Generally we would not think of CO₂ as a pollutant because it is a natural constituent of air, however, the excess of carbon dioxide in our atmosphere has pushed it over the edge so that it is adversely affecting our environment.
The most commonly quoted problem caused by an increase of CO₂ in our atmosphere is ‘GLOBAL WARMING’, however as we shall see below this is just one of many factors which should concern us all.
This is happening because CO₂ permits short wavelength visible radiations to pass through to the earth but traps the longer wavelength infra-red radiations (heat waves) reflected by the earth’s surface.
The increased CO₂ in the atmosphere will ‘trap’ more heat waves and lead to excessive heating of the atmosphere. This heating is called the GREEN HOUSE EFFECT – the International Panel for Climate Change (IPCC) has predicted that Earth’s mean temperature will increase between 1.4 to 5.8 degrees Celsius in this century.
The Green House effect will potentially cause a multitude of adverse changes to our wonderful planet.
These changes will cause mass displacement of people as well as mass deaths of plants and animals. Some of these changes may already be affecting large areas of our planet, for example:
Take a look on the internet and you will find a multitude of examples…
Carbon dioxide reacts with water molecules and forms carbonic acid, this contributes to ocean acidity. An estimated 30 – 40% of the carbon dioxide released by humans into the atmosphere dissolves into oceans, rivers and lakes, thereby increasing the acidity which is now affecting ocean bio-systems.
The projected rate of increasing oceanic acidity could also slow the biological uptake of calcium carbonates, thus decreasing the ocean’s capacity to absorb carbon dioxide. This highlights the very difficult understanding of what happens when we upset the Carbon cycle. One thing does not lead to just one change but to a complex matrix of changes. No wonder climatologists have so much trouble predicting what will happen. The changing acidity in our oceans will upset many ecosystems and may lead to mass extinctions of plant and animal life.
Carbon is stored in soil and can remain there for thousands of years before being washed into rivers by erosion or released into the atmosphere through soil respiration. Between 1989 and 2008 soil respiration increased by about 0.1% per year. In 2008, the global total of CO₂ released from the soil reached roughly 98 billion tonnes. The most likely explanation for this increase is that rising temperatures have increased rates of decomposition of soil organic matter, which has increased the flow of CO₂ into the atmosphere. This will be a difficult trend to reverse and can only lead to a more rapid increase in atmospheric CO₂.
Humans also affect the oceanic carbon cycle. Current trends in climate change lead to higher ocean temperatures, thus modifying ecosystems. Also, increasing ocean acidity and polluted runoff from agriculture and industry change the ocean’s chemical composition. Such changes can have dramatic effects on highly sensitive ecosystems such as coral reefs. One of the most obvious effects is coral bleaching – putting it bluntly this is where coral reefs die, leaving just dead calcium carbonate monoliths. This is a double whammy because coral polyps also use CO₂ to build the reefs so removing CO₂ from the water.
Coral reefs are the rain forests of the oceans, they host a vast range of animal and plant species. Already 50% are dead or severely damaged, many others are stressed, this is already a massive biological disaster.
Inside coral polyps there are tiny green photosynthetic algae, called zooxanthellae, which absorb CO₂, but are also a large source of O₂ for our atmosphere. The death of corals means less of these algae.
In addition to the acidification of the oceans other chemical reactions are triggered which result in a net decrease in the amount of carbonate ions available. This makes it more difficult for marine calcifying organisms, such as coral and some plankton, to form biogenic calcium carbonate, removing yet another CO₂ sink from the Carbon cycle.
At the current rate within 10 years it is thought parts of the Arctic ocean will be corrosive to biogenic calcium carbonate.
Worldwide there could be huge repercussions for food supplies. The micro- organisms form the base of the oceanic food chain and disrupting their health threatens the wider food chain, including the fisheries that a billion people depend on.
Note: Members of the Inter Academy Panel, 105 science academies have issued a statement on ocean acidification recommending that by 2050, global CO₂ emissions be reduced by at least 50% compared to the 1990 level. This seems an impossible dream with current thinking.
