en.wikipedia.org/wiki/Little_Ice_Age
Decades ago, when doing an undergraduate unit in Earth Science, I learned about the Little ICE AGE (ca. 1350 to 1850) and the Mediaevil Warm Period that preceeded it. At my time of studies there was no widespread alarm about global warming; no perception abroad that CO2 emissions brought on by human activity such as the burning of fossil fuels was having any noticable impact on global climate/weather patterns. ALL of this has come about in the intervening decades since.
Among the symptons of the MWP and the following LIA were the following:
When Vikings discivered and colonised Iceland about 800AD they discovered a green land devoid of glaciation except at highest altitudes of volcanic peaks. BY Mid-17th century most of ICELand was covered by an ice sheet - restricting setlement to the coast where the fishermen-descendents of the Norse colonisers eked out a miserable earthly existence.
Likewise the southern tip of Greenland colonised by Viking settlers around 1000AD. WHEN they first arrived they settled in a land so warm they not only had ample pasture for their livestock, the climate was even warm enough to permit them to grow crops like barley. Their economy for the day was a prospereous one. AFTer about 1350 iceburgs drifting south along their western coastline (from the expanding ICE further north) sheetmade trading voyages made seaborne trading voyages from Iceland and Europe increasingly hazardous - to the point where around 1430 these ceased altoghether. BEING isolated was a disaster for the Greenlanders for they relied upon imports of salt from distant EURope to cure meat for winter provisions. BY around 1500AD the entire community had perished - become extinct due to the effects of the LIA.
IN THE south of England, as long as you planted them on the southern slopes of hillsides facing the sun, you could grow wine grapes in England. THERe were abbeys and priories in this region that specialised in making wine for sacrimental and consumption purposes. THE Onset of the LIA can be mapped out by the retreat of western Europe's wine belt from England to the LOIRE VALLEY of France. BY early Tudor times you could no longer grow the wine grape in England at all. Today thanks to a warming climate over the past 150 years, some landowners in the south of ENGland have established small acerages of grapes and make wine as an amatuer interest.
In its day the LIA caused frequent crop failures (or short harvests) in EUrope and not infrequent faMINES. THE Centuries of the LIA also represent western (Atlantic coastal seaboard) Europe's halycon era of outward seaborne merchantile expansion; overseas conquest and NEW WORLd colonisation. I sometimes wonder whether there is a connecting link?
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WE can safely say two things:
THERE is more CO2 in the atmosphere today than in past centuries; not only due to the burning of fossil fuels but because to the inability of the ecosystem to absorb it quickly enough. BEARIng in mind that nature itself produces CO2 and other greenhouse gases - plants need it to produce their celluose plant tissue through photosynthesis. IT is just that presently the "supply" of CO2 into the atmosphere exceeds "demand" by the ecosystem thanks to human activity.
The second thing we can say with confidence is that over the past 150 years, especially in the more northerly, high temperate and sub-polar latitudes, the climate has warmed up to the point where we are almost back in the MWP scenario. YOU can now grow the wine grape in ENgland again, while Iceland has reverted back into the approximate state it was in when the Vikings discovered it. THE southern tip of GREENland has likewise become once more inhabitable.
Does this mean that the higher levels of CO2 in the atmosphere is necessarily the cause of recent global warming? Because the two have occurred over the (Historically brief) recent period does not necessarily mean that there is a causal connecting link between the two.
THE point that those currently giving vent to the hue and cry over the effects of global warming miss is that the Earth's climate is not and never has been static. IT HAS gone through warm periods and cold periods even in the historically brief time that our human species has existed on this planet - for reasons that are still unclear. THE current recent 150 years of warming may not be the result of human activities at all but a "regression back to form" that would have happened even if mankind had remained pre-induatrial.
It is for the above reason that yours truly is a global warming/greenhouse gas skeptic - like all other contributors to this discussion to date.
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