550 ppm May Not Be Enough to Protect Against Climate Change & Global Warming

Summary:
550 ppm (parts per million) carbon dioxide equivalents explained; potentially dangerous despite best efforts.




Stabilizing at 550 ppm CO2e may not be enough to protect against the worst effects of climate change & global warming. To clarify further, if there were in total 1,000,000 'balls' of atmosphere, of the 1,000,000, 550 balls would be carbon dioxide balls (standard unit of greenhouse gases is CO2e - carbon dioxide equivalents). For the Copenhagen climate summit, 550 ppm is the target by 2050; the goal is to have no additional balls of carbon added to the atmosphere. Why? Because at 550 ppm the temperature has a 76% chance of not exceeding 5 degrees C. Good odds of getting to a dangerous temperature, but still avoiding catastrophe.

Currently the world is at 430 ppm CO2e (or 430 balls of carbon dioxide for every 1,000,000 balls of atmosphere). In pre-industrial times, around the 1850s, the world had 280 ppm of CO2e in the atmosphere (280 balls per 1,000,000 atmospheric balls). Every year the planet adds 3 balls into the air, or adds 3 ppm of CO2e into the atmosphere. In four decades the planet is extremely likely to get to 550 ppm CO2e. The likely outcome would be global warming temperature increase of 5C.

But that is just an estimate; it is reasonable to go beyond 5C at 550 ppm. Computer simulations consistently point to stabilization of carbon in the atmosphere to 550 ppm because it is extremely likely to occur by 2050, under "business as usual" (often abbreviated to 'BAU' in technical papers). By stabilizing at 550 ppm we hope to stop throwing balls of carbon into the atmosphere all together. By then we'll wait and see how much hotter the planet will get. Box 8.1 taken from the Stern Review (2007) reveals humbling percentages pertaining to carbon emissions levels. Once at 550 ppm there is a 7% chance of exceeding temperatures greater than 5 degrees C; there's a 2% chance of exceeding 6 degrees C; and a 1% chance of exceeding 7 degrees C. Humans have never experienced a temperature past 5 degrees C than what it is now.

So what’s the big deal with 5 degrees C? To compare a temperature change of 5 degrees C: 10,000 years ago the climate was 5 degrees colder than it was today and ice sheets extended from the North Pole down latitudes of present day New York. Doing nothing about climate change, the path of least resistance, may see us past a 7-degree increase of temperature. The consensus in science is that each year the likelihood of shooting past 550 ppm (and therefore 5 degrees C) by 2050 is growing. As Stern has suggested, if we limit throwing carbon dioxide balls into the sky now, the cost of success will be 1% of global GDP. As we've covered in the Justmeans American Climate Change Policy Series it would cost the USA $444B to cover it’s own losses under BAU, which equates to 3.7% US GDP. It's smarter and cheaper to act now; collective strength spreads the costs thin.

Why Current Economic Climate Change Models Too Optimistic

Democrats go ahead with climate change bill despite Republicans who demand more time and analysis, a poor model-based strategy dissected.

Recently, Democrats of the Environment and Public Works committee pushed through a climate bill without a single Republican present. Seven Republicans, also members of the committee, boycotted the meetings to discuss the climate bill, claiming insufficient time to study it and demanding that the Environmental Protection Agency conduct further economic analysis. These politicians are duplicating practices of inaction and misinformation. Demanding more studies at this point in time is counterproductive. Often the work of climate change policy requires estimations on the future. Short of a crystal ball, climatologists and economists assess rather conservatively the possibilities of the future. Unfortunately, policy-makers take for granted the fact that many models regarding the economics of global warming understate the adverse effects and costs of climate change.

Freeman & Guzman (2009) have outlined in greater detail six reasons that current economic models are overly optimistic. Firstly, the model's optimism about temperature rise, which corresponds to the fact that many politicians consider studies with the mid-range increase of 2-3C in mind (highly optimistic). Secondly, asymmetry around point estimates is a concern because it leaves room for misinterpretation. For example, as temperature rises its costs to mitigate see an increasing (near exponential) rate. So when considering mitigation costs between 2.5 degrees C and 5 degrees C, the costs to mitigate are not twice as much at 5C, but are about ten times more. Thirdly, failure to account for catastrophic events undermines the studies' comprehensiveness. Fourthly, failure to account for non-market costs, like human health, implies they are negligible to these studies (hard to imagine human health to cost zero dollars). Fifthly, studies' failure to account for cross-sectoral impacts paints an incomplete picture especially in an interconnected world where one housing industry calamity in the US can put the whole world in peril. Sixthly, long-term projections (growth and productivity), which are hardly considered in economic models, could double the estimates of harm in many prominent studies to date.

Scientific practices can also put into question optimistic climate scenarios. Many scientists have to be organized across continents and often agree on conservative estimates in order to agree at all. The IPCC FAR (2007) report required 2,800 reviewers to agree on its 2,946 pages. The report was condensed into a 58-page summary for policy makers, which leaves out many considerations that are important for the reader to understand the limitations of the findings. An example of admitted guesswork on the first page the Working Group I Policy-Maker Summary (in tiny font) states: "Note that a number of uncertainty ranges in the Working Group I TAR (Third Assessment Report) corresponded to 2 standard deviations (95%), often using expert judgement."

Models are helpful, but only if they are used correctly. In the end, Democrats are right to push forward a climate change bill without Republican support; Americans have had more than a decade of non-participation in climate change agreements. Now it is time to act.