What is climate change? Causes and effects of global warming

Global warming, climate change, climate crisis, climate breakdown and climate emergency are all terms that describe a major threat to life as we know it on our planet, but what are people talking about when do they use these terms?

Climate and Weather report

The first important aspect of understanding global climate is to distinguish ‘climate’ from ‘weather’.

Weather refers only to short-term changing atmospheric conditions in a place or area while climate refers to much longer weather behavior and can change from season to season.

But there’s also Earth’s global climate, which is understood by combining long-term climate records to build a picture of trends affecting our planet.

While weather patterns can change in just hours, climates typically take hundreds, thousands, or even millions of years to change.

However, since the middle of the 20th century, scientists around the world have been warning that climates around the world, which had been stable for thousands of years, are beginning to change rapidly and it is human activity that is largely responsible. at the root of the current crisis. changes.

What is happening?

Overall, the world is getting warmer – that’s why the process is often called “global warming”.

The average global temperature on Earth has increased by more than 1C (2F) since 1880. Two-thirds of this warming has occurred since 1975 alone, at a rate of about 0.15 to 0.20C per decade.

However, the world is not warming evenly. Some regions, such as the Arctic and Antarctica, are warming faster than others, and rising average temperatures can have many other consequences, which is why the process is better described as “climate change” or “climate degradation”.

From a human perspective, the huge range of negative impacts on us and other species means it can be considered a ‘climate crisis’ or a ‘climate emergency’.

How is the climate changing?

The Earth’s climate is constantly changing, and before examining why scientists believe humans have such a large impact on the climate, it is important to recognize that various natural factors cause major changes in the climate.

These include:

  • The distance from the Earth to the Sun. This waxes and wanes over a 100,000 year cycle, during which Earth’s orbit becomes more elliptical and then more circular again. Currently, Earth’s orbit is most circular, and over the next few millennia, each year during the northern hemisphere summer months, Earth will reach the farthest point from the sun as our planet conducts its 12-month orbits, at which point less solar radiation reaches Earth. It is believed that this cycle – known as Milankovitch Cycle – is an important factor in the onset of ice ages.
  • The Sun can also produce different levels of solar radiation. He does this over a period of 11 years. In the past, average temperatures loosely tracked solar activity (within a small range), but since the 1950s there has been no net increase in solar radiation, indeed, in recent decades, the activity of the Sun has even slightly fallen compared to the decades of the late 20th century, when average global temperatures increased markedly.
  • The oceans covering 70% of the earth’s surface have also a significant impact on the climate. This big, wet, blue thing is constantly exchanging heat, carbon and moisture with the atmosphere, as powerful currents move masses of water around the world, impacting local climates. , and clouds form over the oceans that are highly reflective and can reflect the sun’s energy back into space. Changes in the heat and carbon storage capacity of the world’s oceans – due to factors such as ice cover, sea level and carbon dioxide levels – can impact many other processes affecting climate, such as ocean currents, salinity, temperature and surface winds.
  • Volcanic eruptions are also natural processes that can have major impacts on the climate. When a mighty volcano erupts, huge amounts of sulfur dioxide, dust, and ash are ejected high into the atmosphere, which can reflect sunlight and have a temporary cooling effect that can last for several years, although it is not permanent.

Human-caused climate change

Records show that for the past 6,000 years the Earth was on a long trajectory of slow cooling, which then suddenly ended at the end of the Victorian period, around 150 years ago. By this time, the human world had already embarked on a global drive for industrialization – a process still ongoing.

The dawn of industrialization sparked a planetary-scale rush to extract exceptionally combustible and energy-rich fuels such as coal, oil and gas to supply the energy needed for an endless array of processes. , including manufacturing, transport, heating and cooling of buildings and domestic installations. use.

This boom in fossil fuel extraction is still going on. Although many countries are increasingly turning to renewable energy sources, in 2020Fossil fuels still accounted for 84% of global energy production, and companies around the world still plan to continue extracting them.

When fossil fuels are burned, they emit gases that trap heat from the sun in the atmosphere, warming the planet like a greenhouse. This is why they are called greenhouse gases.

As the process of industrialization has changed societies and produced breakthroughs, especially in the fields of medicine and agriculture, human populations have increased sharply around the world.

In addition to growing populations requiring greater energy resources – especially in wealthier societies – more people also need more food. As a result, agriculture has had an increasing effect on land use and greenhouse gas emissions, especially for meat production.

The main greenhouse gases are:

Carbon dioxide



Nitrous oxide


They all come from different processes, have different concentrations in the atmosphere, and have different impacts on different time scales.

Carbon dioxide accounts for about 80% of all greenhouse gases in the atmosphere, but methane, which accounts for about 10%, is much more potent, but over a shorter period.

Nitrous oxide accounts for about 7%, and fluorinated gases, which are man-made and very potent greenhouse gases emitted by various industrial processes, make up the remaining 3%.

Impacts of the climate crisis

A warming world has terrifying consequences. We are already seeing many impacts of climate change, in the form of extreme weather events and an increasing rate of sea level rise, but if the current rate of warming continues, the worst is yet to come.

Scientists have warned that we will see more frequent and intense periods of drought; devastating heat waves that could increase desertification and render parts of the world uninhabitable; more powerful storms; flood; ocean warming; melting of the glaciers; receding sea ice; lack of snow cover; rising sea levels and the destruction of coastal cities where millions of people live, and the collapse of biodiversity, risking famines and global food shortages, and therefore increasing the risks of conflict and increase the likelihood of mass migrations.


Responding to the multiple threats posed by the climate crisis is expected to be one of our species’ greatest challenges yet.

Indeed, for many societies, a successful response will involve major recalibrations of fundamental values ​​and expectations of people, as well as profound changes in the systems and institutions on which our societies have been built over the last century or more.

But if we fail to live up to this recalibration, the dire repercussions will intensify and loom before us as an increasingly sinister specter.


The only thing humans need to do to slow our journey to fiery catastrophe is to stop producing greenhouse gas emissions.

The other essential thing we need to do is undo the damage we have done to the natural world – this will remove pollutants from the atmosphere and help slow down the heating process.

Governments around the world are currently taking only small steps to reduce certain emissions and to protect and restore a few select ecosystems. These are glimmers of recognition of the problem, but there is still much to be done.

Teresa H. Sadler