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Ecology

Climate Change

The climate has been changing for millions of years. The history of the planet has seen periods of successive heating and cooling since before man walked the Earth. However, the Industrial Revolution marked the entrance of humans into the climate game, contributing additional factors that have accelerated this rhythm. In fact, almost half of the CO2 released into the atmosphere between 1750 and 2011 has been released in the last forty years.

Text and Photos: Javier A. Pinzón

Simple observation of each of the available measuring instruments is enough to confirm that our planet is warming at a faster than normal rate. Changes have been observed on the atmospheric surface layer, in ocean water temperature and levels, and in the size of glaciers, snow cover, and atmospheric water vapor. Scientists from all over the world have verified this evidence through diverse independent climate indicators.

Warming is not the same everywhere: the highest temperatures are recorded over landmasses and the lowest over oceans. Similarly, temperatures are higher in higher latitudes than in the tropics. Based on average temperatures, therefore, the increase doesn’t seem very threatening:  from 0.6°C to 0.9°C over the past century.

However, in 2016 the planet set its third consecutive annual heat record, with temperatures around 1.1° C higher than the pre-industrial average. The 21st century has already experienced 16 of the 17 warmest years since we began recording temperatures in 1880. In the Arctic, for example, the 2016 summer ice flow was the second smallest ever recorded (2.57 million square miles, second only to the flow of 2012). In certain parts of Russia, temperatures were 6°C or 7°C higher than normal. At the other end of the Earth, in Antarctica, during the austral spring (November), the polar ice field (layer of ice floating on polar oceans) shrank nearly 1.2 million square miles in average area over the past thirty years.

Ocean levels continue to rise, and although the phenomenon was thought to be gradual, it seems to be accelerating; one study shows that sea levels have increased 25% to 30% faster from 2004 to 2015 than from 1993 to 2004. This makes small islands in the places most affected by this phenomenon. But what is the cause?

The Earth’s climate is always changing, and for a number of reasons. To determine the main causes of the current changes in climate one must first establish whether a particular change is the result of normal fluctuations produced by forces within the climate cycle. For example, large-scale ocean variability, such as the fluctuations produced by the El Niño Phenomenon (ENSO) in the Pacific Ocean, with decennial and centenarian cycles, is a leading cause of internal climatic variability.

Several formal studies have used climate models in controlled experiments to test whether current climate changes can be attributed to forces within the climate cycle. Because each force has its own unique model, they are referred to as “fingerprints.” In order to produce a meaningful assessment, a climate model must reliably simulate the fingerprints and natural variability associated with each of the forces. No model can perfectly replicate all weather characteristics, but a number of detailed studies indicate that simulations using current models are reliable enough to carry out attribution assessments.

To what, then, can these changes be attributed? According to the World Meteorological Organization, they are influenced by a number of factors.

NATURAL FACTORS

The Sun

The Sun is the main force behind the Earth’s climate because it provides most of the planet’s energy. The sun’s energy output increased by about 10% from 1750 to 1950, contributing to an increase in temperature on Earth of about 0.1°C during the early 20th century. And yet, although the Earth continues to heat up, data collected since 1979 show no long-term change in solar energy production. Until 2011, this production had only increased by 2% since 1750.

Changes 

in the Earth’s Orbit

The Earth’s orbit is elliptical; around January 4th every year our planet is 3% closer to the Sun than on July 4th. This change in the distance between Earth and Sun causes the planet to receive about 7% more solar radiation in the upper atmosphere in early January than early July. If the current climate change were due to a change in Earth’s orbit, a greater difference would be expected in solar radiation in the upper atmosphere between January and July, but this is not the case.

Precession

Precession is a change in orientation of the rotation axis of a rotating body. For long periods of time the Earth precedes in its axis, a change that directly affects the time and the intensity of the seasons. Repetitive cycles in the Earth’s orbit can influence the angle and distribution of sunlight. The inclination and oscillation of the Earth’s axis and the degree to which its orbit is elongated produce Milankovitch cycles. Scientists believe that these cycles triggered and ended the ice ages during the last million years. But these changes take millions of years and, therefore, cannot explain warming during this century.

