And that would be a super depressing future to live in.

We can't rule out the possibility that there is a source of energy that we don't yet know about, though.  For instance, nobody knew about fission or fusion at the end of the 19th century (but there were some strong hints of something already then, though, since the heat output of the sun couldn't be explained by known processes and the age of the earth).

We can't rule out the possibility that there is a source of energy that we don't yet know about, though

While that is true, it seems like today there really is a deeper understanding of the universe, compared to past generations. If there were some other form of energy to tap into, given the fidelity of our tools, surely there would be hints of it at least. While nuclear energy sources were not known about, there were physical hints, looking up at the sun or finding something like uranium ore.

As far as I know, and I may be wrong so feel free to correct me, there aren't any hints about other forms of energy that can be used.

it seems like today there really is a deeper understanding of the universe, compared to past generations.

Of course.  And we know for sure that we're missing something, since we can't explain the subatomic reality in terms of the larger scale reality or vice versa.  There is no direct evidence of a new energy source in that, though.

We can't rule out the possibility that there is a source of energy that we don't yet know about, though

While that is true, it seems like today there really is a deeper understanding of the universe, compared to past generations.  If there were some other form of energy to tap into, given the fidelity of our tools, surely there would be hints of it at least.  While nuclear energy sources were not known about, there were physical hints, looking up at the sun or finding something like uranium ore.  

As far as I know, and I may be wrong so feel free to correct me, there aren't any hints about other forms of energy that can be used.

I guess you don't hold much hope for that EM drive

IPCC refers to global changes, which is what's most relevant for global warming.  In my region the sea level is dropping by about 50 cm per century. The bay that I swam in as a kid does seem shallower now (there is not much tidal difference).  It has likely more to do with that I'm taller now than the actual ~15 cm sea level drop, though.

I wonder how coral reef bleaching (the destruction of the great barrier reef over the past 2 years) and the migration of infectious agents further north with climate change will factor in.  I was also reading about the lowering difference between the poles and the tropics leading to more blocking and more extreme weather.

I will be wrong, though, if it turns out that fusion can never become practical.

And that would be a super depressing future to live in.

I'd think we'll have controllable fusion within 50 years.

There are several different controlled fusion technologies today, but nobody has yet figured out a way to do it in which more energy can be extracted in a usable form than what was put in to power the reaction to begin with.  It is kind of like having a fire so hot that you can't quite figure out how to work with it.  The other problem is funding.  Most research designs and experiments are very expensive to run, and end up turning into money sinks.  If they don't produce promising results it makes funding for new research into fusion technology more difficult to come by.

The good news is that there are still a lot of new reactors being developed and tested, both by universities and private investigators, which have lower cost and show a great deal of promise above earlier designs.  As long as high energy plasma research itself is an active field then I think there is hope for a future with fusion energy.

I wonder how coral reef bleaching (the destruction of the great barrier reef over the past 2 years) and the migration of infectious agents further north with climate change will factor in.

Yeah, these both become more problematic with more warming.  There are large number of issues raised by a warming world, and they interrelate.  

A good example of this, and in my opinion one of the most worrying, is food security.  Agriculture is impacted by a combination of higher evapotranspiration rates, increased drought frequency and severity, and loss of arable land in low lying river deltas due to sea level rise and salt intrusion.  Some have suggested that the increased CO2 in the atmosphere would help, and in fact it does, but not nearly enough to offset these other factors.

The effect on agriculture is also a good example of the latitudinal dependence of climate change -- it severely impacts low and mid latitudes, while high latitudes can benefit.  Unfortunately, most of the area of Earth lies at low and mid latitudes, and so are more of the developing nations, which are less able to adapt to these changes.

I wonder how coral reef bleaching (the destruction of the great barrier reef over the past 2 years) and the migration of infectious agents further north with climate change will factor in.

Yes.  It's a bit Deja vu, though, for those remembering the forest dieback scare around 1980.  It was a huge environmental issue in eastern Europe, Scandinavia, north-west Russia and to some degree in north America, I believe.  It was a fact in those days that the forests were dying mass scale, that more than 50% of the trees in several countries were affected, and the consensus was that the cause was soil acidification due to industrial SO₂ pollution.  Researchers did large surveys and found evidence of affected trees at a large scale even far from the industrial areas responsible for the pollution, even worse the further away the trees were, calling for immediate inter-governmental action.  Scientists were dead seriously predicting that much of the forest would simply be gone by 2000.  So what happened?

