4 ms·

These findings make the discussions about climate change very difficult. Because now we have 'proof' that the icecaps were not there a long time ago. The same

These findings make the discussions about climate change very difficult. Because now we have 'proof' that the icecaps were not there a long time ago. The same applies to glaciers. Some melt away exposing ancient forests. So I think the whole climate change discussion should be about the influence of humans on the speed of the change. We know climate was different in our history. But when the climate changes too fast we can't prepare for it.

mikeash 7y ago
We can’t hide the fact that climate has changed naturally in the past. We just have to point out the important differences, like speed (as you say) and the fact that advanced civilization with seven billion humans wasn’t around for previous changes.
graeme 7y ago
Why? Human civilization didn’t exist at the time that the ice caps weren’t there. The contemporaneous sea levels and temperatures wouldn’t have suited us, especially our current civilizations in the tropics.
api 7y ago
As George Carlin famously quipped, it's not about saving the Earth. The Earth will be fine. We on the other hand may be fucked.
- DennisP 7y ago
  He's right, if your definition of "fine" includes things like the Permian mass extinction.
  - DennisP 7y ago
    ...Evidently some people here think it's inconceivable that we could be replicating the Permian extinction. Here's a recent MIT study supporting that claim. http://news.mit.edu/2019/carbon-threshold-mass-extinction-0708 http://news.mit.edu/2019/carbon-threshold-mass-extinction-07...
DennisP 7y ago
The fact that the climate has gone through major warming events in the past is the reason we're so concerned about climate change. If the planet had been stable for a couple hundred million years, we'd know there are strong negative feedbacks that keep it stable. Instead we see instability and positive feedbacks. For example, we see minor amounts of warming caused by orbital variations, followed by massive releases of greenhouse gases bringing several degrees of additional warming. So we know that we only have to warm the planet a little, e.g. by our own greenhouse releases, to tip the planet into a warming cycle that does much more damage than we directly did ourselves. That's why people keep talking about thresholds and carbon budgets and deadlines. If we take things too far, it will be out of our hands; the planet will keep warming even if we stop our own emissions entirely. A great introductory source on the geological history of climate, and the evidence for it, is Hansen's Storms of My Grandchildren.

mikeash 7y ago

We can’t hide the fact that climate has changed naturally in the past. We just have to point out the important differences, like speed (as you say) and the fact that advanced civilization with seven billion humans wasn’t around for previous changes.

graeme 7y ago

Why? Human civilization didn’t exist at the time that the ice caps weren’t there. The contemporaneous sea levels and temperatures wouldn’t have suited us, especially our current civilizations in the tropics.

api 7y ago

As George Carlin famously quipped, it's not about saving the Earth. The Earth will be fine. We on the other hand may be fucked.

DennisP 7y ago
He's right, if your definition of "fine" includes things like the Permian mass extinction.
- DennisP 7y ago
  ...Evidently some people here think it's inconceivable that we could be replicating the Permian extinction. Here's a recent MIT study supporting that claim. http://news.mit.edu/2019/carbon-threshold-mass-extinction-0708 http://news.mit.edu/2019/carbon-threshold-mass-extinction-07...

DennisP 7y ago

The fact that the climate has gone through major warming events in the past is the reason we're so concerned about climate change. If the planet had been stable for a couple hundred million years, we'd know there are strong negative feedbacks that keep it stable. Instead we see instability and positive feedbacks. For example, we see minor amounts of warming caused by orbital variations, followed by massive releases of greenhouse gases bringing several degrees of additional warming. So we know that we only have to warm the planet a little, e.g. by our own greenhouse releases, to tip the planet into a warming cycle that does much more damage than we directly did ourselves. That's why people keep talking about thresholds and carbon budgets and deadlines. If we take things too far, it will be out of our hands; the planet will keep warming even if we stop our own emissions entirely. A great introductory source on the geological history of climate, and the evidence for it, is Hansen's Storms of My Grandchildren.