Amber Jenkins is a climate change communicator at JPL. In previous lives she was an atom smasher, journal editor and wannabe Shakespearean actress.
Over on My Big Fat Planet, Carmen Boening, a scientist in the Climate Physics Group at NASA's Jet Propulsion Laboratory, is sharing news from the United Nations Climate Change Conference in Poland. Read her reports on the discussions shaping climate change policy and the emotional speech delivered in the wake of Typhoon Haiyan.
In this new series on "Big Fat Planet," we will answer selected questions about Earth's climate submitted by readers. Recently, a reader asked: "Is there still time to reduce climate change, or is it too late?" The following answer is from Dr. Chip Miller, a researcher specializing in remote sensing of carbon dioxide and other greenhouse gases at NASA's Jet Propulsion Laboratory. He is principal investigator of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) and was deputy principal investigator for NASA's Orbiting Carbon Observatory satellite mission, which was designed to measure atmospheric carbon dioxide from space.
This is a question that has been asked many times and many studies have investigated similar questions: What level of climate change is "acceptable"? What constitutes "dangerous interference" in the climate system?
The short answer is that it's not too late to act, but our past actions may have already locked in certain outcomes and action is needed to avoid more substantial impacts in the future.
In the 1990s and early 2000s it was generally felt that a doubling of carbon dioxide (CO2) in the atmosphere compared to pre-industrial levels -- that is, CO2 concentrations increasing to about 500 parts per million (ppm) - was "acceptable." However, the series of studies from the Intergovernmental Panel on Climate Change (IPCC) has found that as climate models improve, average worldwide surface temperature is projected to increase well beyond the "acceptable" level of 2.0 degrees Celsius (3.6 degrees Fahrenheit) by 2100. (See the IPCC website for the reports and most recent information.)
Jim Hansen (head of NASA's Goddard Institute for Space Studies) has been one of the more outspoken advocates of curtailing CO2 emissions immediately to return atmospheric CO2 levels to about 350 ppm (the level of carbon dioxide that was in the air in the late 1980s). The challenge here is that even if human emissions of CO2 were cut to zero today, there is an inertia in the climate system that would continue for hundreds to thousands of years as the system attempts to re-equilibrate. (See Hansen's Royal Society paper, "Climate change and trace gases," for more details.)
Michael Oppenheimer [Professor of Geosciences and International Affairs at Princeton University] and colleagues have taken a different approach to assessing climate change risk - they define the likelihood of certain environmental outcomes for different levels of atmospheric CO2 accumulation. (See their 2002 Science paper, "Dangerous climate impacts and the Kyoto Protocol," for a look at three potential outcomes at different CO2 levels.)
“Perception of climate change,” J. Hansen, M. Sato & R. Ruedy, Proceedings of the National Academy of Sciences (6 August 2012); doi: 10.1073/pnas.1205276109.
An interesting recent paper from Dr. Son Nghiem at NASA’s Jet Propulsion Laboratory and colleagues finds that the bottom of the Arctic Ocean controls the pattern of sea ice thousands of feet above on the water’s surface. The seafloor topography exerts its control not only locally, in the Bering, Chukchi, Beaufort, Barents and Greenland Seas, but also spanning hundreds to thousands of miles across the Arctic Ocean.
How? The seafloor influences the distribution of cold and warm waters in the Arctic Ocean where sea ice can preferentially grow or melt. Geological features on the ocean bottom also guide how the sea ice moves, along with influence from surface winds.
Interestingly, the study also links the bottom of the Arctic Ocean with cloud patterns up in the sky. The ocean bottom affects sea ice cover, which affects the amount of vapor coming from the surface of the ocean out into the air, which in turn influences cloud cover.
The researchers, who also come from NASA's Goddard Space Flight Center, the Applied Physics Laboratory and the National/Naval Ice Center in the U.S., use sea ice maps taken from space with NASA’s QuickSCAT satellite, as well as measurements from drifting buoys in the Arctic Ocean. They compare the sea ice and seafloor topography patterns to identify the connection between the two.
