When and how bad?

[wili]

 "there isn't evidence that a warmer world has less agricultural production potential and there is plenty of contrary evidence"

There is, you just don't want to hear it, for some reason.

The standard figure is that for every degree centigrade of temperature increase, we will see about a 10% decrease in total food production.

Note that the last few decades have seen the introduction of the 'Green Revolution' that brought about higher yields through careful breeding of high yield seeds, but also massive inputs of NPK and ff-driven mechanization. The advances and advantages from these strategies have just about played themselves out.

We are now at the second highest price for food for this time of year in modern history, after 2011. Food stores are at historical lows. Maybe we'll luck out and dodge a bunch of climate bullets in the next few years. But the imminent collapse of the Arctic sea ice cap does not bode well for relatively stable climates prevailing in the Northern Hemisphere (where most land is and where most ag takes place.)

Way too much cold or heat, rain or drought, for way too long is what will likely become the norm in most of the major ag regions in the world. If that sounds like a good formula for bumper crops, go long on ag stocks.

[ggelsrinc]

"there isn't evidence that a warmer world has less agricultural production potential and there is plenty of contrary evidence"

There is, you just don't want to hear it, for some reason.

The standard figure is that for every degree centigrade of temperature increase, we will see about a 10% decrease in total food production.

Note that the last few decades have seen the introduction of the 'Green Revolution' that brought about higher yields through careful breeding of high yield seeds, but also massive inputs of NPK and ff-driven mechanization. The advances and advantages from these strategies have just about played themselves out.

We are now at the second highest price for food for this time of year in modern history, after 2011. Food stores are at historical lows. Maybe we'll luck out and dodge a bunch of climate bullets in the next few years. But the imminent collapse of the Arctic sea ice cap does not bode well for relatively stable climates prevailing in the Northern Hemisphere (where most land is and where most ag takes place.)

Way too much cold or heat, rain or drought, for way too long is what will likely become the norm in most of the major ag regions in the world. If that sounds like a good formula for bumper crops, go long on ag stocks.

Then your standard figure should apply to warming that has already happened and food production didn't decline. Instrumental records show about a 0.6+ degree C higher temperature than the 1901-2000 mean of 13.9 degrees C. Here is a NOAA chart that shows about a 0.6 degree increase between 1980 and 2010, just like the years that had two and a half times more natural catastrophes:



Show me the 6% decline in total food production, between 1980 and 2010! Is there some reason why only future warming causes this food reduction and actual warming that has happened doesn't? Hearing something has nothing to do with believing it.

When someone posted a statement that a warmer Earth was a drier Earth, I didn't hear anyone believing the doomsday forecast correct that statement, which we all should know is wrong. Global land precipitation increased 2% during the 20th Century.

[DrTskoul]

Ehhm. Forget something. Agriculture production has been increasing to feed a larger population. Therefore a 6% productivity loss would appear as a reduced increase. There are evidence that productivity of certain crops per acre has stagnated the last decade (e.g. rice in Japan)

[Shared Humanity]

"there isn't evidence that a warmer world has less agricultural production potential and there is plenty of contrary evidence"

There is, you just don't want to hear it, for some reason.

The standard figure is that for every degree centigrade of temperature increase, we will see about a 10% decrease in total food production.

Note that the last few decades have seen the introduction of the 'Green Revolution' that brought about higher yields through careful breeding of high yield seeds, but also massive inputs of NPK and ff-driven mechanization. The advances and advantages from these strategies have just about played themselves out.

We are now at the second highest price for food for this time of year in modern history, after 2011. Food stores are at historical lows. Maybe we'll luck out and dodge a bunch of climate bullets in the next few years. But the imminent collapse of the Arctic sea ice cap does not bode well for relatively stable climates prevailing in the Northern Hemisphere (where most land is and where most ag takes place.)

Way too much cold or heat, rain or drought, for way too long is what will likely become the norm in most of the major ag regions in the world. If that sounds like a good formula for bumper crops, go long on ag stocks.

Then your standard figure should apply to warming that has already happened and food production didn't decline. Instrumental records show about a 0.6+ degree C higher temperature than the 1901-2000 mean of 13.9 degrees C. Here is a NOAA chart that shows about a 0.6 degree increase between 1980 and 2010, just like the years that had two and a half times more natural catastrophes:



Show me the 6% decline in total food production, between 1980 and 2010! Is there some reason why only future warming causes this food reduction and actual warming that has happened doesn't? Hearing something has nothing to do with believing it.

When someone posted a statement that a warmer Earth was a drier Earth, I didn't hear anyone believing the doomsday forecast correct that statement, which we all should know is wrong. Global land precipitation increased 2% during the 20th Century.

I certainly would not argue with your point that a warmer world will be a wetter world. I do disagree with your suggestion (perhaps I've misread you) that this wetter world is somehow responsible for the increase in agricultural production. To chart this increase in food output and a similar increase in rainfall and conclude that the latter is responsible for the former is simplistic. To suggest an increase of production in the face of a warming world is evidence that a warming world will not have a negative impact on food production is simplistic as well.

I am not an expert in farming but it would seem the discussion on this thread has, in a meaningful way, proposed very real mechanisms to suggest global warming's near term impact on food production could be dramatic and not in a good way.

I do know this. Farmers don't farm with charts. They deal with a very real, local environment to produce food. Flooded fields in the spring delay planting. Very dry summers can prevent the healthy tassling of corn required to produce a good crop. Abnormally warm springs, followed by a hard frost, can destroy an entire seasons output of peaches and apples. Six feet of snow in the fields can wipe out large numbers of sheep.

I have read a lot of research about and agree with the argument that the melting of the arctic is causing an increase in weird weather. Weird weather will not benefit agriculture.

[Shared Humanity]

The Green Sahara is a product of changes of the 23,000 year North Africa monsoon cycle, but the experts claim there is some other trigger than insolation changes for both the onset and end, because it happens to quickly. I'd say some change in ocean circulation is the most likely trigger. The prevailing winds in the center of the Sahara switch direction.

There are very good reasons why food production didn't flourish throughout the entire continent of Africa (like switching from summer to winter crops as you go north to south and livestock infected by tsetse), which is a topic besides the point that world food production managed to increase significantly during the 30 years when weather related natural catastrophies were two and a half times more likely in 2010 than in 1980 and that comes from a trend and not anecdotal cherry picked data. This increase in exceptional weather events isn't something just happening, it's been happening and the insurance companies have been charging for climate change since 1973.

I think the collective mindset of societal collapse because of climate change follows this path. The data that climate change exists and is anthropogenic is overwhelming and should be convincing to reasonable people. I think the collective mindset sees mankind as the villain and looks for a way for the Earth to counterattack the villain as if the Earth is a sentient life form. I think it's motivated by frustration that things aren't being down to stop AGW. We've all been told about overpopulation since we were born, but at least the older people have the experience of living a lifetime of claimed food production disasters that never happened. The claims predate any concerns about global warming. The odds that someone will spend their entire lifetime without food related societal collapse, just like I have, are much more likely than these doomsday forecasts.

In 2011, 66 million people starved worldwide. U.N. studies show an additional 975 million are "chronically malnourished", another way of saying they are starving to death. With a population of nearly 7 billion, the odds that you are starving is actually 1 in 7. Bully for you if you live in a country where this is not happening. Tell the Sudanese or Somalians (Choose your own if these two examples don't suit you.) they are mistaken to conclude they are dealing with food related societal collapse.

In the U.S. there is one institution that has completely embraced the idea of AGW and this is the U.S. military. They have been working on military strategies to deal with the anticipated societal collapse caused by this warming. They have published reports arguing that global warming is the largest threat to security in the world. (These are easy to find if you'd like to read them.) They have enlisted some of our premier researchers to provide the knowledge to understand the regional effects that will occur (not an easy task and fraught with uncertainty) so they can prepare for them.

Of course, there is a possibility these military types are just alarmists.

[birthmark]

"there isn't evidence that a warmer world has less agricultural production potential and there is plenty of contrary evidence"

There is, you just don't want to hear it, for some reason.

The standard figure is that for every degree centigrade of temperature increase, we will see about a 10% decrease in total food production.

Note that the last few decades have seen the introduction of the 'Green Revolution' that brought about higher yields through careful breeding of high yield seeds, but also massive inputs of NPK and ff-driven mechanization. The advances and advantages from these strategies have just about played themselves out.

We are now at the second highest price for food for this time of year in modern history, after 2011. Food stores are at historical lows. Maybe we'll luck out and dodge a bunch of climate bullets in the next few years. But the imminent collapse of the Arctic sea ice cap does not bode well for relatively stable climates prevailing in the Northern Hemisphere (where most land is and where most ag takes place.)

Way too much cold or heat, rain or drought, for way too long is what will likely become the norm in most of the major ag regions in the world. If that sounds like a good formula for bumper crops, go long on ag stocks.

Then your standard figure should apply to warming that has already happened and food production didn't decline. Instrumental records show about a 0.6+ degree C higher temperature than the 1901-2000 mean of 13.9 degrees C. Here is a NOAA chart that shows about a 0.6 degree increase between 1980 and 2010, just like the years that had two and a half times more natural catastrophes:



Show me the 6% decline in total food production, between 1980 and 2010! Is there some reason why only future warming causes this food reduction and actual warming that has happened doesn't? Hearing something has nothing to do with believing it.

When someone posted a statement that a warmer Earth was a drier Earth, I didn't hear anyone believing the doomsday forecast correct that statement, which we all should know is wrong. Global land precipitation increased 2% during the 20th Century.