The World Health Organization (WHO) has calculated that by 2020 human-triggered climate change could kill 300,000 people worldwide every year The agency combined models of recent and projected climate change with data on several health dangers that are known to be affected by climate:
It is thought their estimate of deaths is conservative. Not only are the underlying assumptions conservative, but the analysis only concerns a few of the relatively better-understood health risks of climate change.
The amounts of two important nutrients, zinc and iron, were found to be lower in wheat, rice, soybeans and field peas grown in open-air fields where the scientists created CO₂ concentrations at the level they forecast for Earth by roughly 2050, about 550 parts per million.
“This is important because almost two billion people globally receive most of these two nutrients (zinc and iron) by eating crops,” said University of Illinois plant biology professor Andrew Leakey, one of the researchers.
The study found that in wheat grown under elevated CO₂ conditions there were about 9 percent lower levels of zinc and 5 percent lower levels of iron compared to wheat grown under normal conditions. The rice grown with elevated CO₂ levels had 3 percent less zinc content and 5 percent less iron.
Inadequate zinc intake affects the immune system and makes people more vulnerable to premature death from maladies like malaria, pneumonia and diarrhoea.
Iron deficiency is linked to increases in maternal mortality, anaemia, reductions in IQ and reduced work productivity.
Not only that, but in wheat and rice, there was also a lower protein content at the elevated carbon dioxide levels.
We are already struggling to provide enough nutrition for the world population as it is, this can only make it worse.
Plants give off water through tiny pores in their leaves, a process called evapotranspiration that cools the plant, just as perspiration cools our bodies. On a hot day, a tree can release a large volume of water into the air, acting as a natural air conditioner for its surroundings. The plants absorb carbon dioxide for photosynthesis through the same pores (called stomata). But when carbon dioxide levels are high, the leaf pores shrink. This causes less water to be released, diminishing the tree’s cooling power.
According to a new study by researchers at the Carnegie Institution for Science, in some regions such as parts of N.America and Eastern Asia, more than a quarter of the warming from increased carbon dioxide is due to its direct impact on vegetation. Think about it – if doubling CO₂ levels causes about 4 degrees of atmospheric warming then 1 degree of that warming could be due to the effect of CO₂ on plants. More broadly, it shows that the kind of vegetation that’s on the surface of our planet and what that vegetation is doing is very important in determining our climate. We need to take great care in considering what kind of changes we make to forests and other ecosystems, because they are likely to have important climate consequences.
Rising sea levels represent a direct physical threat from climate change. Some coastal populations will be threatened by inundation from the water’s slow, inexorable rise, while even larger areas will be subject to periodic danger from intensified storm surges. The IPCC predicts that global sea levels will rise 18-59 centimetres over the next century. Most of that calculation represents the expansion of water as sea surface temperatures warm; melting of polar ice will also contribute, but the details of this process are not understood well enough at this time to quantify.
Many of our major cities will become more vulnerable to flooding and may in time lead to mass migration of humans to drier areas.
The melting of the ice caps will affect the deeper cold Ocean currents which in turn will affect the warm currents. Models to predict the effect of these changes on all ocean ecosystems is very complicated but needless to say it is likely to be disastrous to many.
It may be OK for species such as fish to flee from adverse environmental conditions, but for animals and plants which live on the sea bed, this is not an option.
A static organism can adapt to change but this is a slow process. Current environmental conditions are changing too rapidly for most species to adapt and so the chances are, many will die out.
There is now evidence that permafrost in the northern tundras is melting due to climate change.
Permafrost is any rock or soil material that has remained below 0 Centigrade continuously for 2 years or more. This can range in depth from a few metres to one kilometre deep and underlies 12 to 18% of the exposed land surface in the Northern Hemisphere and to a lesser extent in the Southern Hemisphere – see Figure 1 showing where permafrost exists in the Northern Hemisphere.
What is Happening?
The long-term records of the near-surface temperature, obtained from different parts of the permafrost zone in northern regions, show a significant warming trend during the last 30 years. This recent climate warming brought soil temperatures to a surprisingly high level, about 1 to 3°C warmer than long-term averages. Within some areas, temperatures are very close to 0°C and at some sites long-term degradation has already started.