The SO₂ pollution was real and caused some real, though not catastrophic problems (acidification of lakes, for instance).  But the forest dieback was greatly exaggerated and the soil acidification hypothesis was simply not correct.  When forests in Scandinavia were surveyed, it was to assess the SO₂ damage, and the finds were accordingly misinterpreted.  In reality most of the damage was natural, caused by fungi or salt or other causes.  For instance, when it was found that coastal areas were worst hit, it fitted nicely with the idea of airborne pollution from industrial Europe, since most precipitation falls near the coast.  In reality the researches were mostly seeing the effect of salt in the air.  There were scientists pointing out the possibilities of natural causes and that the damage might not be entirely new, but such talk was highly unpopular.  The causes were complex, but you can't present something ambiguous publicly.

The catastrophe didn't happen.  The scare did lead to actions against SO₂ pollutions and emissions were reduced.  Did it save the forests?  That would be stretching the truth quite a bit.  Then it might be argued that the exaggeration was necessary to reduce the unhealthy SO₂ emissions.  Perhaps, but dishonesty can backfire.

Is coral bleaching a similar exaggeration?  It will be interesting to see.  There's no way we can turn down the sea temperature in a few decades anyway.

A good example of this, and in my opinion one of the most worrying, is food security.  Agriculture is impacted by a combination of higher evapotranspiration rates, increased drought frequency and severity, and loss of arable land in low lying river deltas due to sea level rise and salt intrusion.  Some have suggested that the increased CO2 in the atmosphere would help, and in fact it does, but not nearly enough to offset these other factors.

More atmospheric CO₂ helps, and there are other benefits from warming.  It's pretty obvious that a warmer climate will increase the growing season at higher latitudes, where most of the warming is expected, and will push the arable limit further.  The tricky bit is to determine how much warming can be had before negative consequences cancel the benefits.  Currently, the situation doesn't look so bad.  In my lifetime the world populations has doubled, yet there are fewer who starve (both relatively and absolutely).  Of course, this has more to do with globalisation and improved technology than with warming. In other words we're much better prepared for climatic changes than previous generations were.

I'm not so sure that the doubling of population is a good thing- in our cities, denser populations are linked to higher rates of pollution and lower life expectancy.  At some point, hopefully the population will flatten out and not continue to double.

About bleaching and climate change, the interesting thing is, while at first the oceans behaved as heat sinks, it seems that now that period had ended.  If bleaching has major effects on sea life (since coral reefs are the major source of life in the oceans) sooner or later it will impact us.

For now, it seems as though the major impacts of climate change are for island nations and for the Arctic regions.

Oh, were you talking about acid rain?  Our own factories in NY were doing that and it caused a huge die off of fish in local lakes where the lakewater's pH was lowered.  We changed our emission laws to fix that.  It wasn't Europe's fault, it was our own polluted factories doing it.

Acid rain is a fairly localized problem since the SO2 precipitates or otherwise loses concentration quickly.  The same is not true for ocean acidification, which when coupled with the rising temperatures is a significant concern to the health of the oceans.  We also know this from historical precedent with the geologic record.

It's pretty obvious that a warmer climate will increase the growing season at higher latitudes, where most of the warming is expected, and will push the arable limit further.  The tricky bit is to determine how much warming can be had before negative consequences cancel the benefits.

About 2C, even after accounting for CO2 fertilization effect, and before accounting for increased drought frequency/severity.

The key reason has to do with geography and geometry.  The impacts of the warming on agriculture are more severe at low latitude, which is also where most of the area of Earth is.  (Half the area of the Earth lies within 30° of the equator.)  But the more sinister aspect of this is where the populations are, and where the industrial vs. developing nations are, in relation to whether impacts are positive or negative.  The most vulnerable nations are also the ones facing the most severe impacts.

It is possible to achieve food security with a warming and more populous world, but probably not if we keep to business as usual and deal with the consequences only as they appear.

https://cgspace.cgiar.org/bitstream/han ... sequence=6

I don't see any good reason to make the world more populous outside of what the religious fanatics say- and I tend to think oppositely of them so that's a no go  More people= worse for the environment, more pollution, higher stress levels, etc.

