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Wednesday, 13 January 2021

Earth set to reach deadly 'tipping point': Planet's ability to absorb a third of all human-caused carbon emissions could be HALVED in the next two decades, study warns

  • Researchers created temperature curves for every one of Earth's biomes 
  • This allows them to calculate a temperature where photosynthesis slows down 
  • As temperatures rise around the world more areas will reach this tipping point Earth is on the brink of a deadly climate change 'tipping point', study warns, with the planet's ability to absorb a third of human-caused emissions likely halved by 2050. 

    Researchers from Northern Arizona University created temperature curves for every major biome around the world to predict the likely impact of a warming world.

    Plants help mitigate global warming through photosynthesis, absorbing carbon dioxide and releasing oxygen back into the air - doing the Earth's 'breathing'.

    Over the past few decades, Earth's biosphere has taken in more carbon than it has released but that trend is slowing down and possibly reversing, the team found. 

    Between temperatures of 64.4F and 62.4F, depending on the biome, the amount of carbon a plant can process slows down - creating a tipping point for photosynthesis.

    Due to global warming forcing average temperature up, the planet has a 'steadily growing fever', warns lead author Dr Katharyn Duffy, that will eventually turn some of the worlds carbon sinks into sources of carbon, speeding up climate change.  

    Graphic depicting the temperature tipping point at which Earth's plants will start decreasing the amount of human-caused carbon emissions they can absorb

    Graphic depicting the temperature tipping point at which Earth's plants will start decreasing the amount of human-caused carbon emissions they can absorb

    Right now, less than ten percent of the terrestrial biosphere experiences temperatures beyond the photosynthetic maximum, discovered by the researchers.

    But at the current rate of emissions, up to half the terrestrial biosphere could experience temperatures beyond that productivity threshold by 2050.

    And some of the most carbon-rich biomes in the world, including tropical rainforests in the Amazon and Southeast Asia and the Taiga in Russia and Canada, will be among the first to hit that tipping point. 'Much like the human body, we know every biological process has a range of temperatures at which it performs optimally and ones above which function deteriorates,' said Dr Duffy. 

    'So we wanted to ask how much can plants withstand?'   

    Co-author Professor George Koch, of NAU, added: 'Different types of plants vary in the details of their temperature responses but all show declines in photosynthesis when it gets too warm.'

    Between temperatures of 64.4F and 62.4F, depending on the biome, the amount of carbon a plant can process slows down - creating a tipping point for photosynthesis. Stock image

    Between temperatures of 64.4F and 62.4F, depending on the biome, the amount of carbon a plant can process slows down - creating a tipping point for photosynthesis. Stock image

    The new study is the first to detect a temperature threshold for photosynthesis from observational data at a global scale.

    THE PARIS CLIMATE AGREEMENT: HOLDING TEMPERATURES TO BELOW 3.6F

    The Paris Agreement, which was first signed in 2015, is an international deal to control and limit climate change.

    It hopes to hold the increase in the global average temperature to below 2°C (3.6ºF) and pursue efforts to limit the increase to 1.5°C (2.7°F). 

    In June 2017, President Trump announced his intention for the US, the second largest producer of greenhouse gases in the world, to withdraw from the agreement.  

    However, his successor President-elect Joe Biden has committed to rejoin the Paris climate agreement.

     The Paris Agreement on Climate Change has four main goals with regards to reducing emissions:

    1. A long-term goal of keeping the increase in global average temperature to well below 2°C above pre-industrial levels

    2. To aim to limit the increase to 1.5°C, since this would significantly reduce risks and the impacts of climate change

    3. Governments agreed on the need for global emissions to peak as soon as possible, recognising that this will take longer for developing countries

    4. To undertake rapid reductions thereafter in accordance with the best available scienceWhile temperature thresholds for photosynthesis and respiration have been studied in the lab, the Fluxnet data provide a window into what ecosystems across Earth are actually experiencing and how they are responding.

