Is Climate Change Already Increasing Population Migration Pressure?

L. David Roper, a retired physics professor in Virginia thinks so:

Media reports about the migration of children from Central America into the U.S. have blamed it on extreme violence in those countries due to drug gangs. The high use of illegal drugs in our country places most of the blame for the drug trade on some of us. However, there is a more insidious and basic blame that rests on all U.S. citizens which the main U.S. media almost never mention.

For many years countries of Central America have been experiencing extreme droughts and floods and consequent large declines in food production. Such extreme weather events are enhanced, and probably caused, by global warming. Honduras is ranked with Bangladesh as the two countries most susceptible to disasters caused by global warming; this year the Honduran rice crop was decimated by massive floods. The top three countries in the world that suffered the most from extreme weather over the last 20 years are Honduras, Myanmar and Nicaragua. El Salvador and Guatemala crop yields have been reduced by floods from violent storms. Guatemala and Nicaragua have had prolonged droughts.

For the last few decades the U.S. has been a major cause of global warming by burning fossil fuels, especially coal and oil. So, the root cause of the migration from north to south [sic] is global warming caused by burning fossil fuels in the U.S.

Is this premature?


  1. Is this premature? Yes and no...
    Insofar as we can say that the changes described are indeed characteristic of already existing climate shifts, then it is possible to argue the point.
    For a more challenging scenario, consider the steadily increasing traffic of illegals crossing the Mediterranean from North and West Africa. Part of the reason is certainly economic, but another part is political - these people are going from a greater to a lesser insecurity. Given the risks associated with that choice, we should be alerted to the level of risk these people face if they don't migrate.
    Linking to Michael's main piece on Food, the pressure to relocate is probably currently more derived from economic realities than climate ones. However, it should be recognised that the two are not unconnected. What is driving the shift is a combination of need and inequity - these people are looking for something better than they can hope for if they do nothing - and relocation is a promising starting point.
    It is accepted that climate insecurity feeds into political and economic insecurity and probably makes it worse. On the other hand, as we say elsewhere, better local governance is probably able to improve the situattion in the short term, if the political will exists.

  2. Yes. It's a̶n̶g̶s̶t̶y̶ ̶g̶i̶b̶b̶e̶r̶i̶s̶h̶rather silly.

    'The high violence in Central American countries is not because of inherent defects in the humans that live there; it is because of natural human reactions to terrible living conditions, much of it due to global warming.'

    No, much of it due to bad governance, some of it to imperialism, a small bit due to climate, a tiny bit due to climate change.

    Incidentally, here's Roper's source for Honduras, Haiti and Myanmar being the worst hit by extreme weather in the last 20 years: Germanwatch's Global Warming Risk Index 2014.

    I haven't given it a proper read yet but it seems that those three countries 'top' (bottom?) the table almost entirely because of three hurricanes: Mitch hitting Honduras in 1998; (Cyclone) Nargis hitting Myanmar in 2008; and Hurricane Sandy hitting Haiti in 2012.

    At most, global warming boosted the damage these storms caused and/or made them slightly more or less likely, so the Index would appear to be misnamed. (Also, the death tolls look inflated.)

    I haven't tracked down his source for this unlikely - and garbled - statement: 'Honduras is ranked with Bangladesh as the two countries most susceptible to disasters caused by global warming.'

  3. > consequent large declines in food production

    Some statistics are in order, Shirley, if you want to make that kind of assertion. I can't be bothered to find any, but I did find wot sez:

    Looking back at the past few decades, Latin America has done more than its share to contribute to global agricultural production and trade. While there are significant differences from country to country, the region is overall a net food exporter. Exports of agricultural products have grown at about 8% annually since the mid-90s, and now make up about a quarter of the region’s total exports – more than LAC’s share of any other sector in world trade. Latin America is also a bigger player at a global level: it now represents 13% of agricultural trade, up from 8% in the mid-90s.

    Well, all right, that's not quite "Central America" but my point remains: we need to check his assertions first.

  4. I'm inclined to agree that climate is not a major factor, but that is what makes this all so tricky. It's impossible to run the world experiment more than once. These matters can be expected to be ambiguous for a long time.

    Clearly there's something humans could be doing better in this situation, as in so many others. There seems to be a tendency in some to treat climate as dominantly the cause of problems already. This seems a sort of simple albeit muddled proxy for the ideal of people running the world in some better way. I think this confusion may be worth watching - some people use "climate" in a much broader sense than climatologists do.

    But increased agricultural productivity is as confused a measure of climate damage as Pielke Jr's storm damage metric. This ties into the food article - poor people cannot eat coffee, for example, but coffee is better for productivity measures than yams.

  5. I think the tendency to look for present attribution and impending crisis is a function of the advocacy process, rather than a reflection of the science. Bottom line is that not enough people think that future generational harm is meaningful or relevant, so the advocates of change are eager to find a meme which will engage the uncertain.

    A side thought - if CC can be established to represent a 'clear and present danger' to US security, I believe this permits executive powers which can bypass the fiasco that is House politics at the moment and force enactments which would otherwise be blocked for political reasons. This is not dissimilar to what was done, using the EPA to force action on public health grounds.

    Not wanting to get too miserable about the human condition, but wealthy societies throughout history have depended on the existence of sub-classes of human labour, whether it's slavery, imperialism (cheap foreign labour), or political repression. I'm not sure in what ways the present global inequity situation is any different to these precedents. Any thoughts?

  6. Strictly scientifically speaking, perhaps the quibbles about attribution are correct. But in a real world sense, it seems to me that events are accumulating. I would agree that the Central American problem is a bad one, since endemic crime seems to be the main problem. But there has been serious work done on Africa and the Middle East, and I would contend that increased drought is not helping, and there will be more of that. Refugees are a complex human problem, but starvation doesn't help. Here's one article, which also brings forward Fergus comment on military. I've listened to several presentations by our military on planning and it is being done, not in the future but now.