I think one of the things being overlooked in this discussion is that the temperatures being discussed are average temperatures. Reality is that the weather will become increasingly extreme. So the average temperature may only be increased by 2ºC for a given year, but all sorts of extreme weather events can occur -drought, flood, late-season cold snaps, heat waves, etc.

It may only take one extreme weather event per year to wipe out or greatly reduced crop yield in a given region. That, imv, is the real problem.

[mati]

In the U.S. there is one institution that has completely embraced the idea of AGW and this is the U.S. military. They have been working on military strategies to deal with the anticipated societal collapse caused by this warming. They have published reports arguing that global warming is the largest threat to security in the world. (These are easy to find if you'd like to read them.) They have enlisted some of our premier researchers to provide the knowledge to understand the regional effects that will occur (not an easy task and fraught with uncertainty) so they can prepare for them.

Of course, there is a possibility these military types are just alarmists.

Heres a DOD  report

http://www.fas.org/irp/agency/dod/dsb/climate.pdf

[ggelsrinc]

Ehhm. Forget something. Agriculture production has been increasing to feed a larger population. Therefore a 6% productivity loss would appear as a reduced increase. There are evidence that productivity of certain crops per acre has stagnated the last decade (e.g. rice in Japan)

Rice production per acre doesn't control worldwide food production or even rice production. Rice isn't grown everywhere it can be grown and is grown to meet market demand just like all other food.

I didn't make the statement that it's generally accepted total world food production will decrease 10% for every degree C the temperature increases. The statement doesn't say anything about increasing production to offset that loss, it categorically states there will be a loss.

[ggelsrinc]

"there isn't evidence that a warmer world has less agricultural production potential and there is plenty of contrary evidence"

There is, you just don't want to hear it, for some reason.

The standard figure is that for every degree centigrade of temperature increase, we will see about a 10% decrease in total food production.

Note that the last few decades have seen the introduction of the 'Green Revolution' that brought about higher yields through careful breeding of high yield seeds, but also massive inputs of NPK and ff-driven mechanization. The advances and advantages from these strategies have just about played themselves out.

We are now at the second highest price for food for this time of year in modern history, after 2011. Food stores are at historical lows. Maybe we'll luck out and dodge a bunch of climate bullets in the next few years. But the imminent collapse of the Arctic sea ice cap does not bode well for relatively stable climates prevailing in the Northern Hemisphere (where most land is and where most ag takes place.)

Way too much cold or heat, rain or drought, for way too long is what will likely become the norm in most of the major ag regions in the world. If that sounds like a good formula for bumper crops, go long on ag stocks.

Then your standard figure should apply to warming that has already happened and food production didn't decline. Instrumental records show about a 0.6+ degree C higher temperature than the 1901-2000 mean of 13.9 degrees C. Here is a NOAA chart that shows about a 0.6 degree increase between 1980 and 2010, just like the years that had two and a half times more natural catastrophes:



Show me the 6% decline in total food production, between 1980 and 2010! Is there some reason why only future warming causes this food reduction and actual warming that has happened doesn't? Hearing something has nothing to do with believing it.

When someone posted a statement that a warmer Earth was a drier Earth, I didn't hear anyone believing the doomsday forecast correct that statement, which we all should know is wrong. Global land precipitation increased 2% during the 20th Century.

I certainly would not argue with your point that a warmer world will be a wetter world. I do disagree with your suggestion (perhaps I've misread you) that this wetter world is somehow responsible for the increase in agricultural production. To chart this increase in food output and a similar increase in rainfall and conclude that the latter is responsible for the former is simplistic. To suggest an increase of production in the face of a warming world is evidence that a warming world will not have a negative impact on food production is simplistic as well.

I am not an expert in farming but it would seem the discussion on this thread has, in a meaningful way, proposed very real mechanisms to suggest global warming's near term impact on food production could be dramatic and not in a good way.

I do know this. Farmers don't farm with charts. They deal with a very real, local environment to produce food. Flooded fields in the spring delay planting. Very dry summers can prevent the healthy tassling of corn required to produce a good crop. Abnormally warm springs, followed by a hard frost, can destroy an entire seasons output of peaches and apples. Six feet of snow in the fields can wipe out large numbers of sheep.

I have read a lot of research about and agree with the argument that the melting of the arctic is causing an increase in weird weather. Weird weather will not benefit agriculture.

I used the chart to show an increase in temperature of 0.6 degrees C from 1980 to 2010 and I've also used a chart showing there were two and a half times more natural catastrophies in 2010 than 1980. Both charts show trends and not cherry picked data. wili made this statement:

The standard figure is that for every degree centigrade of temperature increase, we will see about a 10% decrease in total food production.

....and he was asked why past temperature increases didn't result in a reduction of total food production.

Now, let's recap! When the statement about a warmer Earth being a drier Earth was made by someone making their first post, I didn't bother to correct it. It isn't my point that warmer means wetter, it's science. I have posted maps of major staple production and cold stops the northern expansion of agriculture in the Northern Hemisphere. Cold also determines the start and stop of growing seasons, even in milder latitudes like where I live. Today in my area, you can put crops in sooner and harvest them later than you could in the past and that increases agricultural production.

Starting when I was 16, I worked in a cannery during the summer for three years that only canned corn for human consumption and it had about a 5 week canning season. If a week is added earlier and later in the growing season, that's a 40% increase in that cannery's production. If you want to can corn for a 5 or 7 week period each year, you don't plant all that corn at the same time and the same logic applies to all kinds of food. In the case of the cannery, it's only so big and can only can corn at a certain rate. If someone is making fresh produce, the market to buy it is only so big. Anything produced beyond what the market will buy isn't food, it's waste. Increasing the growing season increases the time a product can be canned or sold as fresh produce and it increases overall food production.

Weird weather has never helped agriculture since it's invention and it isn't anything new. In the case of reducing worldwide food production, the weird weather has to be severe enough to destroy the crops, reducing overall production and that hasn't happened. It doesn't happen because the concept applies simplicity to the dynamic process of agricultural production. It's void of any understanding of the economics of food production, like being able to sell the food is required for it to be food. Wheat production declined last year because the price of wheat is low, so they switched to corn. World corn production increased, regardless of loses during the US drought. Overall, food prices have increased enough to stimulate added production, like in Brazil and Brazil is on the path of becoming a major producer of agriculture, if you don't think it already is. Other factors like longer growing seasons and crops being able to grow in areas formerly too cold aren't considered in the doomsday accounting that considers the Earth at production capacity and only factors in crop loss due to severe weather. That isn't a realistic model of worldwide food production and that's why the model can't be applied to past warming. Some food that is destroyed before harvest gets replaced by what would never become food without that market opening up. Just producing something doesn't mean it will ever be used whether it's food or something else that can't be marketed.

[ggelsrinc]

The Green Sahara is a product of changes of the 23,000 year North Africa monsoon cycle, but the experts claim there is some other trigger than insolation changes for both the onset and end, because it happens to quickly. I'd say some change in ocean circulation is the most likely trigger. The prevailing winds in the center of the Sahara switch direction.

There are very good reasons why food production didn't flourish throughout the entire continent of Africa (like switching from summer to winter crops as you go north to south and livestock infected by tsetse), which is a topic besides the point that world food production managed to increase significantly during the 30 years when weather related natural catastrophies were two and a half times more likely in 2010 than in 1980 and that comes from a trend and not anecdotal cherry picked data. This increase in exceptional weather events isn't something just happening, it's been happening and the insurance companies have been charging for climate change since 1973.

I think the collective mindset of societal collapse because of climate change follows this path. The data that climate change exists and is anthropogenic is overwhelming and should be convincing to reasonable people. I think the collective mindset sees mankind as the villain and looks for a way for the Earth to counterattack the villain as if the Earth is a sentient life form. I think it's motivated by frustration that things aren't being down to stop AGW. We've all been told about overpopulation since we were born, but at least the older people have the experience of living a lifetime of claimed food production disasters that never happened. The claims predate any concerns about global warming. The odds that someone will spend their entire lifetime without food related societal collapse, just like I have, are much more likely than these doomsday forecasts.

In 2011, 66 million people starved worldwide. U.N. studies show an additional 975 million are "chronically malnourished", another way of saying they are starving to death. With a population of nearly 7 billion, the odds that you are starving is actually 1 in 7. Bully for you if you live in a country where this is not happening. Tell the Sudanese or Somalians (Choose your own if these two examples don't suit you.) they are mistaken to conclude they are dealing with food related societal collapse.

In the U.S. there is one institution that has completely embraced the idea of AGW and this is the U.S. military. They have been working on military strategies to deal with the anticipated societal collapse caused by this warming. They have published reports arguing that global warming is the largest threat to security in the world. (These are easy to find if you'd like to read them.) They have enlisted some of our premier researchers to provide the knowledge to understand the regional effects that will occur (not an easy task and fraught with uncertainty) so they can prepare for them.

Of course, there is a possibility these military types are just alarmists.

The government will study just about anything and that doesn't increase the chance of it happening. Our government built the largest naval base in the world on land subsiding because of an ancient asteroid impact, so sea level rise is a very important topic to them. There are many strategic reasons why the military has been interested in the arctic and climate change. The best information of worldwide production of anything comes from the CIA.

Don't you think the Sudan and Somalia would produce more food if they weren't envolved in decades of war and lawlessness? Starvation and war have been going hand in hand since their beginning. The starvation in the world is not a product of too little food production and it doesn't mean food production is near it's capacity. The process for international cooperation involves economics and politics. The world wasn't feeding itself when there were 6 billion, 1 billion or populations before the industrial age added CO2. History doesn't paint a rosy picture of food production feeding the whole world. If the present was evaluated with the past, is there evidence of things being worse now?

