There are a few people who will now appear on the blog who will be extremely peevish about Molina’s talk, because he simply clearly stated the scientific consensus. We are now living in the anthropocene, when so many people exist that that we are affecting the planet’s functions. CO₂ and CH₄ concentrations have been changing rapidly in recent decades, along with changes in temperature, and the fact of the matter is that the changes in the chemical composition of the atmosphere are causally connected to changes in temperature.

He showed long term records of 450,000 years of temperature and chemistry, which show regular changes in temperature and chemical composition, even of regular cycles of change. But recent changes are much larger, and the changes in the last century were not expected from known natural causes — they don’t fit the prior pattern. Only pseudoscientific (he was not at all mealy-mouthed: yes, he called the people who question anthropogenic change to be pseudoscientific) papers currently question the causal relationship of human activities to climate change.

There are some events that should give us pause. The glaciers feeding China’s rivers are shrinking, and the Tibetan plateau has important role in climate of China — what happens when China’s huge population faces major droughts? He mentioned specific events like Katrina, the exreme weather events. We can’t tell for certain that an individual event is climate change related, but statistics show a pattern of increasing events, such as wildfires and droughts. 400 million people are living under extreme drought conditions, and very dry land has increased worldwide in a short period of time: 15% of land was so classified in 1970, but it’s now up to 30% in 2002.

Trends show that greenhouse gases are increasing. What needs to be done? We need a revolution in the way society functions to prevent CO₂ from rising abouve 350-450 ppm. Can it be done?

Molina is generally optimistic. He thinks that we can limit CO₂ with existing technologies. His recipe is improved fuel economy, more efficient builidongs, improved power plant efficiency, substituting natural gas for coal, using carbon capture and storage, developing alternative power sources (nuclear, wind, solar, biofuels), and forest management. We need to do ALL, there will not be a single magic bullet that solves the problem.

He argues that we are not running out of fossil fuels (there is lots of coal), but we are running out of oil. However, we will run out of atmospheric capacity to cope with emissions before we run out of oil.

We are playing a game, like roulette. We are gambling: to win, a policy should result in a temp increase of less than 2° C. What policy does is shift the probabilities of winning — we are paying to move from one roulette wheel with bad odds to another with lower risk. We want to buy stabilization of probabilities and reduce uncertainty, and it’s not that expensive. An investment of a few percent of GDP produces a big improvement of our odds. He compared it to a hypothetical airplane trip. If you were told you could board a plane right now that has a 10% chance of both engines failing, or you could wait a few hours to take a different plane that cost 10% more but had a negligible chance of engine failure, which would you do? For most of us, the choice is simple, since the first plane has a good chance of catastrophic failure, and we’d rather avoid that sort of thing.

Less optimistically, he brought up the possibility of tipping points and the instability of the system. It is a big worry that we have a risk of entering practically irreversible modes: he gave the example of melting of arctic summer ice, since once the ice cap is gone, it is not trivial to restore it. Some tipping points may occur relatively soon. We are at risk of catastrophic climate change.

He ended with simple actions we should take now:

• Put a price on carbon emissions.

• Increase investment in energy tech research

• Expand international cooperation

• Emphasize win-win solutions

The big problem is that right now 3/4ths of the planet is striving to reach the ecoonomic standards of the developed countries — they should, and they have every right to aspire to it, but it is physically impossible for them to do it with the same wasteful strategies of the developed nations.