In its definitive scientific synthesis report, the Intergovernmental Panel on Climate Change (IPCC) today issued its strongest call for immediate action to save humanity from the deadly consequences of unrestrained greenhouse gas emissions.
This report — signed off by 130 nations including the U.S. and China — slams the door on any argument for delay and makes clear we must under no circumstances listen to those who urge that we wait (who knows how long) to develop as yet non-existent technology [this means you President Bush, Newt Gingrich, Bj¸rn Lomborg]. As the New York Times put it:
Members of the panel said their review of the data led them to conclude as a group and individually that reductions in greenhouse gasses had to start immediately to avert a global climate disaster that could leave island states submerged and abandoned, African crop yields decreased by 50 percent, and cause over a 5 percent decrease in global gross domestic product.
… this summary was the first to acknowledge that the melting of the Greenland ice sheet from rising temperature [which would raise the oceans 23 feet] could result in sea-level rise over centuries rather than millennia.
And readers of this blog know the IPCC almost certainly underestimates the timing and severity of likely impacts because it ignores or downplays key amplifying feedbacks in the carbon cycle (see “Are Scientists Overestimating — or Underestimating — Climate Change” especially Part II and Part III). Indeed, IPCC head Rajendra Pachauri — a scientist and economist — admitted as much:
He said that since the panel began its work five years ago, scientists have recorded “much stronger trends in climate change,” like a recent melting of polar ice that had not been predicted. “That means you better start with intervention much earlier.”
How much earlier? The normally understated Pachauri warns:
“If there’s no action before 2012, that’s too late. What we do in the next two to three years will determine our future. This is the defining moment.”
In short — time’s up! America — we better pick the right President in 2008.
To balance the bad news, the IPCC and its member governments agree on the good news — action is very affordable:
In 2050, global average macro-economic costs for mitigation towards stabilisation between 710 and 445ppm CO2-eq are between a 1% gain and 5.5% decrease of global GDP. This corresponds to slowing average annual global GDP growth by less than 0.12 percentage points.
But how is that possible? How can the world’s leading governments and scientific experts agree that we can avoid catastrophe for such a small cost?