Anthropogenic Climate Change

Hear dat. The world could burn down and blow away so far as he's concerned, as long as the advertising revenue kept coming.

RCP8.5 tracks cumulative CO2 emissions at least to 2050 if not after.

I think the conclusion that Zuck is kneecapping anything that could help Democrats because he’s personally pro-Trump is reasonable.

It doesn’t have to be about money, there’s always personal ideology to consider.

Edited by Silasw on Aug 20th 2020 at 10:07:02 AM

It could be money and ideology, I suppose.

Personally I think when it comes to the US Republican Party and the billionaires supporting them, seperating out money and ideology is impossible.

So apparently "climate change inactivist" is a word now.

I like it, it really emphasizes that 1) Climate Change clearly exists and 2) they want to do nothing about it.

For the ultra-rich, it has to be both. Their ideology is what it would need to be to protect their financial interests (ie, low taxes, deregulation, federal contracts).

Floods Washed Away More Than 25% of Nigeria’s Rice Harvest.

I don't think this was mentioned before, The Western Coast of the USA has been set ablaze and wildfires are still burning since the last week, the scientific consensus is that much like the Australian fire this problem has been exacerbated by Climate Change.

I can't but think on Timothy Snyder's fear that this could lead to atrocities on the Global South

Indeed, that's the real horror of Climate Change. How its effects cascade into worse things. Change in temperature leads to crop failure which leads to unrest which leads to civil war or resource wars which leads to mass death and destruction of infrastructure.

This is why Biden needs to win, so we can start actually doing something to stop the US from driving humanity off a cliff.

Edited by Fourthspartan56 on Sep 11th 2020 at 12:09:19 PM

Well, I'm all for a Biden win, but let's keep the pressure up even afterward. He's no radical environmentalist.

As for global warming atrocities, there are those who think that the Syrian Civil War was essentially about control over dwindling water resources. The whole Middle Eastern refugee problem was far worse due to environmental degradation.

Certainly, I didn't suggest otherwise.

Regarding the wildfire situation in the Western USA. I meant to write a detailed post explaining how exactly climate change alters wildfire behaviours and more importantly precipitation, so here goes nothing. In case you wonder where I got any of the information below from, it's from reading probably thousands of academic publications over the years and synthesizing their knowledge. I have read much more stuff on California's climate, which is why I'll be mentioning that place prominently in my discussion.

The thermodynamic effects of climate change on the water cycle A.K.A Why do "the rich get richer" in a changing climate?

One rather obvious effect of a warmer climate is increased evaporation. As a consequence, atmospheric water content tends to increase according to a scaling that matches the Clausius-Clapeyron relationship. More water in the atmosphere also means more water available for rainfall, which thus increases commensurately with evaporation. Let's call this "increase factor" I.

Because of atmospheric circulation, some places in the world receive either more or less precipitation than evaporation. This is what scientists call "P-E" and is positive in wet regions and negative in dry ones. With global warming, the increased moisture capacity of the atmosphere means that both P and E increase (because P*I-E*I∝I) and as a consequence the difference between the two does as well. That means that regions that are dry (P smaller than E) become even drier (the difference between P and E becomes even larger) and wet regions become even wetter. This is called the "dry get drier" or "dry get drier, wet get wetter" mechanism - or, in (strictly speaking not entirely accurate) analogy with the economics concept, "the rich get richer".

Note in particular that since I is a positive number, it is not possible for the sign of P-E to change from a change of I alone; i.e the thermodynamic effect cannot make a dry area wet or a wet area dry as defined by P-E.

Wait, rainfall does usually get stored by the soil before it evaporates! Yes, and the fact that vegetation does as well is the reason why wildfires become worse with climate change.

However, evaporation does not just occur on falling rain, but also on water stored in the soil from past precipitation. And the "holding capacity" of soil, unlike that of air, does not by default increase with temperature. Soils cannot store arbitrary quantities of increased precipitation, thus:

• At some point the soil "overflows" - water runs off. Thus even increased evaporation cannot fully compensate for increased precipitation when both coincide, thus river discharge/groundwater recharge/floods tend to become worse even if P-E stays the same or declines.
• Because the recharge is limited by the holding capacity, unlike evaporation, the latter can dry out the soil more quickly and thus reduce soil moisture to lower levels. Thus soils on average are drier even if P-E stays the same or increases.
• This last point also applies to vegetation, not just to soil.

Thus, a warmer climate features more severe droughts and drier and thus more flammable vegetation. Even if P-E or precipitation stay the same or increase. This evaporation/heat effect is the main mechanism through which California's long drought 2013-2017 was aggravated by climate change, for example. I can't actually find a study that discusses the same concept as it relates to wildfires, but I am sure there are some.

