Any historical examples of destructive climate warming?

Question

Summation: Local cooling climate changes, since the last ice age seem relatively common and all seem to cause significant harm to human population. But I can't find instances of the reverse, warming climate changes that caused harm. If anything, the correlation seems reversed, warming climate change brings benefits. (Note: Droughts to not indicate warming.)

Are there any known or suspected historical i.e. Holocene climatic warming associated with negative impacts on human populations?

Details:

This one caught me by surprise. I had assumed episodes of destructive warming would be common and well documented.

I am reading The Great Famine: Northern Europe in the Early Fourteenth Century by Medieval scholar William Chester Jordan. The book regards a massive famine that hit Western/Northern Europe 1315-1322. Until recently, the Great Famine was overshadowed by the "Great Mortality" pandemic episode of the Black Death which struck 1346–53. Computerization of period sources in the last 20 years has allowed researchers to correlate much wider patterns than in the past and the event is now know to have been much wider in area and of longer duration than realized.

Besides the scale, what makes the Great Famine possibly unique is that it was caused by three or more years of continuous rain i.e. it rained roughly 9 out of every 10 days, Spring, Summer and Fall.

The rain essentially drowned the seedlings in spring, the roots in summer, then rotted crops in the fields towards fall. In addition, the extraordinary wet conditions caused a "murine" an outbreak of diseases in almost all domestic animals but particularly cattle e.g. Hoofed animals often had their hooves (which are just giant toenails) so constantly immersed that eventually they just sloughed off. Other's died of water born illnesses.

I was intrigued by the event because I assumed before reading the book that the catastrophe must have been a localized example of the "The Big Sog" outcome predicted by some climate models in which the increase in world temperatures leads to significantly higher humidity world wide which causes incessant rain. I knew that the effected years fell into the Medieval Climate Anomaly which definitely represented a sustained warming in Europe and likely most of the Northern Hemisphere.

However, the chronicles, various accounting records and climate proxies all show a dramatic cooling, with brutal winters of intense cold, deep snows and ice packs forming on the Northern shores Europe. The overall climate/weather-patterns had shown a general but widely oscillating cooling pattern since the late-1200s. After the 1320s, Europe (at least) slipped into "The Little Ice Age".

It was this cooling that allowed the Black Death to spread by altering the way in which the Y. Pestis bacteria clump inside the fleas that carry it. The same dynamic of cooling, rain, harsh winters and plague outbreak, occurred in 542 in the Mediterranean world during when several years of cooling probably caused by a volcanic eruption, reduced harvest, drove nomads southward and nearly destroyed the Byzantine and Sasanian empires.

During the Medieval Anomaly it appears that the climate of MesoAmerica, North America west of the Sierras grew dryer with years and possibly decades of drought conditions. However, the overall temperatures seemed to have cooled.

Drought conditions can cause higher peak daytime temperatures because of the loss of cloud cover, but these peaks are offset by nighttime lows by the same mechanism, just as occurs in deserts. The actual heat content of the atmosphere, its enthalpy, which drives weather and climate, actually decreases because most of the heat is held in the atmospheric humidity and the biomass. It's easy to see how cooling can cause droughts.

I'm looking for the kind of increase in enthalpy predicted for world wide by current climate models.

If such events are unknown, that would be a separate question.

Answer 1

To answer the question

Are there any known or suspected historical i.e. Holocene climatic warming associated with negative impacts on human populations?

One recent (actual) example that come to mind is the sea level rising. Here we see that since the early satellite measurements in 1993, sea level rise was about 8 cm. On the same page, less reliable gauges indicated a coastal sea level rise of 20 cm between 1870 and the late 1990.

Some Islands are particularly vulnerable to sea level changes, in regard with fresh water supplies, soils and shore degradation following storms and strong high tides, etc. Marshall Island (~2 m), Maldives (~1 m) are examples of emplacements with very low mean ground level. It is really a question of time before these places become unlivable.

While these are small islands, other populous places are quite vulnerable to similar situations such as Bangladesh.

Answer 2

Your question covers a lot of ground and maybe should be broken up into parts.

Written human history is only a few thousand years old. Over most of that period there's been a gradual cooling. Source.

You also have to say where. European farming is probably more susceptible to cold spells. Middle Eastern farming to drought and hot spells. USA farming, some of both. Certainly the NorthEastern settlers were badly affected during the year without summer, but had there been Midwestern or California farm during 1816, they (Might) have come out OK.

While it's not brought up very often, one of the possible causes of the Syrian conflict over the last 5-6 years is drought and food shortages possibly brought on by climate change. Article here.

There's geological records of extinction being tied to climate change, but warming and cooling. Article (here) and here.

Another problem, if you go back a few thousand years is that it's not just warming and cooling but Milankovich cycles are a factor. Milankovich cycles (not the rise and fall of ice ages) are thought to drive the Greening and droughting of the Sahara. Article here.

