Everything you should know about climate change: present and future

We can't talk about climate change unless we truly understand what it is. This requires an understanding of the difference between two basic concepts that are often confused: weather and climate.

While they both refer to local temperatures or precipitation conditions, their time scales differ. Weather is the state of the atmosphere at a given time and place. It is caused by a combination of climate elements including, but not limited to, precipitation, wind and temperature. This means that it can change rapidly, affecting a limited area, and is therefore complex to predict.

In contrast, climate is the atmospheric weather pattern. This concept encompasses longer-term, seasonal changes, occurring over a wider geographical area. Unlike the previous concept, it can be measured over time with a series of parameters such as temperature or precipitation, which we study to make predictions.

Climate change, therefore, refers to changes in weather patterns on a larger spatial/temporal scale, such as rising average temperatures or decreasing precipitation in a region or even on a global scale. These changes may arise from natural causes, e.g. through variations in the solar cycle. However, human activities have been the primary source of climate change since the 19th century. This is largely attributable to the burning of fossil fuels like coal, oil and gas.

Climate change:  the greenhouse effect

Through its leading exponent in the field, The Intergovernmental Panel on Climate Change, science has proven that weather patterns are changing at an unprecedented rate. Higher temperatures, a decline in rainfall or an increase in extreme weather events, such as heat waves or floods, are some examples of climate change.

Science has conclusive evidence that the current climate change is anthropogenic in origin. This is caused by a change in the composition of the atmosphere triggered by increased carbon emissions from human activity. This change is referred to as the greenhouse effect, something we have all heard about and whose implications are profoundly negative for life on Earth.

We have to understand what the atmosphere is made of in order to understand the greenhouse effect. The atmosphere is made of many gases, including greenhouse gases (GHGs). GHGs help to keep some of the incoming solar radiation in our atmosphere, raising the planet's temperature and allowing life on Earth.

Our present predicament stems from an increase in the concentration of GHGs in the atmosphere to historically unprecedented levels as a result of human activity. Last June 2022, the global benchmark observatory at Mauna Loa recorded a CO2e concentration of 421.72 ppm.

This increase is causing solar radiation that was previously reflected from the atmosphere to be retained, causing it to overheat. This is known as the greenhouse effect and it negatively affects our planet, causing global climate change.

How is the climate changing?

According to data from the Sixth Assessment Report "Climate Change 2021: The Physical Science Basis” drawn up by the IPCC, the planet is warming at an alarming rate. The global average surface temperature of the Earth has undergone successive increases over the last four decades, reaching approximately 1.1°C higher in 2011–2020 than in 1850–1900.

On top of that, 2019 and 2020 have been the warmest on record. Specifically, 2019 recorded the warmest winters and 2020 equalled 2019's record for the warmest summer months since records have been kept.

The recently published Emissions Gap Report Report 2022 points to a record-breaking global emissions level of 52.8 GtCO2eq in 2021. The projected emissions gap by 2030 is thus 15 GtCO2e for the 2°C pathway and 23 GtCO2e for the 1.5°C pathway. In other words, if all global commitments to combat climate change in the medium term are taken into account, the temperature increase at the end of the century will lie in the 2.4–2.6°C range. If only the measures implemented to date are considered, the increase would be 2.8°C.

What are the consequences of global warming for life on Earth?

The IPCC projects that if global warming exceeds 1.5°C, even if it exceeds that global average temperature temporarily before falling again, human and natural systems will face serious additional risks, including some that are irreversible.

We're already seeing some of the consequences of climate change. For instance: rising sea levels, polar ice cap and glacier melting, more recurrent extreme weather events, loss of biodiversity or climate migration, etc.

Notwithstanding all this, there is still time to tackle climate change, though it will require major transformations in today's society that must largely be implemented in the next 8 years. Even if this transformation does not completely close the emissions gap, everything counts. Implementation is necessary to move towards a carbon-neutral future that will allow us to limit global warming and deliver other social and environmental benefits such as clean air, green jobs and universal energy access.