One other thing we didn't address is the impact of pesticides like neocortinoids on crucial species like bees and butterflies and other pollinators.  I dislike how much pull big corporations have in what they are allowed to use- we have more than enough superfund sites already, and these companies have been covering up for decades- until they got sued when their own employees got sick and the companies were forced to turn over internal documents showing what was going on and how much they were covering up.  The following site has some useful information.

https://renchemista.wordpress.com/category/superfund/

http://webcache.googleusercontent.com/s ... clnk&gl=us

https://www.google.com/url?sa=t&rct=j&q ... AmXBTrhqhA

Archive for the ‘Superfund’ Category
“The Lawyer Who Became DuPont’s Worst Nightmare” PFOA
Posted in 3M, Dow Chemical, DuPont, Endocrine Disruption, PFOA, PFOA/perfluorooctanoic acid, PFOS, Superfund, tagged 3M, Dow Chemical, DuPont, perfluorooctanoic acid, PFOA, PFOS on January 10, 2016 | 1 Comment »
The Lawyer Who Became DuPont’s Worst Nightmare

By NATHANIEL RICHJAN. 6, 2016


https://renchemista.wordpress.com/

About 2C, even after accounting for CO2 fertilization effect, and before accounting for increased drought frequency/severity.

I think there is low confidence for that statement.  Because:

• Assuming 2C is the global, annual average, what we really need to know is the increase in the lower latitudes, and how the changes are distributed over the seasons and daily cycle.
• 2C seems low since observations so far suggest that most of the heating is at high latitudes and at night, both generally beneficial to yield.  It would make low latitude agriculture extremely sensitive.
• If the benefits since 0C are cancelled out at 2C and things are roughly symmetric, the optimum is 1C, or where we are now.  If the warming continues, we should soon see effects since 2C would roughly correspond to Little Ice Age challenges (though different challenges).  I think we should have seen new severe regional effects already if this is the case.
• Temperature isn't really the issue anyway, but what temperature does with precipitation and extreme weather events, and we have low confidence for that link.

As for droughts, the confidence so far is low.  AR5:

Confidence is low for a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century, due to lack of direct observations, methodological uncertainties and geographical inconsistencies in the trends. Based on updated studies, AR4 conclusions regarding global increasing trends in drought since the 1970s were probably overstated. However, this masks important regional changes: the frequency and intensity of drought has likely increased in the Mediterranean and West Africa and likely decreased in central North America and north-west Australia since 1950.

We must also consider other possible causes for the dryness changes that we think have happened (natural cycles or land change).  And once reason why the confidence is low is that the changes have not been very large, even though we're halfway to the 2C turning point if we accept your statement.

There are a few important misconceptions and errors in your reasoning that I would encourage you to think about:

Assuming 2C is the global, annual average, what we really need to know is the increase in the lower latitudes, and how the changes are distributed over the seasons and daily cycle.

This is not an assumption -- your understanding of how this is determined is backward.

The study of climate change impacts is performed at the local and regional scale through global climate models, and we do understand the relationship between various warming thresholds (or more generally, different SRES scenarios at different times), and what the changes are with respect to latitude, season, etc.  So the global warming threshold we state for the context of crossing some threshold of impact risk is the conclusion from examining what these changes are in detail, not the assumed starting point.

For example, how that temperature change is actually distributed with respect to season looks like this:



If you examine the literature or IPCC figures you may also find similar representations for a number of other climate variables, and detailed analyses of how they impact us.  Another example (quoted from WG2)

"A principal emergent global public health risk is malnutrition secondary to ecological changes and disruptions in food production as a result of changing rainfall patterns, increases in extreme temperatures (high confidence; IPCC, 2012a; see also Section 11.6.1), and increased atmospheric CO2 (Taub et al., 2008; Burke and Lobell, 2010; Section 7.3.2.5). Modeling of the magnitude of the effect of climate change on future under-nutrition in five regions in South Asia and sub-Saharan Africa in 2050 (using Special Report on Emissions Scenarios (SRES) A2 emissions scenario) suggests an increase in moderate nutritional stunting, an indicator linked to increased risk of death and poor health (Black et al., 2008), of 1 to 29%, depending of the region assessed, compared to a future without climate change, and a much greater impact on severe stunting for particular regions,such as 23% for central sub-Saharan Africa and 62% for south Asia (Lloyd et al., 2011). The impact of climate-induced drought and precipitation changes in Mali include the southward movement of drought-prone areas which would result in a loss of critical agriculturally productive land by 2025 and increase food insecurity (Jankowska et al., 2012)."