[Bruce Steele]

Ggelsrinc, I worry that you are correct and we really haven't reached food production limits yet. I used to think fossil fuel limits would slow things down more than has happened yet. The world seems to spin along with 4.00 dollar fuel. Much higher in some places. Food costs aren't breaking the bank and there is enough capital around to invest in a few thousand more coal powered electrical generating power plants. World population levels are still increasing for cattle and humans. So long as the solution is more fossil fuels to grow a bigger infrastructure build bigger tractors we still have an issue. Maybe you are right and for the next decade as the arctic hits summer melt for a week or a month things still don't go to much off kilter. We increase emissions to 35 gigatonnes per annum and then we start into the 2030's . No problems yet . But this is where you gotta start to wonder. Maybe two months of an ice free arctic really starts to have bigger consequences than we can know right now. Something we just haven't even imagined yet because we don't have a good analogy for what happens to the climate when you stuff 500+ billion tons of carbon into the atmosphere in 200 years. So there is the rub, you can't use former interglacials, historical records, or even fossil records to project where this ends up because we haven't stopped our emissions trajectory. We still have full throttle.We burn fuel to keep the wheels from coming off but we have exceeded all rates of carbon emission the world has produced before. Even if the world continues to feed itself, power it's infrastructure and increase it's human population we haven't addressed the cause of the arctic melt(Co2) the cause of a 30% change in ocean pH, or the ocean heating. We don't know exactly where this goes but an " all of the above energy policy" or don't worry we can feed ourselves,  or any other steady as she goes kind of mindset is simply Russian roulette.   

[ccgwebmaster]

In short, regardless of whether one thinks it takes year or decades - it's hard to rationally see how the current trends and situation culminate in anything other than an apocalyptic crunch?

We can make all the theories we like about agricultural output - nothing alters the basic fact that an increasing number of people in many nations are struggling to afford food right now, and that condition tends to escalate conflict risk at all levels.

So there are plenty of people in more affluent nations happy to trust in the markets, happy to tell me how much agricultural output will grow, how wealth will insulate us from the bulk of the suffering while the poor nations bear the brunt? If you're right, great - the economy will pick up, food prices will come down - and I can stop dwelling on the idea of bullets as a good investment in food security. If you're wrong, well - it's probably going to be brutally irrelevant by the time that becomes unambiguously clear.

Maybe the smart money is making the counter argument (in public at least) after all, taking that viewpoint...

[ggelsrinc]

Ggelsrinc, I worry that you are correct and we really haven't reached food production limits yet. I used to think fossil fuel limits would slow things down more than has happened yet. The world seems to spin along with 4.00 dollar fuel. Much higher in some places. Food costs aren't breaking the bank and there is enough capital around to invest in a few thousand more coal powered electrical generating power plants. World population levels are still increasing for cattle and humans. So long as the solution is more fossil fuels to grow a bigger infrastructure build bigger tractors we still have an issue. Maybe you are right and for the next decade as the arctic hits summer melt for a week or a month things still don't go to much off kilter. We increase emissions to 35 gigatonnes per annum and then we start into the 2030's . No problems yet . But this is where you gotta start to wonder. Maybe two months of an ice free arctic really starts to have bigger consequences than we can know right now. Something we just haven't even imagined yet because we don't have a good analogy for what happens to the climate when you stuff 500+ billion tons of carbon into the atmosphere in 200 years. So there is the rub, you can't use former interglacials, historical records, or even fossil records to project where this ends up because we haven't stopped our emissions trajectory. We still have full throttle.We burn fuel to keep the wheels from coming off but we have exceeded all rates of carbon emission the world has produced before. Even if the world continues to feed itself, power it's infrastructure and increase it's human population we haven't addressed the cause of the arctic melt(Co2) the cause of a 30% change in ocean pH, or the ocean heating. We don't know exactly where this goes but an " all of the above energy policy" or don't worry we can feed ourselves,  or any other steady as she goes kind of mindset is simply Russian roulette.   

Scientists use former warm periods to predict the outcome of a warming Earth and the Earth is responding to recent warming in a predictable manner based on how it did so in the more distant past. It should be obvious that warming will melt that arctic sea ice and melt GIS, WAIS and alpine glaciers, just like it did last time. It will melt the permafrost and change the tundra, allowing taiga to move northwards. Science says that will be the results and observations confirm that is the case. The science says prior to AGW the Earth was cooling and it's agricultural potential was declining. The science says cooling decreases agricultural potential and not warming.



Source: http://en.wikipedia.org/wiki/Climate_change

That map comes from a wiki article on climate change and the article spends plenty of time discussing paleoclimatology, just like I have. Antarctica gets ignored in the map, but when you add ice sheets it becomes obvious that a glaciated Earth was not a very productive Earth. The map shows closed forest defined as 70% canopy and extreme desert defined as less than 2% vegetation. The largest obvious change between the early Holocene and today is the North Africa and Asian deserts, but if you look closely you will see changes in the extent of closed forest. Closed forest that isn't boreal is considered prime agricultural area. In the early Holocene those areas had trees, but in the present day map there are plenty of areas designated to be forests that have been cleared for agriculture. China and Southeast Asia aren't growing their rice in a forest. That forested area in Manchuria is where China grows it's wheat and corn. In short, the map of the present Earth is more about the potential to have a closed forest than truly having them.

Only our present economy requires using fossil fuels for agriculture or any other use and other fuels can be used. I don't anticipate running out of fossil fuels, but I do expect the world to eventually give them up. Agriculture will get more involved with biomass/biochar and become a net energy producer, while removing atmospheric CO2 and producing more productive land. Sea level rise and ocean acidification are very real concerns about climate change, but they just don't motivate people and governments to act. It's possible GIS could start getting public attention, when they consider the eventual cost of replacing all those cities and infrastructure, but my guess is it will be the exception weather personally affecting people's lives that will be the wakeup call. Nations trying to industrialize using coal are going to have the same problems all have had.

[ggelsrinc]

In short, regardless of whether one thinks it takes year or decades - it's hard to rationally see how the current trends and situation culminate in anything other than an apocalyptic crunch?

We can make all the theories we like about agricultural output - nothing alters the basic fact that an increasing number of people in many nations are struggling to afford food right now, and that condition tends to escalate conflict risk at all levels.

So there are plenty of people in more affluent nations happy to trust in the markets, happy to tell me how much agricultural output will grow, how wealth will insulate us from the bulk of the suffering while the poor nations bear the brunt? If you're right, great - the economy will pick up, food prices will come down - and I can stop dwelling on the idea of bullets as a good investment in food security. If you're wrong, well - it's probably going to be brutally irrelevant by the time that becomes unambiguously clear.

Maybe the smart money is making the counter argument (in public at least) after all, taking that viewpoint...

Show me the trend you are talking about!

According to estimates by the FAO there were 925 million under- or malnourished people in the world in 2010.[9] This was a decrease from an estimate of 1023 million malnourished people in 2009.[10] In 2007, 923 million people were reported as being undernourished, an increase of 80 million since 1990-92.[11] It has also been recorded that the world already produces enough food to support the world's population.
 
As the definitions of starving and malnourished people are different, the number of starving people is different from that of malnourished. Generally, far fewer people are starving, than are malnourished. The numbers here may provide some indication, but should not be quoted as a number of starving people.
 
The share of malnourished and of starving people in the world has been more or less continually decreasing for at least several centuries.[12] This is due to an increasing supply of food and to overall gains in economic efficiency. In 40 years, the share of malnourished people in the developing world has been more than halved. The share of starving people has decreased even faster.

Source: http://en.wikipedia.org/wiki/Starvation#Starvation_statistics

The farmers producing food in those affluent countries get 20% of the cost of the food. No one has made money until everything is done to sell that food on the market, so there are plenty of money concerns banking on that outcome. Markets are required even with subsistence farming, because yields can't be accurately predicted to produce the exact amount that would be personally needed. It's smart to produce more, insuring you can meet your needs, and sell the excess, instead of allowing it to go to waste. On an individual basis, farming has never been a guarantee of food production. 

[fishmahboi]

With the recent churning of the Arctic Ice hinting at the possibility of a melt out this summer, I have a feeling the consequences could be quite dire for food production and society itself.

[wili]

Thanks for bringing this important issue up here, fmb.

As Neven noted on the blog, snow cover has a bigger effect on mid-latitiude weather during spring and (early?) summer than does sea ice extent. There are large areas of negative snow-cover anomaly, especially over northern Siberia.

I do think that if we see a really big loss over the next few weeks due to this event, it may have an effect on weather further south before the end of the Summer.

In light of the current cyclone, many commenters over at the blog seem to be revising downward their estimates for sea ice coverage minimum in September, what do people think the specific consequences would be in the next 12 months if we approach or fall below the 1 million sq k extent mark?

[ccgwebmaster]

In light of the current cyclone, many commenters over at the blog seem to be revising downward their estimates for sea ice coverage minimum in September, what do people think the specific consequences would be in the next 12 months if we approach or fall below the 1 million sq k extent mark?

I would think we would just get increasingly extreme weather with related damage to infrastructure and agricultural output, increasing pressure on food prices and related conflict/social instability? (if you're asking next 12 months)

My perception (open to corrections) is that what happens in a melt season effectively has more effect on the next year than the current one agriculturally speaking as by the time the sea ice approaches minimum many crops have already gone through their complete lifecycle and been harvested. In that sense we're seeing the effects from the 2012 melt currently as much as anything else.

If that were so - whatever happens this year won't truly start to bite until next year. If I were purely guessing - a majority/total loss of ice this year could substantially escalate extreme weather next year.

