Suggested Scientific Concepts on Urgency

For the substance of your comments, choose one (or at the most two) of the following scientific concepts to highlight the need for urgent action. Of course, you should also feel free to develop your own concept.

-- Global warming is already underway and is accelerating (e.g. Arctic sea ice extent and depth, glaciers melting, sea level rise, extreme events, etc.)

-- Scientists are concerned that ‘tipping points’ or points of no return might be reached in the climate system--e.g. substantial Greenland ice sheet melt, tundra methane release, ocean carbon release, etc.--at which point the impacts are irreversible on a human timescale.

-- Carbon dioxide (CO2) levels have already far exceeded any seen over the past 800,000 and probably the last 2 million years. This puts us in the position of playing “catch-up,” even if we begin reducing emissions right away.

-- Recent evidence suggests that climate change consequences are occurring faster than expected by many scientific papers written even a decade ago, thus emphasizing the rapid pace of change.

-- It seems unlikely that natural systems can adapt as quickly as the changes are occurring, and slowing the pace will help. Humans may be able to adapt to some level of warming, especially if the pace of change slows and the higher temperature projections are not reached.

-- The world is already committed to a certain level of warming due to heat-trapping gases that are presently in or on their way to the atmosphere. At the present time, these heat-trapping gases are not being removed from the atmosphere by the ocean as fast as they had previously been. This means current emissions have a greater impact than an equal volume of emissions released several decades ago.

-- There is a cumulative effect of overloading the atmosphere with carbon and there are inherent delays associated with trapping heat day in and day out long after the initial source released the carbon. The responsible course of action suggests we be concerned about future generations—our emissions today are setting our children’s climate future.

-- Scientists have a general sense about the possible ‘safe levels’ of CO2 in the atmosphere or about a temperature limit that is needed to avoid dangerous climate change. We are dangerously close to those levels already and so should take quick action to reduce emissions (e.g. recent NAS study, etc.)

-- The costs of inaction are very high—the longer we wait to get started, the bigger the problem and higher the costs.

Last revised date: January 13, 2011

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