Raining Feedback Loops

December 19, 2014

d7dfe440-98af-11e3-a20a-4197883a2af2_calif-terra-nasa-2014Rain and gloomy-dark outside this early Friday on a small patch huddled near California’s north coast — getting close to a month now, of rain and gloomy-dark — more rain forecast for days to come, maybe some decent sun on Tuesday of next week.

After a near-continuous drenching for awhile now — since July, San Francisco’s rainfall is at 193 percent of normal, Oakland’s at 191 percent. Shasta Lake up 35 feet since Thanksgiving — so, how’s the drought?

(Illustration: NASA satellite image of California’s drought, found here).

According to the US Drought Monitor, its latest report released yesterday (via Mother Jones): ‘A wet December (to date) has provided California a foothold for drought recovery, but 3 straight winters of subnormal precipitation will take time (possibly several consecutive wet winters) to fully recharge the reservoir levels and subsoil moisture back to normal.’
My underline for emphasis — that’s a long time, ‘several‘ usually meaning ‘seven,’ maybe?
The week’s summary offered a “Cautious optimism, but still a long way to go” type outlook.

Julia Lurie at MotherJones adds a bit tentative:

So how much rain would the state need to end the drought completely?
11 trillion gallons, according to a NASA study from two days ago.
As CNN reported, that’s “the amount of water that flows over Niagara Falls in about 170 days’ time.”
The drought this year has been particularly scary because California’s reservoirs, which are supposed to supply farmers and communities with water in dangerously dry times, were already depleted after two previous years of drought.
The rain over the past two weeks has helped restore this backup supply, though as the chart below shows, California’s reservoirs are only 57 percent as full as they usually are at this time of year.

Just indicators how really bad this particular drought. Earlier this month, from Bloomberg:

Record rains fell in California this week.
They’re not enough to change the course of what scientists are now calling the region’s worst drought in at least 1,200 years.
Just how bad has California’s drought been?
Modern measurements already showed it’s been drier than the 1930s dustbowl, worse than the historic droughts of the 1970s and 1980s.
That’s not all.
New research going back further than the Viking conquests in Europe still can’t find a drought as bad as this one.
To go back that far, scientists consulted one of the longest records available: tree rings.
Tighter rings mean drier years, and by working with California’s exceptionally old trees, researchers from University of Minnesota and Woods Hole Oceanographic Institute were able to reconstruct a chronology of drought in southern and central California.
They identified 37 droughts that lasted three years or more, going back to the year 800.
None were as extreme as the conditions we’re seeing now.

And last week, a NOAA study reported California’s drought looks to have been caused by natural conditions, or “natural variability,” and not necessarily man-made climate change — a high pressure system off the West Coast has done the deed, nature’s way.  The report, though, didn’t deny/close the door.
From Climate Central:

Even though the drought may not have been caused by climate change, the drought’s effects may be worse because of hotter temperatures on land that may be caused by global warming, the study says.
Kevin Trenberth, senior scientist at the National Center for Atmospheric Research in Boulder, called the study useful, but said it comes up short in many ways.
“I would contend that all droughts are largely natural in the sense that they arise from internal variability in the atmosphere-ocean system,” he said.
“But this study completely fails to consider what climate change is doing to water in California. It completely misses any discussion of evapotranspiration and the increased drying associated with global warming.”
The extra heat in the atmosphere from global warming enhances drying on the surface and increases the risk of heat waves, worsening the effects of a drought, Trenberth said.

An effect of increasing warmth is definition of the word, ‘exacerbate,’ or worse, an effect similar to pouring kerosene on an oil-patch fire. In business as normal, in shadow of the recent Lima, Peru, UN conference kicking the climate-change can down the road, ‘worsening’ is ineed worse.
This past Wednesday, NASA scientists at the American Geophysical Union meeting in San Francisco unveiled a fairly-dire climate update.
Yesterday, from Wired:

One of the ways our planet manages its heat budget is by storing solar energy in the oceans.
In recent years, the Arctic has been taking in more than its usual share of heat energy, which could be bad news for our steadily warming planet.

Every summer, the Arctic ice cap partially melts away, and freezes again in the winter, covering more or less (OK, mostly less) the same area it has in the past.
But, because recent years have had record levels of sea ice loss, a lot of that winter ice is barely a year or two old, and less than 6 feet thick.
When summer comes back around, this thin ice melts quickly, exposing the ocean below to solar radiation.
Since 1982, the average onset of the annual summer melt season has moved up by seven days.
This creates a solar radiation feedback loop.
The thin ice melts earlier in the summer when the sun is higher in the sky, which exposes the heat-sinking ocean surface to collect even more solar radiation.
This causes a feedback loop, as more heat is absorbed into the ocean, which in turn causes more melting.
Currently, the average temperatures in the Arctic are rising twice as fast as the rest of the globe.

And seemingly the world is caught in a brain-battering, memory-non-feedback loop: Seemingly long ago, a warning via Science Daily, May 22, 2006:

Studies have shown that global climate change can set-off positive feedback loops in nature which amplify warming and cooling trends. Now, researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have been able to quantify the feedback implied by past increases in natural carbon dioxide and methane gas levels.
Their results point to global temperatures at the end of this century that may be significantly higher than current climate models are predicting.

And we all go loop de loop.

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