US climate report points to human activity as primary cause of climate change

By Bryan Dyne
13 May 2014

The US government has released its National Climate Assessment (NCA), a report that details the full extent of the impact of human activity on climate change, with a focus on the United States. The results are in line with the UN’s fifth report from the Intergovernmental Panel on Climate Change: the world is warming, the consequences are becoming more and more severe and humans are the primary cause of climate change.

In its overview, the NCA declares that, “Multiple lines of independent evidence confirm that human activities are the primary cause of global warming of the past 50 years.”

The Obama administration unveiled the report along with statements from the president. The White House is seeking to present a portrait of concern, even though the administration has done nothing to address climate change during its more than five years in office.

A team of more than 300 climate scientists, researchers and support staff worked with 60 government officials to produce the 841-page document. It provides a comprehensive look at the shifts in the global climate over the past half-century, the problems already presented by global warming and how these manifest locally.

Since 1895, the average surface temperature across the US has risen between 1.3 to 1.9 degrees Fahrenheit (F), the majority of which occurred since 1970. With emissions as they currently stand, temperatures are projected to rise a further 2 to 4 degrees F in the next few decades. Sixteen different projections were used to estimate that by the year 2100, there will be a temperature increase of between 3 and 10 degrees F. The range depends primarily on whether carbon emissions can be reduced or whether they will continue to increase at current rates. These estimates agree with those for the average surface temperature globally.

Natural causes for the temperature increase were explicitly ruled out by the NCA. Data considering natural factors such as volcanic activity, changes in solar energy output and naturally occurring cycles were collected from a variety of instruments monitoring these effects for the past five decades. One bit of information was striking—for more than a century, an average of 30 billion tons of carbon dioxide has been put into the atmosphere by humans per year, 100 times as much as all volcano eruptions during that time period combined. Last month was the first time in history that the average carbon dioxide concentration levels in the atmosphere rose above 400 parts per million, up from a more or less constant 280 ppm before 1800.

Climate scientists used this data to produce a model for temperature with just natural factors at work alongside one with both natural and human activity. The observed temperature changes for the past 50 years match the human-induced climate change model almost perfectly.

The green band models how temperature would have changed based solely on natural causes. Note the slight decrease in temperature. The blue band is a simulation of temperature changes caused by natural and human factors. The black line represents the observed temperatures for the past century, showing that human influences must be included when considering climate change models. Credit: US Global Change Research Program

Additionally, the report explains that climate change is not expected to be uniform. Short-term temperature fluctuations are a result of natural processes, such as volcanic eruptions that may produce a slight cooling effect, and the inherently chaotic nature of the climate system. The trend, however, is a clear increase in temperatures across the US.

Local fluctuations are expected as well. The prevalence of longer droughts in California and heavier precipitation in the Northeast and Midwest are expected to occur. Soil moisture in the Southwest and Great Plains regions is expected to drop between 5 and 15 percent by the end of the 21st century. At the same time, fiercer winter storms are predicted for the northern Atlantic coast and areas around the Great Lakes. On both coasts, sea levels are estimated to rise 1 to 4 feet in the next 100 years.

Moreover, it is not just the air but also the oceans that are warming. Over the past century, ocean temperatures have risen by 1 degree F. Combined with higher levels of carbon dioxide in the atmosphere, this has resulted in higher levels of sea surface carbonic acid as carbon dioxide slowly dissolves. This in turn dissolves the calcium carbonate shells that are vital for plankton and coral reefs, organisms vital to the ocean (and world) food chain. Laboratory studies mimicking oceanic acidity over the past 200 years found that plankton, reefs and other organisms were far more prone to die in the current ocean than their counterparts from the pre-industrial era.

The NCA also details the impact on human life. Smoke from larger and more frequent forest fires, greater amounts of surface ozone and longer pollen seasons have already produced increased cases of allergies, asthma, bronchitis, respiratory problems and cardiovascular emergency room visits. Areas of higher temperatures or unusually high and low precipitation are more likely to suffer diarrheal pathogens (i.e., Salmonella and Campylobacteriosis).

Other diseases result from changing global climate patterns. The risk from diseases that are normally contained in one geographic region are dengue fever, West Nile virus, Rocky Mountain spotted fever, plague, and tularemia. Lyme disease is also on the rise as ticks are able to spread more during the longer summers and warmer winters.

Increased heat waves are also a major threat to human life. The past decade was the hottest on record, with 2012 being the hottest recorded year. High temperatures correspond to more heat stroke deaths as well as higher rates of kidney, cardiovascular, respiratory and cerebrovascular disorders and diseases.

Despite the dangers this report underscores, the government is doing nothing to address the problem. The hype surrounding the NCA is instead aimed at this year’s midterm elections. Obama declared in one interview that “this is not some distant problem of the future,” while the administration’s science advisor, John Holdren called the report the “loudest and clearest alarm bell to date.”

In fact, the administration followed the policy of its predecessor in undermining any international agreements to address climate change. At every climate summit during his administration, starting with Copenhagen in 2009, the White House has demanded that restrictions on carbon emissions be far less than those of developing countries such as India and China.

On every matter that has touched the interests of big business, the Obama administration has worked to undermine environmental considerations. Most notorious was the response to the BP oil spill of 2010, the worst environmental disaster in US history. The spill was made possible by pro-corporate regulatory mechanisms, and the administration responded to the disaster by doing everything it could to defend the profit interests of the energy giant.

Obama’s policies on the environment, as with everything else, have been dictated by the interests of the corporate and financial elite. Globally, the competing nationalist interests of ruling classes—a basic component of the capitalist system—have made impossible any coordinated, international response to the global problem of climate change.


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