Climate Climate & Energy

What is the safe upper limit for atmospheric CO2?

The nation's top climate scientist, NASA's James Hansen, apparently now believes "the safe upper limit for atmospheric CO2 is no more than 350 ppm," according to an op-ed by the great environmental writer Bill McKibben. Yet while preindustrial levels were 280, we're now already at more than 380 and rising 2 ppm a year!

Like many people, in the 1990s I believed 550 was the target needed to avoid climate catastrophe -- but now it's clear that:

1. 550 ppm would lead to the greatest disaster ever experienced by human civilization -- returning us to temperatures last seen when sea levels were some 80 feet higher. This is especially true because ...
2. long before we hit 550, major carbon cycle feedbacks -- the loss of carbon from the tundra and the Amazon, the saturation of the ocean sink (already beginning) would almost certainly kick into high gear, inevitably pushing us to much, much higher CO2 levels (see here, here, and my book).

Exactly when those feedbacks seriously kick in is the rub. No one knows for sure, but based on my review of the literature and interviews of leading climate scientists, somewhere between 400 and 500 ppm seems most likely. It could be lower, but it probably couldn't be much higher.

So I, like the Center for American Progress and the world's top climate scientists, now believe 450 ppm is the upper bound. That said, I have spent two decades managing, analyzing, researching, and writing about climate solutions and can state with some confidence that:

1. Staying below 450 ppm is technologically doable, but would be the greatest achievement in the history of the human race, by far. It would require a global effort sustained for decades, comparable to what the U.S. did for just the few years of World War II (the biggest obstacle is not technological, but political -- conservatives currently would never let progressives and moderates pursue such a strategy).
2. If 350 ppm is needed (and I'm not at all sure it is) then the deniers and delayers have won, since such a target is hopeless.

In 2008, I will devote a fair amount of ink bits to laying out the solution (there really is only one), but to understand why 450 is so hard, and 350 all but inconceivable, let's look at the odd way McKibben describes the solution:

2007 was the year of warm temperatures and wacky weather

The year 2007 was typified by warm temperatures and wacky weather. This year in the U.S., 263 all-time high temperature records were tied or broken. New York City was hit by a tornado in August, the same month that more than 60 percent of the U.S. was abnormally dry or in drought. The Middle East […]

Today: Chris Allen

Today's member of the "Inhofe 400" truly epitomizes the expertise and credibility of the group of experts that the good senator has assembled to demonstrate the obvious flaws in the theory of human-induced global warming.

He is Chris Allen, weather director at WBKO, the ABC affiliate for south-central Kentucky. On his blog, Chris says this about global warming:

My biggest argument against putting the primary blame on humans for climate change is that it completely takes God out of the picture. It must have slipped these people's minds that God created the heavens and the earth and has control over what's going on. (Dear Lord Jesus...did I just open a new pandora's box?) Yeah, I said it. Do you honestly believe God would allow humans to destroy the earth He created? Of course, if you don't believe in God and creationism then I can see why you would easily buy into the whole global warming fanfare. I think in many ways that's what this movement is ultimately out to do - rid the mere mention of God in any context. What these environmentalists are actually saying is "we know more than God - we're bigger than God - God is just a fantasy - science is real...He isn't...listen to US!" I have a huge problem with that.

2007 was the year of splitting the difference

The triumph, for yet another year, of those who want to split the difference and, basically, do nothing (i.e. those whose key climate strategy is to invest in good ole technology or at least to say they want to invest in technology) -- this means you President Bush, Newt Gingrich, Bjørn Lomborg, OPEC (!), Shellenberger and Nordhaus (depending on what day you happen to catch them), and possibly Andy Revkin (and maybe even E. O. Wilson -- say it ain't so!)

By the way, the (lame) outcome of the energy bill ought to make VERY clear that funding clean energy technology at the level it deserves ($10+ billion a year) is NOT politically easier than regulating carbon (contrary to what Shellenberger and Nordhaus keep saying).

Conservatives hate both strategies -- and we will certainly need the money from the auctioning of carbon permits to pay for the technology, since it is now clearer than ever that such money won't come from 1) raising taxes [as if] or 2) shifting money away from huge government oil subsidies even when oil is at $90+ a barrel!

This post was created for ClimateProgress.org, a project of the Center for American Progress Action Fund.

PNG agrees to let palm-oil producers raze rainforest

Everyone at Bali cheered when the Papua New Guinea delegate dissed the Bush team:

We seek your leadership. But if for some reason you are not willing to lead, leave it to the rest of us. Please get out of the way.

Oh, snap! [Sorry, couldn't resist one last 2007 Daily Show-ism]

Now comes the heartbreaking news:

Venture-capital star ain’t no clean-tech expert

Vinod Khosla may be a "venture-capital star" who is now putting a lot of money into biofuels -- but he is no clean-tech expert, as he proved during a keynote address at ThinkEquity Partners' ThinkGreen conference in San Francisco. In remarks that should worry anybody relying on his judgment, Khosla said:

Forget plug-ins. They are nice toys. But they will not be material to climate change.

Today: Thomas Ring

Recently, Senator James Inhofe published a list of 400 "prominent scientists" who have recently voiced significant objections mainstream climate science. In response to this list, I recently blogged that many of those listed lacked qualifications (see also here).

I'm betting that Sen. Inhofe doesn't want you to actually read the list of skeptics, but just read the headline and accept their conclusion. Here at Grist, however, we don't do what the good senator wants us to do very often. So in the spirit of non-compliance, I'm going to institute a semi-regular series where I examine the qualifications of some of the "experts" on the Inhofe 400 list.

Italian village first host to outbreak of spreading tropical disease

Congratulations to Castiglione di Cervia, Italy, the first place in modern Europe to feel one dismal effect of a warming world: a tropical disease out of its natural habitat. This summer, more than 100 people in the village of 2,000 came down with fever, exhaustion, and terrible bone pain later found to be caused by […]

Unlike the U.S., European governments are cutting back on agrofuel goodies

European biodiesel makers have entered a rough patch. The price for their main feedstock, rapeseed, has risen more than 50 percent since the beginning of the year. But the price of the final product, biodiesel, has plunged, because producers are churning out far more biodiesel than the market can absorb. Similar conditions hold sway among […]

The poverty of fossil fuels becomes apparent

Martin Wolf makes what I think is a really bad argument in the Financial Times:

We live in a positive-sum world economy and have done so for about two centuries. This, I believe, is why democracy has become a political norm, empires have largely vanished, legal slavery and serfdom have disappeared and measures of well-being have risen almost everywhere. What then do I mean by a positive-sum economy? It is one in which everybody can become better off. It is one in which real incomes per head are able to rise indefinitely ...

This is why climate change and energy security are such geopolitically significant issues. For if there are limits to emissions, there may also be limits to growth. But if there are indeed limits to growth, the political underpinnings of our world fall apart. Intense distributional conflicts must then re-emerge -- indeed, they are already emerging -- within and among countries.