Climate change: the causes and effects

Life on Earth exists thanks to a combination of three factors: our distance from the Sun, the chemical composition of our atmosphere and the presence of the water cycle. The atmosphere, in particular, ensures our planet has a climate that is suitable for sustaining life thanks to the natural greenhouse effect. When the Sun’s rays reach the surface of the Earth, they are only partly absorbed, while the rest are reflected outwards. Without the presence of the atmosphere, they would be dispersed into space; instead, most of them are trapped and redirected back towards the Earth by gases present in the atmosphere (mainly carbon dioxide and methane, but also water vapor, etc.) called greenhouse gases because of the effect they produce. This captured heat is added to the heat absorbed directly from the Sun’s rays. It’s important to add that without the natural greenhouse effect, the average temperature on the planet would be around -18°C instead of the current average of about 15°C. The causes of climate change If the greenhouse effect is such an advantageous phenomenon, why are we so concerned about it today? What is the significance of global warming? And what is meant by climate change? Climate change has always existed over the course of our planet’s history. But the global warming that we have been seeing for around the last 150 years is anomalous because it is the result of human activity. It’s called the anthropogenic greenhouse effect and occurs in addition to the natural greenhouse effect. With the industrial revolution, man suddenly began pumping millions of metric tons of carbon dioxide and other greenhouse gases into the atmosphere, doubling the quantity of CO2 present in the atmosphere compared with the minimum levels of the last 700 thousand years (410-415 parts per million compared with 200-180 parts per million). This can be observed on a daily basis thanks to surveys by observatories such as the one active in Mauna Loa, in the Hawaii archipelago. For around 15 years, the data produced by thousands of scientists all over the world, analyzed and organized by the Intergovernmental Panel on Climate Change (IPCC), has confirmed that global warming derives from the anthropogenic greenhouse effect, i.e., it is caused by human activity. In reality, the scientific basis for the connection between the levels of carbon dioxide and rises in temperature was established back in the last century, thanks to the work of Nobel Prize winner Svante Arrhenius, later confirmed by American scientist David Keeling in the 1960s. The consequences of climate change Over the course of the last century the average temperature of the planet rose by 0.98 °C and the trend we’ve been seeing since 2000 would indicate that, unless interventions are made, a further rise to reach 1.5° by 2030 is likely. The impact of global warming is already evident: arctic sea ice has been shrinking by 12.85% each decade, while coastal tide logs show that sea levels have been rising each year by 3.3mm since 1870. The decade 2009-2019 was the hottest ever recorded and 2020 was the second hottest year ever, only just behind the record year of 2016. The “fire seasons” have become longer and more intense, like the one in Australia in 2019; since 1990 the frequency of extreme weather events, such as cyclones and floods, has also increased, occurring even at atypical moments of the year compared with the past and at devastating levels of intensity. Phenomena such as El Niño have become more irregular and have caused dangerous droughts in areas already threatened by chronic aridity, like East Africa, while the Gulf Stream is slowing down and could well change route. Plant and animal species are migrating in unpredictable ways from one ecosystem to another, creating incalculable damage to biodiversity around the world. Defining all this with the term climate change is accurate but does not give the full picture of what is happening. We must begin by talking about the climate crisis because the climate has always been changing, but never so quickly and never in the presence of such rigid and complex infrastructure as can be found in the cities and production systems of industrialized countries. The solutions to climate change Human activities, such as burning fossil fuels and destroying rainforests, have an increasing influence on the climate and the Earth’s temperature. This adds huge quantities of greenhouse gases to those naturally present in the atmosphere, increasing the greenhouse effect and global warming. Causing the most damage is, above all, the consumption of coal, oil and gas, which represent the majority of greenhouse gas emissions. In 2019, according to McKinsey’s Global Energy Perspective 2019, fossil fuels were responsible for 83% of total CO2 emissions and the production of electricity from coal-fired power stations alone contributed 36%, even though in 2020 – on account of the Covid-19 pandemic – emissions fell dramatically (source: World Energy Outlook 2020). It is estimated that the current trend of CO2 emissions due to burning coal is responsible for around a third of the increase of 1°C in average annual temperatures above pre-industrial levels, making it the largest source of emissions in all of human history. In absolute terms, oil is the second largest source of emissions, having produced 12.54 billion tons of CO2 (86% of the total carbon emissions of 14.55 billion tons) in 2019. The destruction of forests also causes substantial damage: trees help regulate the climate by absorbing carbon dioxide from the atmosphere, so if they are destroyed, this beneficial effect is diminished and the carbon stored in those trees is emitted into the atmosphere, adding to the greenhouse effect. Finally, the increase in intensive animal farming and the use of fertilizers containing ozone contribute to increasing emissions of greenhouse gases. International agreements How to remedy the situation? At the United Nations Framework Convention on Climate Change (UNFCC) conference (COP 21) in December 2015, international representatives adopted the Paris Agreement, which provides a credible framework for achieving decarbonization, with long-term goals to tackle climate change and a flexible structure based on contributions from individual governments. The signatory nations committed to limiting the increase in temperature to below 2° centigrade compared with preindustrial levels, with efforts to contain this to within 1.5°C, with the ultimate goal of passing peak emissions as soon as possible and achieving carbon neutrality in the second half of the century. Despite the success of COP21, many questions concerning the Agreement have remained unresolved. In 2018, COP24 in Katowice, Poland, approved the implementation guidelines of the Paris Agreement (the so-called Paris Rulebook). In 2021, COP26 in Glasgow reaffirmed the commitment to achieve Global Neutrality by 2050. The road ahead towards decarbonization is clear and is known as the energy transition: the shift from an energy mix based on fossil fuels to one with zero carbon emissions and based on renewable energy sources. Technologies that support decarbonization already exist, are efficient and should be implemented at all levels. A significant contribution to decarbonization will come from the electrification of final consumption. This means replacing fossil fuel-based technologies in all sectors – from homes to local and long-distance transport, to heavy industry – with technologies that use electricity produced from renewable sources, reducing not only greenhouse gas emissions, but air pollution as well, particularly in cities. Science offers clear data, projections and carefully studied future scenarios. Climate change waits for no one and will not stop on its own. What is required is a substantial cultural change, a true paradigm-shift. There is already widespread agreement on what needs to be done: it now needs to be turned into reality.

The climate crisis: the causes, the effects and the solutions

The climate crisis: the causes, the effects and the solutions

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