Week 8: Planetary Boundaries Framework Pt. 3 - Post 1

Planetary Boundaries Framework Pt. 3 - Notes

Week 8 - Planetary Boundaries Framework Pt. 3 Notes

Lecture 1 - Biodiversity Loss

Professor Johan Rockstrom

-Think of it, without the living species everything from vegetation, trees to animals and small insects, pollinators, we would have no biomass, there would be no carbon sequestration, there would be no rainfall because a large portion of our fluxes of water originate from the canopy, from vegetation transpiring and evaporating water back to the atmosphere. It regulates the flows of fresh water, regulates the flows of carbon, nitrogen and phosphorus. The living biosphere is a fundamental component in regulating the stability of the entire Earth system.

-And this relates to two components. One is the genetic diversity; the treasure of genetic code, which forms the adaptive capacity of the entire Earth system. But it's also the diversity of functions that we know today that in order to develop, for example, food for a world population of 7 billion people we need the functions and landscapes for pollination, the function of microorganisms in the soil to develop organic matter which in turn delivers nutrients for plants, without which we would have no food.

-We're really mismanaging biodiversity in the world. In fact we are today, based on the observations we have, in the sixth mass extinction  of species in the world, the first extinction to be caused by another species, and one of these six, for example, being when we lost the dinosaurs 65 million years back on Earth. So these are big, dramatic changes,

-EXP. illustrated here for example when it comes to how we're dealing with global fisheries. Just over the past sixty years from the 1950s and the onset of the great acceleration when we started the exponential rise in pressures on planet Earth, you see here the extraordinary social-ecological journey of not only increased landings of fish, but also that fish efforts are changing dramatically from small scale fisheries to large scale industrial fisheries where we are basically vacuum cleaning large tracts of oceans, not only in shallow waters but also in deep ocean regions. We have the classic examples of collapse of fisheries; like the cod fisheries off the shores of Newfoundland.

-Once we cross a tipping point with regards to loss of fisheries we can actually lock the system in a situation where the fish does not even come back. So these are big, dramatic changes that we need to incorporate in our understanding of the resilience of the Earth system.

+So loss of one species in this case over-fishing, has a propelling effect on seabird populations which risk collapse, in fact, in many parts of the world.

-(Exp - Bees) So again, understanding that biodiversity - without biodiversity we cannot have modern agricultural systems, and therefore we get locked in an undesired state in terms of delivering human well-being.

-How many species we're losing, over time. And this indicator called the extinction rate per million species per year, which is a good indicator of the pace of loss of biodiversity. The natural background rate of loss is roughly one species per million species per year, that's the normal background rate.

-We estimate as a first guess that a boundary lies somewhere between ten and hundred lost species per million species each year. So the boundary was placed at ten species lost per million species per year. Now today we're losing species at roughly ten to hundred times faster that rate. That's why we can today say with quite a high degree of confidence that we've actually transgressed and are in a danger zone on biodiversity.

-Extinction rate only gives us a measure of diversity, it doesn't give us any measure of the functions biodiversity plays.

Key Point - The correct answer is "local" and "regional". Biodiversity loss is the result of local (ex. the Newfoundland Cod collapse), and regional (ex. linked changes in seabird populations) pattern changes in ecosystems. Because living organisms have many linked functions in the Earth system, losses of genetic richness, species and habitats have systemic global consequences, which is why scientists have proposed a planetary boundary.

Key Point - Biodiversity loss leads to a reduction in the number of species left that can carry out a given function, or in other words, functional diversity. Also, biodiversity loss implies a reduction in genetic diversity, which makes this particular species more vulnerable. For example, if a disease breaks out in a population with low genetic diversity, it may wipe out the whole population if no individuals are able to fight the disease. On the whole, biodiversity loss therefore, leads to an increase of vulnerability of ecosystems; without the presence of certain species, the ecosystem risks being locked in a different state (ex. fishery collapses). This implies decreased resilience, i.e. the system loses the capacity to change and adapt while simultaneously remaining within the same state.

Key Point- A safe boundary within which we have a high likelihood of being able to rely on biodiversity, the richness of all species on Earth, as a support for human development.

Lecture 2 - Land and Water Use Change

Professor Johan Rockstrom

-Now for land use the absolute critical issue to recognize is that what determines the ability of land areas to regulate fresh water, regulate flows of different nutrients, be habitats for biodiversity, and regulate fresh water flows, is what kind of ecosystems we have. And what we're finding is that the number one biome system to regulate the stability of the Earth system is our forest systems.

-Cropland is the largest human-caused land use change on Earth. And we used it because we have good data on cropland extent and cropland change. Now in the updates that we're doing we're focusing much more on what you see on this slide, namely directly analyzing how much of the different critical forest systems do we need to regulate the Holocene stability on planet Earth.

-And we're finding from science that the rainforests in the world, the temperate forests, and the boreal forests are the most critical ones in regulating Earth resilience.

-And this has dramatic effects for local biodiversity, devastating effect for local indigenous communities, but it also directly affects the entire regulation of the climate system and the regional patterns of rainfall across vast areas. So these are truly regulating functions at the planetary scale. And we only have three remaining rainforest areas: the Indonesian, southeast Asian, the Congo Basin in Africa, and the Amazon rainforest in Latin America.

