<p>We might have some wiggle room, or might be past the tipping point, but we do not have enough info to be sure. It depends of unknown strength of known positive feedback loops, like: </p>

<ul>
<li>melting permafrost releasing potent greenhouse gas methane</li>
<li>drying permafrost bogs release CO<sub>2</sub> or even burn</li>
<li>warming ocean might release <a href="https://en.wikipedia.org/wiki/Methane_clathrate" rel="nofollow">https://en.wikipedia.org/wiki/Methane_clathrate</a> (methane ice) - remember Deepwater Horizon?</li>
<li>and likely more.</li>
</ul>

<p>What we are certain is, the more CO<sub>2</sub> we release, the closer we will get to the tipping point, after which different climate might stabilize, close to <a href="https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum" rel="nofollow">PETM</a>, the onset of which has been linked to an initial 5 °C temperature rise and extreme changes in Earth’s carbon cycle. It lasted about 170K years. Alligators in Alaska, ocean level 270 feet (90 m) higher), lots of arable land and many big cities (London, New York, Shanghai) submerged, etc. </p>

<p>How big human population such different planet can support? We don't know, but I am not sure we should try to find out the hard way.</p>

<p>Or another way to formulate this: <strong>Can Earth support intelligent life? We don't know, we are about to find out.</strong></p>

<p>One solution for <a href="https://en.wikipedia.org/wiki/Fermi_paradox" rel="nofollow">Fermi Paradox</a>  ("Where is everybody?") is that technological civilizations like ours destroy their environment and go extinct. </p>

CC BY-SA 3.0
2016-01-26T22:34:25.113Z
+1 for last 2 lines. Nice answer.
coblr
CC BY-SA 3.0
2016-01-27T09:00:41.037Z
@fractalspawn but unrelated to the question.
Gimelist
CC BY-SA 3.0
2016-01-27T17:59:29.387Z
@Michael: true, but it was an interesting relation to another question of mine and I thought that made it special beyond the bare minimum.
coblr
CC BY-SA 3.0
2016-01-26T17:26:00.243Z
2016-01-27T09:01:13.870Z
2016-01-27T09:01:13.870Z
Peter M. - stands for Monica
<p>According to satellite datasets (RSS), last year was not even close to being warmest ever. The warmest year still is 1998, and the second warmest is 2010.</p>

<p>It is beyond me why NOAA or NASA GISS (who use NOAA's data), ignore satellite measured temperatures, which give far more accurate and complete picture of the world's global temperature.</p>

<p><a href="https://i.sstatic.net/QrG2f.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/QrG2f.png" alt="RSS satellite measured global temperature anomaly"></a></p>

<p>Below is a map of the coverage of the data NOAA and NASA GISS uses. I find it hard to believe they can tell us the global temperature in sufficent accuracy to claim whether some individual year was some hundredths of degrees warmer than some other.</p>

<p>There are almost no data on the oceans, Antarctis, Africa or the north pole. Just extrapolating the little data they have over thousands of kilometers just isn't going to produce accurate enough data to detect such a small changes.</p>

<p>This in mind, I'd rather turn to the satellites, which show nothing to be worried about.</p>

<p><a href="https://i.sstatic.net/icCzO.gif" rel="nofollow noreferrer"><img src="https://i.sstatic.net/icCzO.gif" alt="global temperature coverage"></a></p>

CC BY-SA 3.0
2016-01-27T21:57:57.743Z
See https://earthscience.stackexchange.com/questions/6820/uah-and-rss-lower-troposphere-data for some information on the datasets derived from the MSU instrument (uah and rss ingest the same data but process it differently) and there is mention that the instrument is sensitive to ENSO conditions.
casey
CC BY-SA 3.0
2016-01-28T20:37:03.933Z
There's actually good agreement between satellite and surface measurements. The RSS graph you posted seems less dramatic because (1) it only goes back to 1979, not 1880 (2) the data aren't smoothed so there's more noise and (3) the temperature is in °C, not °F. If we plot the RSS data and NASA's GISS data on the same scale, [both the year-by year variation and the overall trends are similar](http://i.imgur.com/mcnBoNZ.png) (and that goes for HADCRUT and UAH too).
Pont
CC BY-SA 3.0
2016-01-28T21:02:38.777Z
To back up your claim of "almost no data on the oceans", you've added a picture explicitly labelled "**land-only** temperature". A land-only data set does indeed have rather poor ocean coverage, but the NASA and the NOAA analyses both include extensive ocean data.
Pont
CC BY-SA 3.0
2016-01-27T19:29:29.167Z
2016-01-27T20:38:59.270Z
2016-01-27T20:38:59.270Z
WiggleTiggle
<p>Runaway climate change is, given our current state of knowledge, only something that could be confirmed in historic context - in the rear-view mirror. Inconveniently, there's likely to be a much-diminished version of human civilisation around to observe it, if and when it does happen.</p>

<p>In other words, it's too early to tell if we've passed a catastrophic tipping point.</p>

