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How are plants be affected by climate change ?




PART 1 : A major problem


We have seen in our previous article on The disappearance of plants, a fatality? that one of the main causes of extinction of plants is the destruction of their natural habitat. Another factor is climate change. In the report made by Kew Botanical Gardens, two out of five species of plants and fungi are in danger of extinctionas, a direct result of climate change.


In this new article, we will look at the different consequences of climate change that are affecting plants. And the impact that plants have on climate change.


Climate change


Climate change refers to long-term variations in temperature and weather patterns. These changes can be natural variations, for example related to solar cycles. Since 1800, human activities are one of the main causes of climate change. Due to an increase in the combustion of fossil fuels such as oil, gas or coal, these generate a kind of blanket around the Earth trapping the heat of the sun and causing a rise of temperatures.



The main consequences of climate change are:

-Fires

-Flooding


The average temperature of the planet has increased by 1.1°C between 1850 and 2017, and France has experienced an increase of 1.5°C since 1900 (c.f. Fig.1), the consequences of climate change can vary from region. For example, the report of the World Meteorological Organization states that the polar regions are warming twice as fast as the rest of the world. But recently this report indicated that Europe is warming twice as fast as the rest of the world.



Fig 1: Average surface air temperatures from 2011 to 2020 compared to a 1951 to 1980 baseline average. Source: National Aeronautics and Space Administration Goddard Institute for Space Studies

The greenhouse effect is a natural phenomenon that contributes to the maintenance of temperature levels, but its excessive concentration due to human activities intensifies this phenomenon and provokes global warming.











And in France?


In France, climate change is mainly visible through the increase in forest fires. The Mediterranean Basin is particularly exposed, it is defined as a "Hotspot" of climate change, that is to say that it is warming up more rapidly than the rest of the world. But climate variations affect all regions, some are more particularly affected, this is the case in the mountains, in the Alps or the Pyrenees more affected than the plains. The melting of the snow cover and the retreat of the glaciers leave rocky and barren lands that reflect less solar radiation than the snow and ice, so these rocky areas warm up and retain the heat.


Did you know that dust cloud episodes in the Sahara accelerate the melting of ice and snow in the mountains? Snow and ice are covered with a layer of sand that causes a decrease in reflectivity, as a result sand-covered snow absorbs more heat and melts faster.


There are many drivers of global warming. In France, the main emitters of greenhouse gases are industry, transport and agriculture (c.f. Fig.2)


Fig 2 : Répartition par source des émissions de GES en France entre 1990 et 2019; AEE 2021


How is climate change affecting plants?

BD Tom Astuce sur les déplacements des zones géographiques
BD Tom Astuce sur les déplacements des zones géographiques

-Changes in geographical distribution

Fig 3: OPCC; The Pyrenean Climate Change Observatory, OPCC, aims to monitor and understand the phenomenon of climate change in the Pyrenees to help the territory adapt to its impacts.

The transformation of environments is reflected by the disappearance and appearance of certain species, also by the displacement of certain geographical areas as shown in the diagram with the example of the melting of snow cover. As the climate warms up, the areas of distribution (this is the area that defines the geographical distribution of a species) migrate to colder areas (see Fig. 3).


-Risk of invasion and/or expansion of exotic species

Climate change favors the movement of new exotic species, as a result of new and more favorable climatic conditions, but also because of the decline of native species.


-Early flowering

Based on a study by Vigie Nature, plant leaves and flowers appear between 2.5 and 5 days earlier for each degree of temperature increase.


-Development of diseases

The temperature increase disturbs the metabolism of the plants, which favors the development of parasites. Forests are not saved, as droughts lead to hydric stresses that benefit the development of parasites such as bark beetles.


-Disappearance of pollinators

Insect pollination contributes to 9.5% of the world's food production, but some insects are very sensitive to environmental conditions, such as the bumblebee, which is one of the most important pollinators, so their decline leads to the decline of the plants they pollinate.


-Change in common species

Some species become more frequent over time while others disappear. For example, the Madrid Brome (Anisantha madritensis), is increasing and conversely the Alpine Gentian (Gentian alpina), is decreasing. The plants that are maintained and that easily colonize the spaces are those that have a higher thermal preference index, so they prefer the heat.


5 plants threatened by climate change


1. Quiver tree (Aloe Dichotoma)

Present in the arid regions of the south of Africa. Its young shoots do not resist to climatic hazards, so this species has difficulties to reproduce.


