<blockquote>
  <p>Is there a large, documented consensus on any estimate of sea level
  raise or any other more "direct" effect on the human population?</p>
</blockquote>

<p>As Will said in a comment, IPCC has some estimates on that matter, although they vary depending on which emission scenario you choose. From the technical summary of the <a href="https://www.ipcc.ch/srocc/chapter/technical-summary/ts-4sea-level-rise-and-implications-for-low-lying-islands-coasts-and-communities/" rel="nofollow noreferrer">IPCC Special Report on Ocean and Cryosphere in a Changing Climate</a>, section "Projections":</p>

<blockquote>
  <p>Future rise in GMSL [global mean sea level] caused by thermal expansion, melting of glaciers and ice sheets and land water storage changes, is strongly dependent on which Representative Concentration Pathway (RCP) emission scenario is followed. SLR [sea level rise] at the end of the century is projected to be faster under all scenarios, including those compatible with achieving the long-term temperature goal set out in the Paris Agreement. GMSL will rise between 0.43 m (0.29–0.59 m, likely range; RCP2.6) and 0.84 m (0.61–1.10 m, likely range; RCP8.5) by 2100 (medium confidence) relative to 1986–2005.</p>
</blockquote>

<p>As for the meaning of this sea level rise on human population, it's better to look at the <a href="https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/spm-section-3/" rel="nofollow noreferrer">summary for policymakers of the same report</a>:</p>

<blockquote>
  <p>The increasing frequency of high water levels can have severe impacts
  in many locations depending on exposure (high confidence). [...] Extreme sea levels and
  coastal hazards will be exacerbated by projected increases in tropical
  cyclone intensity and precipitation (high confidence). Projected
  changes in waves and tides vary locally in whether they amplify or
  ameliorate these hazards (medium confidence).</p>
</blockquote>

<hr>

<p>On a more "philosophical" note, it is really difficult to predict the effect on humans because of the <a href="https://en.wikipedia.org/wiki/Self-defeating_prophecy" rel="nofollow noreferrer">prophet's dilemma</a>. If we know bad things are going to happen, we will (or at least we should...) take measures to prevent them. Then the predicted things will not happen, making the prediction seem wrong, even if it was right at the time it was made! So we can predict that the sea level will rise (it will, no question about that), but we cannot predict the effect this rise will have on humans, because they will likely adapt to it before the effect happens.</p>

CC BY-SA 4.0
2020-02-06T12:57:32.883Z
2020-02-06T12:57:32.883Z
Jean-Marie Prival
<p>I have seen ample consensus amongst reputable scientists that the earth is getting warmer, and this fact is due to human activity (e.g <a href="https://climate.nasa.gov/faq/17/do-scientists-agree-on-climate-change/" rel="nofollow noreferrer">https://climate.nasa.gov/faq/17/do-scientists-agree-on-climate-change/</a>)</p>

<p>The affirmation "97 percent of the scientists with the relevant expertise agree that climate change is real and caused by humans", in particular, gets a lot or airtime.</p>

<p>I have not yet, however, seen similar consensus for the effects of climate change. </p>

<p>Is there a large, documented consensus on any estimate of sea level raise or any other more "direct" effect on the human population?</p>

<p>Variation is not a problem, as long as a significant percentage of scientists/papers affirm at least X of variation of sea level, and X is enough to be a big problem</p>

<p>(Or the analogous affirmation for a different climate change effect)</p>

<p>To be more concrete, is there a survey of scientists or a meta analysis paper that mentions a significant effect, that would affect how humans live, and that shows 90% or more of agreement (of the relevant papers or the relevant scientists)?</p>

CC BY-SA 4.0
2020-02-06T01:34:30.273Z
Are you asking about "research on consensus" or the documentation of consensus? Or are you asking a question about Earth Science? It's hard for me to understand exactly what the question is and what kind of answer you are interested in. I think you might be asking about what current models predicting for future sea level increases, and how much variation there is between models, but *you've used the word "consensus" five times* which might suggest that you are uncomfortable with there being variations between different models.
uhoh
CC BY-SA 4.0
2020-02-06T01:36:15.277Z
If you do want to ask specifically about "research on consensus" or the documentation of consensus then there is also [Academia SE](https://academia.stackexchange.com/), though I don't know if it would be on-topic there.
uhoh
CC BY-SA 4.0
2020-02-06T03:07:49.253Z
@uhoh, hopefully this is a bit clearer?
josinalvo
CC BY-SA 4.0
2020-02-06T03:15:38.327Z
Okay helps a bit but it's still going to be hard to answer this here in Stack Exchange because things like "seems credible to me" are subjective, and the question still feels to me like it is still asking for something to be *demonstrated to your satisfaction,* but let's wait and see how other users respond. Earth Science isn't the study of what "a significant percentage of scientists/papers affirm". If you need statistics compiled by the popular media, them maybe [Skeptics SE](https://skeptics.stackexchange.com/) might be a better place? Here we ask specifics question about the science itself
uhoh
CC BY-SA 4.0
2020-02-06T03:23:41.420Z
For example, see [my comments here](https://earthscience.meta.stackexchange.com/questions/1802/what-is-the-most-effective-way-to-counter-climate-change-denial#comment4963_1802)
uhoh
CC BY-SA 4.0
2020-02-06T08:15:13.883Z
I'd recommend the IPCC for the scientific consensus. They have graded language which they use to indicate the amount of scientific agreement in their reports e.g. low confidence, virtually certain, etc. It's all on their website.
Will
CC BY-SA 4.0
2020-02-06T12:14:20.123Z
@uhoh: this question was born in the skeptics stack exchange.
josinalvo
CC BY-SA 4.0
2020-02-06T12:14:55.190Z
@uhoh do recent edits make it more objective and answerable?
josinalvo
CC BY-SA 4.0
2020-02-06T15:59:10.907Z
Notably, the several lines of research establishing what degree of consensus existed among climate scientists about the reality of climate change were a response to denialist claims that there was no such consensus. Studies of the various impacts tend to rely on expertise to a degree that the opinion of non-specialists isn't terribly meaningful.
jeffronicus
<climate-change>
What are the affirmations regarding the effects of climate change that have a high degree of consensus amongst climate scientists?
josinalvo
# What are the affirmations regarding the effects of climate change that have a high degree of consensus amongst climate scientists?