Since the seafloor does not change significantly over many years, sea ice patterns can form repeatedly and persist around certain underwater geological features. So computer models need to incorporate these features in order to improve their forecasts of how ice cover will change over the short- and long-term. This ‘memory’ of the underwater topography could help refine our predictions of what will happen to ice in the Arctic as the climate changes.
Source: “Seafloor Control on Sea Ice,” S. V. Nghiem, P. Clemente-Colon, I.G. Rigor, D.K. Hall & G. Neumann, Deep Sea Research Part II: Topical Studies in Oceanography, Volumes 77-80, pp 52-61 (2012).
This is a new image of our planet at night, as taken by a new NASA and National Oceanic and Atmospheric Administration (NOAA) satellite orbiting above us. Scientists recently unveiled this global composite image (and the one below), constructed using cloud-free nighttime images. They show the glow of natural and man-made phenomena across the planet in greater detail than ever seen before. City lights can tell us about how humans have spread across the globe.
Many satellites are equipped to look at Earth during the day, when they can observe our planet fully illuminated by the sun. But with a new sensor onboard the NASA-NOAA Suomi National Polar-orbiting Partnership (NPP) satellite launched last year, scientists now can observe Earth's atmosphere and surface during nighttime hours.
For more Earth at night images, see this article.
You might think from the amount of “climate science debate” that is given airtime in the U.S. media that it’s undiscovered territory. But it’s not. The science is very well established and goes back a long way. Global warming is not a new concept.
The Victorians knew about it. John Tyndall (born 1820) knew about it. So did Svante August Arrhenius. In April 1896, Arrhenius published a paper in the London, Edinburgh and Dublin Philosophical Magazine and Journal of Science entitled “On the influence of carbonic acid in the air upon the temperature of the ground.” (Arrhenius referred to carbon dioxide as “carbonic acid” in accordance with the convention of the time.)
Arrhenius’ paper was the first to quantify how carbon dioxide contributed to the greenhouse effect — carbon dioxide warms up the Earth by trapping heat near the surface, a bit like swaddling the planet in an extra blanket. Arrhenius was also the first to speculate about whether changes in the amount of carbon dioxide in the atmosphere have contributed to long-term variations in Earth’s climate. He later made the link between burning fossil fuels and global warming.
Another person who “knew” some time ago was Frank Capra. Graduating from Caltech in 1918, he went on to become a famous filmmaker responsible for “It’s a Wonderful Life” and other movies. But one that stands out, at least for nerds like me or people with an interest in climate change is “Meteora: The Unchained Goddess”, released in 1958.
Made for Bell Labs, this most awesome educational film speaks of “extremely dangerous questions”:
Dr. Frank C. Baxter: “Because with our present knowledge we have no idea what would happen. Even now, man may be unwittingly changing the world’s climate through the waste products of his civilization. Due to our release through factories and automobiles every year of more than six billion tons of carbon dioxide, which helps air absorb heat from the sun, our atmosphere seems to be getting warmer."
Richard Carlson: "This is bad?"
Dr. Frank C. Baxter: "Well, it's been calculated a few degrees rise in the Earth’s temperature would melt the polar ice caps. And if this happens, an inland sea would fill a good portion of the Mississippi valley. Tourists in glass bottom boats would be viewing the drowned towers of Miami through 150 feet of tropical water. For in weather, we’re not only dealing with forces of a far greater variety than even the atomic physicist encounters, but with life itself."
In 1958, they knew about the effects of heating up the planet. In the 1800s they knew about it. Today, the biggest challenge facing climate scientists lies in predicting how much our climate will change in the future. It’s not a trivial task, given how complicated the climate system is — we can barely predict in detail more than a week’s worth of weather. We’re not viewing Miami through bottomed-glass boats yet, but we’re already beginning to see some of the predictions of global warming — melting sea and land ice, sea level rise, more extreme weather events, changes in rainfall and effects on plants and animals — be borne out.