Climate change is happening, and it is undeniably caused by humans. The latest damning report from the Intergovernmental Panel on Climate Change (IPCC) lays that out clearly, stating that “it is unequivocal that human influence has warmed the atmosphere, oceans and land”.
The report warns we will likely exceed 1.5°C of warming, the most ambitious target set out by the Paris Agreement in 2015, even if the world rapidly cuts emissions. If that sounds terrifying, it is – but all is not lost. To get a grip on this global calamity, we must first understand what’s causing it. Then we can understand how to mitigate it.
Here’s the latest science on where we are with climate change and what our options are to prevent the worst.
What is climate change?
Climate refers to the average weather in a particular place – or across the entire planet – over very long periods of times. While the weather can change a lot from day to day, measuring the climate shows us the bigger picture: whether a particular place is getting hotter, wetter, or if ice is melting faster, for example. Climate change is when those average conditions start to shift. And when it comes to human-induced climate change, the starkest shift has been the alarmingly rapid increase in global average temperatures caused by greenhouse gas emissions.
Why do greenhouse gases even exist, anyway? Life on Earth needs energy from the sun. It gets it through the sun’s rays hitting the surface of the planet and the radiation bouncing back toward the atmosphere as heat. Before it can escape, greenhouse gases, such as carbon dioxide, methane and nitrous oxide, trap some of the heat – this is known as the greenhouse effect; the gases act like a blanket around the planet, keeping it warm. Without them, the Earth would be about -18°C.
But, since the Industrial Revolution, humans have burned fossil fuels such as coal and oil in ever-increasing quantities. In turn, this also meant we began pumping way more greenhouse gases, especially carbon dioxide, into the atmosphere. As a result, more of the sun’s heat hasn’t been able to escape back into space, resulting in the planet warming up.
Between 800,000 years ago and the start of the Industrial Revolution, the concentration of carbon dioxide in the atmosphere was about 280 parts per million (ppm). Since then, it has increased exponentially, at a rate of about 0.17 per cent per year. In the second half of the 20th century, the Great Acceleration resulted in a massive increase of human activity, such as energy consumption, resource use and transport, which in turn had an equally large environmental impact, as carbon emissions increased dramatically after the 1950s. When the Mauna Loa Observatory in Hawaii, the longest-running continuous record of atmospheric carbon dioxide concentrations, began recording carbon dioxide levels in the atmosphere in 1958, the number already stood at 315 ppm. In 2015, it surpassed 400ppm. Today, the concentration of carbon dioxide in the atmosphere has risen to annual averages of 410ppm. That means over the last 170 years, human activities have increased atmospheric carbon concentrations by over 45 per cent above pre-industrial levels. And we’re emitting more every year; we now emit 40 per cent more carbon each year than we did in 1990.
All this has resulted in the world being the warmest it has ever been. The global temperature is 1.1°C higher than between 1850 and 1900. While that might not seem to be a lot, it has and will have massive repercussions on the climate, involving long-term shifts in weather patterns across the planet.
How do we know for sure the planet has been getting hotter? From the reams of data scientists have collected over centuries, from systems including satellites that orbit the planet to temperature measurements taken on ships as far back as 1880 and geological records inside trees. There are also more obvious indicators: the glaciers and ice sheets around the world are melting at a speed that has nearly doubled in the last two decades; the atmosphere is more humid and snow cover is decreasing.
What is causing climate change?
It is extremely likely that most of this warming can be traced back to human activity.
Since 1850, humans have emitted 2,400 gigatonnes of carbon dioxide, according to the latest IPCC report. The United States is responsible for emitting more carbon dioxide than any other country to date up until 2017 – it is responsible for about 25 per cent of emissions. China is second on around 13 per cent. All the 28 EU countries put together have contributed 22 per cent to global emissions. Lower income countries have played a considerably smaller role. The entire continent of Africa has contributed just three per cent of total carbon dioxide emissions. In fact, the richest half of the world emits around 85 per cent of global carbon dioxide emissions annually. But previously low-income countries such as China are playing catchup: in 2019, it emitted the highest levels of greenhouse gases (not just carbon dioxide), at 27 per cent of all global emissions.
