4 Climate
change:
the complex
gears
that challenge the
Humanity

• Gilvan Sampaio de Oliveira is a researcher at the Earth System Science Center (CCST) of the National Institute for Space Research (INPE). He has an undergraduate degree in Meteorology from the University of São Paulo (USP), and an MSc and PhD in Meteorology from INPE. He is the author of several books about climate change and the El Niño and La Niña phenomena, as well as many scientific papers in international and national journals.
  
  Carlos Nobre is a retired INPE researcher. He is currently the president of the Brazilian Education Ministry’s Graduate Education Support Agency, CAPES, and the scientific director of the National Institute of Science and Technology for Climate Change. He has an undergraduate degree in Electronic Engineering from Brazil’s Aeronautics Institute of Technology and a PhD in Meteorology from the Massachusetts Institute of Technology. He has been a member of the Intergovernmental Panel on Climate Change (IPCC) for several of its assessment reports, including IPCC’s Fourth Assessment Report, which won the Nobel Peace Prize in 2007, together with Al Gore. He is a member of the Brazilian Academy of Sciences and the Academy of Sciences for the Developing Nations (TWAS), and a foreign member of the National Academy of Sciences of the United States of America.

The planet is a complex system (which we term the Earth system), in which many variables – external and internal, including human actions with global effects – combine to produce the climatic conditions we have observed. The components of the Earth system constantly interact like cogs in a watch’s gears, and it is hard to isolate the influence of each one. Obviously, these interactions are far more complex than simple gears.

When solar radiation reaches the Earth, it is received by the atmosphere and surface, and then converted into heat and other forms of energy, producing the circulation of winds and ocean currents, for example. At the same time, the different types of surface – vegetation, desert, water, snow or ice – have a fundamental effect on the quantity of solar radiation that will be absorbed or reflected.

Once each region’s climatic patterns have been established, especially those related to temperature, precipitation and moisture, they dictate the types of living organisms that will proliferate in the planet’s different areas. In a reciprocal manner, living beings – especially plants – will also decisively affect the climate as they receive and emit greenhouse gases, among other influences they have on the environment. Through agriculture and industry, humans appear in this complex system, putting pressure on the environment. All of these factors, operating concurrently, have an influence on Earth’s climatic configurations.

To understand how this complex planetary system functions, scientists have created the field of study called “Earth system science,1” in which natural, social and other sciences interact in a single context. The goal is to understand the dynamics of complex interaction between natural and social systems, with bio-geophysics, biogeochemistry and biodiversity on the one hand, and human systems such as politics, culture, economics and demographics on the other hand. To better observe the physical elements that make up this science’s object of study, specialists tend to classify the different parts of the Earth system in the following spheres, which overlap and interact with each other: the photosphere, atmosphere, hydrosphere, biosphere, cryosphere and lithosphere.

The hydrosphere is composed of water, the most abundant substance on the planet, covering around 77% of the surface. It is mainly formed by sea water, where the dynamics of ocean currents distributes heat across the globe and helps to make many regions inhabitable. The oceans are also largely responsible for providing the atmosphere with water vapor. The atmosphere then transports it to the continents, where it turns into clouds and rain, feeding rivers and lakes, besides contributing decisively to life throughout the planet.

All the frozen water existing on Earth makes up the so-called cryosphere (part of the hydrosphere), which has a major influence on climate. Because it is a light color (white), ice is an excellent reflector of solar rays. However when ice floating on the sea surface melts (due to a rise in Earth’s sea surface temperature, for example), the solar rays that were previously reflected are now absorbed by a darker ocean. This absorption of solar radiation raises the local air temperature, inducing ever more melting of ice, in a cycle that accelerates the reduction of the area covered by it.

Another important sphere is the atmosphere, a layer of gases surrounding the Earth, whose composition is one of the climate’s key elements. Its most commonly found substances are nitrogen (which makes up around 78% of the total volume of gases) and oxygen (approximately 21%). Other substances, such as water vapor, carbon dioxide, methane and ozone, despite appearing in small concentrations, play a central role on climate, as they induce the natural warming of the surface of the planet and troposphere (the lowest and densest layer of the atmosphere) through the atmospheric greenhouse effect: the higher the concentration of these gases, the greater the warming is.