    Dr Duffy said: 'We know that the temperature optima for humans lie around 37 degrees, but we in the scientific community didn't know what those optima were for the terrestrial biosphere.'

    For her research, Dr Duffy teamed up with Woodwell Climate and the University of Waikato who developed a new approach that allowed the team to generate temperature curves for every major biome and the whole globe.

    Findings reveal a critical temperature tipping point beyond which plants' ability to capture and store atmospheric carbon, known as the 'land carbon sink', decreases as temperatures continue to rise.

    Temperature 'peaks' for carbon uptake - 64.4F for some plants and 82.4 degrees F for others - are already being exceeded in nature, the authors warn.

    This means that in many biomes, continued warming will cause photosynthesis to drop while respiration rates rise exponentially, tipping the balance of ecosystems from carbon sink to carbon source and accelerating climate change.

    Co-author Professor Vic Arcus, of the University of Waikato in New Zealand, added: 'The most striking thing our analysis showed is that the temperature optima for photosynthesis in all ecosystems were so low.

    'Combined with the increased rate of ecosystem respiration across the temperatures we observed, our findings suggest that any temperature increase above 64.4F is potentially detrimental to the terrestrial carbon sink.

    'Without curbing warming to remain at or below the levels established in the Paris Climate Accord, the land carbon sink will not continue to offset our emissions and buy us time.'

    The UN Paris climate agreement commits governments around the world to take actions that restrict global temperatures from increasing by more than 3.6F above preindustrial levels by 2100. 

    The findings have been published in the journal Science Advances.

    Revealed: MailOnline dissects the impact greenhouse gases have on the planet - and what is being done to stop air pollution

    Emissions

    Carbon dioxide

    Carbon dioxide (CO2) is one of the biggest contributors to global warming. After the gas is released into the atmosphere it stays there, making it difficult for heat to escape - and warming up the planet in the process. 

    It is primarily released from burning fossil fuels such as coal, oil and gas, as well as cement production. 

    The average monthly concentration of CO2 in the Earth's atmosphere, as of April 2019, is 413 parts per million (ppm). Before the Industrial Revolution, the concentration was just 280 ppm. 

    CO2 concentration has fluctuated over the last 800,000 years between 180 to 280ppm, but has been vastly accelerated by pollution caused by humans. 

    Nitrogen dioxide 

    The gas nitrogen dioxide (NO2) comes from burning fossil fuels, car exhaust emissions and the use of nitrogen-based fertilisers used in agriculture.

    Although there is far less NO2 in the atmosphere than CO2, it is between 200 and 300 times more effective at trapping heat.

    Sulfur dioxide 

    Sulfur dioxide (SO2) also primarily comes from fossil fuel burning, but can also be released from car exhausts.

    SO2 can react with water, oxygen and other chemicals in the atmosphere to cause acid rain. 

    Carbon monoxide 

    Carbon monoxide (CO) is an indirect greenhouse gas as it reacts with hydroxyl radicals, removing them. Hydroxyl radicals reduce the lifetime of carbon dioxide and other greenhouse gases. 

    Particulates

    What is particulate matter?

    Particulate matter refers to tiny parts of solids or liquid materials in the air. 

    Some are visible, such as dust, whereas others cannot be seen by the naked eye. 

    Materials such as metals, microplastics, soil and chemicals can be in particulate matter.

    Particulate matter (or PM) is described in micrometres. The two main ones mentioned in reports and studies are PM10 (less than 10 micrometres) and PM2.5 (less than 2.5 micrometres).

    Air pollution comes from burning fossil fuels, cars, cement making and agriculture

    Air pollution comes from burning fossil fuels, cars, cement making and agriculture 

    Scientists measure the rate of particulates in the air by cubic metre.

    Particulate matter is sent into the air by a number of processes including burning fossil fuels, driving cars and steel making.

