Of Drought and Rains and Climate Change

(This post has been later edited for clarity and addition of information)

We on the west are having quite the winter this year! Torrential storms (accompanied by hurricane force winds) are soaking the state of California*, hopefully ending a punishing 5 year drought.

I see, though, in my perusing of various websites on the topic, that some are wasting no time in zealously claiming that these rains demonstrate the falsity of climate science (while tossing in some unrelated decades old red herrings for justification), which has been telling us to expect more drought in the future as the earth warms. But again, the skeptics are wrong.

Yes, climate scientists have accurately predicted more drought as we move into a future of global warming, but that’s not all they’ve predicted. Read closer, and you’ll find that they’ve also forecast more weather “extremes”, which includes crazy storming like those we are now experiencing.

Both intense drought and excessive flooding are projected to increase by at least 50% towards the end of the twenty-first century – Jin-Ho Yoon, et al. 2015

“Under current climate scenarios, such drought-busting ‘atmospheric rivers’ will hit Northern California twice as often by 2100 as they do now, said U.S. Geological Survey hydrologist Mike Dettinger. ‘When the atmosphere is warmer, it holds more water vapor, so there is a huge increase in the number of these atmospheric rivers.'” ‘Atmospheric Rivers’ to Soak California as Climate Warms. 2014

Explains NOAA, “The hydrologic cycle describes the movement of water between the oceans, land, and atmosphere. Two important factors are relevant: (1) warmer air can hold more water vapor (moisture), and (2) warmer air causes more evaporation… As the world continues to warm, the air will hold more moisture and more water will be evaporated, so there will be an increase in heavy rain events producing more frequent flooding. But more evaporation with hotter temperatures will dry out the soils more and increase water demand, which is one component in the water demand versus water supply drought equation. More demand translates to more frequent and intense droughts. So, in this climate warming scenario, an accelerated hydrologic cycle will result in more severe droughts (especially in the summer) interspersed with periods of intense flooding.”

All of these tendencies increase opportunities for both more frequent and more severe floods in California under projected climate changes. – Michael Dettinger. 2011

A recent study has underlined this disparate effect. It represents a further fine-tuning of the data.

It would be expected that a warmer world will also lead to more rain when and where it falls. But it’s counter intuitive to most of us. When most people think of global warming, they think of deserts. After all, warm means dry, doesn’t it? But stop for a second and consider some of the warmest places on our planet, the equatorial tropics. They also happen to be the wettest (rainiest) places on earth.

What climate scientists have been saying is that, the planet is getting hotter, not necessarily drier everywhere all the time. Heat is the main effect here. But with that heat will come both much drier and wetter weather than normal. Thus, rather than falsifying it, the severity of the storms we are having is yet more evidence of change. The rapidity of our changing climate means that these boom and bust events will become more extreme with stronger droughts and flooding.

Now here’s something that’s counterintuitive: Can global warming also be responsible for locally colder weather, as well? Yes, and here’s how: ice at the poles, via the “polar vortex” (cold air swirling around, but contained at the poles by the jet stream) has been acting as a moderating force to keep the overall lower latitude temperatures fairly steady. But what happens when that ice begins to melt, and fast? Then there’s suddenly much more evaporation, which means more water, cold water, and air, ends up in the polar atmosphere. The problem is that that extra cold has been imbalancing the jet stream. Now it’s encroaching farther down into the lower latitudes, bringing more intense cold snaps. You can think of it like a swamp cooler: put ice in on a hot day and it melts fast, cooling down the air. BUT (and it’s a big but) that’s only until the ice is finally all gone. Then watch out!

It seems the easy balance we’ve enjoyed for thousands of years is, unfortunately, ending.

The thing to realize about climate change is that what we humans are doing is putting fossil fuels, prehistoric carbon from many millions of years worth of decomposed plants and animals, including that which had been filtered from the air from volcanic eruptions by ancient forests, back into the atmosphere (to the tune of about 10 billion metric tonnes annually) in an extremely short period of time. It’s true that living plants and the oceans absorb CO2, but we are overwhelming them. The result is a lot left in the skies, and that quantity acts like a visible and invisible blanket to trap heat from the sun. To deny that all of this cause, dumping more and more carbon into the atmosphere, can have any effect, is to deny physics. To every action, there is a reaction.

In light of all this, it would be a serious mistake, in my humble, non-scientist opinion, for politicians to imagine that all is now well, and California can continue grow as usual. As the LA Times said last June, California needs to conserve water like the drought is here to stay.

One last thing to keep in mind is that, though skeptics like to cast aspersions on the integrity of the climate science community, even if scientists were somehow wrong about climate change, which they aren’t, still, they are acting with the best available knowledge, tools and evidence that they can muster. Mistakes can and do happen in science, as they do with any human enterprise, but unlike others, science is a process of constant revision. It’s a search for the truth, with many people checking, double checking and checking again the work of others. Personally, we may not agree with everything that is done in the name of science, but as a whole, it has been a bastion of fact in a world of fiction.

*Not to mention the resulting floods. 188,000 evacuated, emergency declared as California’s massive Oroville Dam threatens floods.

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