One thing I'd like to know is - can we assume that the jet stream circulation patterns themselves will persist in something resembling their current guise? Clearly they are changing - with significant effects on the weather we experience - but looking a little further into the future:

- will they just keep changing as now, further intensification of the new behaviour?
- or will they disappear totally to be replaced with some new atmospheric circulation pattern?

[Shared Humanity]

Current wind map for the U.S. 

http://hint.fm/wind/

Tornadoes are firing up all across Oklahoma, Kansas and Missouri. You can see the stationary low over western Minnesota. It has been sitting there for almost 3 days and is pulling all of the Gulf moisture in that is feeding the storms.

[OldLeatherneck]

.....................One thing I'd like to know is - can we assume that the jet stream circulation patterns themselves will persist in something resembling their current guise? Clearly they are changing - with significant effects on the weather we experience - but looking a little further into the future:

- will they just keep changing as now, further intensification of the new behaviour?
- or will they disappear totally to be replaced with some new atmospheric circulation pattern?

Last week, Neven posted a lengthy article, on the ASIB, by John Mason, "A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming".

http://neven1.typepad.com/blog/2013/05/everything-you-want-to-know-about-the-jet-stream.html

I haven't has the time to read and digest it in it's entirety, however, I think this article will provide a starting point to better understanding of the relationship between declining artic sea ice and the jet stream, which in turn drives all weather-related events in the Northern Hemisphere.

[ccgwebmaster]

I haven't has the time to read and digest it in it's entirety, however, I think this article will provide a starting point to better understanding of the relationship between declining artic sea ice and the jet stream, which in turn drives all weather-related events in the Northern Hemisphere.

Finally took a bit of a look at it (not inundated with time myself), but it doesn't seem to draw any conclusions beyond "more of the same" (ie a trend towards worsening extreme weather due to ongoing changes of the type we are seeing so far).

I suspect nobody really knows - it's a lottery.

What I am wondering is - there is some evidence so far that the distribution of the major atmospheric cells is changing (when we say the jet stream is moving on average further north or the intertropical convergence zone for that matter). That much seems likely to continue short term.

But is there any reason to suppose the earth system will always operate with this number of atmospheric circulation cells?

http://minerva.union.edu/failinge/earths_convection_cells.html

Is there any reason not to suppose at least some probability of the number of cells changing - eg to become less (if that is the result implied by a shallower thermal gradient, I don't really know enough to speculate).

One presumes a rather dramatic change, even compared to the intensification of extreme weather occurring so far. I'm curious if there is any suggestion it might happen - or if anyone knows (beyond doubt) that the earth system has throughout at least the last 250 million years had the existing 3 cells per hemisphere?

[John Batteen]

I've often pondered this myself ccg.  I don't think we'll find out until it happens.

[ClimateChange]

ggelsrinc

These claims about famine associated with a warmer Earth are nonsense. Overall the world will become more productive in agriculture with it warming, but people don't live in the whole world, so even if it's totally better, there will be some big time losers in certain locations.

I've looked at maps for food production and the common theme is it's too cold north to make more food than we presently do. I can post the maps for you, but they are easy to get in wiki just by researching the staples. I've looked at corn, rice, wheat, millet, soybean and potato and they have world production maps showing the area producing the products. It's only logical and common sense that northern areas are more cold stressed to reduce yields than southern areas have been warmed and since trees existed next to the Arctic Ocean in the past, there is plenty of room to expand agricultural production northward. The logic behind this massive famine caused by global warming rests on the assumption that mankind is at it's food production limit and that is a bogus claim. The majority of food production is done to accommodate established markets, because a farmer will go broke mindlessly producing without a means to sell their product. It doesn't take much land to produce more food than people want, so try it sometime and see if you can even give away the food! It's not that hard to produce food and I don't see people giving up mowing their lawns to create food.

I am a little unsure how to respond to the above.  In one respect you are seeming to support my contention that the collapse of industrial agriculture is quite a ways in the future still.  However, almost all of the reasons above you give to support your position are incorrect based upon my knowledge of agriculture and climate science.

To wit:  You are confusing Thermal Maximum conditions in the high latitudes with what the conditions are going to be like in 30-40 years.  you cannot do this.  In the northern hemisphere the fertility of the soils as one moves north towards the poles becomes less favorable to  agriculture production.  Growing seasons are shorter.  The weather conditions, while generally warmer, are going to remain volatile and there will still be frequent cold snaps and frosts/freezes.  Soils will not warm as quickly in the spring as they do farther south and this will retard planting and seed germination.  Fall frost will still be earlier.  Available sunlight is always going to be less optimal than further south. Your argument that a warmer world is wetter is correct, but the real issue is that rainfall patterns are quickly changing and what we should expect are longer and hotter dry spells,  more intense rainfall and less even rains.  Lastly, as someone else mentioned we can expect significant pest and plant disease problems as time goes on.  Agriculture is not going to be more productive going forward in any significant amount (unless we have big breakthroughs in GMO crops, and chemistry - not my favorite idea by the way) and there are very good arguments out there that ag productivity has already plateaued and what we should expect to happen in the next 20 years or so is the setting in of a  long decline in productivity.

We can and will push the industrial ag system hard from here on in until we can't any longer.  As you say, and as I have shown with the numbers above, there is slack in the system and if we improve in the areas possible and eliminate policies which burn food in vehicles we can handle significant declines in yields.  For a limited period of time. Just when that time is is, of course, the question.    I have seen no reasoning that supports a timeframe beyond about 2050 for major shortfalls in food production.

I'm not confusing Thermal Maximum conditions in high latitudes with our present Earth, because causing warming sets the motion for the Earth to go to another thermal maximum, but such changes take time. The facts point to major changes in climate patterns during our Holocene interglacial as evidence with changes in the Sahara. The Sahara is big enough to affect climate, whether it's a desert or not. Since we know for a fact that the Sahara was green and the monsoon patterns were changed, it doesn't surprise me that major climate pattern changes are necessary for that to occur. It doesn't surprise me that there will be more precipitation as the world warms, but it must surprise people using computer models to claim worldwide drought in 2060.

What the Thermal Maximums should tell a scientist is here is a real life Earth showing the consequences of warming. Our 400 ppm CO2 Earth is not going to behave like the 400 ppm CO2 Pliocene Earth that had different thermohaline circulation, it's going to behave like it did during the Holocene Thermal Maximum and the Eemian. Every area of the Earth doesn't have a fossil record of the HTM and Eemian, but there is usually a record not that far away to give details about that past climate for that area which is the best guess of what the future climate will be. It only makes sense that future warming will imitate past warming, so what present warming trend runs contrary to thermal maximum data?

Here is an interesting thing I came across and used against Denialistas who tend to talk about the expense of making changes for global warming. The first part of the video is interesting too, but around 8:30 a gentlemen giving a representation as a reinsurer (insurers that insure insurance companies) makes a point that they were assessing risk from climate change since 1973. I found the chart he used to show that a person in 2010 was around 2.5 times more likely to be a victim of a natural catastrophy than a person 30 years earlier in 1980 and the increase is climate related. Reinsurers aren't in business to lose money so any risk they believe they are taking is reflected in their rates and rates the insurance companies they insure charge consumers. That means someone having insurance since 1973 has been paying for global warming, whether they know it or not and that date is fascinating because there wasn't much concern about climate change in academic cycles at that time. There should be some good data on crop loses that adjust for price and look at incidents. Someone in crop insurance should have data that can properly assess risks.





Here are some maps for world food production.













It isn't poor soil preventing food production in the north, it's a shortened growing season caused by the cold. Notice the difference in corn and wheat production in the Great Plains and compare it to Manchuria! As the Earth warms the growing season in the north becomes longer and that allows food production to expand in the north. Notice also that food production tends to follow population trends. The fact that there are the Great Plains and places like it on Earth indicates grasses are preferred over trees in those locations, so it's only natural that wheat would grow well there. Notice also that the areas for producing wheat and potatos are very similar in Eurasia!

I remember seeing a short documentary as a child at the movies showing hugh vegetables being grown in Alaska and that was long before global warming concerns. The food looked like it was made for giants, things like carrots longer than your arm. That was a case of someone knowing what they were doing. In Chemistry we call it cooking when we follow the process to get the desired results and sometimes the whole process can be very complicated. The same kind of discipline is required in the kitchen, garden or lab. If you do it right, you will get the desired results. The failures in commercial agriculture involve being subject to variables, like rain. That's why irrigated marginal land that is well drained can become very productive because it removes the important variable of water from being a concern. It isn't that hard to test and add nutrients and the cost of adding the nutrients can be reduced by maintaining proper humus levels. Without some buried organics to bind the nutrients, they will drain away from the soil adding expense to replace them. That said, what percentage of the world's crops are grown with conditions to optimize yield? When farmers get 20 cents of the dollar spent on food, someone is looking out for their interests in that remaining 80 cents and the commodity has to already exist at that point.

The whole story on the corn/ethanol deal also involves our government purchasing corn to maintain prices and paying to store it as it rotted away. I recall visiting a farm of a friend back then who raised Appaloosa horses and his father and he were in the corn business, growing some on their property and using their corn equipment on additional fields to justify it's cost, which wasn't cheap. Even with a full time well paying job off the farm, the corn business then was very risky and farmers were struggling. If that equipment broke down in the field, some machinist skills were usually required to get it operational.

Another part of the ethanol story involves it replacing the carcinogen MTBE, which replaced the neurotoxin tetraethyl lead. Methanol would also work and ethanol can be made with crops like sugar beets or cane, so less corn is required. Corn is only food if something gets to eat it and paying for storage so it can rot away with starving people in the world doesn't make good sense.