Egypt was lush and fertile until about 4,200 years ago when it was hit by a killer drought. The Sahara desert was lush and fertile as recently as 6,000 years ago. The Egyptian downfall (and the downfall of civilizations in parts of India and Pakistan) about 4,000 years ago is associated to local climate change. Articles here and here. There was a gradual global cooling during that period around 4,200 years ago, so that might be worth looking into.

To research this properly I'd look at multiple parts of the Earth. Your evidence seems much too European focused and I'd not look at just warming and cooling but localized Milankovich driven effects such as the African monsoon mentioned in the article on the Sahara, above.

You wrote this, but this is inaccurate:

the "The Big Sog" outcome predicted by some climate models in which the increase in world temperatures leads to significantly higher humidity world wide which causes incessant rain.

Warmer weather doesn't lead to greater humidity. Humidity is percentage of saturation. Warmer air holds more water, so it has a higher saturation limit. The humidity as the percentage of peak saturation, doesn't necessarily increase with warmer air, in fact, warmer temperature likely drops humidity levels on average, while increasing atmospheric water vapor.

What this means, generally speaking, is that it takes more water to be evaporated for for the air to get saturated, so it rains less often, on average, but it also rains harder when it does rain. Now, that's grossly oversimplified because rainfall has to do with rising and falling moist air and rapid cooling to create condensation, but I've read no theories that say that man made climate change will make it rain more often. In fact, I've read the opposite.

Snowfall is the source of many rivers flow rates. Less snow means less river flow and global warming often means less snow. Plant transpiration also drops as CO2 levels rise, so the effect is that you have plants and rivers putting less water back into the atmosphere as a result of climate change. This leads to drier air where the land relies on recycled water. Land that relies on oceanic evaporation should be fine and perhaps wetter on average due to climate change. Land that relies on snow runoff and transpiration from plants returning water to the air should get drier and in combination with warmer air being able to hold more water and less water returning to that air, there should be regions of significant decrease in rainfall and increase in droughts due to climate change. A curious effect of man made climate change is that it might somewhat green the Sahara, but it will likely create other deserts, especially in regions that rely on recycled rain water, not water evaporated off the ocean.

When you say this:

Drought conditions can cause higher peak daytime temperatures because of the loss of cloud cover, but these peaks are offset by nighttime lows by the same mechanism, just as occurs in deserts. The actual heat content of the atmosphere, its enthalpy, which drives weather and climate, actually decreases because most of the heat is held in the atmospheric humidity and the biomass.

That may be accurate about deserts and total heat around the desert, but deserts are a small part of Earth's surface. 70% of the earth is covered by oceans, so the primary driver to how much water vapor is in the atmosphere of the earth is surface temperature above the oceans. As the Earth warms, there should be more water vapor on average (growing deserts probably won't be enough to undo that), and because water-vapor is a greenhouse gas, that should play a role in trapping more heat. Total amount of water vapor in the atmosphere is a feedback mechanism, that should lead to an increase in warming overall, not cooling.

Not sure you'll like my answer, as I disagree with a few of your points, so, feel free to take it with a grain of salt.

Corrections welcome.

Answer 3

Maybe it's outside the scope of your question (I.e. droughts) but the lack of rainfall associated with warming climates does (and is) affecting saline water intrusion along coastal aquifers, which inevitably affects our fresh water access...!

Answer 4

We should not expect to see expect to see historic examples of destructive climate warming. Volcanic eruptions can cause rapid, short lived regional and global cooling by introducing sulphate aerosols to the upper atmosphere and blocking and reflecting sunlight but there are no equivalent phenomena that trigger rapid, short lived warming.

Answer 5

6000 years ago during the Holocene Climatic Optimum the Sahara desert was covered in lakes and vegetation. All this went away when the world cooled.

Answer 6

I like this question as it makes you think about lots of things. Answering the question specifically gives me, based on my own somewhat incomplete knowledge of human history, the answer: Not really, no specific examples of human catastrophe from warming.

So now we wonder why.Clearly the concept of an average global temperature (as used in discussing climate change) is a mathematical construct and does not represent a temperature where all people live , to be crude about it. The earth has poles (very cold) and equator (very hot). Humans tend to live in the bits in between. If climate changed gradually we would expect humans to move gradually further north or further south if it started to become uncomfortable or difficult. However we know from personal experience that we go on holiday where it is hotter, often much hotter, and cope very well for a fortnight even for a temperature increase of 20 degrees C. When it get really cold however, say in a harsh winter in England, and the temperature is sub zero, maybe -15 degress C, for a few days we find it much harder to cope.

Maybe if we plot a graph of "human copeability" v local environment temperature change it will be nowhere near linear. The other factor that comes to mind is that cooling produces ice and snow which are physical things you need to deal with, e.g. effect on transport and also can be a tipping point for certain crops e.g. frost damage. So just a few unusually cold days/nights could destroy a crop wheras it takes a more prolonged excess of heat to damage crops, again probably a non linear graph.

Overall I expect we may find human populations that live in the colder parts of the planet are living much nearer to the "edge" of survivabilty compared to those living in the hottest parts of the planet. I seem to remember reading somewhere that humans originated in Africa (a hot bit) so our "design" is for near equator temperatures +- (some range).