If the first session of plenary lectures focusing on cosmology made us feel somewhat insignificant compared to the huge time scales involved in studying the universe, the second set of talks underlined how dramatic man’s impact on Earth has been and the challenges facing scientists in communicating this.
"The warming of the climate system is unequivocable."
In a sobering talk about the Anthropocene, a new geological period that marks the time during which our activities have had a major impact on Earth’s ecosystems, Paul Crutzen walked us through a long list of data and graphs about our effects on our home planet.Change was the theme of the talk, and Crutzen started with an old black and white photographer of himself and his grandmother, explaining “I’ve changed a lot since then too, as you can see.” Man-made changes listed by Crutzen included the fact that almost half of the surface of the Earth has been transformed by human action. The use of fertilisers has resulted in a dramatic increase in nitrogen fixation – the rate of increase due to agriculture clearly exceeds that by processes that are independent of man. There has also been an increase in water use – the most striking figure was that it takes almost 10, 000 litres of water to produce 1kg of coffee! Crutzen emphasised that we’re not adhering to the polite visitors’ pledge to “leave no trace” and insisted that "the warming of the climate system is unequivocable."
The next talk, by Mario Molina, reviewed some of the scientific understanding about climate change then moved on to ask whether there’s anything we can do about it. Reminding the audience about the greenhouse effect, whereby some of the energy from the sun becomes trapped inside the earth’s atmosphere, and is radiated back down to the lower atmosphere following absorption by greenhouse gases, Molina reminded us why changing the composition of the atmosphere results in increased temperatures. The now well-known “hockey stick” graphs show that the concentration of greenhouse gases such as carbon dioxide and methane have increased for the past 10, 000 years, but most dramatically in recent times. This correlates with various measures of increasing global mean surface temperature.
"Reducing emissions to the levels required isn’t a small change, it needs a revolution in our relationship with energy use."
Molina then moved on to the problems with communicating climate change. Scientists are used to talking about their data in terms of probabilities, but often this can leave the conclusions around the data open to misinterpretation and allow others to latch on to apparently unresolved questions. Molina explained “Scientists don’t tell society what to do, they simply propose what might happen in certain circumstances.” One of the decisions taken based on the scientific data is the Copenhagen Accord – an agreement to take action to restrict the increase in global temperature to 2 degrees Celsius. Most of the current emissions of greenhouse gases result from energy use and Molina stressed that “reducing emissions to the levels required isn’t a small change, it needs a revolution in our relationship with energy use.” The solutions need to be multiple and wide-ranging, he suggested.
"Do you talk to your dentist about your heart problems? You should talk to climate scientists about climate change."
Pre-empting the following talk by Ivar Giaever, who was offering a sceptical take on climate change, despite his speciality in superconductors, Molina finished with a reference to the need for dialogue with the experts: "Do you talk to your dentist about your heart problems? You should talk to climate scientists about climate change."
"I pick and choose [data] when I give this talk…"
Giaever immediately countered on beginning his talk, declaring "I’m glad I get a chance to speak for myself." He then complained that scientists‘ belief in climate change had become a religion which allowed no room for debate and proceeded to present his own selection of data as to why he believed carbon dioxide has no role in global warming. Freely admitting "I pick and choose [data] when I give this talk…" he concluded by asking "Is climate change pseudoscience? If I’m going to answer that question, the answer is: absolutely."
Coming full circle back to Crutzen’s introductory black and white photo, Giaever finished by showing two photos of himself and his wife, comparing how they looked when they were married and more recently, also remarking that change happens over time. For me, it would have been interesting to see if a debate between all of the speakers, with a detailed discussion of the data, would have resulted in more overlap in their perspectives than just their family albums.