The problem with this is we're going to be going WAY past 400 ppm. That's just where we are now. The current oil, gas, coal system in place almost guarantees 450-500 ppm. And likely higher unless drastic action is taken now. I think we're already near record-breaking Holocene levels and we're not seeing a Green Sahara now, so this suggests there may be other factors at play -- or else the natural processes simply cannot keep pace with the rate at which we're causing warming (perhaps because there's still ice caps, in the absence of human intervention like we've seen here where the 400 ppm was reached in such a sudden spike, a 400 ppm earth would have much reduced ice cap coverage and presumably this influx of additional water may help to supercharge the water cycle I'd imagine). In any case, I've wondered about that whole Panama isthmus thing too. I think an interesting thought is whether the closing of the Isthmus would always result in cooling, or if only led to cooling in the standard, low-CO2 atmosphere. I could see in a future globally-wamed hothouse, high-CO2 atmosphere, the closure of the Isthmus actually promoting additional warming. Without the venting to the much larger Pacific basin, the hothouse climate may superheat the relatively small and shallow (and largely tropical) Caribbean and Gulf to astronomical levels, and this heat would in turn be circulated throughout the Atlantic basin leading to a superheated ocean, causing enhanced warming for much of North America and Eurasia. There's really no good analog to what we're going to be experienced.

Also, I agree that a warmer world will be a wetter world and not a drier world. And for a while I was confused as to the projections of increased drought (see Aiguo Dao's research). But the Palmer Drought Index (the standard drought index) is highly sensitive to temperature -- hot temperatures lead to increased evaporation and plant stress thereby promoting drought, even in the absence of subnormal rainfall. The PDI models suggest large parts of the world will dip to -10 in a high-CO2, globally-warmed atmosphere (much of Europe and the Mediterranean, much of North America (except for Alaska, central and northern Canada). This suggests drought may be a permanent feature even in a somewhat wetter world, or it suggests the PDSI is not a useful tool for analyzing drought in a warming world. I'm thinking it may be the latter. Last year, for instance, which was by far the hottest on record in the U.S. featured a major drought. Nonetheless, it was by no means a drought of unprecedented ferocity (the 30s, 50s, maybe 88 probably saw more severe droughts). However, the PDSI repeatedly showed week after week that last year's drought was unprecedented (meaning the country as a whole achieved record low PDSI readings even below those of the worst years of the Dust Bowl). This was due to the temperature sensitivity of the PDSI and the fact that last year was so ridiculously hot in the U.S. that it overwhelmed the index and caused the index to malfunction in a sense. I believe this is what Dao's papers are really picking up on, so I don't think it will be as bad as one might believe from a cursory glance at his work. It still will be very bad for the U.S. Great Plains which look to turn much hotter (and also drier) probably leading to a semi-arid steppe climate largely unsuitable for widespread agriculture except for irrigated lands. It's kind of ironic that the U.S. stands to lose a lot from global warming (at least agriculturally) especially compared to Russia and Canada, and yet that's where the heaviest concentration of deniers are found. If only these people realized...

[ccgwebmaster]

One of the themes to persistently arise in this thread is the idea of surplus capacity in food production. A theme I've regularly encountered (here to some extent, but especially in other places) is the idea that the US feeds the world. I thought this chart rather illuminating in showing where calories are produced (as well as putting US production into context).


(found on http://stockmarketnotes.blogspot.com/2011/04/which-country-is-worlds-largest-food.html)

The takeaway lessons I find in this are:

• The US is significant, but there are multiple critical regions, some larger than the US, that provide the majority of global calories between them. What happens in those other regions is critically important globally, and both the media (at least in western nations) and most discussion forums largely appear to ignore these other regions, or at least discuss them far less than their significance arguably merits
• As some of those producing areas enjoy very favourable farmland resource per capita compared to others, there might be something to the argument that deploying more labour in western nations could boost production under recent historical conditions* if the necessary social shift could be accomplished and viable crop types permitted

* I'm not sure I include present conditions, as extreme weather appears to be rising in incidence, and I'm not sure if deploying more labour into agriculture could still boost calorie production in present and near future conditions (it ought to also be noted that some crops are more labour intensive than others, so it also depends which crops are suitable in a given region)

[Lynn Shwadchuck]

I'm completely blown away by how much time and typing has gone into the seven pages of posts on this unanswerable question, and how it has an especially high number of views. Clearly this is the question that is on our minds.

I've been gardening like mad for four years and am finding that the unpredictability of the weather makes it really hard. A few years ago this part of Canada was predicted to have it easy as the planet warmed. But this floppy jet stream has all sorts of pockets of bad weather getting stuck long enough to harm crops. We had a terribly dry season last summer and this year spring has been too cool for germination in some plants.

My point is the only thing we can predict is unpredictability. And that's exactly why the powers at the top can keep refusing to change direction.

[Neven]

I've been gardening like mad for four years and am finding that the unpredictability of the weather makes it really hard.

I'm planning to start gardening next year, and this is something I'm particularly worried about. We're going to build a greenhouse that's about 25-30 square feet big just to have some degree of control over growing conditions. But maybe we should plan something bigger...

[Lynn Shwadchuck]

Neven, I know. I'm realizing why quite a few people around here have made little hoop houses. But that's mostly for things like salad greens, which I haven't bothered with for years since it has to be shipped from afar most of the year.

Honestly, what's really helpful in working on resilience in the face of a more or less dire future is to build up a local food system rather than devote ourselves to the illusion of independence, of self-sufficiency. Supporting our farmers' market is more important to me than succeeding in growing a winter's worth of carrots. And I'm prepared to exist on food that most western consumers would consider grindingly boring. Think of the Irish who lived on potatoes an a little cabbage and a tiny bit of milk. Deep-rooted permaculture crops like trees and shrubs that produce fruit and nuts have a better chance of surviving weather ups and downs than eggplants and peas. If a time comes when we're lucky to have a couple of 25 pound sacks of dry beans under the bed, fruits and nuts on our own land will be a boon.

So, to tie this in with the topic at hand, the soil and aquifer depletion caused by the huge monoculture farms of the bread baskets of the world adds to the threat of seasonal weather disappointment. I expect that the just-in-time network of shipping fresh foods to chain stores could fail and we should be prepared to adapt over time. Canada's E-coli meat fiasco has revealed a weakness that's endemic in the global market in fresh meat. As someone above said, it's a waste of land and other inputs to be feeding animals to build protein.

The effects of global warming are complex. Who knows how many rural people in developing countries have given up fighting the increasingly tough farming battle and trekked to urban centres where they're willing to work for a dormitory bed and not much more. This takes jobs from westerners who then expect cheap corn-based food at Wal-Mart, which can only be grown with the subsidies of a corrupt government and serious misuse of land.

[ccgwebmaster]

I've been gardening like mad for four years and am finding that the unpredictability of the weather makes it really hard.

I'm planning to start gardening next year, and this is something I'm particularly worried about. We're going to build a greenhouse that's about 25-30 square feet big just to have some degree of control over growing conditions. But maybe we should plan something bigger...

Perhaps something more on this sort of line:
http://en.wikipedia.org/wiki/Domed_city
http://www.thearcticinstitute.org/2011/10/5654-umka-domed-city-in-russian-arctic.html

[Neven]

That's a bit too big, ccgwebmaster.   

[ggelsrinc]

ClimateChange-

I find the Sahara significant because it proves minor changes in global temperature can produce major changes in the climate over large areas, even during a relatively stable temperature interglacial times. The changes in the North Africa monsoon require changes in ocean and air currents. Eastern equatorial Atlantic upwelling declines enough to warm the ocean while changes in the easterly trade winds bring wetter times to the Sahara.

The cooling of the Atlantic Ocean after the remnant of the circum-equatorial current was cut off by North and South America connecting is well documented. Our last 400 ppm CO2 Earth was cooling and getting drier because CO2 levels were declining as the Himalayas weathered.

A Hothouse Earth is a 22 degree C Earth. 400 ppm CO2 during the Pliocene didn't produce a Hothouse Earth even with the old thermohaline circulation and warmer oceans. The Pliocene Earth had similar conditions to make it prone to glaciation, such as a large continent or landlocked ocean at the poles, but wasn't as sensitive to changes in insolation like our present world. The warmer oceans buffered the global temperature changes caused by Milankovitch Cycles. These large temperature variations in Ice Age Cycles are a recent product of Earth's cooling.

The other major events around that time was Africa colliding with Europe and reduction in forests with expanding grasslands, savannahs and deserts. Grasslands at high latitudes have an albedo like a tundra in the winter cold when snow covered, so the world's albedo changed to colder.

Your analysis of PDI is reasonable. I don't dismiss extreme weather producing drought, but I don't expect drought to be as widespread in 2060 as they claim. We've been living with the catastropes of extreme weather for awhile. I think the evidence shows temperature increases can trigger major shifts in climate patterns. If a climate shift for a region turns out to be really nasty, there is no way to change it back.

[wili]

"temperature increases can trigger major shifts in climate patterns. If a climate shift for a region turns out to be really nasty, there is no way to change it back."

You got that part right!

Some more points to consider:

[ggelsrinc]

We have methane analysis from ice cores during interglacial thermal maximums, including the Eemian which was much warmer than the Holocene. There is evidence of methane increases, but not evidence of massive methane releases. Of course, there is evidence of methane being released as the arctic warms and there is evidence of methane being released since mankind was smart enough to notice it.

