Thank you very much, Mr. Chairman and members of the committee.
I'd like to echo what Dr. Peltier said regarding the very wonderful summary that Dr. Stone made about the IPCC Summary for Policymakers.
Let me say I've been involved in the last three IPCC assessments: the second one, which appeared in 1995-96; the third that was published in 2001; and the last one that appeared, at least the Summary for Policymakers, in 2007.
I would rather not be prescriptive as to the type of things the government should do, so I'm going to make myself available for questions on the science.
But I want to raise one small issue that was touched upon by John Stone, and that issue is the commitment to warming that is already in the cards for change that has occurred. If you look at the report, what you'll find is that even if we were to maintain and stabilize emissions immediately--and it's not even emissions, but levels of carbon dioxide immediately--we're still committed to a 0.1-degree-per-decade warming, up to a total of about half a degree warming in the centuries ahead.
Every policy option that's on the table, that is, all of the various scenarios put forward by the various working groups of IPCC, leads us to about a 0.2-degree-per-decade warming over the next couple of decades. The difference between the scenarios lies after that point, so the decisions we make today are really coming to effect on time scales greater than two decades.
We have decisions that lead us to paths where atmospheric carbon dioxide levels can stabilize, or those business-as-usual type scenarios where it doesn't stabilize. The time scale over which this occurs.... And if you ask the question, what levels of carbon dioxide or emissions do we need to get to as a globe, the working number is that if we get below 60% to 90% global emissions reductions, then we will stabilize carbon dioxide levels at greater than the level that is above a two-degree warming, and that's not necessarily an acceptable level.
So the types of targets that people are looking at are the targets greater than 60%, of the order up to 90% by the year 2050, in order to stabilize levels of greenhouse gases at a level that is not deemed to be “dangerous”. That level of dangerous is often defined to be two degrees or so, and the reason why it is defined to be that is because our estimates of when Greenland ice sheets, for example, past the point of no return, are shortly above a two-degree warming, about a 2.5- to three-degree warming.
I'll stop there and be ready for any questions on any aspect.