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Good News about Global Warming?

Until last week the consensus among climate scientists was that it takes about 30 years for the full climatic warming of carbon emissions to take effect. That meant that today we are only experiencing the total impact of carbon emissions generated before 1985 and additional warming will continue until 2044 no matter what we do. Turns out that the 30-year delay was based on scientists’ informed guesswork rather than quantitative studies.

NPR reported last week that “[f]or the first time” a study by two scientists at the Carnegie Institution for Science “evaluated how long it takes to feel the maximum warming effect caused by a single carbon emission.” The study indicated that it only takes 10, not 30 years.

In other words, based on this study we’ve already felt the impact of carbon emitted before 2005, and what we’ve spewed since only locks us into further changes through 2024. While the scientists caution that once the increase occurs temperatures will remain high for decades, it means whenever we cut emissions it will stop further warming more quickly.

This appears to be good news because the old understanding gave rise to inaction among many who take climate change seriously. Some despaired because if it is going to take years for our movement to get strong enough to force emission cuts, and we already will be locked into 30 more years of warming at that point, it will be too late to save us from civilization-ending catastrophes or even worse.

Several authors have tried to counter such defeatism by citing historical precedents for making basic changes quickly. The civil rights movement and the recent push to legalize gay marriage are the examples given most often. These are very significant and rapid social movements, but unlike cutting carbon emissions, they are not fundamentally economic. Ending legally sanctioned slavery was a major international economic change, but it took almost 100 years to accomplish, from the beginning of the 19th century in England, to the 1880’s in Brazil. Some authors have cited the rapid economic shifts of the New Deal to demonstrate that, at least in this country, we can change our economy fast.

But all these movements were reactions to existing conditions. Any delay between our change and response was based on human resistance, not natural systems that were beyond our control. Thus, the 30-year delay appeared to be a scientific certainly that rendered our current challenge historically unprecedented. A significantly diminished time lag appears more manageable.

The brief NPR story provides insufficient information for me to assess how much hope this should give us. Further studies may tweak the 10-year figure up or down. But these findings do remind me that while climate science knowledge has grown, it is still evolving. We need to stay on top of research in this area and disseminate the best current information without treating it as dogma. We also need to be prepared for the climate change deniers who will point to such changes as proof that the scientists don’t know what they are talking about.

Most importantly, we should also take heart that there is scientific evidence that even if we can’t force needed change before the impact of global warming gets worse, any victories we win will cut off further warming three times more rapidly than we previously thought.
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