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Anthropocene Anxieties – Maybe We Should Strive for Only 1 Degree Global Temperature Increase?


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Some good news on the climate front

Friday 13th of March, and yet there was some good news. IEA reported that in 2014, for the first time in the 40 years for which it has been collecting data, emissions of CO2 remained unchanged while the global economy strengthened by 3%. Emissions in 2014 totaled 32.3 billion tonnes CO2. Global emissions have remained flat or fallen on three previous occasions – late 1980s, 1992, and 2009 – but in all cases these events coincided with an economic downturn. IEA attributed the 2014 decoupling of emissions from economic activity as primarily the result of actions taken to expand use of green energy in China and in the EU. The world’s efforts to reduce CO2 emissions are beginning to bear fruit.

There were other signs that the need to address climate change is being taken seriously in jurisdictions and in corporate board rooms around the world. On 12th February, the Ontario government had posted a climate change discussion paper to its website, for public comment. This is clearly a first step towards announcing further climate initiatives in coming weeks. That is new initiatives by a Province that has already made changes that have shifted its electricity sector markedly away from fossil fuels towards renewables. A quick check on Google today using the phrase ‘new climate initiatives’ brought up the following among the first 20 hits – they are not a careful selection of the most important, just a random handful of what seemed to be on web in mid-March.

On 24th February, Citi, the global banking corporation, announced plans to lend, invest and facilitate a total of $100 billion within the next 10 years to finance activities that reduce the impacts of climate change and create environmental solutions that benefit people and communities. This announcement follows a previous pledge of $50 billion investment that was completed 2 years ahead of schedule in 2013. As well as renewable energy and energy efficiency projects, Citi will be looking at projects that reduce GHG emissions in other sectors, such as transportation. As well as helping communities in the 40 largest urban regions around the world, Citi has also set itself ambitious footprint-reducing targets of 35% less emissions, 30% less water use, and 60% less waste produced by 2020, compared to 2005. Bank of America and Wells Fargo have introduced comparable (though smaller) programs.

On 18th March, Governor Jerry Brown announced a $1 billion plan (already funded and approved) to address California’s drought. A mix of short-term relief and long-term infrastructure investments, the plan uses $273 million to address water supply by desalination and measures to recycle or use more efficiently, and $600 million in infrastructure for flood control. As Brown stated, California’s water problems are a result of climate change, and while the issue today is drought, it could well be floods once the drought breaks. Tougher regulations on use are also coming.

Also on the 18th March, an announcement in the journal Science drew my attention to a just-released proposal by 71 academics across Canada, with expertise in climate science, other natural science, social science, political science and policy. Acting partly out of frustration with the Harper government’s evident disinterest, they had come together to develop ten key policy orientations, illustrated by specific actions, that could be adopted to kick-start Canada’s transition toward a low-carbon society. As they state in a Foreward, “We offer it as input to Canadian decision-makers, opinion leaders, and elected representatives in preparation for our upcoming federal election followed by the 2015 Paris-Climate Conference.” Their proposal is realistic, feasible with existing technology, and could bring Canada into line with the US in terms of proportional reductions in GHG emissions. Their major push in the near term is to move towards 100% use of renewable energy in the electricity sector by 2035. It’s too soon to tell if this report will encourage the Harper government to get busy. So far, apart from the reported whispered conversations between Environment Canada and the Provinces there has been only silence. Of course Stephen Harper and Leona Aglukkaq might be busily quilting away in some back room of the Parliament building, fabricating a “Canadian” plan from what the provinces have been doing all along. Such is the leadership from behind that has dragged Canada back from near the front of the pack on global environmental issues.
Harper and Aglukkaq - postmedia news

PM Harper and Environment Minister Aglukkaq might be laughing about how small a national climate policy they can get away with. They plan to quilt a policy from the independent initiatives of the Provinces – beats developing anything real. Photo © Postmedia News.

On 19th March, Forbes has a glowing account of the work of Environmental Defense Fund over the last 10 years with major US corporations to improve their carbon footprints. It’s headed ‘Can Walmart save the planet?’ and it lists significant achievements by McDonalds (recyclable packaging), AT&T (efficient water use), and FedEx (hybrid-electric vehicles) as well as Walmart (energy efficiency changes in Chinese supplier factories). Large corporations will invest in environmental improvements when those investments save money in the long term, and in a world transitioning away from use of fossil fuels, energy efficiency and use of green energy are sound investments.