Dr. Peter Wadhams' initial statement about this not happening before needs to be put in the light that mankind didn't cause the arctic to warm before. Mankind is melting the arctic sea ice, but that doesn't mean it hasn't melted before. If the Earth didn't release large amounts of methane before, like during the Eemian, why would it do so now? Considering we aren't that many years away from the Holocene Thermal Maximum, which was less warm than the previous thermal maximum (Eemian), why do these scientists believe this to be a great danger? What organic source was available for the arctic to produce additional methane that hasn't been venting during warm arctic periods? Some tundra area isn't going to be bubbling methane because it was forested thousands of years ago. An area that became warm enough and had conditions to grow peat is the type of area that sequestered carbon that could become a large methane source. An ocean area that allowed phytoplankton to bloom would also qualify, if the right conditions for decomposition were met. The arctic has only had a small window in recent geological time to be productive enough to produce a new organic source to make methane. When I examine the increases in atmospheric methane since historical times, I see most of the increase directly coming from mankind and not the Earth.

The "When and how bad" of it right now is the severe consequences of global warming are too distant in the future for them to be taken seriously by too many of the world's people. Hansen talks of tipping points, so melting ice means the ice will eventually be melted. I prefer thinking of it as a trigger to events causing climates to shift and the evidence of past warming show the shifts. Warming the Earth would have to trigger changes in ocean and air currents thus altering a regions climate for better in some cases and worse for others. Heat that isn't melting ice can find plenty of other purposes, so increasing ocean and air temperatures would fit the arctic. Areas around glaciers and permafrost areas will have their own individual stories. Losing all those cities and land areas to sea level rise will be a hugh burden for future generations.

[wili]

We've had an unusually long interglacial period that has allowed (relative) warmth to penetrate deep into these deposits. Much of it is now may be on a hair trigger--right on the verge of release. But it may be that these science, some of whom have studies this area of the Arctic about as long as anyone has, are all wrong. There is certainly a range of opinion among Arctic specialists about how quickly these deposits would take to be released into the atmosphere. But do we always want to bet that it is always the most optimistic estimates that are right? Do you do that in other areas of life?

Another point about ice cores is that methane, since it is such a small molecule (relative to CO2, for example), can more easily migrate away from the part of the ice where it was originally captured iirc. So it is harder to detect large methane spikes in that record than in others. Not surprisingly, we do not have perfect knowledge of what went on in the past. Some (not saying anyone does here) would choose to see such sorts of uncertainty to mean that probably nothing shocking or sudden or catastrophic ever happened in the past, and furthermore, that that means nothing catastrophic can happen now or in the future. Others of us find uncertainty to be more...anxiety producing. Each to his own, I guess.

[ccgwebmaster]

Another point about ice cores is that methane, since it is such a small molecule (relative to CO2, for example), can more easily migrate away from the part of the ice where it was originally captured iirc. So it is harder to detect large methane spikes in that record than in others. Not surprisingly, we do not have perfect knowledge of what went on in the past. Some (not saying anyone does here) would choose to see such sorts of uncertainty to mean that probably nothing shocking or sudden or catastrophic ever happened in the past, and furthermore, that that means nothing catastrophic can happen now or in the future. Others of us find uncertainty to be more...anxiety producing. Each to his own, I guess.

I don't understand how anyone can find the uncertainty reassuring when it widens the range of possibilities, and where we have no idea what the probability distribution looks like for those possibilities.

We know methane plays a key role in climate change due to the link with temperature (along with carbon dioxide).

We also know we are changing the system at a rate virtually without precedent where the nearest analogs are major mass extinctions far removed from the normal glacial cycles. There are gigatonnes of methane (free gas!) eligible for rapid release over decadal timescales (Shakhova) and the 20 year GWP is 105x (Shindell).

Where on earth can there be room for complacency without it being delusion? The simplest facts speak for themselves.

[wili]

Well put, ccg.

Especially important for our discussions here is what Wadhams says from about 14:15 to about 15:40:

The net result of a warming tundra is not an increase in potential agricultural productive capacity; just the opposite. As we have already seen, GW does not mean steady, even warming, but rather disruptions of climactic systems such that you have greater and greater extremes that persist for longer and longer periods: biblical flooding, parching droughts that last for years, intense cold snaps, and super heatwaves.

None of these are conducive to agriculture.

Also worth reading very carefully if you missed it when it was posted over at the blog are these observation from someone who has done extensive work in this area:

In another lifetime, as my first adult scientist experience, I studied arctic ecology at/near Barrow, AK in the early 70's. A primary interest was the distribution of plant types by microclimates and ecotones/ecoclines... There's a whole nother language.

The simple summary: It's complicated.

The high arctic is?was a desert, with less than 8 inches of precip per year, on very flat plains, where a meter high ridge line can be seen three to four miles away. Whole plant communities are determined by height above the permafrost/water table level. That interface is not only the primary source of liquid water, but also the place where nutrients are found. Nobody grows in the winter, which is/was 9 months/yr. We took aerial photos of the plants in full summer, and could map out the microelevation changes by colors of the plant communities.

At that point in time, the local ecology was still relatively stable, kind of the end stage of 'the old days', I'm guessing.

Major limiting factors include water, nutrients, and winter cold. Shrubs look more like trees where they are protected by being buried under the snow in winter (a drainage cut along a river bank) - being above the snow exposes to brutal winds and the occasional browsing caribou herd.

Northern forests are limited in extent at the edges by the arctic winds, and have to expand from center out, creating a critical mass wind buffer as they go (almost entirely by underground tillering from older plants - not much useful plant sex in the far north).

In the winter, everything is white with frost or snow, and there's no sun anyway. The albedo effects are limited to the summer growing season, which is pretty short, though one impact here is any extension on that season length. The albedo impacts permafrost depth, which is a huge issue, since there lies all those nutrients, water, and that sequestered carbon.

In summer, the ground above the permafrost is saturated with water, and is mostly peat of some form (all that carbon), with variable density. You can't drive vehicles over most of this without destroying the surface, leaving linear tracks of black water that become rivers over time as the albedo melts the sidewalls...

Muskeg is the swampy forestland that extends fingers up from the south. That ground is similarly saturated over frozen peat, with short stubby fir trees that point every which way around the dead that lie in herringboned disarray. You can't walk in that stuff, let alone drive through. Roads are major messes, that re-route water, and require constant maintenance (and turn to jelly with earthquakes). Off road vehicles tear the place to pieces, see above.

Not gonna be much agriculture in that world, except as slow encroachment from the edges.

Posted by: pjmattheis | April 04, 2013 at 15:15

http://neven1.typepad.com/blog/2013/04/a-drastically-greener-arctic-to-come.html#comments

One more note: we now have what Neven has dubbed a "Persistent Arctic Cyclone" that shows no signs of dissipating in the foreseeable future. Is there a chance that this kind of massive swirling vortex at the top of the world is going to become an essentially permanent feature of the earth's climactic system, at least during the spring through fall?

If so, how the heck is that going to effect conditions in mid latitudes and beyond?? (WAGs are welcome, as that is almost all we have to go on these days in this brave new climactic world.)

...
NB--In the above video, the other three are very reputable climate scientists and Arctic experts, but Wasdell is not. Not to say that he doesn't have some good 'big picture' perspectives to contribute, but he does sometimes seem to be a bit off or out of date on some details. And of course there are other 'experts' who have other perspectives, but no one reputable that I have heard thinks that there is nothing to worry about from the Arctic, especially in the longish term.

[ggelsrinc]

If you have scientific evidence to support your Doomsday scenarios of massive methane releases or losing agricultural capacity, then post and prove it! There isn't historical evidence that worldwide societies have collapsed in the past, because our past is too recent. Discussing how to farm the tundra evades the fact that the world doesn't produce it's food in the tundra. What about the climate change between where food is produced and the tundra? I don't claim future climate change is a cake walk, but I do claim the idea that our past climate change was a cake walk is equally false. That so-called stable Earth wasn't as stable as perceived. Isolated civilizations in the past have vanished due to climate change, but the world we live in isn't an isolated civilization.

If there is an interglacial warm period that didn't have more CO2, methane and more life, then show it to me! Is it not a fact that the Earth shows increases in CO2, methane and the amount of life as it warms? Claiming the methane has migrated more in an ice core than CO2 doesn't explain it not being there in large enough quantities to prove massive methane releases. It's been warm enough during the Eemian to melt GIS and rebound the southern areas from below sea level to produce forests.

I don't claim global warming is a good thing, but it's the reality of the moment and I don't see our message to be cautious of such changes being implimented in policy. All environments have good things that can change to worse with climate change, but that doesn't mean the bad things in those environments also can't change to be better. The world as we know it is the net sum of such past changes. The fact that there is good in the most barren of environments doesn't negate that such environments also have bad things present by being barren.

I believe the evidence shows mankind warming the Earth during a period of it's decline by cooling, but that is one of the net sums of mankind changing the Earth's environments. We also cut down forests and cooled the Earth. Ask yourself if the environment you live in has been altered by mankind from it's original form and I would say most of the world's people will say yes. The structures on this property and the yard aren't like it's natural environment. The road connecting it to the rest of society isn't a natural environment for whatever area it exists. If the area where I live returned to it's natural forest environment, that environment would be warmer than it's present condition would allow and let me point out that a few changes in a person's property can make that area cooler. Having a lawn isn't warming the Earth, but it is changing the biodiversity of that area. I'm not aware of any natural environment being a garden.



 

[ccgwebmaster]

If you have scientific evidence to support your Doomsday scenarios of massive methane releases or losing agricultural capacity, then post and prove it!

The scientific evidence has been cited.

