Climate Scenario 3 Catastrophic Climate Change

This scenario provides the basis for chapter 6 in this volume, by Sharon E. Burke, on catastrophic consequences of climate change for national and international security through the end of the twenty-first century. On the basis of current scientific understanding, we assume that abrupt, global catastrophic climate events cannot plausibly occur in the next three decades, but could plausibly do so over the course of this century. To examine the consequences of such events, scenario 3 extends the rapid warming and attendant accelerated impacts associated with scenario 2 to the end of the twenty-first century, leading to assumed rapid loss of polar land ice, abrupt 2-meter (6.6-foot) sea level rise, and the collapse of the North Atlantic MOC. We therefore assume warming that is double the best estimate of modeled surface warming under emissions scenario A1B for the year 2100 (see table 3-1).

Although doubling an IPCC projection is arbitrary, the result—5.6°C (10.1°F) warming by 2095 relative to 1990—compares well with the upper-end projection of a group of models that incorporated carbon cycle feedbacks and therefore simulated higher atmospheric CO2 growth rates than did the IPCC models.13 When adjusted to account for changes in non-CO2 greenhouse gases and atmospheric particulates, the models including carbon cycle feedbacks produced an upper-end projection of a 5.6°C (10.1 °F) temperature rise in 2100 relative to 2000. These models still did not incorporate all possible positive feedbacks, such as increased greenhouse gas emissions from thawing permafrost, so our most extreme warming scenario could potentially prove conservative. Even so, there is little utility in assuming higher projected temperatures, as impacts have generally not been assessed for twenty-first-century warming greater than 5°C (9°F).14

Emergency Preparedness

Emergency Preparedness

Remember to prepare for everyone in the home. When you are putting together a plan to prepare in the case of an emergency, it is very important to remember to plan for not only yourself and your children, but also for your family pets and any guests who could potentially be with you at the time of the emergency.

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