Y-Axis 2

  • Policy
  • Climate
  • Economy

Choose among four types of policies. Business as usual assumes that there are no controls on CO2 emissions. Choosing an optimized policy allows the computer to choose an emissions reduction plan that maximizes welfare (measured by the present value of utility). A simulated carbon tax allows you to pick a global tax rate on emissions for each of three periods. A climate treaty allows you to choose emissions reductions from a 2005 baseline for each of three target dates and the portion of world emissions that are subject to the treaty.

Be aware that optimized policies can take about ten seconds to run, depending on your input parameters—and a bit longer longer if you’re using a BEAM carbon cycle.

Tax rate
($/ton C)

  • 0 500
  • 0 500
  • 0 500

Emissions reduction
(% 2005 emissions)

  • 100 0
  • 100 0
  • 100 0

Sliders decrease in value, as smaller numbers indicate more aggressive emissions reductions.

(% of globe)

  • 0 100
  • 0 100
  • 0 100

How bad climate change will be? Climate sensitivity is a measure of how much temperatures will increase as we increase CO2 in the atmosphere. A higher sensitivity means a greater temperature increase for a given level of emissions. Harms determines how much those temperature increases hurt people and the economy. A higher value means that harms increase faster as temperatures increase.

less than expected more than expected

How much will temperatures go up? Or: how much will temperature increase in degrees C from a doubling of atmospheric CO2?

less harm more harm

How large will the harms to the climate be, due to an increase in temperatures?

How will the economy perform without climate change? Growth determines how fast the economy grows. A higher value means that the economy grows more quickly. Energy efficiency determines how much CO2 the economy produces for a given level of output. A higher value means that the economy becomes energy efficient over time more quickly. Cost of clean energy determines how much it costs to replace fossil fuels with clean energy such as solar or wind. The model assumes that the costs of clean energy goes down over time. A higher value means that the costs decline slowly so that clean energy is more expensive.

slower growth faster growth

Decline in the rate of growth in productivity over time.

less energy efficient more energy efficient

Reduction in energy intensity per decade. Or the rate of decline in energy use per $ of GDP.

less expensive more expensive

The rate of decline in costs of reduction emissions—hpw fast will these costs decline over time?

    Download runs as: