## Energy, the Environment, and What Mathematicians Can Do

Our heavy reliance on fossil fuels is causing two serious problems: global warming, and the decline of cheaply available oil reserves. Unfortunately the second problem will not cancel out the first. Each one individually seems extremely hard to solve, and taken together they demand a major worldwide effort starting now. After an overview of these problems, we turn to the question: what can mathematicians do to help?

To see the slides of this talk, click here. To see the source of any piece of information in these slides, just click on it!

For online discussion of this talk, go here for the first part and here for the second part.

If you're interested in math, energy and the environment, visit my blog and check out the Azimuth Project, which is a collaboration to create a focal point for scientists and engineers interested in saving the planet. We've got some interesting projects going.

Also try these:

Also check out the list of relevant conferences, and add to it if you know more!

Here are some things that didn't make it onto the slides:

• Here are some graphs that provide a longer view of temperatures on Earth.

The last 1000 years:

Different colored lines are different reconstructions—click for details, and also a larger view.

The last 12,000 years:

Note what seems to be a 'jump discontinuity' at the far right edge of the graph. That's because temperatures (as well as CO2) are rising very fast by geological standards. You can see that the Earth came out of the last ice age roughly around 12,000 years ago, reached its maximum temperature, started cooling down... but now it's getting hotter.

Going back still further:

According to this graph, if the Earth's temperature rises 1°C from its 2005 level, it'll be the hottest it's been in 1.35 million years.

For even longer views try my temperature webpage.

• As Pacala and Socolow pointed out, to use wind power to reduce our coal burning by 1 gigatonne of carbon per year, we would need to increase the amount of wind power produced worldwide by a factor of 50, starting from its 2004 level. This sounds difficult, but to grow by a factor of 50 over 50 years, wind power would only need to grow at an average annual rate of 10.5%. And according to the Renewables 2010 Global Status Report, the average annual growth rate over the five-year period from the end of 2004 to 2009 was much higher than this: namely, 27%!

According to the same source, peak wind power capacity reached 159 gigawatts in 2009. So, reaching Pacala and Socolow's goal of 2000 gigawatts now requires multiplying the world production of wind power by a factor of 12.5. To reach this goal by 2054 now requires an average annual growth rate of only 5.8%.

• As Pacala and Socolow pointed out, to use photovoltaic solar power to reduce our coal burning by 1 gigatonne of carbon per year, we would need to increase the amount of peak photovoltaic solar power worldwide by a factor of 700, starting from its 2004 level. ("Peak" solar power refers to how much a facility generates on a sunny day. "Photovoltaic" solar power means solar cells.)

A factor of 700 sounds like a lot, but to grow this much over 50 years, solar power would only need to grow at an average annual rate of 14%. And according to Renewables 2010, the average annual growth rate over the five-year period from the end of 2004 to 2009 was much higher than this: namely, 60%.

According to the same source, by 2009 peak photovoltaic power reached 24-25 gigawatts worldwide. So, reaching Pacala and Socolow's goal of 2000 gigawatts now requires multiplying peak photovoltaic solar power by a factor of 80. To reach this goal by 2054 now requires an average annual growth rate of 10.3%.