How to cool the Earth, will trees save us, and what is the worst-case scenario for the future?

    31 May 2021

    The problem of climate change is already there. A 2013 UN report said that it’s necessary to keep the planet warming at less than 2 ° C in order to avoid irreversible changes in ecosystems, and in 2020 this figure was already 1.2 ° C. Many believe that if not decisive action is taken to delay climate change, adaptation will be much more costly and more risky.

    Let’s get acquainted with Knife, Institute for Global Climate and Ecology and Greenpeace (Russia) analysis why change is now called the climate crisis. Also we’ll check what it means for the lives of ordinary people and what tools are in the arsenal of climate specialists.

    First of all, Polina Karkina, Climate Projects Coordinator in Greenpeace (Russian Branch), explains what climate crisis is.

    Global warming is just one aspect of what is happening to the Earth’s climate today. In addition to the increase in the average annual temperature of the planet (in 2020 it was already 1.2 ° C from the pre-industrial level), the number of extreme weather events is growing: forest fires, melting glaciers, etc. As a result, coastal cities are threatened with flooding, storms and floods are becoming stronger; people do not have enough food, drought, deadly heat, melting permafrost, infrastructure collapses, etc.

    All this phenomena scientists today call the climate crisis – and this concept is now becoming the main one. The very word “crisis” already suggests that the situation is very serious.

    All of the above are the consequences of warming “only” by a little more than 1 ° C. But if the planet warms up further, the scale of negative consequences will also grow.

    The main cause of the climate crisis is greenhouse gas emissions due to human activities: burning coal, oil and gas, deforestation, farming, waste management. The degree of further warming of the planet will be influenced by how quickly humanity changes its course and moves to green, low-carbon economic development (that is, with low greenhouse gas emissions).

    What is the point of no return?

    Climate change accelerates over time, potentially to the so-called point of no return.

    Climatologists identify phenomena after which the consequences of the climate crisis can become irreversible, for example:

    complete disappearance of sea ice in the Arctic in summer,

    the disappearance of the ice sheets of Greenland and Antarctica,

    collapse of ecosystems of the Amazon forest and boreal forests in Russia and Canada,

    melting permafrost.

    The exact date of the onset of these consequences cannot be given, since future changes will depend on how quickly humanity will reduce greenhouse gas emissions.

    What does the worst-case scenario look like?

    If greenhouse gas emissions are not reduced in the near future, then one of the worst-case scenarios is that the planet will warm by more than 4 ° C by the end of the century or even earlier.

    This scenario can be described as a climatologist’s nightmare for large-scale extreme weather events:

    heat incompatible with life,

    ocean acidification,

    extinction of species,

    significant melting of the planet’s ice sheets and an increase in the level of the World Ocean by several meters,

    resettlement of billions of people,

    outbreaks of infectious diseases,

    conflicts over food and water,

    world chaos.

    This development of events must be avoided. Therefore, the Paris Climate Agreement sets out the goal of not exceeding the temperature rise of the planet by more than 1.5 ° C compared to the pre-industrial level. Greenpeace advocates that governments, businesses and the public make every effort to achieve this goal. Emissions need to be cut drastically today.

    Is there a solution?

    There is a concept of carbon neutrality (zero net greenhouse gas emissions). This is a balance between greenhouse gas emissions and their absorption within the country, so that in the end you get zero. For example, in 2020, China announced its intention to achieve carbon neutrality by 2060, and Japan by 2050. To do this, it is necessary to transform all sectors of the economy, switch to green technologies, and also reduce the current scale of overconsumption.

    Activists of Greenpeace offer what to do today:

    increase the share of renewable energy sources,

    use new technologies in industry,

    encourage the population to switch to sustainable diets (containing more plant than animal products),

    reduce the amount of solid municipal waste,

    transform forestry and more.

    And ordinary people can change their daily habits. This is also very important and really is part of the global efforts to stabilize the climate.

    Geoengineering as a radical intervention in the fate of the planet

    Scientists have a highly undesirable, but possibly effective way to interfere with the life of the Earth which is called geoengineering. This is a targeted large-scale intervention in the natural systems of the Earth that should help slow climate change.

