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Understand what climate change is and what its possible causes and consequences are

Edited and resized image by Andy Brunner, available on Unsplash

Climate change, climate change, or climate change are climate variations in temperature, precipitation, and cloud cover on a global scale. But, before understanding what climate change is, it is necessary to establish that there is a difference between “climate” and “weather”. Have you ever heard someone complain that the weather is closing when it looks like it's going to rain? Or that the weather somewhere is too hot? So it is. Climate and weather are not the same thing.

• Climate change already affects the health of new generations

When we say "weather" is bad, we are referring to local weather changes within shorter time periods such as minutes, hours, days and even weeks. The "climate" refers to periods of medium to long term and can be characterized regionally or globally. In other words, climate can be considered an average of time over several seasons, years or decades.

So what is climate change? We already know that it does not refer to changes that occur from one day to another, but over several years or decades. A common mistake is to believe that climate change is the same thing as global warming. Global warming is, yes, a consequence of climate change that has been happening over the years, but not the only one. Furthermore, this is not the first time that our planet has undergone global climate change. It is a little more difficult for us to visualize the issue of climate change, as the time scales involved are very large, and its impacts are less immediate.

• What is thermoaline circulation

Another question that often arises about climate change is: how can it cause episodes of extreme cold if the Earth is experiencing "global warming" and not "global cooling"? The fact is that no single event can prove or disprove the global warming thesis. At global levels it is only possible to make hypotheses when analyzing the Earth's history in geological time, which is very long.

The increase in the emission of greenhouse gases increases energy retention in the oceans and in the atmosphere, causing an increase in the intensity, frequency and impact of extreme weather events, whether cold or hot. Understand:

Evidence of climate change

Edited and resized image by Agustín Lautaro, available on Unsplash

The Earth's climate has changed throughout history, and in the last 650,000 years the planet has gone through seven cycles of glacial advance and retreat. The last Ice Age, which took place 7,000 years ago, came to an abrupt end and marked the beginning of the modern age of climate and human civilization.

• Climate change can increase poverty in Brazil

Although there are still controversies among some members of the academic community regarding global warming, global climate change is an already accepted and well-established fact among most scientists. The Intergovernmental Panel on Climate Change (IPCC), for example, considers the scientific evidence for global warming indisputable.

Edited and resized image of Dikaseva, is available on Unsplash

The current warming trend is an important point within this matter, as most of it is caused by anthropogenic influence, and it has been amplifying at an unprecedented rate over the last 1300 years.

Satellites and other technological advances have allowed scientists to see the big picture, collecting diverse types of information about our planet and its climate on a global scale, which over the years have revealed signs of climate change.

The deformation of icy cores in Greenland, Antarctica and mountain glaciers show that the Earth's climate reacts to changes in the levels of greenhouse gases released into the atmosphere. They also show that, in the past, major changes in global climate have occurred quickly, geologically speaking: in tens of years, not in thousands or millions.

• What is the greenhouse effect?

Below, see some photographic evidence of the consequences of climate change:

1. Mýrdalsjökull

Left, September 16, 1986. Right, September 20, 2014 - Image: NASA

Mýrdalsjökull is Iceland's fourth-largest ice cap, covering the Katla volcano in the far south of the country.

2. Aral Sea

Left, August 25, 2000. Right, August 19, 2014 - Image: NASA

The Aral Sea was the fourth largest lake in the world until the 1960s, one of the largest bodies of inland saline water in the world and the second largest sea in Asia. It has shrunk dramatically over the past 30 years. One of the main reasons is crop irrigation: water was taken from the rivers that kept the Aral Sea full. As a result, there have been noticeable changes in the local climate, contaminated dust storms, the loss of fresh water and crises in the local fishing industries. By the late 2000s, the Aral Sea had lost four-fifths of its water volume.

3. Lake Powell

Left, March 25, 1999. Right, May 13, 2014 - Image: NASA

Prolonged water shortages have caused a dramatic drop in the water level in Lake Powell. The images show the northern portion of the lake, which stretches from Arizona to Utah, USA. The 1999 image shows the Lake with its water levels close to its full capacity, and in 2014 with 42% of its capacity filled.

4. Alaska

Melting glaciers in Alaska.

Left, 1940. Right, August 4, 2005 - Image: NASA

the documentary Chasing Ice shows effect of climate change on Arctic glaciers.

Causes of climate change

Climate change can be caused by natural factors such as changes in solar radiation or movements in the Earth's orbit. However, the IPCC says there is 90% certainty that the increase in temperature on Earth is being caused by human action over the past 250 years.

Most scientists in the field agree that one of the main causes of the current global warming trend is human influence on the expansion of the greenhouse effect. It is worth remembering that the greenhouse effect is a natural process, on which life on Earth depends. If all the radiant energy from the sun on Earth returned to space, we would have a planet without heat and uninhabitable for life as we know it, but anthropogenic influence has been interfering in order to intensify the greenhouse effect, causing an abrupt global warming that already has been harming several species and ecosystems. Over the past century, fossil fuels, such as coal and oil, have been burned, which has increased the concentration of atmospheric carbon dioxide (CO2). This is because the process of burning coal or oil combines carbon with oxygen in the air to form CO2. To a lesser extent, deforestation for agriculture, industry and other human activities has increased concentrations of greenhouse gases (GHGs).