Industry as a whole accounts for the most emissions – about 21 per cent. The biggest emitters are the production of cement, iron and steel. But many other industrial processes, including pharmaceuticals, fertilisers and clothing, all contribute substantially to emissions.
The production of electricity – to light our homes, charge our phones and make our cups of tea – accounts for a quarter of greenhouse gas emissions. The electricity used in buildings accounts for 12 per cent of that, and electricity from industry another 11 per cent.
Agriculture creates another quarter of emissions. From deforestation to free up land to grow crops and farm animals to the methane emissions from livestock to the nitrous oxide from fertiliser use, keeping the world fed contributes significantly to global emissions.
The transport industry relies overwhelmingly on fossil fuels, which means getting us from A to B contributes about 11 per cent to emissions. Our shelter – buildings – contribute six per cent. That figure includes building them in the first place and then the energy required to keep them lit, warm or cool.
Today, we get most of our energy through burning fossil fuels such as coal, oil, and gas. In 2019, almost 85 per cent of our energy needs were met by the big three. But burning fossil fuels releases carbon dioxide and other greenhouse gases into the atmosphere, and our addiction to them has meant that we emit around 50 billion tonnes of greenhouse gases each year.
Carbon dioxide isn’t the only gas being released. Other greenhouse gases, including methane and nitrous oxide, which contribute the most to warming after carbon dioxide, are on the rise too. Methane contributes 16 per cent of greenhouse gas emissions, and nitrous oxide about six per cent. Since the pre-industrial era, concentrations of both gases have increased by around 60 and 25 per cent respectively. Methane is about 80 times more efficient at trapping heat than carbon dioxide in the first 20 years after it is released, although it stays in the atmosphere for a much shorter time than carbon dioxide
For the rest of the greenhouse gas emissions, deforestation and agriculture are to blame. These activities contribute almost one-fifth to emissions. Forests are natural carbon sinks – it’s estimated that up to 45 per cent of carbon stored in the land is held by forests – but we’ve been destroying them at an alarming rate for timber and to make space for farming land, further compounding the problem. Agricultural processes are a major emitter of methane and nitrous oxide – nearly two thirds of nitrous oxide emissions and half of methane emissions come from agriculture. Cows release substantial quantities of methane and an increased global appetite for meat beef is making the problem worse.
What are the effects of climate change?
The effects of climate change are made clear in the IPCC report. The past five years have been the hottest on record since 1850 – we haven’t experienced temperatures this high in at least 6,500 years. Each of the last four decades has been successively warmer than any decade that preceded it since 1850.
The IPCC lays out five potential climate scenarios based on different socioeconomic trends, including projections of population and economic growth, geopolitical trends and technological development. In the first and most optimistic scenario, we have taken immediate and aggressive measures to cut global emissions to net zero by 2050. This is the only scenario that meets the goal of the Paris Agreement, of keeping warming to 1.5°C, and it predicts it will then dip back down to 1.4°C by the end of the century. In the second scenario, the next-best case, we reach net zero after 2050, but still stay below 2°C warming, settling at about 1.8°C by 2100. In the middle-of-the-road third scenario, where the world follows a path in which socioeconomic trends don’t really deviate from their historical patterns, we do not hit net zero by 2100, but we do hit 2.7°C warming by the end of the century. Getting a bit more pessimistic, in the fourth scenario we reach 3.6°C warming by the end of the century. Finally, in the worst case scenario: we don’t just fail to limit our current emission levels – they double by mid-century. The world is a devastating 4.4°C hotter by the end of the century.
Right now, the world is on track for the middle scenario – where we hit 2.7°C warming by the year 2100. The scenario is fairly consistent with the 2030 climate pledges of many countries under the Paris Agreement, so unless we adopt more aggressive measures to reduce emissions, it’s the future we’re headed for.
We’ll see the effects of this play out on a global scale at a devastating level. Extreme weather events will become more frequent and more devastating: flooding, wildfires, droughts, heatwaves, and they will disproportionately affect poorer populations.
