The Earth is in the midst of one of the most important and urgent environmental crises of our time: climate change.
This change is caused by an increase in average temperatures around the world through global warming, resulting in complex variability in the Earth’s weather patterns.
While records show traces of climate change in ancient times, the current changes are more extreme and difficult to explain by natural factors alone.
This modern climate crisis has been triggered in large part by human activity, particularly the use of fossil fuels and the resulting release of greenhouse gases, some of which are emitted from human daily life, agricultural and industrial activities.
Greenhouse gases trap heat at the Earth’s surface, causing the planet’s temperature to rise. This warming drives a variety of global changes, most notably the loss of glaciers.
In fact, land is currently warming twice as fast as the global average.
Desertification is spreading as a result of climate change, as are more frequent heat waves and wildfires.
The Arctic is particularly affected by warming, with melting permafrost, shrinking glaciers and loss of sea ice.
Higher temperatures are causing more powerful storms and extreme weather events, posing major changes and threats to natural ecosystems and human living conditions.
Some species are migrating to adapt to these environmental changes, while others are unable to and are facing extinction.
Among people, climate change is also causing an increase in diseases, food and water shortages, and economic losses.
The world is making various efforts to combat this climate crisis.
Through the Paris Agreement, adopted in 2015, many countries have set a goal of limiting the temperature increase to no more than 2°C.
However, based on current projections, temperatures are likely to rise even higher by the end of the 21st century.
Reducing the emission of greenhouse gases is crucial in this crisis.
We need to tackle this issue in a number of ways, including increasing the use of sustainable energy sources, improving energy efficiency, preserving and expanding forests, and strengthening local communities’ responses to climate change.
Otherwise, the Earth’s climate will continue to destabilise, posing a major threat to humanity’s future.
Climate change is having a major impact on many environmental factors on Earth.
These changes can occur gradually, but sometimes abruptly.
Efforts are ongoing to understand these impacts through past climate change studies, climate models, and modern climate observations.
In particular, since the 1950s, droughts and heat waves have been occurring simultaneously and with increasing frequency.
In India and East Asia, extreme wet or dry weather tends to occur during the monsoon season.
We also know that the frequency of precipitation is increasing, and that typhoons and hurricanes are becoming more intense.
In 2021, a paper was published in Nature Geoscience analysing the climate change impacts of changes in Hadley cells, which showed that the area affected by tropical cyclones will expand polewards.
A US study on sea level height found that from 1993 to 2020, global sea levels rose by 3.3 ± 0.3 mm per year. By the end of the 21st century, this rate of rise will continue, and there are predictions that it could rise by up to 110cm.
Glaciers on the Antarctic ice cap are threatened with break-up due to increasing sea temperatures, and there is a risk of large-scale melting of the ice sheet.
Sea ice in the Arctic Ocean has been shrinking for decades, and while it is unlikely that the Arctic will be ice-free in summer at 1.5°C of warming, there are projections that it could be ice-free in summer at 2°C of warming.
Finally, the increasing concentration of carbon dioxide in the atmosphere is leading to the acidification of the oceans.
The rising temperature of the oceans is reducing the ability of oxygen to dissolve, which in turn is reducing the concentration of oxygen in the oceans.
These changes are leading to an increase in the number of areas of the ocean with little oxygen, known as dead zones.
Nature and ecosystem impacts
Climate change is having a wide-ranging impact on Earth’s ecosystems.
The effects of modern warming are causing species of terrestrial and freshwater organisms to migrate to the poles or to higher altitudes, as organisms tend to migrate in search of cooler environments.
In addition, global greening is occurring due to increased concentrations of carbon dioxide in the atmosphere, but at the same time, ecosystem productivity in certain regions is decreasing due to heat waves and droughts.
These opposing phenomena make future ecosystem changes difficult to predict.
Climate change is causing phenomena such as the expansion of desertification, especially in subtropical regions, which means an expansion of areas with drier climates.
Rapid progression of global warming is likely to result in rapid changes in ecosystems, which could put many species at risk of extinction.
The ocean responds to warming more slowly than land, but the resulting changes are more rapid. Marine plants and animals have moved to colder polar regions faster than land species.
