Since the dawn of the industrial age, humans have been pumping increasing amounts of carbon dioxide into the atmosphere by burning coal, oil and gas. Researchers at the Mauna Loa Observatory, perched on the side of a volcano on Hawaii’s Big Island, have measured atmospheric levels of this greenhouse gas since 1958. That first year, carbon dioxide averaged 316 parts per million. In May, it reached 410 p.p.m. — an amount never before experienced in the history of our species. This atmospheric carbon dioxide — as well as other heat-trapping gases and other air pollutants emitted by humans — is affecting our planet profoundly.
We helped write the “Climate Science Special Report: Fourth National Climate Assessment, Volume I,” released on Friday by the United States Global Change Research Program. This comprehensive report — the most up-to-date climate science report in the world — is an outstanding example of federal science in action, and is especially noteworthy given the current political climate.
The report concludes that “global climate continues to change rapidly compared to the pace of the natural variations in climate that have occurred throughout Earth’s history.” It finds that “human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century.” The bottom line is that this report confirms and strengthens what the vast majority of climate scientists have known for decades: that climate is changing and humans are primarily responsible.
The report also highlights growing reasons for concern. For example, ocean acidification, which occurs when atmospheric carbon dioxide is absorbed by seawater, is taking place at what is thought to be the fastest rate in at least 66 million years. Coupled with reductions in oxygen content in near-coastal American waters, this poses a significant threat to coastal fisheries and ecosystems. Much of the western United States is facing a growing threat of more severe drought and larger wildfires as higher temperatures, reduced snow pack and earlier spring snow melt reduce water availability during the warm season.
And yet, there is also reason for optimism. The report documents how global carbon emissions may be leveling out, despite continued global economic growth. News reports in just this past year show how the cost of clean energy sources such as wind and solar have decreased dramatically both here and in emerging economies such as China, India and even the Middle East, sending powerful signals to long-term investors and businesses about which way things are trending. And more and more businesses, whether by choice or in response to investor demand, are asking: What risks do we face, if we do not plan for a changing climate?
All humans share this planet. We depend on it for the food we eat, the water we drink, the air we breathe, the natural resources it provides and the places where we live. For that reason, all Americans need to understand the risks we face, and the impact our choices will have on our future.
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