To hear Prop 23 backers tell it, action to address global warming by reducing our carbon emissions and developing a green jobs economy that spurs clean energy innovation is somehow optional, something we can just put aside when it’s inconvenient.

We know this isn’t true. From rising sea levels to more frequent and intense fires to droughts that cause widespread damage to the agricultural industry, global warming represents an immediate and ongoing threat to our economy. Whether in 2010, 2020, 2030, or later, inaction on global warming will doom the California economy and cause higher unemployment for some time to come.

The only way anyone can look at that future and not really care about it is if they deny it – and that means denying global warming.

A new study from Germany’s Max Planck Institute makes clear the urgent need to act, arguing that carbon emissions must peak by 2015 if the worst effects of global warming are to be avoided:

The model, developed by researchers at Germany’s Max Planck Institute for Meteorology, suggests the world’s annual carbon emissions can reach no more than 10 billion tonnes in five years’ time before they must be put on a steady downward path. After that, the researchers say, emissions must drop by 56 per cent by mid-century and need to approach zero by 2100.

Those targets are necessary to prevent average global temperatures from rising by more than 2 degrees C by 2100. Under that scenario, though, further warming can still be expected for years to come afterward.

California’s AB 32 helps address this concern by mandating our carbon emissions be reduced to 1990 levels by 2020. But as I explained yesterday, if Prop 23 passed we probably wouldn’t resume action on global warming until April 2021 at the earliest. By that point, it might be too late to avoid the worst.

Anyone who supports Prop 23 has to explain why it is good for us to let global warming run amok without taking any steps to address it – and the only way they can do that is to deny global warming itself.

Maybe they agree with Carly Fiorina that worrying about global warming is just worrying about “the weather”. Or maybe they just don’t care about the lost jobs and destroyed communities that will result from unchecked global warming. Either way, it’s impossible to back Prop 23 without denying global warming – unless you think the effects of that warming are a good thing for our state.