Thank you, Mr. Chairman.
Members of the committee, John has covered almost every single point that's contained in the Summary for Policymakers of the AR4, and I'm not going to go through the process of repeating them once again.
What I thought I would do is focus on the high latitudes of this hemisphere and the comments the report makes about the situation northern Canada can expect to experience, if not in the next one or two decades, then certainly within the next century.
One of the primary fingerprints of the model predictions and surface observations of the process of global warming is that it is characterized by extremely high amplification at high northern latitudes. I think John has mentioned that we are observing, and models are correctly predicting, a difference by about a factor of two in the increase in mean surface temperature between the globe as a whole and the polar cap.
This has enormous ramifications for our country. For example, two years ago, in the Arctic Climate Impact Assessment report, which was precursory to the present AR4, there were detailed analyses performed of expectations about what the coverage of the Arctic Ocean by sea ice is liable to become before the end of this century.
It's very clear that by 2050—perhaps a little later, but about the middle of this century—there will exist for a significant period of time in the Arctic Ocean a continuous seaway. This has enormous implications for Canadian sovereignty. It has become much discussed in the popular press over the past month or so.
But it is just one of the issues we have to face in our most northern regions. We're beginning to observe very significant areas of permafrost degradation, and the ice cover in the Queen Elizabeth Islands and the Canadian archipelago is also experiencing a very significant decline.
I want to point especially to something that is not covered in the AR4, because these are results that have really come into the scientific literature only in the past six months or so. These results have to do with an experiment that is presently flying in space. It's an experiment called the gravity recovery and climate experiment. It's a two-satellite NASA–American–German collaboration that is flying a tandem of satellites over the pole, which are used to measure the time-dependence in the planet's gravitational field. This system has been focused very strongly on Greenland. One thing that has been very clearly established, based upon only four years of GRACE gravity field observations, is that the Greenland ice sheet is beginning to lose mass at an accelerating rate. Over the past four years, the rate of mass loss has increased by about a factor of four. This reinforces the comments in the AR4 to the effect that outlet glaciers on Greenland have begun to speed up.
This is an extremely important fact of the ongoing change in global climate: high-latitude amplification; increasing rates of mass loss in both alpine glaciers and the Greenland ice sheet.
And the report draws attention to a very important piece of observational evidence from the earth's past, specifically to a time in the past about 120,000 years ago, which is the so-called Eemian interglacial. This is the last time in Earth's history when the northern regions of the planet experienced a degree of warmth similar to the present. In fact, during the Eemian interglacial, the temperature within the polar cap was about five degrees warmer than it is at present. Our AR4 projection is that we should hit that increase in temperature in the polar cap again by about the middle of this century.
In the Eemian interglacial, when temperatures in the polar cap reached this level, the Greenland ice sheet was significantly smaller than it is today. And there was a very significant rise in mean sea level associated with that time, somewhere between four and six metres of sea level rise; we think about four metres associated with the loss of Greenland ice and as many as two metres associated with the loss of west Antarctic ice.
The interest here is a consequence of the fact that during the Eemian interglacial era, these changes, this shift in the temperature in the polar cap, took place on a very long time scale. The system moved very slowly into this new state of a relatively large diminution of polar ice. The experiment we're performing today is an experiment that's being performed on a very much shorter time scale. Our system is way out of radiative equilibrium, we call it. It's never been in a state like this before. The changes in greenhouse gas concentrations have occurred so rapidly that heat is being trapped out of radiative equilibrium primarily in the earth's oceans.
What this means in terms of the ability of Greenland and the west Antarctic ice sheet to maintain stability is an open question. Our climate models have no skill at all in predicting how ice sheets should respond to this out-of-equilibrium radiative regime. This really reinforces the fact that we are performing an experiment on the planet on which we have no way of predicting the outcome. And it should be a cause of great caution in terms of how we approach this from a policy perspective.
Thank you, Chairman.