Questions and answers on climate change

What can a city like Barcelona do in response to a global problem like this?

Cities are part of the climate change problem, as the majority of emissions and energy consumption are concentrated in cities around the world, but for that reason they are also a key part of the solution.

In general terms, the majority of cities are already experiencing the impacts associated with climate change, such as effects on health, increasing temperatures, aggravation of the urban heat island effect, more periods of drought, more flooding, more heat waves, rising sea levels, reduction in water resources, etc.

Local government measures are crucial to managing climate change issues, both locally, because they increase the quality of life of city residents, and globally, since the world’s urban populations make up over 54% of the planet’s inhabitants. In the European Union, 74% of the population lives in urban areas, consuming 75% of the energy.

Cities and their metropolitan surroundings demonstrate a close link between urbanisation, energy use and greenhouse gas emissions. Urban density and layout are key factors in influencing energy consumption, especially in the transport and construction industries.

But... hasn’t Earth survived many episodes of climate changes? Why should we be worried?

Because this is the first time that climate change has occurred with a human population living across the entire globe. It is, therefore, a problem that goes beyond strictly environmental aspects to become a question of ethics and responsibility. In this case, the changes are being caused directly by human actions and not all populations have the same ability to adapt; those who are most affected and who have the greatest difficulty adapting are those who have contributed to the problem the least.

If we do not act, based on the current emissions rate, by 2100 the average temperature of the planet will have gone up by between three and five degrees... Is that all?

Three to five degrees may not seem like a lot, but a global change of just one degree in the average temperature is a huge amount of heat to warm up all the oceans, the atmosphere and the sun. In Earth’s recent history, a difference of five degrees is what separates the last ice age from an interglacial period.

Is CO2 a pollutant? When we talk about atmospheric pollution, does CO2 count?

The presence of CO2 and other greenhouse gases in the atmosphere is natural and, in fact, it is one of the things that allow us to live on Earth, as it keeps the planet at the right temperature. The concentration of these gases is the result of a balance between emissions sources and sinks (processes that absorb or fix them). The problem is not whether or not these substances are pollutants, but the fact that we are increasing the concentrations of them and, thus, their capacity to retain the heat reflected by the Earth. Since the industrial revolution, anthropogenic sources have increased significantly, whilst the majority of sinks (oceans, vegetation, rocks, etc.) have much slower cycles. Current emissions may, therefore, take decades or centuries to be absorbed.

When we talk about atmospheric pollution we are talking about other substances, which, when there are concentrations above a certain level, have a direct effect on health.

Greenhouse effect, global warming, climate change... are they all the same thing?

The greenhouse effect is a natural phenomenon that supports life on Earth. It is related to the absorption capacity, the percentage of solar radiation reflected in the form of heat, and its retention in the atmosphere by greenhouse gases (CO2, N2O, CH4), which represent 1% of the atmosphere’s composition. Increased emissions of these gases due to human activity produces global warming, increasing the average temperature of the planet (currently 15 °C) and, as a consequence, causes changes in the climate and other effects:

  • Reduced snow and ice (increasing albedo)
  • Increased ocean temperatures (reduced sink capacity).
  • Ocean acidification
  • Rising sea level
  • Increases in extreme weather events

Is it possible to be carbon neutral or “zero” CO2?

Any activity that uses energy not produced from renewable sources (solar, wind, etc.) generates CO2 emissions. Some agricultural and livestock activities also generate greenhouse gas emissions. It is therefore, very difficult to find “zero emissions” products or services. What we can do, however, is offset these emissions by calculating the amount of greenhouse gases emitted in manufacturing a product or conducting an activity (for example, an aeroplane journey) and invest in a project that enables us to reduce emissions by the same amount. This means that a product or activity becomes “carbon neutral”.

Carbon footprint, ecological rucksack... are they the same? What do labels tell us?

A product’s carbon footprint is calculated based on the emissions generated during its manufacture “from the cradle to the grave”, i.e. From obtaining the raw materials to its use or consumption. It should not be confused with ecological footprint or rucksack, which is a broader concept that also takes into account other elements, such as water consumption, emission of pollutants, land use, etc. Comparing products is not easy, as there are many factors that affect the amount of emissions. For example, in the case of wines, there are factors such as the energy efficiency of the cellar, the type of glass used in the bottle or the distribution chain (where the wine is sold to and how it is transported). But there are other factors not related to efficiency or saving, such as the distance from the vineyard to the cellar, the yield of the vines or the type of wine made with more or less use of the must. These difficulties in interpreting the situation and the relationship with the “goodness” of a product has meant that very few manufacturers report the carbon footprint of their products. It is mostly an internal tool used to assess the efficiency of introducing measures to reduce emissions. It is predicted that in the near future mechanisms that allow customers to find out the carbon footprint of products will be developed.

Was the Paris Agreement really that important?

The so-called Paris Agreement represents an significant step forward because it is the first time that the problem and its causes were not questioned during climate discussions. Without assessing in detail whether it is the agreement that the planet needs, we can say that it allows a framework to be constructed, showing, for the first time, that the challenge is really being taken on. This signifies the creation of activation and governance framework. It is based on the principle of transparency: all signatories must publicise their goals, which do not have to be same, but consistent with their technological capacity. It also sets out the mechanisms for collaborating with undeveloped countries, showing that the more developed countries are taking responsibility.

Are renewable energies the solution?

Renewable energies are a fundamental pillar to reduce the emissions generated by the energy system. Given the need to rapidly speed up emission reduction rates, however, we also need to tackle areas such as the food production system (agriculture and livestock play an important role in methane and nitrogen oxide emissions, which currently, rapidly increase CO2 emissions). It is equally important to maintain and regenerate the world’s forests.

It will be impossible to achieve the necessary mitigation levels without transforming the social system in a similar magnitude to technological changes. This includes the way in which we work, how we move around and what we eat, amongst other examples.(Josep Canadell Gili, in the Third Report on Climate Change).