2. Acropora Cervicornis and the corals of the world

Corals are particularly sensitive, because of the warming of the seas, this species must be confined in less warm areas.


3. Panicaut viviparous

Present in Europe and only present in protected parks in France, this species is likely to disappear completely within a decade.


4. Lobelia (dicotylédone)

This plant is mainly present in East Africa. Because of the constant rise in temperature, it is threatened.


5. Bazzania bhutanica

It is located in tropical and subtropical dry forests. Because of the destruction of its habitat and global warming, this species is seriously endangered.



PART 2 : Major threats


Human activities


Fig 4:NASA observed temperature relative to the 1850-1900 average as a pre-industrial reference. The primary driver of global temperature increases in the industrial era is human activity, with natural forces adding variability

Based on the NASA report (c.f. Fig.4), human activity is the major factor in global warming with an increase since 1970.












Fig 5 : GHG emissions by sector worldwide; Science et Vie Hors série n°240 2007

The production of energy, through fossil fuels such as oil, coal or gas, promotes the production of greenhouse gases. Industry is responsible for soil and water pollution and waste production, and is responsible for more than half of the emissions of atmospheric pollutants and greenhouse gases.

Agriculture contributes to the production of greenhouse gases through soil and water pollution, but it also has positive effects. Together, these three sectors account for nearly 65% of total global greenhouse gas emissions (c.f. Fig.5).


Fig 6: Agricultural production of the main EU producer Member States in 2017 source: Eurostat

French agriculture is at the top of the list of the world's largest agricultural countries, with a surface area of 670 thousand square kilometers, producing 1.7% of the world's agricultural value. Moreover, France is the leading European agricultural country (c.f. Fig.6), producing nearly 17% of the European agricultural value in 2012, compared to only 14.4% for Germany and 11.9% for Italy. France, which is among the largest producing countries, is thus a key player in the international commodities market.




What are fossil energies? Fossil energies come from the methanization of plants or living beings buried in the ground for several million years, which means that they are limited and non-renewable. For example, coal comes from the methanization of plants such as ferns.

There are two kinds of fossil fuels, the conventional ones (gas, oil and coal) and the non-conventional ones that require a particular extraction, gas and shale oil are part of it. The difference between oil and shale oil is the composition of the rock in which it is found and the techniques used for its extraction (the most used technique is hydraulic fracturing, it consists of drilling the rock to reach the shale layer, between 2000 and 3000 meters below the surface of the ground), it is the same for gas. These unconventional energies present more risks during their extraction for the environment, they require the injection of CO2 in the subsoil which pollutes the water, the air and the soil.


Greenhouse gases


Greenhouse gases are gases that act as an insulating layer for the Earth, trapping heat and warming the planet.

Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are the three main effect gases. They are of natural origin, but their rate in the atmosphere has largely increased due to human activities. In 2019, their total emissions related to human activities represented the equivalent of 30 billion tons (Gt) per year, which corresponds to 80% of CO2 emissions.


-Natural greenhouse gases :

1. Water vapor (H2O), the most important greenhouse gas naturally present in the atmosphere.

2. Carbon dioxide (CO2), is created by the natural decomposition of animal and plant matter. By 2020, its concentration in the atmosphere had risen to 48% above its pre-industrial (pre-1750) level. Trees help regulate the climate by absorbing carbon dioxide (CO2) from the atmosphere.

3. Methane (CH4), is created by the decomposition of plant matter in wet environments. Especially livestock because of industrialization, they produce large quantities of methane when they digest their food. This one is less present in the atmosphere, but it has a more important polluting ratio than the carbon dioxide. It is responsible for more than 23% of global warming, but all animals in general produce methane.


Fig 7: Methane source: Save4planet

4. Nitrous oxide or "laughing gas" (N2O), nitrous oxide is prepared by decomposition of molten ammonium nitrate between 250°C and 260°C.

5. Ozone (O3), ozone is naturally present in the stratosphere (at an altitude of 10-15 km): it protects the planet against dangerous UV rays.


-Industrial" greenhouse gases:

6. Fluorinated gases (CFCs, HCFCs, HFCs, PFCs, etc.), used in cooling systems (refrigerators, air conditioning), as solvents.