2C seems low since observations so far suggest that most of the heating is at high latitudes and at night, both generally beneficial to yield.  It would make low latitude agriculture extremely sensitive.

It is surprising but true.  Many crops at low latitudes are already fairly close to their limits of what they can withstand under warming temperatures, particularly in terms of evapotranspiration. 

If you examine the effects of these changes on agriculture globally and don't account for the CO2 fertilization effect, then the impact is significantly negative almost everywhere:



After you account for the fertilization effect, the impacts are positive at high latitude and negative at low-mid latitude.  This result is very well established in the literature.

If the benefits since 0C are cancelled out at 2C and things are roughly symmetric, the optimum is 1C, or where we are now.  If the warming continues, we should soon see effects since 2C would roughly correspond to Little Ice Age challenges (though different challenges).  I think we should have seen new severe regional effects already if this is the case.

Very different challenges -- remember most of the problem is evapotranspiration related, which is very different when moving from Ice age climate to today vs. today's climate to the near future.

Temperature isn't really the issue anyway, but what temperature does with precipitation and extreme weather events, and we have low confidence for that link.

These studies are performed with temperature and precipitation changes in mind.  Increased extreme weather is less likely to be a benefit to crop production than to hurt it.

As for droughts, the confidence so far is low.  AR5:

Confidence is low for a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century, due to lack of direct observations, methodological uncertainties and geographical inconsistencies in the trends.

We do not expect to observe clear global-scale trends in drought with available data, nor does the impact of climate change on agriculture require one.  Global warming causes precipitation patterns to change on a regional scale, which is happening with high confidence and is examined in these studies of climate change impacts on agriculture.


Ultimately you are approaching this subject from simple intuitions.  I think you should try examining the research into this subject more carefully, and would recommend viewing the summaries of the synthesis reports on climate change impacts and vulnerability (e.g. IPCC AR5 WG2) or commission reports dedicated more specifically to these issues, such as the report I posted above.

This is not an assumption -- your understanding of how this is determined is backward.

You gave a figure, 2C, without specifying its meaning, so I had to make assumptions.  That the figure relates to global temperature.  And also that it's the change since the industrial revolution, or 1880, or something similar.

For example, how that temperature change is actually distributed with respect to season looks like this

It's a projection, which looks similar to what we've seen over the past 50 years or so.  One which I think is very bold for the Arctic.  The 1990-2015 temperature increase looks very similar to the 1920-1935 increase, which was followed by a cooling from 1945-1970.  I think it's bold to declare that history wont repeat this time.
The 2C figure doesn't harmonise well either with the facts that the agriculture revolution happened in a warm world.  Certainly, high latitudes were significantly warmer than today, known from remains of vegetation and geological evidence.  But perhaps it wasn't warmer in the lower latitudes where agriculture was developed.  In which case we must question what we know of how warming gets distributed.
The point is, in order to give a 2C figure, we must know what the distribution will be.  You indicate that we do.  However, would you consider it falsified if the Arctic fails to produce significant warming by 2035?

Many crops at low latitudes are already fairly close to their limits of what they can withstand under warming temperatures, particularly in terms of evapotranspiration.

Let's look at real data (source): The trend is similar for all regions, except small pacific island states, which I think can easily be explained by economical factors rather than climatic (increased import).  It's a bold bet to declare that these graphs will soon show a severe crash.  Since climate changes gradually, it's not unreasonable that the effects also will be gradual, so if we're at the brink of something, shouldn't there already be signs of that in the yield data?
I'll give you credit though for presenting easily testable projections.  Would a yield in 15-20 years that is higher than today be sufficient to falsify?

Global warming causes precipitation patterns to change on a regional scale

Weren't we discussing the sign of the summed regional changes?

Ultimately you are approaching this subject from simple intuitions. I think you should try examining the research into this subject more carefully

I want to see the research tested (hopefully before the fact), in particular research presenting doomsday like projections, or in general bold predictions (which would be difficult to explain otherwise).  Until hypotheses pass the tests, intuition is ultimately their foundation.  I'm challenging the research for tests so we can move beyond intuition.