What do you expect a scientist to say and how do you expect them to say it? Very few of them communicate things in a clear and fully interpreted manner (Hansen being one example of an exception to this rule, and from what I've seen of Storms of My Grandchildren, he isn't complacent about methane).

If you want pure science, you're talking research papers I assume?

The pieces required to conclude the threat exists and is very real are scattered amongst a number of those, but you misunderstand the nature of scientific research if you think that a scientist is going to include a full discussion of the consequences of a large methane release in a paper dedicated to the thawing of subsea permafrost or the process by which 1km wide emission sites are formed or the relationship between atmospheric methane and aerosol forcing.

So what do you want? For a scientist to step back and take the little pieces and warn you this shit's real? Quite a few have done precisely that - and you can find media quotes to prove it. But then you'll say to me it's just media articles or opinions and not proper science, right? And that the scientist in question is just an "alarmist"?

[ccgwebmaster]

In another lifetime, as my first adult scientist experience, I studied arctic ecology at/near Barrow, AK in the early 70's. A primary interest was the distribution of plant types by microclimates and ecotones/ecoclines... There's a whole nother language.
...
Posted by: pjmattheis | April 04, 2013 at 15:15

http://neven1.typepad.com/blog/2013/04/a-drastically-greener-arctic-to-come.html#comments

Thanks for that - I still read stuff at the sea ice blog, but don't always revisit articles for comments (I'm currently gradually withdrawing from online sites and participation in these issues).

It seems to me that plenty of farmers are starting to struggle a bit now - just from the mild effects of albedo loss upon northern hemisphere atmospheric circulation. Mild effects because it's still early days in terms of what we understand to be virtually certain over the next 5-10 years - the progression to an Arctic that is definitively ice free for a substantial part of the season (and possibly totally ice free as some point).

Common sense suggests to me that if we get a significant output change for a small input change in terms of the total change we are expecting that the balance of risk is that the total output change for the total input change is going to be... very significant. But then and again, isn't the total loss of Arctic sea ice during the summer a significant change? Should we not expect impacts from it?

Coming soon to a planet near all of us.

[wili]

Thanks for that

You are most welcome. I stumbled across that bit chasing after something else.

I hope you keep kicking around here for a while. I do appreciate your perspective.

[Lynn Shwadchuck]

@cgwebmaster "(I'm currently gradually withdrawing from online sites and participation in these issues)"
I hope not because you've blown your energy reserve on answering denier questions. This whole blog/forum is for people who look at lots of different scientists' work and arrive at a big picture. Anyone who comes along on a thread like this particular one and says, "Where's the science?" is just not worth the bother.

[JimD]

If you have scientific evidence to support your Doomsday scenarios of massive methane releases or losing agricultural capacity, then post and prove it! There isn't historical evidence that worldwide societies have collapsed in the past, because our past is too recent. Discussing how to farm the tundra evades the fact that the world doesn't produce it's food in the tundra. What about the climate change between where food is produced and the tundra? I don't claim future climate change is a cake walk, but I do claim the idea that our past climate change was a cake walk is equally false. That so-called stable Earth wasn't as stable as perceived. Isolated civilizations in the past have vanished due to climate change, but the world we live in isn't an isolated civilization.

If there is an interglacial warm period that didn't have more CO2, methane and more life, then show it to me! Is it not a fact that the Earth shows increases in CO2, methane and the amount of life as it warms? Claiming the methane has migrated more in an ice core than CO2 doesn't explain it not being there in large enough quantities to prove massive methane releases. It's been warm enough during the Eemian to melt GIS and rebound the southern areas from below sea level to produce forests.

I don't claim global warming is a good thing, but it's the reality of the moment and I don't see our message to be cautious of such changes being implimented in policy. All environments have good things that can change to worse with climate change, but that doesn't mean the bad things in those environments also can't change to be better. The world as we know it is the net sum of such past changes. The fact that there is good in the most barren of environments doesn't negate that such environments also have bad things present by being barren.

I believe the evidence shows mankind warming the Earth during a period of it's decline by cooling, but that is one of the net sums of mankind changing the Earth's environments. We also cut down forests and cooled the Earth. Ask yourself if the environment you live in has been altered by mankind from it's original form and I would say most of the world's people will say yes. The structures on this property and the yard aren't like it's natural environment. The road connecting it to the rest of society isn't a natural environment for whatever area it exists. If the area where I live returned to it's natural forest environment, that environment would be warmer than it's present condition would allow and let me point out that a few changes in a person's property can make that area cooler. Having a lawn isn't warming the Earth, but it is changing the biodiversity of that area. I'm not aware of any natural environment being a garden.
 

ggelsrinc,

You make a strong demand for definitive scientific proof but then you make a statement twice which is wrong scientifically.  Cutting down trees does not make it cooler it makes it hotter.  See below from Wiki:

Trees[edit]

Because forests are generally attributed a low albedo, (as the majority of the ultraviolet and visible spectrum is absorbed through photosynthesis), it has been erroneously assumed that removing forests would lead to cooling on the grounds of increased albedo. Through the evapotranspiration of water, trees discharge excess heat from the forest canopy. This water vapour rises resulting in cloud cover which also has a high albedo, thereby further increasing the net global cooling effect attributable to forests.

In seasonally snow-covered zones, winter albedos of treeless areas are 10% to 50% higher than nearby forested areas because snow does not cover the trees as readily. Deciduous trees have an albedo value of about 0.15 to 0.18 whereas coniferous trees have a value of about 0.09 to 0.15.[4]

Studies by the Hadley Centre have investigated the relative (generally warming) effect of albedo change and (cooling) effect of carbon sequestration on planting forests. They found that new forests in tropical and midlatitude areas tended to cool; new forests in high latitudes (e.g. Siberia) were neutral or perhaps warming.[22]

On top of the tree issue and your demand for science your statement is full of conjecture and strawman arguments.  How scientific is that?

There is abundant scientific evidence on the stresses to agriculture production and the data clearly indicates that global production is certain to peak and then decline.  Industrial agriculture production depends on the use of finite resources.  We live in a finite world.  That which cannot go on forever, won't.

Re methane.  It is true that we do not yet know how quickly the co2 and methane in the arctic is going to come back into the atmosphere.  But the science indicates it is going to, just not when.  It is fair to state however, that as time goes on and more is learned about the mechanisms and the changes in the arctic the science and data imply that the time is likely sooner rather than later and faster rather than slower.  Do not forget when thinking about climate change that never in the past have changes occurred anywhere near the rate which they are occurring now. So past is not a great predictor in all respects for what AGW effects will be.

[ggelsrinc]

Then you should be able to explain why the radiative forcing was reduced by land use. I say it was because of deforestation, but you claim it wasn't. What land use change reduced radiative forcing?

Global greening, the other 'greenhouse effect', is underway

Source: http://science.nbcnews.com/_news/2013/06/01/18669647-global-greening-the-other-greenhouse-effect-is-underway?lite

There is no scientific evidence showing a warmer Earth was a less productive Earth for life and there is plenty of scientific evidence showing a cooler Earth was less productive for life. There is no scientific evidence showing massive methane releases during prior warm periods and we have samples of those ancient atmospheres.

During the Pliocene, the forests were reduced and grasslands, savannahs and deserts expanded. That was cooling. The Europe that Caesar visited in Gaul was warmer before the forests were removed for agriculture and I only mean the land use change, not some "warm period." Cutting down a rainforest warms the Earth, but the whole world isn't rainforest. An area switching from tundra to taiga because of permafrost loss is warming. If you cut that forest down, it will cool that area, because you are mimicking tundra, even without permafrost keeping it that way. Your Hadley Centre study shows this, but the study is based on planting trees. A growing forest is sequestering carbon, but a mature forest isn't. It's already done that job.

Mankind's land use has cooled and not warmed the Earth. It's a scientific fact. If the change in land use didn't primarily involve deforestation, then, what did it involve? Did the deforestation cool or not?

[Glenn Tamblyn]

Just one comment wrt some of the points ggelsrinc has made.

The Paleo record doesn't show warming as severe as is expected if we double CO2 or more. And it doesn't show warming at anything like the <b>pace</b> expected. This is potentially really significant. Much slower warming allows much more time for the different parts of the Earths systems to adjust.
- Slower warming means slower pace of Methane release from permafrost for example; more time for it to convert to CO2 and thus have a lesser warming impact. And more time for it to be sequestered again in the oceans or via weathering.
- Slow sea level change allows for slow changes in clathrate depths - don't forget that clathrates form in any situation where circumstances are conducive.
- Tree-lines can match warming if their rate of advance can keep pace with the warming.

And so on.

The best the paleo record can do is point us at the types of changes that might ultimately occur. But it is less useful at estimating what might occur as a result of the pace of change.

The PETM, which is regarded as the closest analog to our current circumstances, involved a global change of 4-6 DegC. CO2 levels something like doubled. There was a minor extinction event. And there may have been a moderate anoxic event in the deep ocean.

CO2 levels today are rising 10 times faster than during the PETM.

Don't look to the more recent paleo record to put an upper limit on how bad things could get. It will only give us an indicator of the lower limit!

[Glenn Tamblyn]

ggelsrinc

"There is no scientific evidence showing a warmer Earth was a less productive Earth for life and there is plenty of scientific evidence showing a cooler Earth was less productive for life"

I would like to respond to this, indirectly using a tale.

When the first Space Shuttle Disaster occurred there was a great deal of analysis of the cause. Ultimately it was sheeted home to a failure of the O-Ring seals on the Solid Fuel Booster Rockets (SRB).