The dynamic effects of climate change on the water cycle

The existence of dry climates and wet climates, i.e positive and negative values of P-E, is due to atmospheric circulation transporting moisture to and removing moisture from certain areas. Since the atmosphere works as a heat engine and heat engines are fundamentally powered by temperature gradients rather than temperature per se. In practice, owing to condensation/evaporation this means that moisture transport is usually from the colder areas to the warmer ones, adjusted for the effect of rain shadows and the Coriolis force. Most commonly, "warmer" and "colder" refer to sea surface temperatures; this implicates processes like El Niño and La Niña.

Predicting changes to these dynamics with climate change is tough, for a number of reasons:

• Greenhouse gases themselves are usually assumed to change temperatures equally everywhere when you ignore feedbacks. Thus they shouldn't (but may) alter temperature gradients, outside of feedbacks.
• Feedbacks thus contribute most to changes in temperature gradients, but estimating their impact can be difficult. This article illustrates an example where relatively minor changes in cloud and albedo feedbacks can cause the dynamic effect to completely negate the thermodynamic forcing, causing a drastically different climate.
• Just because most global warming is man-made does not automatically imply that changes in temperature gradients are as well. Here's a discussion of how droughts in the southwestern US appear to reflect natural variation to a large degree.
• The same amount of warming might induce different changes in temperature gradients, depending on what caused the warming. As an example, solar-induced warming and greenhouse-induced warming has opposite effects on temperature gradients in the Pacific Ocean.
• Temperature gradients can evolve over time even after greenhouse gas forcing (or feedback mechanisms) have stabilized. These two publications discuss how such "moving" patterns lead first to drought and then to deluge in California after extreme warming in the Arctic.
• Ongoing warming does not necessarily have the same effects on temperature gradients as warming which has stabilized. This publication shows how the tendency of subtropical dry areas to become drier during warming disappears once temperatures stabilize.
• Even with ongoing warming, temperature gradients can change in opposite direction early and late in the warming. This article posits that ongoing warming initially causes a La Niña-like response that over time - about a century - is supplanted by an El Niño like change even if the growth of CO2 emissions is unchanged.

Three final notes on hurricanes and lightning strikes, and their interplay

Tropical cyclones are part of the atmospheric circulation, and fundamentally they operate like a heat engine too. Thus, there is an observation that the birth and strength of tropical cyclones scales with the relative water temperature (i.e temperature relative to a global reference temperature) rather than the absolute value. This is why long term yearly tropical cyclone numbers are relatively constant despite warming. This dependence is more pronounced with birth than strength, i.e strength responds to the absolute temperature too and not just to the relative one. Hence why storms become stronger with warming.

While many wildfires - especially destructive ones, as by definition man-made fires are more common where there are people - are caused by humans, dry lightning is an important source of fires. Witness this year's California fires, many of which were caused by thunderstorms some of which related to the former Tropical Storm Fausto. Lightning that causes wildfires is projected to increase in the future, while we don't know yet much about tropical cyclones-lightning-fires.

Thanks, Septimus, for that informative summary.

Meanwhile, Arctic sea ice has reached its second lowest extent after 2012.

Thats generally when another polar vortex happens later in winter. The lack of sea ice traps in the cold air at the arctic, and tends to flow southward.

Left out two headers from my megapost:

Orography and precipitation

See, when I said that atmospheric circulation is primarily governed by temperature gradients, I left out topography. Mountains can trap moisture - generating orographic precipitation and rainshadows - and they warm and cool more quickly than the surroundings.

• It is not really clear if warming impacts on rain shadows ... although wind-driven transport of precipitation across mountain crests becomes less effective if warmer air leads to more rain and less snow.
• It's a well established fact that global warming is more intense with high elevation, this can enhance thunderstorm activity disproportionately over mountains. This could be missed by climate models that have a low resolution.

Anthropogenic but non-climatic change A.K.A The river will dry up if you pump too much water from it!

A number of lakes and rivers are losing water due to diversions, e.g the Colorado River and the Aral Sea. This happens when too much water is drawn from the rivers. Sometimes climate change helps but there is sometimes a tendency to blame such reductions entirely on climatic factors. Example being the 2015-2016 drying of Lake Poopo in Bolivia. I've seen suggestions that the Great Salt Lake in the USA might be too.

It appears that the Arctic hit the seasonal ice minimum one week ago. Notice the total lack of ice on the Russian side of the Arctic.

First fucking fall in forever that felt like fall.

And I bet it has to do with everyone being inside for most of the year.

I think its going to be a cold winter.

Been toying with writing an explanatory post on Arctic sea ice and the thermohaline circulation/AMOC/Gulf Stream, but the Arctic sea ice thing is complicated by the fact that on many points there isn't scientific consensus.

Climate Disruption Is Now Locked In. The Next Moves Will Be Crucial.

From the NY Times. There's no going back.

I didn't realized how bad California was hit.

Edited by asiacatdogblue on Sep 27th 2020 at 10:41:57 AM

AFAIK California isn't even the US state that will be worst hit. And apparently not by a long shot, either.