An announcement from the White House on 19th March reports plans to shift the share of electricity use by the US federal government to 30% from renewable sources, and to cut emissions by 40% from 2008 levels over the next 10 years, saving the country $18 billion in energy costs. In addition, the government is engaging with major federal contractors to encourage them to strive for similar emissions savings and efficiencies. A number of corporations, including IBM, Honeywell, GE, Humana, Hewlett Packard, Northrop Grumman, and Batelle have already announced their commitments under this plan. These steps are one part of the emissions reductions by 2025 that were announced in November in the treaty with China.

While it’s not an announced plan, my Google search did throw up an insightful piece by MP Elizabeth May, Leader of Canada’s Green Party published on March 9th. In it she used the kafuffle over the Keystone XL Pipeline to talk about the relative costs of different forms of electricity. Citing reports from the International Renewable Energy Agency (IRENA), investment bank Sanford Bernstein, and financial firm Lazard, which all reached similar conclusions, she stated that dramatic falls in the cost of solar infrastructure, and less dramatic decreases for other renewables, were such that in many places around the world, renewable energy is now competitive with fossil fuels. These analyses were all based on ‘levelized’ costs – a full-accounting procedure that takes into account all costs from initial construction of the generating plant to eventual decommissioning at end of life. I had seen previous comment to this effect. Elizabeth May drew the obvious conclusion – the time is fast approaching when Canada will not need pipelines to ship its dirty tar sands bitumen to markets around the world, because nobody will be buying it. (She was more diplomatic than that, although she did note that Canada was the only significant country not a member of IRENA, and wondered if Mr. Harper had ever seen these reports.)

Solar panels being installed on the Ikea store in Etobikoke, Ontario. Ontario has made progress in shifting energy generation away from use of fossil fuels. Image © Colin McConnell / Toronto Star

Now is the right time to up the ante – we need a target of +1oC.

Yes. It is a little bit like watching for the spring thaw on a river, but the signs are all around. Globally, there is starting to be real movement on the climate front. It makes me happy to realize that people are starting to take action. Now I worry that the progress must be sustained and it’s in this regard that I want to raise the issue of the 2oC target that the world has been told, by IPCC and nearly everyone else, is the right target to aim for as we seek to mitigate climate change.

Several months ago, I had discussed the arguments by social scientists Oliver Geden and Silke Beck that the 2oC goal should be raised even higher, because the world was not going to be able to reach it. In their view, we need a ‘realistic goal’, even if it is not environmentally sound. I still think their argument smacks of the same sort of political correctness that has no student ever failing, because it might damage his/her psyche, but that is neither here nor there. I think, for a number of reasons that it is time to up the ante and argue for a still more stringent goal. A +2oC change in global temperature is too much unless we want a radically altered future.

I’m not the first person to think this; nor is it a new idea. Coral reef scientists recognized, more or less at the time the climate community was coalescing around +2oC, that a temperature increase of that magnitude would pretty well close up shop for reef builders. And the organization owes its name to the idea that a 350ppm CO2 concentration in the atmosphere would be far better for us than the 450ppm concentration that conforms to +2oC. James Hansen had recommended 350ppm as a safe maximum CO2 concentration if we wanted to keep polar icecaps frozen. A target of 350ppm puts the clock back to about 1990 allowing coral reefs to persist, and a temperature regime (once equilibrated) about a degree higher than the average for the 20th century. I think, for several reasons, it is now time to start educating governments to recognize that +1oC is a much better goal than anything higher. Better they get to +2 while trying for +1 than that they take us to +3 and some unanticipated tipping points while hoping for +2. And best if the +1oC goal is attained.

I admit that I am arguing for +1oC because I care about coral reefs. They will be sorry shadows of their former glory at +2o (those that still survive), but they will persist at +1oC. But I am arguing for +1oC also because I fear that the changes that are now happening in the Arctic and Antarctic, the changes in the ocean, and the changes to intensity of weather are all turning out to be more severe, more quickly, than people have been saying.