The consequences of this change in the natural greenhouse effect are difficult to predict, but some likely effects are:

• Overall, the Earth will become warmer - some regions may have higher temperatures than others;
• Rising temperatures will likely result in higher rates of evaporation and precipitation, causing some regions to become wetter and others drier;
• A more intense greenhouse effect would warm the oceans and melt ice caps, raising the level of the oceans. Ocean waters would expand due to rising temperatures, also contributing to sea level rise;
• Some plants may respond favorably to increased atmospheric CO2, growing more vigorously and improving water use efficiency.

The role of human activity

The industrial activities on which our modern civilization depends have raised atmospheric carbon dioxide levels from 280 parts per million (ppm) to 379 ppm over the past 150 years. The IPCC also concluded that there is a greater than 90% probability that human-made greenhouse gases (such as carbon dioxide, methane and nitrous oxide) have caused most of the observed increase in Earth temperatures over the past 50 years.

Solar radiation

It is possible that variations in solar activities played a role in past climate change. For example, a decline in solar activity is believed to have triggered a Little Ice Age, between approximately 1650 and 1850, when Greenland was covered by ice from 1410 to 1720 and glaciers advanced into the Alps.

Despite this, there is evidence proving that current global warming cannot be explained by variation in solar activity:

• Since 1750, the average value of energy coming from the sun has either remained constant or increased slightly;
• If the warming was caused by a more active sun, then scientists could expect warmer temperatures in all layers of the atmosphere. Instead, they have observed a cooling in the upper atmosphere, and a warming in the surface and lower parts of the atmosphere. This is because greenhouse gases trap heat in the lower atmosphere;
• Climate models that include changes in solar radiation cannot reproduce the temperature trend observed over the last century or more without including an increase in greenhouse gases.

Effects of climate change

Climate change in the world already has observable environmental effects. Glaciers have shrunk, ice in rivers and lakes has broken earlier, varieties of plants and animals have changed, and trees have blossomed earlier.

Scientists have predicted effects that would result from climate change in the world and are now taking place, such as the loss of ice in the oceans, accelerated sea level rise, and more intense cold and heat waves.

Scientists also believe that global temperatures will continue to rise in the coming decades, in large part due to greenhouse gases produced by human activities. The Intergovernmental Panel on Climate Change (IPCC), which includes more than 1,300 scientists from the United States and other countries, predicts a temperature increase of 2.5 to 10 degrees Fahrenheit over the next century.

According to the IPCC, the effects of climate change will be different for each region, depending on the capacity of each social and environmental system to mitigate or adapt to the changes.

The IPCC predicts that an increase in the global average temperature of less than 1-3 degrees Celsius above 1990 levels will have beneficial impacts in some regions and harmful impacts in others. Net annual costs will increase over time as global temperature rises.

In any case, about 97% of the global scientific community agrees that the warming climate trends over the past century were largely due to human activities.

The chart below contains temperature data from four international scientific institutions. All show rapid warming over the past few decades and the last decade was the warmest on record.

What to do?

Scientific uncertainty about the environmental damage caused by climate change requires that human actions that cause this type of change be guided by the Precautionary Principle. That is, research that seeks to obtain certainty about the possible environmental damage caused by climate change should be encouraged, in addition to the obligation to act in advance to protect the environment and public health in the face of suspicious and uncertain risks, in especially the potentially serious or irreversible ones.

Some precautionary actions against these uncertain risks, and consequently against climate change, are the reduction of greenhouse gas emissions and the effects on global warming. Decreasing deforestation, investments in reforestation and conservation of natural areas, encouraging the use of non-conventional renewable energies, preferences for the use of biofuels (ethanol, biodiesel) over fossil fuels (gasoline, diesel oil), investments in reducing the consumption of energy and energy efficiency, reduction, reuse and recycling of materials, investments in low carbon technologies, improvements in public transport with low GHG emissions are also some of the possibilities. And these measures can be established through national and international climate policies.

As for legislation, in 2009, the National Policy on Climate Change (PNMC) was instituted in Brazil through Law No. 12.187/2009, which showed the country's commitment to reducing greenhouse gas emissions between 36 .1% and 38.9% of projected emissions by 2020. Some instruments used to implement the PNMC are the National Plan on Climate Change, the National Fund on Climate Change and Brazil's Communication to the United Nations Framework Convention on Climate Change.

The National Plan on Climate Change, for example, presents some goals and objectives that will result in the reduction of greenhouse gas emissions, in addition to other environmental gains and socioeconomic benefits, which you can check on the Ministry of the Environment's page ( MMA).

See below a video from the National Institute for Space Research (INPE), which explains about the greenhouse effect, global warming and climate change. The video also cites the influence of the Industrial Revolution on current climate change, future projections made by the IPCC, types of future scenarios, and gives us tips on how we can help minimize the effects or delay global warming.