<p>We don't know what the equilibrium state of the Earth's atmosphere is. It will take 30 years for our current stock of GHG emissions to fully show its effects: and we'll be continuing to release GHGs for a while, so the equilibrium will continue to change.</p>

<p>But it's worth bearing in mind what we can do, when we really have to; World War II saw massive realignments both in industrial production and in expectations within a very short space of time: after decades of delay, it now seems likely that decarbonisation will require at least a similarly fast and large industrial realignment; and it is possible.</p>

CC BY-SA 3.0
2016-01-26T11:48:59.580Z
What exactly do you mean by *It will take 30 years for our current stock of GHG emissions to fully show its effects*?  Clearly some effects, such as sea level rise, take much longer.
gerrit
CC BY-SA 3.0
2016-01-26T19:04:58.933Z
@gerrit given we need about 30 years of weather to see the climate clearly, then that's the amount of time it will take to get a good measure of the size of the forcing. Equilibrium is a different matter - that could take centuries (if indeed it ever actually happens on a planet with life).
410 gone
CC BY-SA 3.0
2016-01-26T19:36:53.980Z
@gerrit: Because CO2 is "the gift that keeps on giving" (to borrow a phrase).  Adding X amount of CO2 this year doesn't just turn up the temperature this year, it increases the rate at which solar energy is captured, and thus causes a temperature increase that goes on for perhaps decades or more, until a new equilibrium is reached.
jamesqf
CC BY-SA 3.0
2016-01-26T19:41:13.720Z
@jamesqf Sure.  What I found confusing, however, is the phrase *to fully show its effects* — after 30 years it is just *beginning* to show its effects.  To fully show its effects we need far more time.
gerrit
CC BY-SA 3.0
2016-01-26T11:16:28.900Z
2016-01-26T11:16:28.900Z
410 gone
<p>2015 had the <a href="https://www.washingtonpost.com/news/energy-environment/wp/2016/01/20/its-official-2015-smashed-2014s-global-temperature-record-it-wasnt-even-close/" rel="nofollow noreferrer">highest global temperatures on record</a>, as discussed in <a href="https://earthscience.stackexchange.com/questions/7316/why-is-the-temperature-still-rising">this question</a>, beating the last record ... in 2014. </p>

<p><a href="https://i.sstatic.net/HzU6v.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/HzU6v.png" alt="enter image description here"></a> </p>

<p>Are we now in a <a href="https://en.wikipedia.org/wiki/Runaway_climate_change" rel="nofollow noreferrer">runaway climate change</a> regime, where zero further human impact on the environment will not prevent change to the equilibrium state of the Earth's atmosphere?</p>

CC BY-SA 3.0
2016-01-26T18:14:19.490Z
Because two consecutive years == evidence of runaway effects?
DSKekaha
CC BY-SA 3.0
2016-01-27T19:17:19.403Z
@DSKekaha two consecutive years supported by a graph showing a clear upward trend for the past 65 years, to be fair. Though even looking at temperatures over 100 years is not enough of a context, IMO. Which is unfortunate, because time scales over 100 years don't make a lot of innate sense to life forms that only live 100 years.
TylerH
<climate-change>
Is 2015's record average temperature evidence that we are now experiencing runaway climate change?
christopherlovell
# Is 2015's record average temperature evidence that we are now experiencing runaway climate change?

(Asked by: username_0 on 2016-01-26)

2015 had the [highest global temperatures on record](https://www.washingtonpost.com/news/energy-environment/wp/2016/01/20/its-official-2015-smashed-2014s-global-temperature-record-it-wasnt-even-close/), as discussed in [this question](https://earthscience.stackexchange.com/questions/7316/why-is-the-temperature-still-rising), beating the last record ... in 2014.

[![enter image description here](https://i.sstatic.net/HzU6v.png)](https://i.sstatic.net/HzU6v.png)

Are we now in a [runaway climate change](https://en.wikipedia.org/wiki/Runaway_climate_change) regime, where zero further human impact on the environment will not prevent change to the equilibrium state of the Earth's atmosphere?

**Tags:** climate-change

> **Comments:**
> **username_1**: Because two consecutive years == evidence of runaway effects?  
> **username_2**: @username_1 two consecutive years supported by a graph showing a clear upward trend for the past 65 years, to be fair. Though even looking at temperatures over 100 years is not enough of a context, IMO. Which is unfortunate, because time scales over 100 years don't make a lot of innate sense to life forms that only live 100 years.  

---

## 3 answers

### Answer by username_9 on 2016-01-26. Score: 22 | Accepted answer

Runaway climate change is, given our current state of knowledge, only something that could be confirmed in historic context - in the rear-view mirror. Inconveniently, there's likely to be a much-diminished version of human civilisation around to observe it, if and when it does happen.

In other words, it's too early to tell if we've passed a catastrophic tipping point.

We don't know what the equilibrium state of the Earth's atmosphere is. It will take 30 years for our current stock of GHG emissions to fully show its effects: and we'll be continuing to release GHGs for a while, so the equilibrium will continue to change.

