Climate is cyclic. Throughout the ages, the Earth’s climate has changed often;

Figure 3.7 shows some examples of climate changes in Greenland;

Even though the number of humans in some of the eras and ages shown in those charts was far smaller than what it is now, Greenland was never a much populated place

Evidence and Impact of Global Climate Change

Global Climate Change is due to both antropic/human causes and natural causes:

Less/more solar activity (e.g. due to sun storms);

Impact of volcanic activity (excessive dust can cool off the atmosphere);

Variations in the Earth’s orbit (Chile’s and Haiti’s earthquakes both changed the axis of the Earth, which changes its orbit) with changing distances from the Sun;

Other phenomena that explicit different trends in global temperature are:

Excessive melting of the Arctic Sea (40% thinner now than in 1970s);

All major non-polar glacial systems are in rapid retreat;

The timing of egg-laying for animals and the flowering for plants has changed as the climates have warmed, changing the distribution of life species as well;

Precipitation has increased in the northern hemisphere, especially destructive rain storms;

Last, but not least, El Niño and La Niña events; the waters of the Southern Pacific warm up causing a reverse whirlpool which affects climate on Earth in the form of extra thunderstorms, heat waves, tsunamis, typhoons etc.

The scale of changes in global temperatures since the 1980s are unprecedented, which leads many researchers and geographers to hypothesise that human activity may be a significant part of the cause.

“There seems little doubt that global warming is occuring, although some researchers question whether it is due to natural processes or human activities such as the consumption of fossil fuels”.

Nevertheless, global warming is a very much present and ongoing issue on Earth today, and it is of great importance for us to understand its behaviour.

Events that may possibly occur, as a consequence of climate change:

Reduced crop yields; Less availability of water (especially in dry

areas);

Land degradation; Rising sea levels; Reduced biodiversity; Deforestation; Tropical cyclones (Typhoons in northwestern

Pacific - Asia/ Hurricanes in Northeastern Pacific – North America)

Destructive thunderstorms (increasing flooding problems)

Serious financial costs.

There is also concern that global warming might cause tropical cyclones (typhoons/hurricanes) to become more frequent and much more intense;

Typhoons are low pressure atmospheric particle cells (from dust/vapor/gases) that cause winds to exceed speed of 120 km/h.

They exist over the warm oceanic waters from which they draw their energy and moisture

When they move over cool water, they lose strenght; however, when they move over warm or hot water (a direct consequence of global warming) they can gain strenght, size, intensity and speed, becoming devastating to nature and to mankind (one good example is the Hurricane Katrina, which killed almost 2 thousand people in 2005)

We have already seen that the greenhouse effect is, in fact, important for life to exhist on Earth;

However, if the concentration of gases that make the greenhouse effect possible – gases that retain heat (i.e. Carbon Dioxide, Nitrous Oxide and Methane) gets too high, things start to turn ugly

Researchers say that, since the Industrial Revolution in the late 18th century, the concentration of these gases in the atmosphere have been growing, which, in turn, is making the global temperature rise an average of 0.8 ºC since 1880

Atmospheric Carbon Dioxide

Since the late 1950s, however, the trend of global climate change has accelerated, given to an increase of 17,5% in the annual average concentration of atmospheric CO2 (carbon dioxide)

Have you ever heard of the Kyoto Protocol? K.P. is a world treaty, created in 1997,

which aims to restrict emissions of greenhouse gases, especially Carbon dioxide (CO2)

[Ten years earlier, in 1987, the Montreal Protocol was a treaty to reduce the use of CFC (Chlorofluorocarbon), which helps to destroy the Ozone layer]

IPCC and The Kyoto Protocol

In Kyoto, however, it was agreed that: ◦ a) CO2 levels had increased substantially since the Industrial

Revolution (1750-1850) and that this trend was expected to continue;

◦ Humans had been responsible for much of this increase;

Nevertheless, there was a disagreement regarding how much of the increase in temperature was due to higher CO2 concentrations;

There’s a controversy regarding how bad x how good CO2 levels can be to nature: Some say it is vital to plants and the Flora (and, thus, to the Fauna also); Others say it’s harmful and it would raise the Earth’s temperature and melt polar ice caps.

It is agreed by people from all points of view that the greenhouse effect is *real*.

Greenhouse gases such as H20 (water vapor) and CO2 in the atmosphere reduce the escape of long-wave (emitted from cooler bodies) infrared radiation (heat) from the Earth into space.

Therefore, when we increase the concentration of CO2, we effectively increase the energy input to the earth.

At the end of the Kyoto meeting, 38 industrialized countries (including Brazil) decided to cut their emissions of six greenhouse gases that were linked to global warming (CO2/CH4 – methane/N20 – nitrous oxide/ SF6 - sulfur hexafluoride/HFC – hidrofluorocarbon/PFC – perfluorocarbon)

By 2005, when the Protocol was made official, 191 countries had ratified it.

COUNTRIES THAT HAVE SIGNED AND HAVEN’T SIGNED THE KP (Blue: didn’t sign/Dark Blue: withdrew from KP/ Brown: signed/ Dark Brown: signed after 1997/ Gray: No position taken – not consulted)

The countries that have agreed to sign the Protocol are obliged to reduce emissions of CO2 to na average of 5,2% below 1990 levels during the five-year period of 2008-2012

Compared to not doing anything, this initiative represents a reduction of almost 30% in greenhouse gas emissions

Results of the K.P.

Significant work on the issue of climate change has been undertaken by a group known as the Intergovernmental Panel on Climate Change, or IPCC, established jointly by two UN (United Nations) bodies, UNEP (PNUMA) and WMO (OMM);

The IPCC comprises the elite of the world’s leading scientists and researchers on Climatology, Biogeography, Metereology and Geography

IPCC

Several reports have been published by the IPCC on Global Climate Change;

Each report consists of 4 large volumes that were finalized at conferences held in Shanghai (CN), Geneva (CH) and Accra (GH) in late 2000 and early 2001.

The report suggests that humanity stands on the edge of a cataclysm as a consequence of global warming

How do they reached this conclusion? By means of extensive measurements

undertaken in the upper atmosphere (Thermosphere), under the sea, on tundra and desert, on ice caps, in pollen sediments and bird nesting records, with satellites and weather balloons.

The preliminary finding made in 1995 concluded that the balance of evidence suggests a discernible human influence on global climate

The conclusion reached in a further report was far more alarming: using 6 different projections about how economies would grow and how they’d make the transition to non-carbon forms of energy, it was concluded that the global average temperature would rise 1,7°C to 6,1°C before the year 2100; which means that, since the current average temperature on Earth is 15°C, by the beginning of next century it’ll be 21°C!

This temperature would mean a huge rise in the amount of energy trapped in the lower atmosphere (troposphere) increasing the rate of almost every natural process except the volcanic (eruptions) and the tectonic (quakes);

The IPCC states that there’s no doubt that the climate is warming. The organism notes that the biggest increases in temperature have been in the lowest 8 km of the atmosphere, which is where human impacts are greatest