Problems for Phytoplankton

On 28th February, I briefly commented on the article by Philip Boyd and colleagues in the December 2014 issue of Nature Climate Change. They had demonstrated that the changes occurring in the oceans are quite variable from one location to another, and that different combinations of change in properties mean that responses of biota will vary geographically in some cases quite substantially. The following images show the extent of variation in just four of the ocean properties they examined.
Boyd et al Fig 1 nclimate2441-f1

Extent and direction of change in temperature, pH, and concentrations of silicates and nitrates across the oceans. The colors scale as average degrees C, pH, and mmol/m3 in 2081-2100 compared to 1981-2000. Figure © Nature

In three of these cases, the pattern of change (positive or negative) is uniform, although the extent varies from place to place. For nitrates there are places in South-east Asia and the tropical Atlantic where the direction of change is reversed from the usual pattern. The next chart shows this graphically for the full range of properties examined.
Nature Climate Change 5, 1 (2015). doi:10.1038/nclimate2441

Chart from paper by Boyd and colleagues showing direction and extent of change in 15 ocean properties across 13 oceanic regions (SSO to AO), and the mean change for all ocean regions combined. Figure © Nature.

In this chart it can be seen that each ocean region has a unique pattern of change over the 100 year period when all 15 properties are considered, although some pairs [such as the east equatorial Pacific (EEPO), and the north subtropical Pacific (NSPO)] exhibit the same directions while differing in extent of change for each property. Boyd and colleagues discuss the likely responses by different groups of the phytoplankton.
coccolithophores diatoms

Marine phytoplankton come in a wide array of shapes and sizes. Those on left are coccolithophores, one of the major groups in all oceans, while on the right is a mixture of various diatoms, another major group. Photos © Steve Gschmeissner/Science Photo Library (left) and (right)

Perhaps at this point I should remind you of three very important facts concerning marine phytoplankton. First, they come in many shapes and sizes, belonging to many quite different taxa, and they do not all behave similarly in response to changes in oceanic conditions. Second, they are the base of all marine food webs, and the organic matter they construct, through photosynthesis, is the food which ultimately supports all marine creatures, including the fishery species that provide some 16% of animal protein in the diets of humans. Third, in doing all that photosynthesis, they put into the atmosphere almost one half of all the oxygen we breathe (the other half is put there by terrestrial plants). Put these three facts together and you see that the phytoplankton are pretty important to the way the biosphere functions.

Changes to temperature, to pH, or to concentrations of various nutrients will have physiological effects on phytoplankton, but they all won’t respond in precisely the same way. Further, the changes expected may cause adjustments in the geographic distribution of particular species or larger groups altering the local composition of the phytoplankton community. Changes in pH and in silicate concentration can be expected to alter the ease with which species of diatom or coccolithophore construct their external skeletons, and changes in several properties at once can cause synergistic effects that result in a different overall response by a species than the response that would occur to any one of the properties changing alone. As Boyd and colleagues point out, we simply do not yet have the physiological studies of the various taxa of phytoplankton to make even an approximate prediction of the overall effects on the plankton community in any oceanic region. Growth rates, and photosynthesis may be enhanced by warming, but that may be counteracted by a reduction in pH, or of silicates, or iron.

We only have one planet, and I suggest that this article should give us pause. We need to know a good deal more about how phytoplankton are likely to respond before we go merrily altering ocean properties as we are doing by altering the climate. We might find ourselves with a seriously compromised oceanic ecosystem that fails to provide all the oxygen and food that the oceans and we depend upon.

What’s happening to the oceans?

It’s not just the biology of the oceans which is complex. Efforts to understand the processes and pathways involved in the warming of the oceans as climate changes continue to uncover interesting, sometimes disturbing new insights. To put it bluntly, the oceans of the world are not just very large basins full of water, but basins full of water that differs in temperature, salinity, pH, and other attributes from place to place both vertically and horizontally. These differing types of water move relative to one another under the influence of winds, tides, and physics.

I’ve written several times about the giant ocean conveyor that circulates water slowly around the globe, and how surface warming and desalination due to melting of ice may be causing this giant pump to be slowing down. A new article in Nature Climate Change, published on-line on 23rd March, suggests that the ocean conveyor has begun to slow, and that this will lead to a slow-down of the Gulf Stream which runs up the eastern coast of North America, and a significantly larger than average rise in sea level along that coast. Stefan Rahmstorf, of Germany’s Potsdam Institute, and six colleagues scatted across Germany, Denmark, Spain and the USA, state that they now have evidence that AMOC, the Atlantic meridional overturning circulation, has already slowed by about 20% since 1900. AMOC is one part of the global ocean conveyor, responsible for taking surface waters deep and generally, if slowly, stirring the oceans of the world. AMOC plays a major role in this circulation – subsidence of surface waters in the North Atlantic, as they cool and become more dense, drives the Gulf Stream which moves immense quantities of heat from the tropics towards northern latitudes.  Washington Post provides a good coverage.