7. Sulfur hexafluoride (SF6), used in transformers and double glazing (sound insulation).

8. Nitrogen trifluoride (NF3), increasingly used as an industrial degreaser in the manufacture of LCD screens and photovoltaic cells.


The main causes of this climate change are;

-The use of fossil fuels

-Deforestation

-Intensive livestock farming


These causes are linked to the increase in population, which leads to an enormous increase in greenhouse gas emissions (c.f. Fig.8).


Fig 8 : ONU ; sources temperature : CEA, CNRS, météo France


The main issuers

Fig 9: Global greenhouse gas emissions, 2021 report of the European Commission's Joint Research Center

Since 2000, China has been the leading emitter of greenhouse gases, accounting for 30% of CO2 emissions in 2019. This figure should be put into perspective in relation to the country's economic model. China is already in full development with large cities being built. Moreover, Chinese factories are constantly working to create products that are designed and sold all over the world. However, the main fuel used in these factories is coal (c.f. Fig.10), which is the most polluting energy. It is followed by the United States with 13.4% of emissions.

The European Union accounts for 7.7% with France at 0.8%, thanks to nuclear power which emits 70 times less CO2 than coal.







Fig 10: Coal is the main contributor to China's CO2 emissions; source: Global carbon project.

From 1990 to 2020 the European Union has reduced its greenhouse gas emissions by 31%, with measures taken in 2019 to replace coal with gas and renewable energy sources. Measures have been taken to achieve climate neutrality by 2050, you can consult them here.














Agriculture


The destruction of forests is caused by the increase in population but also by agriculture or fires that generate billions of tons of carbon in the atmosphere every year. According to a study conducted by IOP Science, agriculture is responsible for 73% of deforestation, it is the expansion of agriculture (palm oil and soy for example) and livestock that are the main causes of deforestation and forest degradation.


Practices have been put in place to address climate issues:

  • Nighttime irrigation to reduce water stress and avoid greater evapotranspiration than during the day.

  • The implementation of irrigation systems that water only the roots of the plants.

  • The reduction or even elimination of the use of phytosanitary products

  • The late destruction of the CIPAN. In agriculture, a nitrate trap intermediate crop is a catch crop or more generally a crop of secondary interest between two cash crops with the environmental objective of protecting water quality from nitrate pollution.

  • The use of drones to enable real-time diagnosis and observation of the condition of very large crops in order to target the use of water and phytosanitary products.

  • Soil analysis to determine which crops can grow in certain areas and what yields the fields will produce.


Fig 11: Breakdown of greenhouse gases from the agriculture and forestry sectors in 2019 Source: CITEPA, Secten 2020 report

The main greenhouse gas emissions in agriculture are first CH4 which represents 45% of the emissions, then NO2 linked to the crop representing 42% of the emissions








Not all farming methods are bad:

-Reasoned agriculture is an agricultural production system whose primary objective is to optimize the economic result by controlling the chemical substances used (pesticides, fertilizers) in order to limit their impact on the environment.

-Sustainable agriculture is an agricultural practice that is economically viable and sustainable, environmentally sound and socially equitable. The goals of sustainable agriculture must meet the needs of today without compromising the natural resources for future generations.

-Agroecology; term for agricultural practices that link agronomy (science of agriculture) and ecology (science of the environment).


The agricultural sector is part of the causes of climate change, but it also suffers the consequences. Indeed, global warming is the cause of the rise in wheat and corn prices, with a 20% increase since 1980. According to the IPCC, losses due to numerous droughts have tripled over the last 50 years in Europe (c.f. Fig.12).


Fig.12 : RE6 du GIEC

Based on the IPCC, 8% of the current agricultural land will become unsuitable for agriculture by 2100, and this figure could rise to 30% in a more pessimistic scenario.


Did you know that cultivated Christmas trees help during their growing years to capture CO2? Indeed, Christmas trees are excellent consumers of CO2, during its ten years of life, its consumption reaches 18 kg of CO2. A single hectare of Christmas trees retains 12.2 tons of CO2.


PART 3 : Reversing the trend


The main greenhouse gas captors


What is a carbon sink? A carbon sink stores tons of greenhouse gases for centuries, preventing them from being released into the atmosphere.


There are different types of carbon sinks, divided into two main parts:


1. Natural carbon sinks

  • The oceans; they have the largest carbon storage capacity: they sequester nearly 30% of the CO2 emitted by humans. Today, the oceans are a carbon sink threatened by climate change: with pollution, the waters are becoming more acidic and the storage capacity is decreasing.

