As mandated by the Global Change Research Act of 1990, the US Global Change Research Program (USGCRP) releases a comprehensive analysis of global climate trends every four years. November 23rd, better known as Black Friday, marked the early release of NCA4 (The Fourth National Climate Assessment), the fourth such installment under the program. As you sift through the receipts you racked up when the information first broke, here's what you need to know about its contents.

The USGCRP approaches its task by first analyzing climate trends at the global level. It follows by streamlining that data to analyze the effects that such trends may have on the United States specifically in addition to ways that the country can mitigate them. Moreover, the report recognizes that climate change does not occur in a vacuum; it offers a comprehensive look into each of ten key geographic regions in the US, noting that each is affected differently.

Climate change is identified as the umbrella term by which the global commons are changing. "Our changing climate," as identified by the report, draws both atmospheric (increasing greenhouse gas concentration, high temperature extremes, precipitation changes) and maritime (ocean acidification, ice cap shrinkage, rising sea level) trends under its scope. Moreover, each of these pressure dynamics have direct effects on human and animal health.

The atmospheric realm tends to jump to the forefront of one's mind when the words "climate change" are evoked. It all boils down to carbon dioxide; humankind is responsible for the buildup of the famed greenhouse gases, which trap heat within our ozone and cause the temperature to rise. Since the beginning of the twentieth century, ,annual average temperatures across the US have increased by a minimum of 1.8°F . Temperature increase triggers a host of side effects: increased precipitation in some regions is contrasted by drought in others, while the ice caps melt steadily. Since the 1980s, each decade has seen a minimum of 11% of ice caps lost to climate change. As ice melts and is converted into water, sea levels have creeped up against the shoreline. Like the air, water has the ability to retain carbon dioxide, which lowers the pH of the ocean beyond its natural equilibrium. When this phenomenon of acidification is combined with rising sea levels, the oceans have become increasingly uninhabitable for marine life. These trends are not new; however, their emphasis in NCA4 serves as an affirmation of the existence of climate change in a time where it is challenged by the public eye.

NCA4 does more than affirm the mere existence of climate change; it unequivocally defines it as a risk. The prose of the document categorizes "risk" as "threats to life, health and safety, the environment, economic well-being, and other things of value to society." This definition expands upon the categorization of the 2012 Assessment of climate change as a threat to "human health." By zeroing in on the way humans are affected, the USGCRP seeks to mitigate the idea that climate change is a dynamic that affects daily life only tangentially. The past year has seen natural disasters of all shapes and sizes-- from flooding in Houston to wildfires in California-- that the report directly links to climate change. The potential for human injury to skyrocket as these disasters become more frequent is clear. Moreover, NCA4 identifies the probability of "substantial losses to infrastructure and property and [an impediment to] economic growth over this century" if greenhouse gas emissions are not reduced. Agriculture, tourism, and fisheries are but a sample of the industries considered the most vulnerable. As such, NCA4 notes the disproportionate manner in which economic loss may be felt across the country's geographic regions; however, such does not reduce the fact that "the continued warming that is projected to occur...is expected to cause substantial net damage to the US economy."

The report internalizes these risks and the ways in which they may evolve before positing a multilateral response approach. Indeed, according to the USGCRP, it is impossible for response to be effective when it's anything but multilateral. The report overview opens by considering valid sources of change over the past four years, from state efforts in Hawaii to promote coral reef recovery to the work of farmers in the Midwest to combate nutrient loss in their soil. The emphasis on these initiatives builds on the call made in the Third National Climate Assessment to combine "'bottom up' community planning and 'top down' national strategies." Overall, the message is imparted that, within a situation like climate change whereby effects are felt by everyone, affectation emparts some degree of responsibility.

This overview is but the tip of the [melting] iceberg, as it were, when it comes to the findings published by the USGCRP last week. However, the main idea is clear: climate change is here, and if the nation doesn't take action, it and the risks it imparts are here to stay. In a way, NCA4 sends a message contrary to the effect of executive decision to release the report on the busiest day of the year: don't sweep climate change under the rug.