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‘A different planet’

Dr James Hansen

NASA’s Dr James Hansen (Courtesy: Greenpeace)

By Tushna Commissariat

This Tuesday I was in London meeting some exciting and important people in science. While you will have to wait until tomorrow to find out who I met with in the morning, in the afternoon I went along to the closing lecture at Royal Society’s paleoclimate conference Warm Climates of the Past – a Lesson for the Future?. The lecture was given by Dr James Hansen – the head of the NASA Goddard Institute for Space Studies who has been very vocal on the subject of climate change since the 1980s.

In “Earth’s climate history: lessons for the future” Hansen spoke about how observations of past climates coupled with current-day observations suggest that hard-hitting and immediate measures need to be put in place to avoid further global destruction. Rapid reductions in the use of fossil fuels are the best way to do so, he argued.

Hansen began his talk by saying that our basic understanding of the Earth’s paleoclimate history should depend more on global “real-world” geological observations, rather than climate models and theories. He feels that the Earth’s history provides the information that is necessary to better understand climate change today and that researching “climate sensitivity” at any given point depends on the timescale taken into consideration and the “climate state” at that given time.

Hansen went on to say that when some generally “intelligent people” say that the Earth has been a lot colder or warmer in the past, he is quick to point out that he doesn’t think that the global mean temperature was ever more than a degree higher, as far back as the last glacial period.

He categorized the three main factors affecting the global climate over the past 65 million years and presented the amount of warming change they would cause in Watts/m2:

*external effects (solar irradiance): +1 W/m2

*surface effects (continental location – geological changes): ~1 W/m2

*atmosphere (CO2 change): >10 W/m2

He pointed out that the natural change in CO2 has been steady at about 0.0001 ppm/year, whereas the human-generated rate today is at about 2 ppm/year. He also showed that the sea level has been rising at about 3 m per millennium, as compared with the near-constant level it has maintained for the past 6000–7000 years. His hard-hitting statement that “Humans could produce ‘a different planet’” makes it clear that he feels very strong measures need to be put in place to preserve the planet as we know it.

His main suggestion to achieve a more stable climate was a drastic cut in the use of fossil fuels worldwide, by levying high taxes on their use. “We cannot burn all the fossil fuels and yet our governments go along with that,” he said. “A solution has to be a gradually rising carbon tax.” He went on to explain that such a tax would mean that fossil fuels derived from tar sands, for example, would almost immediately stop as it would not make economic sense and that coal would follow soon after. He also feels that such a tax would go a long way toward making clean fuel sources the norm. “Rapid reduction of fossil-fuel emissions is required to succeed in preserving a planet resembling the one that civilization developed,” he said.

On a similar note, a recent Physics World opinion piece, titled “How big is your footprint?” and written by astrophysicist Phil Marshall of the University of Oxford, talks about how physicists carry the responsibility to reduce their own carbon footprints. These can be considerable when you consider the amount of energy that is required to run physics facilities or fly across the Atlantic frequently for conferences. For example, he points to CERN’s Large Hadron Collider energy bill – estimated at about €10m per year – comparable to that of all the households in the region around Geneva. He estimates that US astronomers use an additional 130 kWh per day more than the average citizen.

Marshall also talks about a workshop in Lund, Sweden, this week, where researchers are discussing energy for sustainable science to identify ways to do large-scale physics research with a reliable, affordable and sustainable energy supply that is “carbon neutral”. To read about that and maybe take a look the wiki Marshall runs for green-minded astronomers, take a look here.

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