The rise in warming has caused the ice sheets of Greenland and Antarctica to decrease in mass, and once shrunk, it takes tens of thousands of years for them to regrow. Greenland has lost four trillion tonnes of ice since between 1992 and 2018. The Arctic is likely to be practically sea ice-free at least once before the middle of the century.
Oceans absorb a lot of the atmospheric carbon, but they also absorb heat. The top 100 metres of the world’s oceans have warmed by more than 0.33°C since 1969. And, as the oceans warm, they expand. Combined with the melting of glaciers and ice sheets this means that sea levels are on the rise. Global sea levels have already risen by 20 centimeters since 1900, and the IPCC report says that number is certain to increase. It projects a rise between 28cm and 100cm by the end of the century. This means more frequent and severe extreme sea level events at coastal areas, such as storm surges and tidal flooding.
The oceans act as a crucial carbon sink – they absorb roughly one third of the additional carbon dioxide that humans produce. But the huge bump in carbon levels has meant that the ocean is absorbing too much, which has led to them not only getting warmer but also more acidic – a process known as ocean acidification. Since pre-industrial times, the oceans have become 30 per cent more acidic, resulting in the death of marine life, including vital ecosystems like coral reefs. What’s more, as the temperature of the oceans rises, their carbon-capturing abilities will also decrease.
Increased heat and drought will make food production more difficult and could lead to famines in the worst-hit regions. A third of global food production is estimated to be at risk by the end of the century if emissions continue to rise as fast as they are now. The IPCC projects an increase of up to 183 million people going hungry due to climate change. Staple crops in Africa, such as maize and wheat, have already decreased in recent years.
To find refuge from soaring temperatures and wildfires, animals are moving to different parts of the world to find habitable conditions. We are facing a possible sixth mass extinction. Species across the world are already disappearing at alarming rates. An estimated one million species are at risk of extinction, many potentially within decades. This includes more than 40 per cent of amphibian species, and over a third of marine mammals and reef-forming corals.
The IPCC now warns that extreme weather events will increase in frequency and intensity, and that their root cause can be attributed to human-caused climate change. Heatwaves are now happening about five times more frequently and lasting longer than they would naturally. The chance of a one-in-fifty year heatwave will increase nine-fold under 1.5°C warming. Once-in-a-decade rainfall events are now 1.3 times more likely and 6.7 per cent wetter. Previously once-in-a-decade droughts are now 70 per cent more frequent and could happen every five or six years.
And these extreme weather events will hit poorer countries, which tend to be in tropical regions, the hardest. Low-lying coastal regions will flood, regions will become so hot they become inhabitable and droughts will lead to food shortages and fires. This is despite the poorest countries emitting the least amount of greenhouse gases. The Pacific region in particular is suffering the most severe impacts of climate change, despite emitting the lowest amount of carbon. Climate change will force mass migration, leading to the number of climate refugees rising. More than a billion people could be displaced by 2050, resulting in massive political and social upheaval.
How to stop climate change
Priority number one: we need to stop producing carbon as soon as possible. Global greenhouse gas emissions must peak in the next four years, according to a leaked report from the IPCC. We’ve already drastically overspent our carbon budget – the amount of carbon dioxide that can be added to the atmosphere before it breaches a certain temperature threshold – that we need to get down to around five billion tonnes a year by 2050. In the latest report, the IPCC shows that the world can emit 460 billion tonnes of carbon dioxide, or another 11.5 years of current emissions – after January 1, 2021, before it’s committed to 1.5°C warming.
This means that limiting emissions as fast as possible is critical. But reducing alone won’t be enough – we need to reach net zero. Net zero carbon means balancing the amount of emitted greenhouse gases with the equivalent emissions that are either offset or sequestered. The quicker we get to net zero, the better hope we have of limiting warming. Dozens of countries have committed to reaching net-zero by 2050, including the UK. China, which is now the world’s biggest emitter, has promised to reach carbon neutrality before 2060, and to begin cutting its emissions within the next decade. Some countries have failed to make any commitments towards net zero, including Russia, the world's fourth-biggest polluter, which has no plans to significantly cut emissions by 2050. India, the world’s third-biggest emitter, is debating setting a net zero by 2050 goal but has yet to make any formal pledge.