(Asked by: username_0 on 2020-02-05)

I have seen ample consensus amongst reputable scientists that the earth is getting warmer, and this fact is due to human activity (e.g <https://climate.nasa.gov/faq/17/do-scientists-agree-on-climate-change/>)

The affirmation "97 percent of the scientists with the relevant expertise agree that climate change is real and caused by humans", in particular, gets a lot or airtime.

I have not yet, however, seen similar consensus for the effects of climate change.

Is there a large, documented consensus on any estimate of sea level raise or any other more "direct" effect on the human population?

Variation is not a problem, as long as a significant percentage of scientists/papers affirm at least X of variation of sea level, and X is enough to be a big problem

(Or the analogous affirmation for a different climate change effect)

To be more concrete, is there a survey of scientists or a meta analysis paper that mentions a significant effect, that would affect how humans live, and that shows 90% or more of agreement (of the relevant papers or the relevant scientists)?

**Tags:** climate-change

> **Comments:**
> **username_1**: Are you asking about "research on consensus" or the documentation of consensus? Or are you asking a question about Earth Science? It's hard for me to understand exactly what the question is and what kind of answer you are interested in. I think you might be asking about what current models predicting for future sea level increases, and how much variation there is between models, but *you've used the word "consensus" five times* which might suggest that you are uncomfortable with there being variations between different models.  
> **username_1**: If you do want to ask specifically about "research on consensus" or the documentation of consensus then there is also [Academia SE](https://academia.stackexchange.com/), though I don't know if it would be on-topic there.  
> **username_0**: @username_1, hopefully this is a bit clearer?  
> **username_1**: Okay helps a bit but it's still going to be hard to answer this here in Stack Exchange because things like "seems credible to me" are subjective, and the question still feels to me like it is still asking for something to be *demonstrated to your satisfaction,* but let's wait and see how other users respond. Earth Science isn't the study of what "a significant percentage of scientists/papers affirm". If you need statistics compiled by the popular media, them maybe [Skeptics SE](https://skeptics.stackexchange.com/) might be a better place? Here we ask specifics question about the science itself  
> **username_1**: For example, see [my comments here](https://earthscience.meta.stackexchange.com/questions/1802/what-is-the-most-effective-way-to-counter-climate-change-denial#comment4963_1802)  
> **username_2**: I'd recommend the IPCC for the scientific consensus. They have graded language which they use to indicate the amount of scientific agreement in their reports e.g. low confidence, virtually certain, etc. It's all on their website.  
> **username_0**: @username_1: this question was born in the skeptics stack exchange.  
> **username_0**: @username_1 do recent edits make it more objective and answerable?  
> **username_3**: Notably, the several lines of research establishing what degree of consensus existed among climate scientists about the reality of climate change were a response to denialist claims that there was no such consensus. Studies of the various impacts tend to rely on expertise to a degree that the opinion of non-specialists isn't terribly meaningful.  

---

## 1 answers

### Answer by username_4 on 2020-02-06. Score: 4

> Is there a large, documented consensus on any estimate of sea level
> raise or any other more "direct" effect on the human population?

As username_2 said in a comment, IPCC has some estimates on that matter, although they vary depending on which emission scenario you choose. From the technical summary of the [IPCC Special Report on Ocean and Cryosphere in a Changing Climate](https://www.ipcc.ch/srocc/chapter/technical-summary/ts-4sea-level-rise-and-implications-for-low-lying-islands-coasts-and-communities/), section "Projections":

> Future rise in GMSL [global mean sea level] caused by thermal expansion, melting of glaciers and ice sheets and land water storage changes, is strongly dependent on which Representative Concentration Pathway (RCP) emission scenario is followed. SLR [sea level rise] at the end of the century is projected to be faster under all scenarios, including those compatible with achieving the long-term temperature goal set out in the Paris Agreement. GMSL username_2 rise between 0.43 m (0.29–0.59 m, likely range; RCP2.6) and 0.84 m (0.61–1.10 m, likely range; RCP8.5) by 2100 (medium confidence) relative to 1986–2005.

As for the meaning of this sea level rise on human population, it's better to look at the [summary for policymakers of the same report](https://www.ipcc.ch/srocc/chapter/summary-for-policymakers/spm-section-3/):

> The increasing frequency of high water levels can have severe impacts
> in many locations depending on exposure (high confidence). [...] Extreme sea levels and
> coastal hazards username_2 be exacerbated by projected increases in tropical
> cyclone intensity and precipitation (high confidence). Projected
> changes in waves and tides vary locally in whether they amplify or
> ameliorate these hazards (medium confidence).

---

On a more "philosophical" note, it is really difficult to predict the effect on humans because of the [prophet's dilemma](https://en.wikipedia.org/wiki/Self-defeating_prophecy). If we know bad things are going to happen, we username_2 (or at least we should...) take measures to prevent them. Then the predicted things username_2 not happen, making the prediction seem wrong, even if it was right at the time it was made! So we can predict that the sea level username_2 rise (it username_2, no question about that), but we cannot predict the effect this rise username_2 have on humans, because they username_2 likely adapt to it before the effect happens.


---