Volcanic Eruptions

Another possible explanation for global warming is volcanic eruptions. To correlate this external force to the climate, scientists have studied the climatic effect of some of the largest recorded explosions. These explosions have not, however, been related to global warming. For example, the eruption of Mount Pinatubo in the Philippines cooled the global temperatures in 1991. This volcano expelled an enormous amount of volcanic ash and sulfur dioxide about 18 miles into the atmosphere. These fine particles, called aerosols, remained in the upper atmosphere and circled Earth for more than a year. Strangely enough, the particles dispersed the incoming sunlight and slightly cooled the global climate for two years.

Human Factors

Although the climate has varied for millions of years, changes during the last century have not been attributed to any of these natural forces. On the contrary, according to the latest technical report from the Intergovernmental Panel on Climate Change (IPCC), which summarizes several independent studies worldwide, the recent change in global climate is directly related to human activities that increased the release of greenhouse gases such as CO2.

Measurements of samples of ice and air taken from the atmosphere show that the concentration of CO2 increased from 280 ppm (parts per million) in 1850 to 409 ppm in April 2017, which exceeds the 350-ppm limit established as a safeguard. Several climate models warn that failure to return to this cap would cause irreversible damage to our planet, such as the melting of the Greenland ice sheet and, with this, the release of more carbon stored in the layer of ice underground.

OLYMPUS DIGITAL CAMERA

Parallel to the increase in CO2, a growth in methane and nitrogen oxide gases is also responsible for warming. 78% of these gases came from CO2 released by burning fossil fuels and as a result of industrial processes. 30% of CO2 released was retained on land by plants, 30% in the oceans, and the remaining 40% remained in the atmosphere. The amount absorbed by the oceans is making the water more acidic, which affects the balance of the marine animal food chain.

According to this report, the levels of CO2 released into the atmosphere have increased significantly since the Industrial Revolution. It is estimated that nearly half of the CO2 released between 1750 and 2011 was released in the last forty years. To make matters worse, the planet’s forests —natural processors of these gases— have diminished, also reducing the amount of oxygen released into the atmosphere.

The time scale of observation of these anthropogenic changes is short, but the effect is clear, with a change of almost one degree Celsius in global temperatures in recent decades. This increase in temperature increases water vapor —also a greenhouse gas— in the atmosphere, which will raise temperatures even more.

The Impact 

The impact of warming on human populations is often geographically heterogeneous, because it depends not only on changes in climatic variables but also on socio-economic factors. Changes are most easily observed locally, such as variations in precipitation or melting of snow and ice, which alter hydrological systems, affecting the quantity and quality of water reserves.

These climate changes also lead to ecosystemic change. Many terrestrial, freshwater, and marine species have changed their geographic range, seasonal activities, and migration patterns, and are less abundant or interact differently with other species. This could increase the spread of vector-borne diseases and pests in crops or contribute to the extinction of certain plants and animals that are unable to move or whose processes of adaptation to new conditions are not fast enough. Addressing this global problem is not only a question of national policies; it also requires that individuals change. If we want to stop this trend, we must all make an effort to reduce our personal carbon footprint. And for the sake of our only home, this change must begin now!

 


How to Reduce Personal Emissions

• Wherever possible, switch to clean energy sources. Install solar panels on the roof of your house.

• Use public or alternative means of transport, such as bicycles or electric motorcycles. If you have to buy a car, make it a fuel saving or electric vehicle.

• Avoid using plastic, which is a derivative of petroleum. By reducing its use you reduce your personal emissions. Choose paper or cloth packaging, carry your own water dispenser, and avoid disposable bottles.

• Buy local. Transport of local products consumes less fuel. Consume fresh fruits and vegetables.

• Select environmentally responsible brands.

• Limit the amount of animal protein you consume, especially beef, as production of this food releases large amounts of greenhouse gases.

• Use energy-saving appliances and LED instead of traditional light bulbs, which save 10% energy. Seal your home tightly so that air conditioning and heating are more efficient. This will also help you save money.