Just as we may find ashes from Amazon forest fires in the middle of Antarctica, we are sure that, if we alter the conditions of a given region (by felling and burning forests, for example), we will be inducing the occurrence of alterations in other parts of the globe. The planet is completely interlinked through the atmosphere and oceans.

Through the dynamics of air masses, the atmosphere is largely responsible for the distribution of heat and rain, as the movement of gases does not respect frontiers and influences the whole planet. A classic example of this subject is the El Niño phenomenon (the warming of Pacific Ocean waters near the Equator), which has effects on the entire planet’s climate, including in Brazil. Just as we may find ashes from Amazon forest fires in the middle of Antarctica, we are sure that, if we alter the conditions of a given region (by felling and burning forests, for example), we will be inducing the occurrence of alterations in other parts of the globe. The planet is completely interlinked through the atmosphere and oceans.

Alongside the hydrosphere and atmosphere, the third primordial component of the Earth system is the biosphere, which includes life in its different forms: plants, animals, marine and land organisms, both macroscopic and microscopic. Large forests such as the Amazon play a fundamental role in the process of absorbing water in the soil and evaporation to the atmosphere, contributing to the formation of clouds and rain. The biosphere also has a notable influence with regard to concentrations of carbon dioxide – which plants absorb from the air and return oxygen through photosynthesis.

Finally, there is the lithosphere, the outermost solid layer of the planet, which also plays an important role, especially due to its release of enormous quantities of energy, gases and aerosols through phenomena such as volcanic eruptions. In addition, the movement of the tectonic plates that form Earth’s crust is responsible for shaping the continents, over hundreds of millions of years, thereby affecting the ocean currents, global climatic patterns, the environment, and the composition and distribution of species.

Also considering human beings’ effects on nature, the global scientific community is faced with the enormous challenge of answering the following questions: What is happening to the climate? How may these changes affect our lives, our diet, our health and the environment around us? Is there something we can do to minimize the negative impacts of these changes?

A little over 20 years ago, the majority of countries signed up for the United Nations Framework Convention on Climate Change, an international treaty2 to reduce global warming risks and deal with the inevitable impacts of temperature increases. In 1997, dozens of nations approved an addition to this treaty, the Kyoto Protocol, which recognized the responsibility of developed countries regarding the high levels of greenhouse gas emissions arising from their industrial and agricultural activities and established concrete objectives to reduce these emissions between 2008 and 2012 – later extended to 2020.

These political measures are a response to different climate studies carried out throughout the world and pressure from the global scientific community concerning the importance of minimizing the consequences of human effects on climate change. Among laymen, the best-known international initiative in the area is probably the UN Intergovernmental Panel on Climate Change (IPCC), a group of specialists who are dedicated to compiling scientific data and summarizing the progress of knowledge about climate change to guide decision-making in the field. The IPCC’s work has been reported prominently in the media, underpinning global discussions about climate change, its impacts and steps we can take to deal with climate issues.

In Brazil, interest in the subject of global changes was initially and mainly motivated by the Amazon forest’s importance for the planet’s climate, as it was necessary to understand the consequences of these changes for the forest and the climate. Starting in the 1980s, part of the international scientific community turned its attention to the region. Until the mid-1990s, the majority of research projects carried out there were led by foreign groups, but this work helped to empower Brazilian researchers to do their own work, conducting successful projects about the issue.

Some studies indicate that by the mid-21st century, part of the Amazon may experience a process through which tropical forest is replaced by savannah or semi-deciduous forest, which could mean impoverishment from a biological point of view.

The international scientific community’s efforts to study the Amazon have not been made by chance, of course. The region gives rise to major concerns when we project the potential global impacts of the gradual disappearance of this forest. The Amazon region is home to the largest remaining area of tropical forest in the world, performing a fundamental role in hydrological and climatic regulation for a vast area of South America, besides possessing a large stock of carbon and exceptional biodiversity.3 Despite this, it is known that more than 18% of the native forest has already been destroyed. Some studies indicate that by the mid-21st century, part of the Amazon may experience a process through which tropical forest is replaced by savannah or semi-deciduous forest, which could mean impoverishment from a biological point of view. Nevertheless, there are still few analyses of the effects of climate change on biodiversity. We know that large deforested areas may induce modifications in the hydrological cycle, which would make the regional climate hotter and drier. This would also favor the occurrence of fires, with serious consequences for nature and local communities.