But it's worth bearing in mind what we can do, when we really have to; World War II saw massive realignments both in industrial production and in expectations within a very short space of time: after decades of delay, it now seems likely that decarbonisation will require at least a similarly fast and large industrial realignment; and it is possible.

> **Comments:**
> **username_10**: What exactly do you mean by *It will take 30 years for our current stock of GHG emissions to fully show its effects*?  Clearly some effects, such as sea level rise, take much longer.  
> **username_9**: @username_10 given we need about 30 years of weather to see the climate clearly, then that's the amount of time it will take to get a good measure of the size of the forcing. Equilibrium is a different matter - that could take centuries (if indeed it ever actually happens on a planet with life).  
> **username_11**: @username_10: Because CO2 is "the gift that keeps on giving" (to borrow a phrase).  Adding X amount of CO2 this year doesn't just turn up the temperature this year, it increases the rate at which solar energy is captured, and thus causes a temperature increase that goes on for perhaps decades or more, until a new equilibrium is reached.  
> **username_10**: @username_11 Sure.  What I found confusing, however, is the phrase *to fully show its effects* — after 30 years it is just *beginning* to show its effects.  To fully show its effects we need far more time.  

---

### Answer by username_3 on 2016-01-26. Score: 10

We might have some wiggle room, or might be past the tipping point, but we do not have enough info to be sure. It depends of unknown strength of known positive feedback loops, like:

* melting permafrost releasing potent greenhouse gas methane
* drying permafrost bogs release CO2 or even burn
* warming ocean might release <https://en.wikipedia.org/wiki/Methane_clathrate> (methane ice) - remember Deepwater Horizon?
* and likely more.

What we are certain is, the more CO2 we release, the closer we will get to the tipping point, after which different climate might stabilize, close to [PETM](https://en.wikipedia.org/wiki/Paleocene%E2%80%93Eocene_Thermal_Maximum), the onset of which has been linked to an initial 5 °C temperature rise and extreme changes in Earth’s carbon cycle. It lasted about 170K years. Alligators in Alaska, ocean level 270 feet (90 m) higher), lots of arable land and many big cities (London, New York, Shanghai) submerged, etc.

How big human population such different planet can support? We don't know, but I am not sure we should try to find out the hard way.

Or another way to formulate this: **Can Earth support intelligent life? We don't know, we are about to find out.**

One solution for [Fermi Paradox](https://en.wikipedia.org/wiki/Fermi_paradox) ("Where is everybody?") is that technological civilizations like ours destroy their environment and go extinct.

> **Comments:**
> **username_4**: +1 for last 2 lines. Nice answer.  
> **username_5**: @fractalspawn but unrelated to the question.  
> **username_4**: @Michael: true, but it was an interesting relation to another question of mine and I thought that made it special beyond the bare minimum.  

---

### Answer by username_6 on 2016-01-27. Score: -5

According to satellite datasets (RSS), last year was not even close to being warmest ever. The warmest year still is 1998, and the second warmest is 2010.

It is beyond me why NOAA or NASA GISS (who use NOAA's data), ignore satellite measured temperatures, which give far more accurate and complete picture of the world's global temperature.

[![RSS satellite measured global temperature anomaly](https://i.sstatic.net/QrG2f.png)](https://i.sstatic.net/QrG2f.png)

Below is a map of the coverage of the data NOAA and NASA GISS uses. I find it hard to believe they can tell us the global temperature in sufficent accuracy to claim whether some individual year was some hundredths of degrees warmer than some other.

There are almost no data on the oceans, Antarctis, Africa or the north pole. Just extrapolating the little data they have over thousands of kilometers just isn't going to produce accurate enough data to detect such a small changes.

This in mind, I'd rather turn to the satellites, which show nothing to be worried about.

[![global temperature coverage](https://i.sstatic.net/icCzO.gif)](https://i.sstatic.net/icCzO.gif)

> **Comments:**
> **username_7**: See https://earthscience.stackexchange.com/questions/6820/uah-and-rss-lower-troposphere-data for some information on the datasets derived from the MSU instrument (uah and rss ingest the same data but process it differently) and there is mention that the instrument is sensitive to ENSO conditions.  
> **username_8**: There's actually good agreement between satellite and surface measurements. The RSS graph you posted seems less dramatic because (1) it only goes back to 1979, not 1880 (2) the data aren't smoothed so there's more noise and (3) the temperature is in °C, not °F. If we plot the RSS data and NASA's GISS data on the same scale, [both the year-by year variation and the overall trends are similar](http://i.imgur.com/mcnBoNZ.png) (and that goes for HADCRUT and UAH too).  
> **username_8**: To back up your claim of "almost no data on the oceans", you've added a picture explicitly labelled "**land-only** temperature". A land-only data set does indeed have rather poor ocean coverage, but the NASA and the NOAA analyses both include extensive ocean data.  

---

