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How Bad Will Climate Change Be?

August 22, 2013

Chris Mooney, at Mother Jones, breaks down the 5 most worrisome conclusions of the upcoming Intergovernmental Panel on Climate Change’s 2013 Summary for Policymakers report:

We’re on course to change the planet in a way “unprecedented in hundreds to thousands of years.” This is a general statement in the draft report about the consequences of continued greenhouse gas emissions “at or above current rates.” Unprecedented changes will sweep across planetary systems, ranging from sea level to the acidification of the ocean.

Ocean acidification is “virtually certain” to increase. Under all report scenarios, the acidification of the world’s oceans will increase—the draft report calls this outcome “virtually certain.” As we have previously reported, more acidity “threatens the survival of entire ecosystems from phytoplankton to coral reefs, and from Antarctic systems reliant on sea urchins to many human food webs dependent on everything from oysters to salmon.”

Long-term, sea level rise could be 5 to 10 meters. Journalists are already citing the draft report’s prediction that by the year 2100, we could see as much as three feet of sea level rise. But there is also a more long-range sea level scenario alluded to in the draft report, and it’s far more dramatic and alarming.

This also implies a substantial melting of the Greenland ice sheet. The draft report adds that during the last interglacial period, the melting of Greenland “very likely” contributed between 1.4 and 4.3 meters of global sea level rise, with additional contributions coming from the melting of Antarctica. If Greenland were to melt entirely, it is estimated that sea level would rise by about seven meters.

Much of the carbon we’ve emitted will stay in the atmosphere for a millennium…even after we’ve stopped emitting it. The draft report says that 20 percent of the carbon dioxidecurrently in the atmosphere will stay there for an almost unimaginably long time—more than 1,000 years. Even if we were to completely cease all greenhouse gas emissions, the draft report adds, warming would continue for “many centuries.” “A large fraction of climate change,” the document intones, “is thus irreversible on a human time scale.”

Read Mooney’s full analysis here.

Depressing, no? Well, at least Al Gore is optimistic about the future, at least in this interview with the Washington Post:

But in spite of the continued released of 90 million tons of global warming pollution every day into the atmosphere, as if it’s an open sewer, we are now seeing the approach of a global political tipping point.

The appearance of more extreme and more frequent weather events has had a very profound impact on public opinion in countries throughout the world. You mentioned my movie back in the day. The single most common criticism from skeptics when the film came out focused on the animation showing ocean water flowing into the World Trade Center memorial site. Skeptics called that demagogic and absurd and irresponsible. It happened last October 29th, years ahead of schedule, and the impact of that and many, many other similar events here and around the world has really begun to create a profound shift.

A second factor is the sharp and unexpectedly steep decrease in prices for electricity produced from wind and solar and the demand destruction for fossil fuel energy from new efficiency improvements. The difference between 32 degrees fahrenheit and 33 degrees fahrenheit seems larger than just one degree. It’s the difference between water and ice. And by analogy there’s a similar difference between renewable electricity that’s more expensive than electricity from coal and renewable electricity that’s less expensive. And in quite a few countries in the world and some parts of the United States we’ve crossed that threshold and in the next few years we’re going to see that crossed in nations and regions containing most of the world’s population.

Gore’s optimism, unfortunately, is not really about mitigating the damage that the IPCC predicts. It’s more about finally “winning the conversation” about climate change and starting to react to climate change on a global scale. Of course, we are very late in the “conversation” and much of the damage warming will cause is already baked (get it?) into our future.

Full Gore interview is here.

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