To do this, we have to halt emissions at their source: the burning of fossil fuels. This is no easy task – the world gets about 80 per cent of its current energy from fossil fuels. To make the switch we need to switch to renewable energy, such as solar, wind and geothermal, right now. We’re making good progress on this; solar and wind energy are now cheaper than fossil fuels, and renewable energy was responsible for around a third of global electricity production in 2020.
We can’t forget about the other greenhouse gases. Methane, which is emitted from sources such as leakage from oil and gas infrastructure, agriculture and coal mining, comes right after carbon dioxide in terms of its contribution to warming, and humans are to blame for around more than half of its emissions. Fixing leaks from energy infrastructure, as well as better crop, livestock and land management and a reduced reliance on animal agriculture, can all help stop some of these emissions. The latter measure would also bring down nitrous oxide emissions, which predominantly come from using too much fertiliser in agriculture.
While the imperative is to halt emissions, we also have to find a way to remove the billions of tonnes of carbon dioxide already in the atmosphere. This process is known as carbon removal, or negative emissions. Both of the best-case scenarios set out in the IPCC report rely on carbon removal to some extent – the removal of between 100 and 1,000 gigatonnes of carbon dioxide over the century. But it isn’t a cure-all; carbon removal only buys us a little more time to stop emissions, and, according to the IPCC, carbon removal will only change the direction of some aspects of climate change and will only happen if it removes more carbon than is emitted. Some effects are irreversibly baked in: the ice will keep melting, the sea levels will continue to rise.
Natural methods of carbon capture include planting more trees, or restoring coastal ecosystems, which naturally capture carbon. Another method is through carbon capture and storage, a burgeoning area of research in which carbon is captured at the point of emission and buried underground. But it’s just that – still burgeoning, and doesn’t yet exist in any viable form. There are about 50 carbon capture and storage projects operating commercially. One of the biggest players, Climeworks in Switzerland, is only able to remove about 6,000 tonnes of carbon a year.
There’s room for hope: the IPCC report says that if we reach net zero and remove emissions from the atmosphere, we could see warming fall back to 1.4°C by the end of the century.
What can I do about climate change?
Solving these problems requires large-scale, collective action. So it’s important to note that personal reduction plays a small role in reducing overall emissions – these measures are not enough to solve the problem by themselves, but they do help.
The most effective way for you, the individual, to have an effect on climate change is through your vote. Vote for people and parties who have a strong focus on climate. Political will has the biggest effect on global change. And lobby: contact your local political representative and tell them why you think action on climate change is important (here’s a template for the UK.) Take part in climate activism, such as joining a protest, to make your voice heard and your demands known.
Meanwhile, there are other things you can do to mitigate your carbon footprint. As previously mentioned, people in higher income countries tend to have bigger carbon footprints: the average carbon emissions of a person in the US is 16 tonnes, compared to the global average of about four tonnes.
To have the most impact at an individual level, going flight, car and meat-free is the way. Forgoing your car for a year could save up to 2.4 tonnes of carbon emissions. Avoiding just one roundtrip transatlantic flight saves you 1.6 tonnes. Where you can, opt for public transport or even better, walk or cycle.
The production of animal products has a higher carbon footprint than plant-based, so lowering your meat and dairy intake can reduce your overall carbon footprint although not as much as cleaning up your transport habits. An individual in a developed country switching to a plant-based diet saves almost a tonne of carbon emissions a year.
Another – albeit controversial – method is simple but effective: have fewer children. Having one fewer child is estimated to save as much as 58.6 tonnes of carbon emissions a year (if the potential future emissions of a descendant were calculated based on historical rates and heredity). If that sounds too drastic, making your house more energy efficient is also helpful: insulating your home well can save up to 0.895 tonnes of carbon.
This article was originally published by WIRED UK
