• Farmers may not be able to grow enough food to feed a growing population.
Climate will continue to increase the severity of storms, droughts, floods and wildfires.
• By century's end, sea-level rise could displace hundreds of millions of people.
Reducing poverty will be much more difficult.
• Food and water shortages, along with migrating populations, will destabilize many nations.
To avoid worst-case scenarios, the world's leading scientists tell us we must contain the increase in warming to 2 degrees Celsius. The IPCC warns that on our current trajectory, we're looking at 4- to 5-C warming, way beyond any ability our civilization has to manage or adapt.
Staying under 2-C requires the world to remain within a "carbon budget" of one trillion tons of carbon dioxide emitted since the Industrial Revolution began. More than half that budget has been spent, and corporations and nations control reserves of fossil fuels amounting to five times the amount we can safely burn. This is one budget we cannot afford to bust, yet we're on track to do just that within two or three decades.
Which brings us back to the latest IPCC report talking about steps to avoid those worst-case scenarios. Current global economic growth is 1.6 to 3 percent a year. The report says the cost of staying below 2C would reduce this growth by only .06 percent. Coal, oil and gas will need to be replaced by low- or zero-carbon sources of energy – solar, wind, geothermal, nuclear. Capturing carbon dioxide and storing it underground will also play a role in reducing greenhouse gas levels.
None of this will happen quickly enough, however, so long as fossil fuels remain the cheaper option. Simple economics dictates that the market will gravitate toward the lowest cost. To fix this problem, there's a simple solution: Tax carbon.
If you're like most Americans, your immediate reaction is to say "No way!" to any new tax. Suppress that impulse for a moment while I give you the other part of the equation: Take the revenue from that carbon tax and refund it equally to all households.
By giving carbon tax revenue back to the public, individuals will have the extra income to offset additional energy costs arising from the tax. Done this way, a carbon tax isn't about creating economic hardship, but instead correcting the distortion in the marketplace that gives fossil fuels a competitive advantage.
A number of conservatives Romney economic adviser Greg Mankiw, Reagan Secretary of State George Shultz embrace the revenue-neutral carbon tax as the best solution on climate change.
Republicans in Congress currently balk at President Obama's efforts to cut carbon through new regulations. They see it as an expansion of government, which they philosophically oppose, and are doing what they can to thwart the president's initiative. Chances of avoiding new regulations would be much better, though, if Congress presented Obama with the market-based solution of a carbon tax that recycles revenue back into the economy.
The new IPCC report tells us technology can bail us out of certain climate catastrophe. To give it a fighting chance, let's tax carbon and give the money back to the people.
Mark Reynolds is executive director of Citizen's Climate Lobby.