My head’s in a bit of a whirl this week. I make no secret of the fact that I pick my topics for the digest from a variety of sources but mainly from social media — which, of course, has a serious scientific side that’s at least as strong at its more flippant one.
This week it’s the European Geosciences Union’s conference in Vienna, and the Twitter feed from there is awash with fascinating snippets and links as scientists present a huge variety of research. Open drilling, the Earth’s magnetic field, struggling ecosystems…they’re all there. I thoroughly recommend that anyone with an interest in geoscience gives them (and their US counterparts the AGU) a follow, just to keep up to speed with what’s going on.
There’s a huge amount of other research and activity going on, of course, and in the end I only picked up one article from the conference. Keep an eye open though — there will be plenty more.
Antarctic Ice Cover
If I had to nominate a part of the Earth’s system to illustrate how complicated the whole workings of the Earth-atmosphere system are, I would probably choose ice — or the cryosphere, as scientists call it.
It goes without saying that the volume of ice controls sea levels. According to the National Snow and Ice Data Centre: “Together, the Greenland and Antarctic ice sheets hold about 99 percent of the world’s freshwater ice. If the Greenland Ice Sheet melted away completely, sea level would rise roughly 7 meters, or 23 feet”. And of course, a warming atmosphere increases melting.
Inevitably, it’s more complicated than that. Last week I talked about ocean circulation and how an influx of cold, fresh water can actually cause cooling of ocean currents. And increase in precipitation can also cause an increase in snowfall and growth of ice caps in one part of an ice sheet even as another part melts at an increasing rate.
This week, research from the British Antarctic Survey, presented at the EGU meeting, indicated how scientist use ice cores to demonstrate that over the past two centuries, the annual snowfall in the Antarctic has increased — but the BAS note that this doesn’t compensate for increased melting elsewhere.
Slip-Sliding Away: Landslides in 2017
I mention landslides quite often, but almost always in passing and usually in association with earthquakes, by which they are often triggered, though of course there are other causes, including human activity and plain gravitational action over time. I’ve never really considered them as an individual hazard, as I do for earthquakes and volcanoes.
But of course, that’s what landslides are, and over on the American Geoscience Union’s blog this week there’s a fascinating article on 2017’s fatal landslides, with a statistical analysis and tons of information. (Interestingly, this excluded earthquake-generated landslides.)
It’s well worth a read. In 2017, there were 453 fatal landslides which, between them, caused 4,164 deaths. This total is lower than the number killed by earthquakes but is likely to be higher than deaths resulting from volcanic activity. (I haven’t seen any figures for volcano-related fatalities for 2017, but a study suggests that an average of 540 people per year die from this cause.)
I recommend you look up the blog for details of numbers, trends, seasonality and so on, but I will say that the thing that struck me most was a very sobering fact. It’s that I don’t recall seeing news reports of any of the major landslide events of 2017 and I certainly wasn’t aware that over 1300 people died in just one event.
Perhaps, of course, that’s me. News coverage of events is rolling and often transient, and there are times when I pay considerably less attention to current events than others. But it’s yet another illustration of the degree to which reporting of events, and the response to them, is determined by the context rather than by any quantitative factors.
Coastal Forests and Coastal Erosion
Vegetation — from grasses to trees — plays a valuable part in stabilising the ground and protecting against erosion and flash floods. Along the coast, this interface between land and sea is a potentially vulnerable one and the destruction of vegetation, whether by man or by nature, can lead to coastal erosion — a significant problem both for coastal communities and for ecosystems alike.
This week, a study published in the Journal of Geophysical Research looked at coastal forests in Virginia and used tree ring data to pinpoint interruptions in growth. Among the expected cycles (including known regional climate variation) the researchers were able to tie specific disturbances to known major storms and established that recovery, for the trees, might take up to four years.
The jury is still out on whether current changes to our climate have increased (or will increase) the numbers and intensities of Atlantic storms. But if they do, then there are inplications for the future health of the coastal forests — and those may have repercussions for both erosion and ecosystems.