Climate Change/Mass Extinction Megathread

[mongers]

Nice retort:



Apols if it's already been posted.

[crazy canuck]

From the NYTimes today

NASA scientists announced Wednesday that the Earth's average surface temperature in 2018 was the fourth highest in nearly 140 years of record-keeping and a continuation of an unmistakable warming trend.

The data means that the five warmest years in recorded history have been the last five, and that 18 of the 19 warmest years ever recorded have occurred since 2001. The quickly rising temperatures over the past two decades cap a much longer warming trend documented by researchers and correspond with the scientific consensus that climate change is caused by human activity.

https://www.nytimes.com/interactive/2019/02/06/climate/fourth-hottest-year.html?action=click&module=Top%20Stories&pgtype=Homepage


Trumpists - but its cold outside

[crazy canuck]

The good news is humans can cause global cooling.

The authors found that disease and war wiped out 90 percent of the indigenous population in the Americas, or about 55 million people. The earth, they argue, then reclaimed the land that these populations left behind. The new vegetation pulled heat-trapping carbon dioxide from the atmosphere and into the land, contributing to what scientists refer to as the "Little Ice Age."

"It was a drastic change in the earth's system," said Alexander Koch, the study's lead author and a Ph.D. candidate at the University College London Department of Geography.

The bad news is that last time it was done, it required a 90% reduction of a population.

https://www.nytimes.com/2019/02/05/climate/little-ice-age-colonization.html

[Valmy]

Interesting theory, but I was under the impression the Little Ice Age started in the 1300s.

[crazy canuck]

Interesting theory, but I was under the impression the Little Ice Age started in the 1300s.

odd, is that because it was the first thing that popped up on a google search?

[The Brain]

Interesting theory, but I was under the impression the Little Ice Age started in the 1300s.

odd, is that because it was the first thing that popped up on a google search?

[Valmy]

Interesting theory, but I was under the impression the Little Ice Age started in the 1300s.

odd, is that because it was the first thing that popped up on a google search?

No. I recall a discussion about it in Barbara Tuchman's Distant Mirror, which was when I first heard of it. I recall hearing that climate change was an explanation for how the first Nordic colonies in Greenland disappeared around the same period.

But that is history stuff and not strictly climate science.

[crazy canuck]

Interesting theory, but I was under the impression the Little Ice Age started in the 1300s.

odd, is that because it was the first thing that popped up on a google search?

No. I recall a discussion about it in Barbara Tuchman's Distant Mirror, which was when I first heard of it. I recall hearing that as an explanation for how the first Nordic colonies in Greenland disappeared.

But that is history stuff and not strictly climate science.

Interesting.  From the article there seems to be a debate about it being as long as 1400-1900 - but that would bring it further back in time.

The part that is salient though is the reduction they found in CO2 in the atmosphere after colonization.

[grumbler]

No. I recall a discussion about it in Barbara Tuchman's Distant Mirror, which was when I first heard of it. I recall hearing that climate change was an explanation for how the first Nordic colonies in Greenland disappeared around the same period.

That's the context in which I first heard the term, as well.  Tuchman was confusing the end of the Medieval warming period with the Little Ice Age, though.

[Tamas]

No. I recall a discussion about it in Barbara Tuchman's Distant Mirror, which was when I first heard of it. I recall hearing that climate change was an explanation for how the first Nordic colonies in Greenland disappeared around the same period.

That's the context in which I first heard the term, as well.  Tuchman was confusing the end of the Medieval warming period with the Little Ice Age, though.

Well, one person's end of warming is the other's start of cooling. I am sure some species will be thrilled by the glasshouse Earth we are creating, for example.

[Threviel]

Well, there was a huge depopulation event in the 1300s also, although in the old world, might have started the process.

[Berkut]

Without commenting on the idea that this is an example, I've never really understood the reluctance that some people have to the idea that human activity can change the global environment/climate.

That part isn't that complicated at all. The globe is a basically closed system. It is a giant test tube. But it isn't really that big. We can measure the increase in CO2 for example, and surprise surprise, if we pump a lot of CO2 into the atmosphere, the amount of CO2 in the atmosphere goes up in a clearly measurable way.

The Earth is pretty big...but on the other hand, it really isn't that big. It is a closed system, and doing anything within the system that has a measurable impact on the composition of that system is creating change.

Obviously understanding how it changes is complex, even moreso *predicting* those changes. But there isn't anything magical about it - it is just science. We started thinking about it, what 50, 60 years ago? Hell, I think we've made amazing progress since then considering it was essentially a brand new field of study in many ways. But the basic idea is pretty straightforward. We have a closed system, and we are creating measurable changes, and we need to understand what those changes will do....

I just do not understand the idea that there is skepticism around the very idea that humans could change the earths climate.

[Valmy]

Interesting theory, but I was under the impression the Little Ice Age started in the 1300s.

odd, is that because it was the first thing that popped up on a google search?

No. I recall a discussion about it in Barbara Tuchman's Distant Mirror, which was when I first heard of it. I recall hearing that as an explanation for how the first Nordic colonies in Greenland disappeared.

But that is history stuff and not strictly climate science.

Interesting.  From the article there seems to be a debate about it being as long as 1400-1900 - but that would bring it further back in time.

The part that is salient though is the reduction they found in CO2 in the atmosphere after colonization.

Well I mean if you think about it a bit the Mongols also killed millions and spread the black death with also killed tens of millions. If tens of millions dying can bring about a reduction in CO2 then why wouldn't a previous reduction in population not do the same?

But, as you say, this discovery does not exactly give us a clear way forward 

[Berkut]

Interesting theory, but I was under the impression the Little Ice Age started in the 1300s.

odd, is that because it was the first thing that popped up on a google search?

No. I recall a discussion about it in Barbara Tuchman's Distant Mirror, which was when I first heard of it. I recall hearing that as an explanation for how the first Nordic colonies in Greenland disappeared.

But that is history stuff and not strictly climate science.

Interesting.  From the article there seems to be a debate about it being as long as 1400-1900 - but that would bring it further back in time.

The part that is salient though is the reduction they found in CO2 in the atmosphere after colonization.

Well I mean if you think about it a bit the Mongols also killed millions and spread the black death with also killed tens of millions. If tens of millions dying can bring about a reduction in CO2 then why wouldn't a previous reduction in population not do the same?

Because it isn't the killing that does it, it is the returning land to its native state.

If the Mongols killing a few tens of millions didn't result in the depopulation of large areas that then over several decades returned to a state without human agriculture, it would not have the same effect.

[Valmy]

Because it isn't the killing that does it, it is the returning land to its native state.

If the Mongols killing a few tens of millions didn't result in the depopulation of large areas that then over several decades returned to a state without human agriculture, it would not have the same effect.

Yes. Though there is some indication that did happen. But he Black Death does not seem to have a mortality rate quite as extreme as what seems to have happened in the New World. And though people talk about how the Mongols destroyed massive amounts of peasants and left lots of land to fallow it may not have been on the same scale. They did destroy lots of ancient irrigation systems that never got repaired as well.

Though I find it surprising pre-modern agriculture can have a noticeable impact on the climate like that.