    Since NYTimes has a quota on monthly articles, so here are some extended extracts which I would otherwise omit:

    The CNA Corporation Military Advisory Board found that climate change-induced drought in the Middle East and Africa is leading to conflicts over food and water and escalating longstanding regional and ethnic tensions into violent clashes. The report also found that rising sea levels are putting people and food supplies in vulnerable coastal regions like eastern India, Bangladesh and the Mekong Delta in Vietnam at risk and could lead to a new wave of refugees.

    In addition, the report predicted that an increase in catastrophic weather events around the world will create more demand for American troops, even as flooding and extreme weather events at home could damage naval ports and military bases.

    .... “Tribes are killing each other over water today,” Mr. Kerry said. “Think of what happens if you have massive dislocation, or the drying up of the waters of the Nile, of the major rivers in China and India. ....

    “We’re going to try to lay out to people legitimate options for action that are not bank-breaking or negative,” Mr. Kerry said.

    Pentagon officials said the report would affect military policy. “The department certainly agrees that climate change is having an impact on national security, whether by increasing global instability, by opening the Arctic or by increasing sea level and storm surge near our coastal installations,” John Conger, the Pentagon’s deputy under secretary of defense for installations and environment, said in a statement. “We are actively integrating climate considerations across the full spectrum of our activities to ensure a ready and resilient force.”

    The report on Tuesday follows a recent string of scientific studies that warn that the effects of climate change are already occurring and that flooding, droughts, extreme storms, food and water shortages and damage to infrastructure will occur in the near future.

    In March, the Pentagon’s Quadrennial Defense Review, the agency’s main public document describing the current doctrine of the United States military, drew a direct link between the effects of global warming — like rising sea levels and extreme weather patterns — and terrorism.

    “These effects are threat multipliers that will aggravate stressors abroad, such as poverty, environmental degradation, political instability and social tensions — conditions that can enable terrorist activity and other forms of violence,” the review said.

    Tuesday’s report is an update of a report by the center’s Military Advisory Board in 2007, the first major study to draw the link between climate change and national security. The report’s authors said the biggest change in the seven years between the two studies was the increase in scientific certainty about global warming, and of the link between global warming and security disruptions.

    The 2007 report also described climate change as a “threat multiplier” or a problem that could enhance or contribute to already existing causes of global disruption. The 2014 report updates that language, calling climate change a “catalyst for conflict” — a phrase intentionally chosen, the report’s authors said, to signal that climate change is an active, driving force in starting conflict. ....

    The most recent scientific reports on climate change warn that increasing drought in Africa is now turning arable land to desert. The national security report’s authors conclude that the slow but steady expansion of the Sahara through Mali, which is killing crops and leaving farmers starving, may have been a contributing force in the jihadist uprising in that African country in 2012. Since then, Al Qaeda in the Islamic Maghreb has seized control of northern Mali and remains in conflict with the Malian government.

    .... [Inhofe disses this, an excellent argument for it, I'd say]

    Rear Adm. David Titley, a co-author of the report and a meteorologist who is retired from the Navy, said political opposition would not extinguish what he called the indisputable data in the report.

    “The ice doesn’t care about politics or who’s caucusing with whom, or Democrats or Republicans,” said Admiral Titley, who now directs the Center for Solutions to Weather and Climate Risk at Pennsylvania State University.

  7. Yet the US House of Representatives voted in May to prohibit the DoD from spending any money "to implement the U.S. Global Change Research Program National Climate Assessment, the Intergovernmental Panel on Climate Change’s Fifth Assessment Report, the United Nation’s Agenda 21 sustainable development plan, or the May 2013 Technical Update of the Social Cost of Carbon for Regulatory Impact Analysis Under Executive Order 12866.” Heaven help us!

  8. This:
    " 2. What is the relationship between migration and environmental change?

    It is almost impossible to distinguish a group of ‘environmental migrants’, either now or in the future.
    There are a number of existing estimates of the ‘numbers of environmental/climate migrants’, yet this
    report argues that these estimates are methodologically unsound, as migration is a multi-causal
    phenomenon and it is problematic to assign a proportion of the actual or predicted number of migrants
    as moving as a direct result of environmental change. A deterministic approach that assumes that all or a
    proportion of people living in an ‘at-risk’ zone in a low-income country will migrate neglects the pivotal
    role that humans take in dealing with environmental change, and also ignores other constraining factors
    which influence migration outcomes.

    This is not to say that the interaction of migration and global environmental change is not important:
    global environmental change does have real impacts on migration, but in more complex ways than
    previous cause–effect hypotheses have indicated.

    Foresight’s conceptual approach: global environmental change affects the drivers of migration.
    The decision to migrate is influenced by five broad categories of ‘driver’.These drivers are set out at the
    vertices of the pentagon in Figure ES.1.This framework acknowledges that migration is already occurring in
    most parts of the world as a result of these drivers: indeed there were approximately 740 million internal
    migrants in 2000–02 and 210 million international migrants in 2010. Environmental change will influence
    migration outcomes through affecting existing drivers of migration. This influence is most pronounced for
    economic, environmental and, to a lesser degree, political drivers.This conceptualisation recognises that
    the powerful existing drivers of migration, with economic drivers foremost, will continue to be the most
    powerful in most situations. However, environmental change will affect these drivers by having impact, for
    example, on rural wages, agricultural prices, exposure to hazard and provisioning ecosystems. "

    from here:

    The scenarios document is an eye-opener. Recommended bedtime reading for the unemotional...

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