January 14, 2013

Third National Climate Assessment Unequivocal about Climate Change

Evidence for climate change abounds, from the top of the atmosphere to the depths of the oceans,” reads a draft of the Third National Climate Assessment, published for public review by the U.S. Global Change Research Program on Friday. 

The draft study is unequivocal about the state of climate change: it is already affecting Americans and it is primarily driven by human activity.  According to an excerpt from the study’s executive summary:

Climate change is already affecting the American people. Certain types of weather events have become more frequent and/or intense, including heat waves, heavy downpours, and, in some regions, floods and droughts. Sea level is rising, oceans are becoming more acidic, and glaciers and arctic sea ice are melting. These changes are part of the pattern of global climate change, which is primarily driven by human activity. 

The congressionally mandated study – a result of the Global Change Research Act of 1990 – is intended to provide policymakers with a better understanding of the impact of climate change on U.S interests – from human health and biodiversity to energy production and transportation. The assessment is required every four years, but in practice has been more ad hoc. (This assessment is the third one since the 1990 act was passed by congress.)

The study also provides useful insights to national security and foreign policy practitioners charged with navigating the changing global climate landscape and making sense of the impact on U.S. interests. While the study explores areas for mitigating climate change – that is, reducing greenhouse gas emissions that are adding to climate change – it also emphasizes adaptation to changes that are already locked in as a result of decades of emissions increases. According to the study, “Proactively preparing for climate change can reduce impacts, while also facilitating a more rapid and efficient response to changes as they happen.” 

The draft study is worth a closer examination than we can provide here on the blog. Read the full report here.