“As a human, though, passing both the 400 ppm and (potentially) the 1°C threshold within such a short time period makes it clear we are already living in a different world. We have blown past targets that were being considered as viable when I entered graduate school. We have significantly reduced the options available to us in the future. If we aren’t going to blow past the next set of thresholds — 500 ppm and 2°C — within just a few more decades, we have a lot of work to do in Paris in two weeks and beyond.” Katharine Hayhoe, atmospheric scientist at Texas Tech University responding to a question posed by Climate Central. The Scripps CO2 measurements at the Mauna Loa Observatory on the big island of Hawaii have shown that atmospheric carbon dioxide (CO2) levels climbed above the 400 parts per million (ppm). Because CO2 stays in the atmosphere for a very long time, some scientists say for millennia, our global fever has reached the point that no one alive today, and those that follow us, will ever know a world below 400 ppm again. Even after the horrific events in Paris, over 120 world leaders will still attend the upcoming climate conference, Though a huge march on Nov. 29 by supporters of an agreement to reduce carbon emissions has been cancelled by the French government. In Paris, the most vulnerable among humanity will be pushing for a UN climate goal of 1.5C.Such a goal would be an ambitious one. Some negotiators and onlookers already seem to have given up hope of limiting warming to less than 2°C, much less 1.5°C. Fossil fuel burning, deforestation and other climate-changing hallmarks of industrialization have elevated temperatures 1°C since the 19th century, pushing tides up more than 8 inches. Pledges submitted by nations ahead of the meeting to take steps to slow climate change could yet allow warming to soar to 3°C or more.The longing by low-lying nations to limit warming to 1.5°C has been overshadowed since 2010 by a preoccupation by many with the less ambitious goal. On Wednesday, the U.N. released the latest report to confirm that goal — to limit warming to 2°C, compared with preindustrial times — could be reached through massive globally cooperative efforts that overhaul energy supply chains and reform farming and forest management.Goddard Media simulates carbon dioxide world wide dispersal.Plumes of carbon dioxide in the simulation swirl and shift as winds disperse the greenhouse gas away from its sources. The simulation also illustrates differences in carbon dioxide levels in the northern and southern hemispheres and distinct swings in global carbon dioxide concentrations as the growth cycle of plants and trees changes with the seasons.The carbon dioxide visualization was produced by a computer model called GEOS-5, created by scientists at NASA Goddard Space Flight Center’s Global Modeling and Assimilation Office.The visualization is a product of a simulation called a “Nature Run.” The Nature Run ingests real data on atmospheric conditions and the emission of greenhouse gases and both natural and man-made particulates. The model is then left to run on its own and simulate the natural behavior of the Earth’s atmosphere. This Nature Run simulates January 2006 through December 2006.While Goddard scientists worked with a “beta” version of the Nature Run internally for several years, they released this updated, improved version to the scientific community for the first time in the fall of 2014.