A later TV dramatization of events leading up to the  disaster painted a seriously negative picture of the cause. Maybe hearsay, maybe accurate, but illustrative...

Temperatures on the pad in the days before launch were unusually cold. At a management meeting to decide whether the launch was safe, a lead NASA engineer put pressure on the engineers from Morton Thiokol, the company behind the SRB.

Where the SRB's safe to go?

Their response, partly being the deers in the headlights in terms of their employers standing here, was 'we haven't tested the SRB's in these temperature conditions'.

The NASA guy puts them on the spot.

'So you don't have any engineering data to suggest that there is a problem with launching in this situation'

The only honest answer they could give is 'No!'

So the launch happened and those folks died.

The fallacy was in the idea of expecting that we require evidence of danger.

We actually require evidence of safety!

If we move outside of our zone of familiarity then we should operate on the presumption of hazard until adequately demonstrated otherwise.

[Glenn Tamblyn]

ggelsrinc

"There is no scientific evidence showing a warmer Earth was a less productive Earth for life and there is plenty of scientific evidence showing a cooler Earth was less productive for life"

And an additional point....

"Productive for life...."

We aren't interested in life. We are interested in our life. Us, Our children, our grandchildren and so on....

So what is the evidence for more productive human life? What is the evdenece for increased food production? What is the evidence for a greater biomass rather than simply more species?

I don't care whether there might be more species of Nematodes. I care that the world rice harvest will stop my grand-daughter from starving.

Aren't you falling into the fallacy of assuming that negative consequences need some justification before they happen? Rather than the idea that positive consequences need justification.

[ggelsrinc]

Climate change due to global warming will have a whole list of catastrophes associated with it, but I don't consider massive methane releases or societal collapse with agricultural collapse to be a threat. The satellite pictures show a warmer, wetter, greener Earth.

The first obvious catastrophe is the Earth has 400 ppm CO2, will have 450 ppm in around 15 years and very little is being done to change that trend. The system has warming already built into it, so there is 100% chance we will melt ice and cause sea level rise. I also think there is 100% chance of drastic shifts in the climate of some areas and it will be bad for some places. All those concerns about the rate of change and it's environmental impact are valid concerns. Species can live in a very limited range and it's easy to cause extinction where the climate changes. Climate change will be full of disasters, but I believe mankind will escape the gas chamber, be around and the Earth will even provide popcorn to watch it happen.

I'm hopeful that events in the near future will cause the world to take climate change seriously. Seriously is reductions in all greenhouse gases and working in ways to reduce radiative forcing. We still have a warming price to pay to get rid of acid rain, so the task is more than just reducing CO2 emissions.

[ccgwebmaster]

This thread is spinning around in circles somewhat at this point I feel.

However - and with apologies if it's already been mentioned on the forum:

http://phys.org/news/2012-09-food-crisis-imminent-decade-climate.html

I personally expect more and more of this sort of finding to emerge on a period of years, with a note that it may perhaps be faster and more severe than anticipated as most people are still (I think) not taking the Arctic and it's impact on northern hemisphere weather into account (and possible future impact on thermohaline circulation).

There are far too many downside risks to assume on safety for civilisation for decades, and a decent amount of actual science pointing at real problems in a nearer future timeframe (not to mention changes that have already occurred or are ongoing).

[ccgwebmaster]

@cgwebmaster "(I'm currently gradually withdrawing from online sites and participation in these issues)"
I hope not because you've blown your energy reserve on answering denier questions. This whole blog/forum is for people who look at lots of different scientists' work and arrive at a big picture. Anyone who comes along on a thread like this particular one and says, "Where's the science?" is just not worth the bother.

Not at all, though I've done my share of the denier thing (and found cause to be disappointed with media censorship by even the Guardian removing reasonable comments about methane).

It's more a matter of feeling that plenty of people (relatively speaking) are talking about all these things but not so many are pursuing concrete actions. Accordingly I'd feel happier making sure I push myself to act as much as possible - and in the various online forums I've participated in I can't say I've felt very effective.

If the current flavour of this forum should persist, this would no doubt be one of the very last places I would withdraw from (and there's a good chance at that point it would be because the sky really was falling - at least at a personal level).

[Apocalypse4Real]

Hopefully the following links will be helpful to this discussion:

In regard to food security "improving" due to a greener wetter earth, here is an entire conference that is dealing with climate impact implications, including agriculture:

On May 27-30, 2013, the International Conference on Climate Change Effects occurred in Potsdam. Over 100 papers were presented on climate change impacts including many on agriculture. Take a look at Carter's paper on Northern Hemisphere food security.

Here is the conference papers link: http://climate-impacts-2013.org/index.php?article_id=27

In regard to the world assuming agriculture improvements - most scientists are not. The Chinese do not think so. See: http://english.caas.net.cn/research_update/67347.shtml

USAID does not think it has a positive impact in SE Asia. See: http://www.asianscientist.com/wp-content/uploads/2013/04/mekong_arcc_climate_study_background_brief.pdf

The International Food Policy Institute does not think so:

Here are some findings from there 2009 report:

"The results of the analysis suggest that agriculture and human well-being will be negatively affected by climate change:

• In developing countries, climate change will cause yield declines for the most important crops. South Asia will be particularly hard hit.

• Climate change will have varying effects on irrigated yields across regions, but irrigated yields for all crops in South Asia will experience large declines.

• Climate change will result in additional price increases for the most important agricultural crops–rice, wheat, maize, and soybeans. Higher feed prices will result in higher meat prices. As a result, climate change will reduce the growth in meat consumption slightly and cause a more substantial fall in cereals consumption.

• Calorie availability in 2050 will not only be lower than in the no–climate-change scenario—it will
actually decline relative to 2000 levels throughout the developing world."

For the above, see Climate Change: Impact on agriculture and costs of adaptation, 2009: http://www.ifpri.org/sites/default/files/publications/pr21.pdf

The World Bank has come out with a 2012 report on the imapcts of a 4C world, it is not wetter and more productive. See:
http://climatechange.worldbank.org/sites/default/files/Turn_Down_the_heat_Why_a_4_degree_centrigrade_warmer_world_must_be_avoided.pdf

The World Bank has come out with a report today on near future climate impacts in Sub Saharan Africa, South Asia and South East Asia. It is titled, "Turn down the heat : climate extremes, regional impacts, and the case for resilience" For the full report (English), see:

http://www-wds.worldbank.org/external/default/WDSContentServer/WDSP/IB/2013/06/14/000445729_20130614145941/Rendered/PDF/784240WP0Full00D0CONF0to0June19090L.pdf

Finally, in March, it published a report on anticipated near future impacts on Europe and Central Asia. See, "Looking beyond the horizon : how climate change impacts and adaptation responses will reshape agriculture in Eastern Europe and Central Asia (English)"

http://www-wds.worldbank.org/external/default/WDSContentServer/WDSP/IB/2013/03/22/000356161_20130322155958/Rendered/PDF/761840PUB0EPI00LIC00pubdate03015013.pdf

A greener, wetter, more food productive world with a stable climate or weather system is not in the cards now or in the future as best that most science can forecast.

[ggelsrinc]

The future of world food production requires a broad knowledge of science, economics, agriculture and politics. Economics trumps any problems associated with a world having extreme weather events, because the major money interest in food isn't on the farm producing the food. The world can't have drought in one area without providing more rain to other areas. If I need this ingredient to produce my product and your supply is destroyed, I'll get it from somewhere else. I only picked you as a source because it was the most economical way to produce my product. If the product costs more to produce that way, I'll maintain my margins and pass the extra costs to the consumer.

The research says that sulphur dioxide from factories in Europe and the United States has cooled the Northern Hemisphere, driving the tropical rain belt south - away from the Sahel.
 
Rainfall in the region has declined by between 20% and 50%, leading to severe droughts in 1972, 1975, 1984 and 1985.
 

Source: http://news.bbc.co.uk/2/hi/africa/2042856.stm

Cooling the Northern Hemisphere is consistent with the best knowledge science has concerning the North African monsoon, Green Sahara and Paleoclimatological record. I'm not sure the cooling caused by sulphate aerosols was enough to cause that drought. I am sure that I've seen future drought predictions that are totally inconsistent with Physics and every field of science.

I wouldn't expect a government report to conclude producing anything will be easier. If you ever find a government concerned about the people and not special interests, let me know about it! Higher prices for food because our weather became slightly more extreme is a far cry from near future agricultural and societal collapse. The corporations who insure insurance corporations have been charging a fee for global warming since '73 and long before science had much interest in the subject. We aren't in a last straw/camel back breaking situation when it comes to food production.

When discussing production of anything, the focus tends to be on one side of the balance sheet. Only up and coming production to meet demand focuses on the positive or asset side of a balance sheet and the rest, which has already meet demand, focuses on the negative. The true focus is both sides of the balance sheet.   

[wili]

Thanks, A4R, for those great links. From an abstract to the Carter paper:

urgent action must be taken to mitigate Northern Hemisphere food productivity losses that could occur in the short term. This is most relevant to the food security of the most vulnerable populations because of the resulting effects on world food prices and food surpluses.

And from the Dasgupta paper:

...as the variability exceeds a certain threshold which is the major cause for concern among climatologists, it is expected to have a negative impact on crop yields. As variability of temperature causes the conditions to move away from the optimum growing conditions for crops, yields are expected to fall. At the same time, as variability of precipitation increases, the optimum absorption capacity of soil is affected and this is expected to affect crop yields negatively. These results are consistent with the findings from agronomists’ literature
8
[Battisti and Naylor, 2009]. Analysis also suggests that increasing variability of precipitation and temperature has a persistent negative effect on crop yields...