    Why are particulates dangerous?

    Particulates are dangerous because those less than 10 micrometres in diameter can get deep into your lungs, or even pass into your bloodstream. Particulates are found in higher concentrations in urban areas, particularly along main roads. 

    Health impact

    What sort of health problems can pollution cause?

    According to the World Health Organization, a third of deaths from stroke, lung cancer and heart disease can be linked to air pollution. 

    Some of the effects of air pollution on the body are not understood, but pollution may increase inflammation which narrows the arteries leading to heart attacks or strokes. 

    As well as this, almost one in 10 lung cancer cases in the UK are caused by air pollution. 

    Particulates find their way into the lungs and get lodged there, causing inflammation and damage. As well as this, some chemicals in particulates that make their way into the body can cause cancer. 

    Deaths from pollution 

    Around seven million people die prematurely because of air pollution every year. Pollution can cause a number of issues including asthma attacks, strokes, various cancers and cardiovascular problems. 

    Asthma triggers

    Air pollution can cause problems for asthma sufferers for a number of reasons. Pollutants in traffic fumes can irritate the airways, and particulates can get into your lungs and throat and make these areas inflamed. 

    Problems in pregnancy 

    Women exposed to air pollution before getting pregnant are nearly 20 per cent more likely to have babies with birth defects, research suggested in January 2018.

    Living within 3.1 miles (5km) of a highly-polluted area one month before conceiving makes women more likely to give birth to babies with defects such as cleft palates or lips, a study by University of Cincinnati found.

    For every 0.01mg/m3 increase in fine air particles, birth defects rise by 19 per cent, the research adds. 

    Previous research suggests this causes birth defects as a result of women suffering inflammation and 'internal stress'. 

    What is being done to tackle air pollution? 

    Paris agreement on climate change

    The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. 

    It hopes to hold the increase in the global average temperature to below 2°C (3.6ºF) 'and to pursue efforts to limit the temperature increase to 1.5°C (2.7°F)'.

    Carbon neutral by 2050 

    The UK government has announced plans to make the country carbon neutral by 2050. 

    They plan to do this by planting more trees and by installing 'carbon capture' technology at the source of the pollution.

    Some critics are worried that this first option will be used by the government to export its carbon offsetting to other countries.

    International carbon credits let nations continue emitting carbon while paying for trees to be planted elsewhere, balancing out their emissions.

    No new petrol or diesel vehicles by 2040

    In 2017, the UK government announced the sale of new petrol and diesel cars would be banned by 2040.  

    However,  MPs on the climate change committee have urged the government to bring the ban forward to 2030, as by then they will have an equivalent range and price.

    The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. Pictured: air pollution over Paris in 2019.

    The Paris Agreement, which was first signed in 2015, is an international agreement to control and limit climate change. Pictured: air pollution over Paris in 2019.

    Norway's electric car subsidies

    The speedy electrification of Norway's automotive fleet is attributed mainly to generous state subsidies. Electric cars are almost entirely exempt from the heavy taxes imposed on petrol and diesel cars, which makes them competitively priced.

    A VW Golf with a standard combustion engine costs nearly 334,000 kroner (34,500 euros, $38,600), while its electric cousin the e-Golf costs 326,000 kroner thanks to a lower tax quotient. 

    Criticisms of inaction on climate change

    The Committee on Climate Change (CCC) has said there is a 'shocking' lack of Government preparation for the risks to the country from climate change. 

    The committee assessed 33 areas where the risks of climate change had to be addressed – from flood resilience of properties to impacts on farmland and supply chains – and found no real progress in any of them.

    The UK is not prepared for 2°C of warming, the level at which countries have pledged to curb temperature rises, let alone a 4°C rise, which is possible if greenhouse gases are not cut globally, the committee said.

    It added that cities need more green spaces to stop the urban 'heat island' effect, and to prevent floods by soaking up heavy rainfall. 

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