I have been listening to a lecture by Victoria University climate scientist, James Renwick, who has recently moved to the university from his post as principal climate scientist at NIWA. In the seminar he sets out in broad terms some of the latest developments in the science. It’s a very clear summation, with some recent interesting graphs and charts, showing the direction which in which climate change is continuing to move. Needless to say there’s no change in direction apparent. I recommend the lecture as well worth listening to. I’ll only touch lightly in this post on the scientific content of the lecture; my main purpose is to highlight comments Renwick made along the way indicating the concern he feels about where we are headed.
I was particularly struck by an early statement made after he had remarked on the 2011 emissions reaching a record level of 31.6Gt and pointed to the graph of steadily increasing concentration of CO2 measured at Mauna Loa. I’ve transcribed it:
I feel a kind of morbid fascination with this stuff. It’s a really fascinating science issue – and I’m really interested to find out what’s going to happen to the climate and how much ice is going to melt and what’s the temperature in 2020 going to be and all the rest of it. It’s intriguing, it’s my bread and butter but you know what I feel is – I look at this and say jeez we’re really doing this, we’re doing this experiment, we’re really playing this game with the Earth, we’re gambling with millions of lives and I sort of feel disgusted with myself that I find it interesting from a scientific point of view It’s certainly interesting, but it’s more than interesting — it’s a very dangerous game we’re playing.
Just how dangerous becomes all too apparent as he proceeds. Global temperatures are continuing their steady increase from since around 1970. Sea levels are steadily rising, with the NZ rise similar to the current global mean of 3 mm per annum, roughly double that of the early 20 century. There’s an interesting comment on the temporary drop in sea level rise in 2010 and 2011 considered due partly to the La Niña event but also probably partly to the transfer of water in heavy rains, which he identifies as one of the new things around understanding sea level rise.
Ice is continuing to melt both in glaciers and in the Greenland and Antarctic ice sheets. Information about the ice sheets is improving considerably, including the mapping of ice movement. We don’t know enough yet to understand all the implications for sea level rise, but we’re getting there. He refers to a recent paper suggesting that we may be only a degree or so away from the temperature rise which could get the Greenland ice sheet moving irreversibly. The decline in Arctic sea ice in both the extent and the age of ice he describes as “fascinating in a bad kind of way”.
Renwick points to research suggesting that if we can halve emissions by 2050 then there’s more than a 50% chance of “staying below that 2 degree warming line which everyone appears to think, at a policy level at least, is a good thing to do”. He doesn’t explicitly say so but that two degree boundary is hardly established as safe by any science I have seen, and perhaps the terms in which he characterises the warming line are indicative of that. In any case as the lecture proceeds he recognises the possibility that we might be looking at a 4 degree rather than a 2 degree rise.
On rainfall attribution Renwick notes that model trends in all latitude bands are proving much weaker than observed trends. So things are changing in the direction we might expect but they’re actually changing faster than the models might tell us.
After covering such matters as the widening of the tropical belt by about 3 degrees latitude since 1980, the contraction of the Southern Annular Mode (the westerlies) toward the pole and the likelihood that 1 in 20-year warm periods are likely to become 1 in 2 years, Renwick moves to the implications for political action in the light of the fact that 2 degrees of warming is now virtually certain and that in fact we might be looking at more like 4 degrees:
“…which is extremely risky – large changes to the climate system, large changes to where the rain falls and how much, and food production and sea level rise. Big stakes I must say, but some massive opportunities to do something good and to even make money if you can come up with some clean and green ideas that will sell. But to me there still isn’t really the political leadership there to actually make things happen, which is quite concerning… We don’t have a conception of intergenerational debt, stewardship and all that kind of thing …We’re borrowing the earth against future generations and the earth is staring to bite back.”
I listened to the lecture mainly for its interesting presentation of the advances in the scientific understanding of climate change in the years since the last IPCC report, but the two extracts I’ve transcribed are also valuable for the way they communicate the human concern that accompanies the science. It’s not delivered in ringing tones, but it’s recognisable and surely appropriate. Moreover Renwick is voicing a level of disquiet widespread among climate scientists.
What is unfolding is deeply threatening to human life and the failure to address it adequately at the political level raises disturbing questions about our capacity to act ethically as societies. For climate change is at base now an ethical question. It is to do with the way our actions impact on the lives of others both now and in generations to come. And remedial action is not beyond our control. The ball is in the policy makers’ court. We should keep insisting that they address the issue adequately and with full seriousness.