Obama Takes on Global Warming (But Here is the Rest of the Story You’re Not Hearing)

ABC’s Bill Blakemore, who covers global warming, reports from New York:

Two simultaneous news events at 10:30 this morning — one by President Obama for reporters in Washington, one by climate scientist Susan Solomon via teleconference from NOAA’s laboratories in Boulder Colorado – added urgency to the fight against global warming.

Both spoke, in different ways, of major "irreversible" impacts of global warming on human civilization.

Obama, in a short White House address related to tougher vehicle greenhouse emissions standards, said that “urgent dangers to our national and economic security” from dependence on oil “are compounded by the long-term threat of climate change which, if left unchecked, could result in violent conflict, terrible storms, shrinking coastline and irreversible catastrophe.”

Scientist Solomon spoke of temperature rise that, even despite cutting emissions, cannot be reversed.

"Irreversible climate change because of carbon dioxide emissions," is the title of a new paper published today by the eminent peer-reviewed journal PNAS – Publications of the National Academy of Sciences of the USA… by the American Solomon and three other scientists from Switzerland and France.

"Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels … over the coming century” says the study, “are irreversible dry-season rainfall reductions in several regions comparable to those of the “dust bowl” era and inexorable sea level rise.”

Their study concludes that “the climate change that is taking place because of increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop.”

However, this does not mean there’s no point in cutting emissions, Solomon told science reporters on her teleconference, but rather the exact opposite:

If rising temperatures from CO2 emissions "do not drop significantly for at least 1,000 years" (in the words of the study) then any additional CO2 emissions would heat the planet even further — also for a very long time.

This PNAS paper generally reaffirms findings from other scientists reported by ABC News over the past two years that average global temperature will in any case increase over the next 40 years at least – regardless of worldwide greenhouse emissions cuts made now – before there is even any chance of it leveling off.

Most estimates say average global temperature will increase roughly two degrees Fahrenheit by 2050 – and could level off, though not sink, if greenhouse emissions have been greatly reduced.

For the temperature to level off, the concentrations of greenhouse gas in the air need to level off.

The study by Solomon et al affirms the general scientific understanding that, even if greenhouse gas concentrations  are slashed and  global  temperature can be leveled off by 2050,  average global temperature will not come back down to current or previous levels within a century or two – as Solomon said she thinks many people seem to assume – but rather stay at the new higher levels for at least 1000 years.

The great danger suggested by this and many studies is that if humanity does not start making drastic cuts in greenhouse emissions within the next few years – and cut emissions 50% worldwide by 2050 – then global warming would soar even further after 2050…

… the “Irreversible catastrophe” President Obama spoke of in this morning’s address, if greenhouse emissions are “left unchecked.”

Solomon told reporters that CO2 accounts for about half of global warming, the remainder produced by a variety of other greenhouse gases including methane and nitrous oxide, which, she pointed out, are often easier to limit.

Asked whether current efforts by some scientists and engineers to  invent ways to suck excess CO2 straight out of the air would mean global warming could in fact be reversed after all, she agreed it would, “if by some miracle” such engineering feats could ever be realized.

Otherwise, she said, her study was only further proof of the urgency of the need for humanity to drastically reduce its greenhouse emissions worldwide.