    Anastasia Revokatova, Senior Researcher in Institute of Global Climate and Ecology (IGCE), PhD in Geographical Sciences, explains that geoengineering is divided into two groups, different in the way of influence:

    1. Removal of carbon dioxide from the atmosphere.

    For this, humanity can use a variety of methods. For example, it can capture carbon dioxide from the atmosphere with special installations. Or fertilize the ocean with iron to increase its bio-productivity and thus the flow of carbon dioxide into the ocean (as the fish absorb it). Or plant new and rehabilitating old forests, this is also a method of CO2 removal.

    2. Management of solar radiation.

    The more sunlight is reflected from the Earth, the less heat remains in the atmosphere, therefore, the planet cools. These methods are used in IGCE. The most popular way to manipulate solar radiation is to create a reflective aerosol layer in the stratosphere (about 20 km above the Earth). Sulfates and calcium carbonate are suggested as active substances. This method, in fact, repeats the effect of volcanic eruptions, because after them – if the eruption was powerful and the aerosols hit sufficiently high altitudes – the average global temperature on Earth decreases!

    This is how a volcanic eruption and a tethered balloon, which pumps sulfate aerosols into the stratosphere, reflect solar radiation. A source

    Solar radiation management (SRM) methods do not remove the main cause of global warming – the increase in the concentration of greenhouse gases, but only mask it, increasing the albedo – the reflectivity of the Earth.

    Therefore, these methods are considered auxiliary. They can help cool the planet for a period when other methods are powerless or not yet effective enough (for example, they are only gaining momentum). But none of the scientists claim that solar radiation management is the way to combat global warming. It is necessary to try all other methods, and keep developments and research on the management of solar radiation in reserve.

    We, humanity, can always change something, but at some point it will be much more difficult to do.

    What are “feed-backs” in climatology?

    Forward feedbacks are changes in individual ecosystems that can trigger a chain of effects. For example:

    sea ​​ice is melting due to warming

    decreases the reflectivity of the Earth in the polar regions

    accordingly, more radiation comes to these areas

    they get hotter

    the ice is melting even more

    You can also add to this chain the melting of permafrost, due to which methane, a greenhouse gas, enters the atmosphere, so warming will increase again due to an increase in the greenhouse effect.

    Will planting trees save us?

    No, the planet cannot be cooled by planting trees.

    Firstly, there will not be enough space, since people still need to plant plants somewhere for food.

    Secondly, only the young forest absorbs oxygen. Old forest and fallen trees are decaying biomass that gives off carbon dioxide.

    This biomass needs to be removed and disposed of. In general, all planted forests need to be monitored so that they continue to “work”. But in addition to other methods of improving the climate, planting trees is quite possible to use.

    What to do with CO2 captured from the atmosphere?

    Carbon dioxide can be stored in underground reservoirs, such as cavities from which gas or oil has been pumped out. There are such places both in the seas and on land.

    But in order to pump carbon dioxide somewhere, it still needs to be delivered there. That is, not only to capture CO2 from the atmosphere, but also to build a system that will deliver it to the injection areas, which are sometimes thousands of kilometers away. It’s insanely expensive.

    You can capture carbon dioxide in factories – this is partly done. Then it is pumped into cylinders and can be further used, for example, in the chemical industry, metallurgy, and the food industry. Of course, this does not compare with the volumes in which it must be pumped out of the atmosphere.

    It is most likely safe to pump CO2 underground. But no one excludes some natural disasters, due to which carbon dioxide can be thrown back into the atmosphere.

    There are even such model scenarios. However, it is difficult to imagine that natural disasters will engulf the entire planet at once. I think if there is a failure, it will be in one area. But this can still pose some danger, and it must be taken into account.

    Can the Earth be cooled?

    There are three very real ways to reduce the temperature of the Earth.

    1. Reduce greenhouse gas emissions. This implies a switch to cleaner fuels, alternative energy sources where possible, and a reasonable consumption of resources.

    2. Remove carbon dioxide from the atmosphere. So far, by the methods that have been studied by scientists. But there is also a need for the early development of new methods that researchers are already proposing, but have not yet been fully studied.

    3. Manage solar radiation. Theoretically, this method can be used, there are developments in this area. But until these methods are sufficiently tested and studied, no one will allow them “on the stage.” They are used only in some extreme case, when it becomes clear that all points of no return have been accurately passed without the control system, and research will show that it is now “cheaper” to use the control system in order to keep the temperature at an acceptable level.

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