  • Soils; however, the storage capacity of soils is decreasing since the expansion of urbanization and intensive agriculture, soils capture CO2 through plants and trees that capture CO2 through photosynthesis: it is transformed into organic matter and accumulates in large quantities in the soil.

  • Forests; through the mechanism of photosynthesis, capture 15% of CO2 emissions produced by man, the Amazon representing half of the tropical forests, it stores 450 billion tons of CO2 each year.

2. Artificial carbon sinks

This means locking up carbon dioxide directly underground, for example in old oil wells.


Fig .13 : Carbon sink in Paris. source ecotree

The City of Paris is experimenting with artificial carbon sinks (c.f. Fig.13), (structures visible in the streets), which store as much carbon as 50 trees. However, these sinks are very expensive, not very aesthetic and their storage capacity is limited in time.






The solutions to fight


In 2021 was created the law climate and resilience fight climate disruption and strengthening resilience to its effects. All areas of our lives are concerned;

  • Consuming

  • Produce and work

  • Getting around

  • Housing

  • To feed oneself

  • Strengthen the judicial protection of the environment

For example, it is now illegal to rent out inadequately insulated housing, or the creation of zones that leave the most polluting cars outside city centers in large urban areas.


Other provisions are also being made;

  • Construction of hybrid vehicles

  • Better insulation of buildings

  • Controls on the energy performance of industrial equipment

  • Massive investment in clean energy (wind, geothermal, solar...) and biofuels

  • Stop deforestation of tropical forests, launch of reforestation projects

  • Vegetation of cities; The city of Besançon has set up a vegetation project in the Place de la Révolution, which aims to reduce the impact of global warming in the city. Paris has an urban forest project at the Place de Catalogne, but also at the square of the Hôtel de Ville and the Place du Colonel Fabien.

Some cities have trees in pots, but unfortunately they dry out more quickly. Indeed, they are often cultivated in a peat-based substrate, the plants in containers are quickly thirsty when the sun warms them. But this is not the only problem, their photosynthesis is said to be "null", because there is not enough depth of soil to absorb CO2.

  • As part of the "new strategy" to fight forest fires, President Emmanuel Macron wants to plant a billion trees in 10 years in France, a project that seems difficult to achieve according to some experts, especially for the management of plants. Indeed, the current nurseries may not be able to provide enough tree seedlings in the allotted time. Moreover, one billion trees would represent from 660,000 ha to 2.5 million hectares, which would come up against a problem of space.


And in agriculture?

  • Reduce the use of synthetic mineral fertilizers

  • Develop agroecology and diversify crops

  • Plant messicolous plants


5 individual actions for the climate


1. Choose the train rather than the plane for short stays

Air traffic accounts for 28% of greenhouse gas emissions in France, give preference to the train for journeys that allow it and avoid taking the plane for a weekend.

2. Resist impulse and (sometimes) unnecessary purchases

Consume less and recycle more, we own 3 to 6 times more clothes than 15 years ago. Another action: promote second hand clothes that do not require new resources (LeBonCoin, Vinted, etc).

3. Relocating and greening your diet

Producing a kilo of meat produces 5 to 10 times more greenhouse gas emissions than producing a kilo of cereals. Favour also short circuits, unprocessed local productions and consume in season. For recipe ideas, read our articles on plants.

4. Lower your heating by a few degrees

20% of greenhouse gas emissions are linked to our homes, a house heated with oil or gas means burning more fossil fuels. It is said that the ideal temperatures are 19°C in the day rooms and 16°C in the bedrooms. We can also better insulate our home to reduce the use of heating and install more ecological heating sources (heat pump, solar panels, wood or pellet stoves)

5. Reduce the amount of waste you produce

This reduces 2 problems at the source: the pollution caused by their elimination (combustion, recycling which uses water, etc.) but also the depletion of resources for their creation (extraction of raw materials, etc.). Investing in sustainable products rather than disposable ones (water bottles, cloth rags, cloth menstrual pads, etc.)

6. Keep your smartphone 1 year longer

The environmental footprint of the manufacture of smartphones is mainly due to the extraction of minerals found in the form of metals in smartphones, these minerals are mainly extracted in Asia, Australia, Africa and South America. To date, only 5% of smartphones are recycled.



Conclusion :





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