In their article, Rahmstorf and colleagues present a surprising global temperature anomaly graph. This one shows the change in temperature between 1900 and now. While the globe is almost entirely pink to red as you’d expect given the climate change that has been taking place, there is a conspicuous place in the North Atlantic that has been getting colder. (The only other place doing this seems to be one in north central Africa.)
Rahmstorf Fig 1 edited

Figure 1A from Rahmstorf’s article showing the change in average annual temperature between 1900 and the present. The North Atlantic includes an obvious exception to the general rule of getting warmer. Slowing of AMOC, which moves surface water to depth in this region, has reduced the amount of warm surface water brought to this location from further south. Figure © Nature Climate Change.

The implications of this change in global ocean circulation are far-reaching. As well as including changes to climate in Europe – future warming there will be less pronounced than otherwise – impacts include the likelihood of more extreme sea level rise along the east coast of North America than would otherwise occur. This sea level change is due to the fact that a current in the northern hemisphere raises sea level on its right flank and lowers it on its left flank; Gulf Stream slowing reduces that effect and sea level to the left goes up. North Carolina and Florida, both of which seem to be trying to legislate sea level rise out of existence, have a bigger problem than we all thought they did.

Another recent paper, published on-line in mid-February in Nature Geoscience, suggests that the melting of Arctic sea ice will proceed more rapidly than previously anticipated because of complex patterns of mixing of deep waters in that basin. Tom Rippith of Bangor University, UK, and four colleagues from UK and Norway, report that, other than surface warming, the largest source of heat in the Arctic basin comes from North Atlantic water that flows in at depths between 40 and 200 meters. This North Atlantic water is saltier and about 4oC warmer than the less saline water above it. One might expect a relatively slow mixing with transfer of heat upwards across a sharp boundary layer (a thermo- or halocline). This is what is observed in regions away from continents where overall depth is in excess of 2000 m.

However, what Rippith and colleagues have found is that in continental shelf regions of the Arctic, at depths from 200 to 2000 m, tidal flows interacting with the topography produce sufficient kinetic energy to generate the turbulence necessary for effective mixing across the boundary layer and the transfer of heat to shallower depths is up to 100 times greater. The effect is most pronounced in places where the topography is steepest at shelf edges. Heat flux in the central Arctic basin is about 0.05 to 0.3 Wm-2 (Watts per square meter). In shelf regions sampled, heat flux averaged 22 ± 2 Wm-2, and estimates as high as 50 Wm-2 were recorded at some sites. While these processes are uninfluenced by whether or not sea ice is present, the melting of sea ice does permit greater wind influences on surface water circulation in the basin. This will tend to enhance the transfer of heat into shallower waters.
Rippith ngeo2350-f1

Figure 1 from Rippith’s article showing the locations where they sampled, and the vertical temperature profile at three locations near Svalbard. Note that the off-shelf site (gray line in graph) shows a more step-like transition between cold shallow Arctic water and warm deeper Atlantic water, compared to the profiles from the two shelf locations where heat transfer is greater. Image © Nature Geoscience

To put this starkly, the North Atlantic water is warmer now than it used to be. The heat transfer from this to shallower Arctic waters will enhance melting of the sea ice, and a more open Arctic is one with enhanced mixing, and therefore more efficient transfer of heat. Yet another positive feedback loop is now in operation tending to make the Arctic Ocean lose its sea ice more quickly than climate scientists expected as little as a decade ago.
Rippith ngeo2350-f2

Rippith’s Figure 2 showing heat dissipation against A) depth, and B) topographic slope, with and without sea ice cover. Colors of symbols relate to sites in Figure 1. Steep shallow sites exhibit much greater heat transfer. Figure © Nature Geoscience.

