So explain to me how this happened before we had cars, coal burning plants, all the high level CO2 emissions that is suppose to be the cause of climate change?
From the article. Didn't you read it? Researchers are not sure what caused CO
2 levels more than four times that of present, but consider it evidence that too much CO
2 can cause global warming.
Researchers are not sure what caused the sudden boost of carbon dioxide that set the greenhouse effect on broil. Possible culprits could be huge releases of methane from the ocean, gigantic continent-sized burning of trees, or lots of volcanic eruptions.
What's troubling is that this suggests that the current projections that say the Earth will grow warmer by several degrees over the next century may be on the low end, said the study's lead author, Appy Sluijs of the Institute of Environmental Biology at Utrecht University in the Netherlands.
Also, the findings are proof that too much carbon dioxide — more than four times current levels — can cause global warming, said another co-author, Henk Brinkhuis of Utrecht University.
Study: North Pole Once Was Tropical
But really, what I like best about your post is that you'll happily accept scientists' findings on conditions 55 million years ago while rejecting their findings on the present day. Must be a rightard.
Idiot never heard of Continental Drift?? What are you? A flat earther??
Greg
Would it matter if it did all melt one year? Here’s the point everybody seems to be missing: the Arctic Ocean’s ice has indeed disappeared during summer in the past, routinely.
The evidence comes from various sources, such as beach ridges in northern Greenland, never unfrozen today, which show evidence of wave action in the past. One Danish team
concluded in 2012 that 8,500 years ago the ice extent was “less than half of the record low 2007 level”.
A Swedish team, in a paper
published in 2014, went further: between 10,000 years ago and 6,000 years ago, the Arctic experienced a “regime dominated by seasonal ice, ie, ice-free summers”.
This was a period known as the “early Holocene insolation maximum” (EHIM). Because the Earth’s axis was tilted away from the vertical more than today (known as obliquity), and because we were then closer to the Sun in July than in January (known as precession), the amount of the Sun’s energy hitting the far north in summer was much greater than today. This “great summer” effect was the chief reason the Earth had emerged from an ice age, because hot northern summers had melted the great ice caps of North America and Eurasia, exposing darker land and sea to absorb more sunlight and warm the whole planet.
The effect was huge: about an extra 50 watts per square metre 80 degrees north in June. By contrast, the total effect of man-made global warming will reach 3.5 watts per square metre (but globally) only by the end of this century.
Barring one especially cold snap 8,200 years ago, the coldest spell of the past ten millennia was the very recent “little ice age” of AD1300-1850, when glaciers advanced, tree lines descended and the Greenland Norse died out.
It seems that the quantity of Arctic sea ice varies more than we used to think. We don’t really know how much ice there was in the 1920s and 1930s — satellites only started measuring it in 1979, a relatively cold time in the Arctic — but there is
anecdotal evidence of considerable
ice retreat in those decades, when temperatures were high in the Arctic.
An ice-free Arctic Ocean has happened before