As I was finishing last week’s blog entry, the table of contents for Science arrived in my e-mail. Suddenly I understood why articles dealing with climate change had been few and far between in recent weeks in that journal. Science has devoted most of its issue for 2nd August to the topic of climate change. Science highlights a topic in this way only once or twice a year, and Science covers all aspects of scientific endeavor – getting selected for special attention is a sure sign that climate change is important to the editors.
The special section includes a couple of news items and a series of reviews. The news items include one reporting how studies of ancient climates (chiefly through analysis of pollen grains in sediment cores from lakes) are providing insights to the stimuli that led to the evolution of humans in East Africa in the first place, and one on whether coastal marshes will be able to out-run sea level rise and persist on new shores further inland in the future. There is a delightful item on how old photographs can be valuable data in the effort to appreciate climate change that has already occurred. Yes, there has been enough climate change since the invention of photography to see evident change in scenery photographed at different times in the past 100 years.
The reviews are the real meat in this feast of information (unfortunately they are protected so you have to pay to read them, or go through an academic library portal). R.D. Norris of Scripps Institution of Oceanography, University of California, with colleagues at Scripps, Yale and University of Bristol, UK, provide the marine entry: Marine Ecosystem Responses to Cenozoic Global Change. They start with the hypothesis that future patterns of response to climate change can be gauged by examining patterns of change in the geological past, and they proceed to document patterns of change in a suite of ocean characteristics during the entire Cenozoic Age that period of 65 million years from the end of the Cretaceous (and the extinction of the last dinosaurs) to the present.
Figure 2 from Norris et al, Science 2 August, 2013.
During this period, there have been substantial changes in the characteristics of the oceans. Their Figure 2, a rather complex graph, provides data for atmospheric concentration of CO2, deep ocean and surface temperature, dissolved oxygen concentration, latitudinal distribution of reefs, and sea level. Various proxy measurements are used for each of these. During the early Eocene, 47 to 55 million years ago, CO2 concentrations were very high, temperatures were warm, sea level was up to 60 meters higher than now, and reefs were very sparse or absent. Later in the Eocene, temperatures moderated somewhat and reefs flourished. During the Oligocene and Miocene, a span from 5 to 33 million years ago, CO2 fell, temperatures followed suit and sea level also fell towards current levels. Norris divides this Cenozoic history into two phases – the Greenhouse World of the early Cenozoic through to the end of the Eocene, and the Icehouse World from then to today – separated by a relatively rapid transition.
Using simulations of future expected climate, they suggest that we are now entering another transition back towards something resembling the earlier Greenhouse World. However they caution that the future world will not be an exact replica of the Eocene because the oceans are biologically different to the way they were at the start of the Cenozoic. The differences are represented in their Figure 1, a much simpler diagram that the data-laden Figure 2.
Figure 1 from Norris et al, Science 2 August 2013
In this Figure, the Eocene Greenhouse World is in the center panel, with its high sea levels, extensive shallow seas over continental margins, its lack of sea ice, and its open water ecosystem comprised of small forms of plankton, including an abundance of bacterioplankton, and a lack of large carnivores. The present world, in the left panel, has large carnivores, relatively large plankton, productive surface waters, reasonably high levels of dissolved oxygen (the oxygen minimum layer is relatively small), lower sea levels and coral reefs. The future world, on the right has less productive surface waters, smaller plankton again, although the large carnivores remain, lower levels of dissolved oxygen, higher sea levels again, and no coral reefs. Forget the details. Let’s just say that Norris and colleagues have shown that the oceans have changed greatly in the past, and they are now on a trajectory to change greatly again. The oceans we have always known are going away to be replaced by something rather different.
Last week I wrote about committed climate change. Norris and colleagues point out that the emissions of greenhouse gases we have already released have committed the oceans to change over the next 10,000 years or so. Further, if we continue on the path we are currently on (Norris et al specify they are using the IPCC IS92a scenario of population growth, economic growth and pattern of use of energy), CO2 concentration in the atmosphere will peak at about 1000ppm shortly after 2100 and begin to decline. But the ocean will not stop changing dramatically for 100,000 years. Now that is what I call real commitment. And it scares me greatly.
In another of the reviews, Tim Wheeler and Joachim von Braun, of the University of Reading and the University of Bonn respectively, write about the impacts of global change on global food security. As so often happens, when food security is being considered, the focus is on conventional agriculture, so they say nothing about fisheries – but we already know that fishery yields are falling, that aquaculture will not easily replace the missing fish, and that people who rely on fish for protein are going to have to look elsewhere. What they do discuss is just as or more alarming. Take a look at these two maps.