Moving to the Antarctic, there is more evidence that the glaciers of Antarctica have passed that point where they will begin melting in earnest. A new article published on-line on 16th March in Nature Geoscience reports on studies of the Totten Glacier in East Antarctica. This article is almost unintelligible to the non-specialist, but the Washington Post does a good job of summarizing it. At its face, the Totten Glacier exists as an extensive, mostly floating, ice sheet (35 x 144 km in area) that appears to be melting fast. It will take a while, but with the dissolution of that ice sheet, there is enough ice upstream in that single glacier to raise global sea level 3 meters. The study revealed large, deep cavities under the ice sheet that enable relatively warm deep water to enter, and provide heat from below that hastens the melting. As lead author Jamin Greenbaum, of University of Texas, explained to the Washington Post, the results “support the idea that the behaviour of Totten Glacier is an East Antarctic analogue to ocean-driven retreat underway in the West Antarctic Ice Sheet (WAIS). The global sea level potential of 3.5 m flowing through Totten Glacier alone is of similar magnitude to the entire probable contribution of the WAIS”. In other words, this one East Antarctic glacier could melt to produce as much sea level rise as the melting of the entire West Antarctic ice shelf. While Antarctic melting is still estimated to take several hundred years, the point of such studies is that we now appear to have unleashed a melting process that is not going to stop any time soon – a melting that will raise sea level substantially higher than the 20 cm that the state of North Carolina legislated only two years ago. (Their action was silly then; it seems ridiculous now.)

As if to bear these stories out, NOAA’s National Snow and Ice Data Center (NSIDC) released its report for February and reported that the Arctic had likely reached its maximum sea ice extent on February 25th. Sea ice covered 14.54 km2 on that date, the lowest maximum extent ever recorded. This year’s maximum is 1.1 million km2 below the average for 1981 to 2000, and 130,000 km2 lower than the next lowest year, 2011. It also occurred just one day later than the earliest peak in 1996, and 15 days earlier than average. When we combine the area of sea ice in the Arctic and Antarctic, we have been losing an area of sea ice approximately equivalent to the state of Maryland every year, and the sea ice out there now is predominantly young and thin. There is still a lot of ice around our poles, but there is a good deal less than there used to be. And every indication suggests that it is disappearing ever faster.

And what about changes on the land?

In the early 1980s I took part in a memorable four or five day workshop organized by ecologists at University of South Florida. During the workshop, we were taken on a field excursion, for reasons I do not remember, and in the course of this found ourselves on top of a modest hill with an attractive view of the surrounding land somewhere east of Tampa. Although the hill was barely 20 m high, we were told that we were standing on the highest point of land from this point south in Florida. Pressed further, our hosts admitted that there was one piece of land further south that was higher. That was the landfill west of Miami. I understand that landfill may be even higher now.

Humans have made a lot of changes to the terrestrial parts of this planet, and recent interest in the advent of the Anthropocene has led to enumerations of those changes. Thus the editorial in the 12th March issue of Nature that discussed the Anthropocene begins with a story about Devil’s Mountain, or Teufelsberg, a prominent landmark near Berlin, which rises 80 m above the surrounding plain and is the dump site for the 25 million m3 of concrete rubble removed from the city at the end of WWII. The editorial goes on to mention that, since WWII, our population has increased by 180%, our use of water by 215%, and our use of energy by 375%. During that time we have skewed the composition of the atmosphere, warmed the planet, eroded the ozone layer and acidified the oceans.

In that same issue, Richard Monastersky notes that as well as doubling the amount of methane in the atmosphere, and increasing that of CO2 by 30% (an amount not exceeded in at least the last 400,000 and probably several million years), our agriculture, construction and the damming of rivers are stripping away sediment at least ten times as fast as the natural forces of erosion.
670px-los_angeles_ca_from_the_air Wikipedia

Los Angeles used to be a natural valley environment ringed by hills. Photo © Wikipedia

All in all, we have captured 40% of the land for our own fields, parking lots and cities, and have also captured about 40% of the production via photosynthesis for our own use. Our impacts on climate are just one of many things we are doing to this planet, and our erosion of the natural resilience biodiverse ecosystems possess is leaving the biosphere less capable of withstanding the climate shocks, and other shocks that are sure to come unless we change our ways. A good place to begin is to rein in our impacts on the climate and on ocean chemistry. Put these things all together and I think we need to start a conversation about limiting global warming to +1oC. If we do not, I fear the world we will create as the Anthropocene progresses.