In addition to the degradation of the Amazon forest, another key issue in climate studies is the behavior of oceans. Even if a change in ocean dynamics is seemingly small, it may produce large climate variations in many areas of the planet.

One of the biggest concerns is about the expansion of waters as they heat up. The waters of the ocean’s surface layers have already risen in temperature by around 0.6°C over the last 50 years, and the warming is slowly penetrating the deeper water layers. This warming causes a thermal expansion of water and, added to the volumes arising from glaciers melting and flowing into the oceans, this is resulting in an alarming rise in the mean sea level of around 2 to 3 millimeters per year. This amount may seem insignificant to some people, but scientifically speaking it will represent a very considerable increase after a few decades. The consequences include not only the loss of ecosystems, but also more frequent flooding of coastal cities and increased vulnerability to severe storms.

The oceans are also responsible for absorbing around one-third of all carbon emissions produced by human action, reducing Earth’s amount of atmospheric carbon dioxide, which is associated with the planet’s warming. However, studies show that climate change is negatively affecting the absorption of carbon by the oceans,4 as hotter water is not capable of maintaining as much carbon dioxide as colder water, and ocean warming may possibly lead to an increase in concentrations of the gas in the atmosphere. In other words, we do not yet know for how long the oceans will continue to sequester anthropogenic carbon at present levels. Even more worrying is the fact that the absorption of carbon dioxide by the oceans makes waters more acidic. Ocean acidification could pose serious risks to marine life.

Given the evidence of how the world’s climate is changing, it is up to us to evaluate now the extent to which it is possible to contain this process – or at least the bulk of it occurring as a result of human action – and on the other hand, the extent to which we should organize ourselves to tackle the consequences of global warming. We should consider how countries or cities may experience more frequent natural disasters, including severe storms, floods and prolonged droughts; how to deal with diseases brought about by new climate configurations; and how to adapt agriculture to the new conditions.

Studies show that climate change is negatively affecting the absorption of carbon by the oceans, as hotter water is not capable of maintaining as much carbon dioxide as colder water, and ocean warming may possibly lead to an increase in concentrations of the gas in the atmosphere.

In this context, an important concept is vulnerability to climate effects – “the capacity of a social group or individual to deal with, anticipate and recover from the impacts of disasters.” Research projects in this area consider that different populations have higher or lower levels of vulnerability, depending on factors such as income, culture, education and political power.

In Brazil, a mapping of the vulnerability of different regions to the impacts of climate change has showed, for example, that the Northeast is among the regions that will suffer the most, not only from environmental consequences, but also epidemiological and socioeconomic ones. It is forecast that there will be a worsening of problems such as endemic infectious diseases (malaria, leishmaniosis, leptospirosis and dengue fever), accidents involving natural disasters and extreme weather events (landslides, storms and floods), reductions in agricultural yields and malnutrition in areas already affected by food insecurity.

From the Brazilian economy’s perspective, preliminary results suggest that climate change will have negative effects on the country’s growth and human wellbeing, although some sectors and regions may be positively affected. In addition, one issue to be seriously considered is that climate change may help to reinforce regional economic inequalities in Brazil.

Studies suggest that climate change ought to be analyzed in conjunction with globalization (increase in connections between people in trade and information), environmental changes (degradation of ecosystems, reduced biodiversity and accumulation of toxic substances in the environment) and the weakening of governance systems (via lower health investments, higher dependence on markets, and growing social inequalities), given that all these factors strongly interact in a complex manner.

Preparing for and adapting to global climate change and its impacts, and mitigating its effects, are not only tasks for government leaders. Scientists believe that to reduce the impacts of climate change, greenhouse gas emissions will need to be cut in half by 2050, and eliminated by the end of the century – a bold target, but something that the population may contribute to. Some important initiatives include the following: reduce energy consumption and improve energy efficiency by introducing more renewable clean energy sources such as solar and wind, and by using public transport or bicycles; capture carbon under the ground through sustainable agriculture; and preserve forests, which absorb carbon in the soil and trees. It is estimated that emissions may be reduced by one-third by 2030 if such practices are adopted.

Other steps that are within everybody’s reach are as follows: avoid burning organic compounds or garbage in general; plant more trees and cultivate green areas; reduce and recycle waste; make frequent inspections of vehicles; save water; choose biodegradable products; consume less meat; use less packaging; avoid disposable products; seek to consume organic food… The list is long, and conscientious citizens will certainly find ways to play their part.