By Susan Moore
I’m a believer in climate change because of the book “Storms of My Grandchildren” by James Hansen that I read a few years ago.
For those of you not familiar with Hansen, he is the director of NASA’s Goddard Institute for Space Studies and adjunct professor in the Department of Earth and Environmental Sciences at Columbia University. He is also an alumnus of the University of Iowa and has testified before Congress on climate change.
In the preface to his book, he wrote: “The startling conclusion is that continued exploitation of all fossil fuels on Earth threatens not only the other millions of species on the planet but also the survival of humanity itself — and the timetable is shorter than we thought.”
To better understand the concept of climate change, two terms that Hansen uses a lot — climate-change forcings and climate-change feedbacks — need to be clarified. “Forcings drive climate change. Feedbacks determine the magnitude of the climate change.”
According to Hansen, during the glacial-interglacial cycles of the past million years, climate change was caused by natural forcings, such as the Earth’s tilt and orbit, and modified by such feedbacks as global surface reflectivity and greenhouse gas changes. But today, “Human-made forcings are now in total dominance over the natural forcings.”
The main human-made forcing on Earth is the greenhouse-gas carbon dioxide, or CO2, that comes from burning fossil fuels such as coal, oil and gas. Since human beings started burning these fuels in large quantities, CO2 has accumulated more quickly and at higher levels as measured in parts per million, or ppm, compared with preindustrial age accumulations.
During glacial-interglacial cycles, CO2 levels topped out at less than 300 ppm. Now we are approaching levels of 390 ppm. Higher levels of CO2 mean that the Earth radiates less heat back into space than what it absorbs from the sun. Over the last 100 years, the average global temperature has increased by 1.5 degrees Fahrenheit.
The most important feedbacks “ … all involve water, in either its solid, liquid, or gas form.” Glaciers, for instance, help cool our planet because they reflect back to space most of the sunlight that hits them, but bodies of water and water vapor absorb heat, and a warmer planet leads to a higher probability of more extreme weather events, such as droughts and heat waves, as well as heavier rains and intense storms.
The speed at which our planet is warming is disturbing. Visual evidence of this warming can be seen in the film “Chasing Ice,” which will be showing at the Bijou Cinema at the University of Iowa’s Memorial Union from March 8 to 14. The film follows James Balog, a National Geographic photographer, who started the Extreme Ice Survey in 2007 by mounting 25 cameras onto bedrock located next to glaciers in Greenland, Iceland, Alaska and Montana. The resulting time-lapse photography, outstanding by itself, shows dramatic visual evidence that we are losing our glaciers due to climate change.
The director, Jeff Orlowski, followed Balog and his team as they set up their cameras near the glaciers, not an easy task because of the difficult terrain the team encountered.
Some people believe in climate change because of statistics or anecdotal stories they have heard, but if you want visual evidence, see “Chasing Ice” and ask yourself if seeing is believing.
Be sure to share your answer with everyone you know, including your governmental representatives. This planet needs all the help it can get.
Susan Moore is a member of Iowa City’s Landlocked Film Festival board, which is a co-sponsor of “Chasing Ice.” Comments: email@example.com