Figure 1 from Wheeler and von Braun, Science, 2 August 2013, showing the distribution of hunger in today’s world.
Figure 2 from Wheeler and von Braun, Science 2 August 2013, showing in the top panel a simulation done in 1994 to show the effect of a doubling of CO2 concentration on crop yield, and a more sophisticated (and complex) simulation done in 2010, and looking at 2050 specifically.
The first map holds no surprises. We know that food availability is not a substantial problem in the developed world – we can buy our way out of any food shortage. Food shortages are real in many parts of the developing world, and particularly in Africa and India. The second pair of maps does hold some surprises. First, at least for me, there is the surprise that the simulation done in 1994 seems to have largely captured the geographic pattern of food shortages. Second, the more recent, 2010, simulation reveals that declines in food production are conspicuous as early as 2050, and the area of the world where diminished production capacity occurs are now seen to invade some portions of the developed world. Our ability to buy our way out of any food shortage may become a thing of the past as the absolute capacity to grow food falls. Wealthy people can still starve if there is not enough food to feed them. (And before we Canadians get too complacent seeing the big swaths of green in the 2010 map, let’s remember that the soils of northern Quebec are not particularly fertile, and that the USA is likely to remain a powerful, and now a hungry neighbor in 2050.)
The issue of climate change effects on agriculture has always been complex because warmer weather should equate to longer growing seasons, and more CO2 in the atmosphere should act on plants like a performance enhancing drug on an athlete. There is some reason for optimism. Still, climate change can make weather too hot or too dry as well, impacting crop yields. Over the last decade or so, field experiments in which crops were subjected to enhanced CO2 concentrations have revealed that the stimulating effect of the CO2 is less than some anticipated. As well, new data on effects of climate change on precipitation have revealed that the problem of drought is far more severe than was initially thought. Bottom line, there is a grave risk that the world will become hungrier over the next few decades.
Wheeler and von Braun end their review with six recommendations for policy makers. These are:
1) Climate change impacts on food security will be worst in countries already suffering high levels of hunger and will worsen over time.
2) The food security consequences of doing nothing in response to climate change are potentially large and will increase over time.
3) Food inequalities among communities will become larger.
4) People and communities who are vulnerable to the effects of extreme weather now will become more vulnerable in the future and less resilient to climate shocks.
5) Our climate change commitment as a result of past emissions of greenhouse gases requires immediate adaptation actions to address global food insecurity that is going to appear over the next two to three decades.
6) Extreme weather events are likely to become more frequent in the future and will increase risks and uncertainties within the global food system.
After these sobering messages Wheeler and von Braun conclude with a call for the development of what the call a climate smart food system. I think they are right. I also doubt we will actually move fast enough to achieve this.
Other reviews cover changes to ecologically sensitive terrestrial systems, changes to the ways in which species interact, whether species are going to respond to climate change by adapting, evolving, relocating, or whether they are simply going to become extinct, impacts on infectious diseases, and impacts on sea ice. None of the reviews suggest that the particular problem reviewed is going to be minor. Each review contains little surprises – at least they surprised me – usually surprises that mean the situation is even more dire than I anticipated. Craig Moritz and Rosa Agudo, of Australian National University, did not tell me much about how and whether species will respond, but they did produce a neat graph of temperature over the past
Figure 1 from Moritz and Agudo, Science 2 August 2013, showing global mean temperature five million years into the past and 100 years into the future.
Yes, the Pleistocene must have been an exciting time, but look at what’s coming before 2100. Still, let’s turn to the review of what is happening to sea ice, by Eric Post of Pennsylvania State University, and a suite of co-authors from all over North America, including suitably cold places like Missoula, Montana, Calgary and Edmonton, Alberta, and Fairbanks, Alaska.