-When you change land use we can have so large [a] shift in fresh water flows that it could actually induce tipping points, meaning for example when we cut down forests, take out fresh water in river basins, that we could have permanent tipping points where large tracts of land get locked into desertified states, as one example. So there are examples of how we can induce tipping points when pushing land and water systems too far.

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-So if we move into fresh water and the diagnostic of what makes water a planetary boundary it's in its fundamental diagnostic the role water plays as the bloodstream of the biosphere. Water regulates everything we know in the biosphere, all vegetation growth, all biodiversity depends on fresh water. Humans depend on freshwater… So what we're recognizing increasingly that the global hydrological cycle, which is finite, is fundamentally a prerequisite for the stability of the Earth system: it regulates climate, it regulates biodiversity, and it's fundamentally important for social and economic development.

-Water is a planetary boundary, because it's safeguarding the management of the freshwater cycle, from the local watershed scale to the base of the global scale regulates the entire flow of fresh water which, again, regulates climate and biomass, but also how intimately coupled fresh water is to land management and deforestation. So these are key justifications from science making water and land so important as planetary boundaries.

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+We are soon nine billion people on our planet. Everyone with a right to development and the basis for development will be access to food and fresh water. Recent estimates shows [show] that just to feed humanity in a world in 2050 with nine billion people will require potentially an increase of fresh water use from our current 7000 cubic kilometers of freshwater per year, both in irrigation and rain for that culture, to in the order of 9000-10 000 cubic kilometers per year. This in a planet where already 25% of our large rivers no longer reach the ocean because we're taking out so much water to produce food.

+Yes, we are in a very challenging position in terms of sustaining freshwater and land within a safe space. On the other hand we can, within a safe space, also meet demands for a growing population.

-Calculated a global number of the maximum amount of water that we can consume in our rivers before we end up with a situation where we could see evidence of tipping points.

-exploring based on vast amounts of knowledge that is out in the field on how much water do we need to sustain in our rivers to keep ecosystems functioning, what professionals call environmental water flows.

-our estimates show that we need to keep in the order of 75% on average for all the big forest systems, and we are today actually at a situation where we have cut down more than 25%, we actually only have 62% of forests left on Earth. So we're already in a danger zone with regard to the planetary boundary on forests. estimate shows we need to keep 85% of rainforest systems, that we need to keep 50% percent of our temperate forests which play a lesser important role in terms of its total coverage to maintain Earth resilience, and that we need to keep in the order of 85% of our boreal forests to stay within a safe operating space. And this is a signal or a way of showing that the planetary boundary at the global scale can actually be translated to the operational scale of forest management in large parts of the world.

-25 to 50% of fresh water must be kept in the rivers, and that there's a large variation here is that it depends for each basin on how much fresh water there is, if these are permanent basins, if these are intermediate basins, if these are only infermeral basins, the flux intensity, etc. So there's a lot of intricacy here but it just shows that we can operationalize this at the level of management.

Lecture 3 - Interface with Global Nitrogen and Phosphorus Cycles

Dr. Sarah Cornell

-The global biogeochemical cycles link the living and the non-living parts of the Earth system. Chemical relationships control the general patterns of interaction between geological and biological processes. It's the way that the nutrient elements flow through land, ocean and atmosphere that ultimately regulate all of life on the planet. And human activities are changing all of these basic cycles.

-It's important to keep in mind that these flows are the result of many different Earth system processes, and at the same time it's also important to remember that in the boxes, atmosphere, ocean, biosphere, and so on, we see many processes and feedbacks happening all the time. The Earth system is a very dynamic system.

-N and P are two macronutrients that support modern agricultural systems, and thus our ability to produce enough food for all. The main source of alteration to N and P flows is the excessive use of chemical fertilizers in modern agriculture. It is used in agriculture to stimulate and increase food production. Other sources of nutrient overload of N and P in groundwater, lakes, rivers, and estuaries are industrial processes and fossil fuel-based transport systems.

The numbers show the annual flows between the different stocks of carbon in the Earth system, and the red arrow shows the human disturbance.

The flow diagram shows the natural changes in white and the red arrows show the major changes that humans are causing in the system. The biggest change is the transformation of atmospheric nitrogen into reactive forms, like nitrate and ammonia. We do this because we need that nitrogen as fertilizer for the food production. We also fix nitrogen from the atmosphere through many other processes, industrial processes and transport as well.

-but you can see that that isn't all that we're doing. This nitrogen is not all taken up by crops. A large amount is being released back into the atmosphere where it causes air pollution problems and acid rain, and is a climate greenhouse gas, and the rest is released into rivers and oceans where we have problems of nitrogen enrichment and eutrophication.

+We see biogeochemical and ecological tipping points in area far away from the most intense sources.

Unlike nitrogen and carbon, phosphorus isn't really affecting the atmosphere. The biggest change is that human activities are mining it from the ground and applying it to land surfaces for agriculture, 25 million tons a year. But a large amount of this phosphorus is being mobilized in the Earth system through the watercourses. It goes into our rivers and receiving oceans. It also contributes to nutrient enrichment (eutrophication).

-It's the risk of large and irreversible dead zones in the oceans that really calls for a planetary boundary for phosphorus.