The oceans are also experiencing more frequent heatwaves, which are taking a toll on marine life, including coral reefs, kelp beds, and seabirds.
The acidification of the oceans is making it harder for marine organisms like mussels and barnacles to form their shells or skeletons. Furthermore, coral bleaching caused by ocean heatwaves is taking a heavy toll on coral reefs.
The rapid increase in harmful algal blooms is causing the oxygen concentration in the ocean to decrease dramatically, greatly upsetting the balance of the marine ecosystem.
Collectively, marine ecosystems are under great stress from climate change.
Separately, nearly half of the world’s wetlands have disappeared as a result of climate change and other human activities, posing a major threat to the planet’s biodiversity.
Climate change is causing major changes in human life and the environment.
The effects of these changes are observed all over the world, mainly due to warming and changes in precipitation.
These climate changes are being witnessed on all continents and oceans of the planet. The threats posed by climate change are felt most acutely in low latitude regions and developing countries.
These regions are known to be the most affected by the negative effects of climate change.
As climate change continues, the resulting warming is taking a toll on humans and ecosystems.
These impacts have been assessed as “severe, pervasive, and irreversible”.
This means that the effects of climate change are not simply temporary, but can last for a long time and cause major changes.
Furthermore, the negative impacts of climate change are not evenly distributed across all regions of the world; rather, they are unevenly distributed, with certain regions or social classes being hit harder than others, particularly those with lower incomes in developing or developed countries.
This means that the risks and negative impacts of climate change are likely to exacerbate economic and social inequalities, and international co-operation and action is urgently needed.
Policy action on climate change
Efforts to reduce emissions are global. As of 2019, carbon pricing schemes account for one-fifth of global greenhouse gas emissions.
These carbon pricing schemes are implemented by placing a price on carbon in the form of carbon taxes or emissions trading. Alongside this, subsidies for fossil fuels are also seen as a big problem.
In 2017, fossil fuel subsidies amounted to around $319 billion, and the indirect costs associated with them are estimated to be around $5.2 trillion. Eliminating these subsidies entirely would result in a significant reduction in carbon emissions and a significant reduction in deaths due to air pollution.
The money saved could also be used to transition to cleaner energy.
Increasing environmental standards for vehicles, introducing renewable fuel standards, and tightening air pollution regulations for heavy industry are other ways to reduce greenhouse gas emissions.
Efforts are also underway to increase the share of renewable energy, particularly in the power sector.
From a climate justice perspective, it can be argued that issues related to climate change are not just environmental, but also closely linked to issues of human rights and social inequality.
Therefore, it has been suggested that wealthy countries with high emissions should provide assistance to poorer countries that are less affected by climate change.
The issue of job insecurity should also be considered, as a reduction in the use of fossil fuels can lead to job losses.
To this end, workers who used to work in the fossil fuel sector need education and training to transition to other sectors, and investment in this area should be further expanded.
International agreements on climate change
There are various international agreements to combat climate change. In 1994, the United Nations Framework Convention on Climate Change (UNFCCC) was established, which set a goal of stabilising greenhouse gases, but did not include specific emissions controls.
In 1997, the Kyoto Protocol was introduced, which included binding commitments for developed countries to take the lead in reducing greenhouse gases.
However, the Copenhagen Accord of 2009 was disappointingly low in its targets: while it reached an agreement to limit global temperature rise to no more than 2°C, it was heavily criticised for not meeting its targets.
Then, in 2015, the Paris Agreement was signed, which committed to limiting global warming to well below 2.0°C and, as far as possible, to 1.5°C.
This agreement is seen as replacing the Kyoto Protocol, and while it does not have specific targets for limiting emissions, it does include a process for countries to renew their targets every five years and assess their progress in achieving them.
In addition, the Montreal Protocol to Prevent the Depletion of the Ozone Layer and its 2016 Kigali Amendment also play an important role;
in particular, the Kigali Amendment pledges to limit emissions of hydrofluorocarbons, a powerful greenhouse gas that has been used as a substitute for ozone-depleting substances.
Nevertheless, major countries such as the United States and the People’s Republic of China have been slow to take action on climate change.
Emphasising the need for active engagement from these countries, in 2007, the United Nations Secretary-General, Ban Ki-moon, called on them to engage on environmental issues.