy regulations on cars and appliances greatly exceeds the impact of market forces.
• Energy savings from enhanced–end–use efficiency has been far greater than new production from alternative energy and this will continue to be so. Using a scale model for buildings, it is shown that it is possible (with appropriate investment) to heat a house in Wisconsin with energy of two–persons fighting. To make energy decisions on an economic basis for refrigerators and solar collectors, it is more meaningful to use the cost–of–conserved energy as compared to payback periods.
• Most of the progress on energy since the oil embargo has been on the “demand” side and not the “supply side.” Combined cycle gas turbine power–plants now obtain 60% efficiency and release less than 40% of a coal plant’s CO₂.
• More carbon dioxide raises the Earth’s surface temperature; the concept of little or no rise in temperature is not logical. Several models will quantify this.