Area in Arizona suffering from mega drought with barren slopes, trees turned to tinder.
Three major climate catastrophes concerns us this Earth Day 2020. They are, in likely order of their consequences:
1) Collapse of the Thwaites Glacier in the West Antarctic Ice Sheet.
2) Potable water around the planet threatened by increasingly large, intense forest fires
3) The megadrought ramping up in the western United States.
The catastrophe associated with (1) has been articulated and explained in detail in a recent issue of Eos Earth & Space Science, Vol. 101, No. 3, March, 2020. The location and one of the primary disruptive processes associated with I, i.e. the marine cliff instability, was already illustrated in my earlier (2016) post:
New Study Shows Staggering Losses of Antarctic Ice...
As explained in the Eos recent issue:
One of the reasons Thwaites Glacier is potentially unstable is the great depth of the underlying bedrock below sea level. Glaciers flow under their own weight, slowed by floating ice shelves, which act like dams for the grounded ice sheets behind, and by friction between grounded ice and the rock beneath. As Thwaites loses mass—from above and below—its ice shelf faces a greater risk of failing. In addition, the weight holding the ice sheet against bedrock lightens and ocean water can get below the ice more easily, reducing the friction and allowing the glacier to flow more freely into the ocean.
Typically, glaciers behave “like pancake batter on a frying pan,” according to Ted Scambos, a senior research scientist at the Cooperative Institute for Research in Environmental Sciences in Boulder, Colorado. . If you put a big blob of it on the surface it settles by flowing from the top toward the edge. “But what you get in West Antarctica is a situation where the pancake batter is on an oiled frying pan, so [the whole blob] slides over the frying pan rather than just deforming under its own weight.”
If Thwaites starts thinning and flowing faster, it may begin calving—or losing large pieces of ice—at a faster rate, potentially getting into a runaway situation called marine ice sheet instability. (See diagram shown in link from earlier post above) In this scenario, the glacier’s grounding line, the edge where the bottom of the ice is in contact with bedrock, retreats due to warming and the loss of ice mass. While the current grounding line is 600 meters below sea level, the bedrock farther inland is even deeper, so as the grounding line retreats, a thicker portion of the glacier will be afloat—and flow even faster under its own weight.
Other researchers are using a state- of- the- art underwater robot known as Icefin that can explore the subsurface for several hours on each dive. Icefin can measure conductivity, temperature, depth, and dissolved oxygen, and it packs, among other instruments, a camera and an echo sounder for imaging its environment. Icefin’s measurements have now reported that the water at the grounding line is two degrees above the freezing point. “That is really, really bad,” scientist David Holland told the Washington Post on 30 January when the team announced the findings. “That’s not a sustainable situation for that glacier.”
How much and how fast is Thwaites going to contribute to sea level rise? The final answer isn't yet known, but researchers - many of them - believe that if the final 'wild card' collapse is as bad as they suspect, we could be looking at a sea level rise of dozens of meters.
2) Loss of drinking water from fires
I have only touched on this in earlier posts. One notable ‘State of the World’ report (2000, pp. 46-47), warned that the ever increasing water deficits will likely spark “water wars” by 2025. The situation is likely to be exacerbated by the fracking mania which is rendering millions of cubic feet of water useless for humans after it's been used for releasing natural gas and oil from underground deposits. (However, the COVID-19 pandemic has pretty well put an end to fracking profits - as the glut in oil supply has driven oil prices to hitherto unseen lows)
But the mammoth fires that have erupted recently, e.g. in Brazil's Amazon and in Australia, have taken their own tolls on global fresh water supply.
Here's a sobering datum: More than 60 percent of the water supply for the world's 100 largest cities originates in fire-prone watersheds. Countless smaller communities also rely on surface water in vulnerable areas. When rain does fall - again as a result of climate change - it can be intense dumping a lot of water in a short period of time. The result is that huge volumes of ash, sediment and debris are washed into waterways and reservoirs.
In the case of the Australian fires, most of the more the 25,000 square miles burned in Victoria and New South Wales had been forest, including rain forests. But the forest grasslands and other areas that supply water to millions of people have been rendered vulnerable to intense fires. Very hot fires, for example, burn organic matter and topsoil needed for trees and other vegetation to regenerate.Thus, nothing is left to absorb or retain water. The heat can also seal and harden the ground causing water to run off quickly.
That in turn can clog streams, killing fish, plants and other aquatic life essential for high quality, potable water before it reaches reservoirs.
In fact, in Denver it was found that ash and sediment runoff from two high intensity fires (in 1996 and 2002) clogged a reservoir that handles 80 percent of the water for 1.4 million people The Denver Water authority had to spend about $28 million to recover - mostly to dredge 1 million cubic yards of of sediment from the reservoir.
Would all metropolitan areas have such resources to perform a similar rescue task? That's doubtful. Indeed since that salvage operation, the authority has spent tens of millions more to protect the forests, partnering with the U.S. Forest Service and others.
Given intense fires around the world are predicted to only increase, given the rise in temperatures, we can see this situation will be with us indefinitely and there is no assurance of any long term positive outcome.
A 2-decade long drought that has parched much of the western U.S. has now turned into one of the deepest megadroughts in more than 1, 200 years. The megadrought is imperiling the region's water supply but also the nation's food supply. On Monday, western agricultural leaders warned in a letter to Trump that deteriorating pipelines, reservoirs and water infrastructure - in tandem with the prolonged drought- threatened the U.S. food supply. Ordinarily, in more normal periods, mountain snowpack has served as a vast, slow -release, natural reservoir. However, climate warming has led to less snow and decreasing runoff. A projected 7 degree spike in the ambient temperatures will make this magnitudes worse.
Climate researchers estimate that about half of this megadrought can be taraced to man-made global warming - according to a study in last Thursday's journal Science. In the words of lead author A. Park Williams, a bioclimatologist at Columbia University: "What's happening now is a drought bigger than what modern society has ever seen before. "
The only epoch that even comes close occurred before the Pilgrims landed at Plymouth Rock in 1620. Basically, in the current era, what's happening is that a natural but moderate drought is being exacerbated by temperatures that are 2.9 degrees F hotter than in the past, which has the effect of sucking moisture from the ground.
More specifically, scientists used 31 computer models to compare what's happening now to what would happen in a hypothetical world without the burning of fossil fuels. The team found that on average 47 percent of the drought could be blamed on human-caused climate change.
To be sure, there remains some debate on whether the current drought merits the title of "megadrought" because only two decades of data (from 2000-2019) has been used to define it. Climate scientist Clara Deser of the National Center for Atmospheric Research (not part of the original study) said that while the research is good she thinks the deep drought needs to last at least another decade to qualify as a "megadrought".
Whichever way this works out, we who live in the West can recognize extraordinarily dry conditions when we see them, and even each late Spring is dreaded as a new fire season.
On a positive note for this Earth Day, the air quality from LA to Delhi has never been better. (People in Delhi can now actually see the Himalayas for the first time in 30 years.) Smog and particulates reduced dramatically - given the millions of fossil-fuel consuming vehicles off the road thanks to the ongoing shutdown. Oh, and now an oil price crash owing to a glut in supply and essentially zero demand, e.g.
The Day Petroleum Was Less Than Worthless
Bob McNally, president of consulting firm Rapidan Energy has aptly noted (WSJ today, p. A8):
"The crash in oil prices is a brutal but efficient mechanism to persuade producers to keep oil in the crust."
But will they, i.e. post-pandemic? I doubt it.
See Also:
by Tom H. Hastings | April 22, 2020 - 5:07am | permalink
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