The focus of their review is on the ecological consequences of the increased melting of Arctic sea ice, although they briefly review the extent of loss and the fact that the melting is proceeding rapidly. Their review makes clear that there is a lot we do not know about Arctic ecology. They also told me things I certainly did not know, but Arctic researchers undoubtedly did – such as that a community of algae and phytoplankton that live in close association with the underside of the sea ice are the base of the marine food web in the arctic, and that the increased melting of the sea ice is disrupting temporal patterns of algal and phytoplankton growth, and therefore disrupting food webs, with potentially bad consequences for larger animals. These sea-ice algae and sub-ice phytoplankton represent 57% of the total annual primary production in the Arctic Ocean, and the loss of over two million km2 of sea ice since 2000 represents a stunning loss of habitat. Post and colleagues predict that impacts of sea ice thinning and loss could turn out to be profound simply because of these impacts at the base of the marine food web. Loss of sea ice also impacts larger organisms, particularly marine mammals that haul out on the ice periodically. Walrus and polar bears in particular are going to be more restricted to coastlines, and will experience greater crowding because of this. As well, the melting of the ice will open up channels to migration, bringing together populations that have long been apart and opening up possibilities of disease transmission.
The melting also seems to be having profound impacts on the terrestrial environment. The melting appears to be causing a warming of tundra, with longer growing seasons, more plant growth, and potentially more carbon being taken up by plants. However the warming also means more releases of methane as permafrost melts. Putting it all together, Post and colleagues provide a diagram which suggests that the Arctic that is coming is going to be very different in many ways to the Arctic we have been used to.
Figure 1 from Post et al, Science 2 August 2013, showing how the melting of sea ice is likely to impact Arctic ecosystems.
Of course, one does not really need to read a review in Science to appreciate how much the Arctic is changing. At this very moment, four Canadians (well, actually, two of them are misplaced Irishmen) are rowing the Northwest Passage. They set out from Inuvik in early July and are now about 1/5 of the way towards their destination in Pond Inlet 300km east. This trip could not have been attempted just a few years ago. Their boat is called the Arctic Joule and the scenery looks bleak.
The Arctic Joule en route in the bid to row the Northwest Passage.
The reviews in Science all focused on environmental issues. Only the article by Wheeler and von Braun touched on economic issues with respect to food security. But the impacts of climate change are not only environmental. They also hit our economy. That point was made clearly by Gail Whiteman of Rotterdam University, and Chris Hope and Peter Wadhams of Cambridge, in an article published in Nature July 25th. They began their article with, “Unlike the loss of sea ice, the vulnerability of polar bears and the rising human population, the economic impacts of a warming Arctic are being ignored.” Has a nice ring to it, doesn’t it? They go on to report that the release of methane from thawing permafrost beneath the East Siberian Sea, will have impacts on the global climate that will cost $60 Trillion unless we act to minimize or slow the melting. This cost represents the expense of dealing with the extreme weather, poorer health and reduced agricultural production that will result. It’s an expense that will be borne mainly by poorer countries.
Sixty trillion dollars is an amount that is not very different to the size of the global economy ($70 trillion), and that is for the East Siberian Sea alone. The cost for the full Arctic will be far larger, especially when one factors in the impacts other than methane releases. Whiteman and colleagues justify that cost by pointing to the existence of 50 Gigatonnes of frozen methane hydrates on the East Siberian shelf. This methane hydrate will melt perhaps over a 50 year period, perhaps much more rapidly, and it is likely to happen in the next couple of decades if we continue to warm the planet as rapidly as we have been doing. The jolt to climate could be profound, and the jolt to our economy will be massive. Whiteman and her colleagues call for the creation of an economic model of climate change as a matter of urgency, because it is time we knew the full economic costs of the climate change we are causing. Chris Hope, in an interview with CBC News made specific reference to the benefits of opening up the Arctic to oil, gas, and mineral exploration. He said that the benefits could be in the billions of dollars, but the costs of Arctic melting will be in the tens of trillions. There is no way that the thawing of the Arctic will be, overall, an economic plus for countries like Canada, and its time our politicians recognized this fact.
Earth, as seen by Chris Hadfield, southwestern Australia in view, close to sunset.
We still live on a beautiful blue planet. It’s a place where one can wake up every morning to the warmth of the sun and marvel at the way each morning looks clean and new. It’s still a place where one can find absolute tranquility in nearly untouched wilderness, and revel in an ecology that works so intricately to sustain itself. It’s also a place where too many people awaken hungry, in impoverished cities, with little hope that things will get better in their lives. You’d think the most intelligent primate that ever existed, the one with the big brain, the one that despite his relatively puny size, came out of Africa to conquer the world, create great art and literature, build complex civilizations, and even manage to put two or three individuals on the surface of a nearby moon for just a few hundred hours… you’d think this ape would be bright enough to figure out that it is well past time for prevaricating. It is well past time for getting serious and doing something to correct the imbalances we have created by our profligate use of fossil fuels. I’ll try to be more positive next time.
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