JoNova

A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).


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Running out of time in the Holocene…

At some point, the ice sheets want their land back

We’re balanced at the end of a ten-thousand-year warm spike, in an ocean of ice-ages, reshaping our economy to try to stop a half a degree of warming.

Those glaciers are coming… | Photo by Diego Delso

The last million years have been whipsawing climate action. While modern Homo sapiens sees two degrees of warming as an apocalypse, for most of the last million years it would have been God’s gift to Pleistocene man.

….

Ken Stewart compared the current interglacial with the last three, and found our favourite – the Holocene — has already run longer than all of last three did.*

Global Warming or Global Cooling: Keep an Eye on Greenland

Ken Stewart

There are several ways of identifying the start and end of interglacials. I have chosen points when Antarctic temperatures first rise above zero and permanently fall below zero relative to 1999. Graph 3 shows the length of time between these points for the previous three interglacials compared with the Holocene.

The Holocene has lasted longer than the previous three interglacials: and is colder.

The point […]

Surprise: The Last Ice Age was colder than anyone thought. Blame CO2!

We panic about the next half degree of warming (above the 1.5 we’ve already had) but the depth of the ice age was savagely cold. For years the experts told us what Earth’s temperature was then, but apparently they were wrong.

And yet corals and rainforest survived. Plus turtles, whales, kittens — lots of things. And all without research grants.

Nice line on the Nobel gas calibration with ground temperatures. Nice proxy.

Two studies have come out in the last 10 months both showing that at its coldest point about 25,000 years ago, the Earth was on average six degrees cooler Celcius than it is today. And this new study includes estimates of temperatures of tropical land near the oceans which ought to be more stable and less prone to big extremes.

This comes from a newer style of proxy based on noble gases dissolved in ground water. It appears to be quite an accurate proxy, judging by the graph to the right. And it solves a lot of problems with other proxies. We can take samples from all around the world instead of just the polar ice caps (like we can with ice cores). […]

Glaciers on the move: Two minutes of extreme climate change on Swiss Alps, Italian beaches

The next ice coming to Europe might look something like the last ice age shown in this simulation. A time when Venice will be top of a long paddock that stretches to Albania.

In school children are taught to hyperventilate about the last 30m retreat of glaciers that never stayed put ever.

Instead, they could be studying this… (click to start)

At the 24,000 year BC point glaciers have wiped out Zurich, Bern, Geneva.

Image the effect on people if this were shown everytime a Swiss Alps disaster story was run?

OK, so it is a model

Advance and retreat of the Alpine glaciers during the last glacial cycle from Julien Seguinot on Vimeo.

About 25000 years ago, Alpine Glaciers filled most of the valleys and even extended onto the plains. Using a computer model that contains knowledge on glacier physics based on modern observations of Greenland and Antarctica and laboratory experiments on ice, help from traces left by glaciers on the landscape, and one of the fastest computers in the world, this animation is an attempt to reconstruct of the evolution of Alpine Glaciers in time from 120000 years ago to today.

Meanwhile, WWF […]

Fossils show models can’t predict how climate affects animals

Fossils show those dang mammals lived in all the spots they weren’t supposed to live in. Climate models don’t predict the climate, and animal distribution models don’t predict (or in this case hindcast) animal distribution either. How little we know, and how adaptable is biology?

This calls into question all the headline prophecies about the extinction of cute furry critters due to climate change.

The modelers were sure that animals would be unable to cope with temperature changes and would not have lived in the same places as they do now during a climate so different. By crikey, it was an ice age! Yet those small mammals, whose defining biology is that regulate their own temperature, flummoxed the models by living nearer the glacier sheets where the models predicted they would not live.

All the alarming forecasts of local extinctions of mammals come from assumptions built into modern models that fail in multiple ways. The temperature changes from the last 20,000 years show that these mammals have already survived massive shifts, both colder and warmer, and that anything we face in the next century is but a flea on a hippo.

In the graph, the dots are the fossils, the […]