Figure 2 shows expected changes in Arctic temperatures by the year 2090. Blue solid line is current permafrost boundary (orange). The blue dashed line is projected permafrost boundary by 2090.
Although widespread changes to permafrost usually take centuries, the IPCC estimates that by the mid-21st century, the area of permafrost in the northern hemisphere will decline by 20-35%. Additionally, the United Nations Environmental Programme suggests the depth of thawing could increase by 30-50% by the year 2080.
So what will this melting do?
Damage the infrastructure
The ground in areas with permafrost is normally suitable for building, however scientists at the University of Alaska have found a temperature increase in permafrost from -4 to -1°C. Such a warm-up reduces the ability of the ground to support large structures by 70%. For example – recently in Norris and Yakutsk, Russia, more than 500 tall buildings have been significantly damaged.
Similar damage has been reported on roads and pipe lines.
It is also affecting Northern transportation – in some areas surface travel is possible only when the ground is frozen solid, but as the permafrost melts so this times reduces. In fact, over the last 30 years in some areas the number of days vehicles can use perma-roads each year has reduced from 225, to less than 25 days per year.
Erosion and the frequency of landslides are expected to increase once the permafrost decreases.
Danger to indigenous people and ecosystems
Climate changes can affect the vegetation on the tundra. In Arctic Russia alone, 200,000 indigenous people live partly as nomads, surviving by reindeer herding. Erosion and changes to the landscape are expected to have a negative effect on their traditional lifestyle and threaten their livelihoods.
Speeding up the greenhouse effect
For thousands of years the tundra has worked as a carbon sink, because dead vegetation does not rot but is stored in the ground. Thinning of the permafrost allows micro-organisms to break down the biological material. In this process, methane and carbon dioxide are released. In Alaska it is documented that the tundra has changed from being a carbon stock to becoming a source of carbon to the atmosphere.
The carbon is mostly released as methane, because the rotting process is happening in wet soil with little or no supply of oxygen. Frighteningly methane as a greenhouse gas is about 21 times more powerful than CO₂.
It is thought upper layers of permafrost contain more organic carbon than is currently contained in the atmosphere. Massive volumes could be released by the end of the century.
Where permafrost is melting, areas of woodland are now referred to as ‘drunken forests’ – the name needs no explanation.
The Bush administration reported that in Alaska on the Kenai peninsula, a forest nearly twice the size of Yellowstone National Park is in the last phases of a graphic death. 38 million spruce trees are dead or dying from a huge increase in spruce bark beetles. In the past the beetles feeding on the evergreen trees didn’t survive the winter, now populations have exploded as temperatures rise.
Sergei Kirpotin, a botanist at Tomsk State University in Russia reported that the once-frozen peat bogs of Siberia – bigger than France and Germany combined – began to “boil” furiously in the summer of 2006 as methane bubbled to the surface.
The Disaster Scenario
It’s not hard to imagine a disaster scenario surrounding permafrost. As the atmosphere warms, permafrost melts, which releases greenhouse gas, which further warms the atmosphere, which speeds up the permafrost melting, and so on. Currently, climate models do not incorporate the effects of methane released from melting permafrost, which means even the most extreme warming scenarios we’ve come up with might not be extreme enough. A spike in atmospheric methane concentration could set off catastrophic global warming.
One of the biggest consequences of climate change is at the invisible micro biotic level – species are becoming extinct, others are multiplying, these organisms are the basis of all food chains. Changes at the base of a food chain affect every level, all the way to humans sitting right at the top. Needless to say this will fundamentally affect our food sources, some may be better, some may be worse – who knows!
Crop yields are likely to fall in the tropical and subtropical world, especially at latitudes with many poorer countries where most of the world’s hungry and malnourished live today.
The Gulf Stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates at the tip of Florida, and follows the eastern coastlines of the United States and Newfoundland before crossing the Atlantic Ocean.
Following recent debate, there is consensus that the climate of Western Europe and Northern Europe is warmer than it would otherwise be due to the North Atlantic drift, one of the branches from the tail of the Gulf Stream.
We are now seeing a slowdown in this current and scientists judge that there is up to a 10% likelihood of a Gulf Stream shutdown before year 2100, though many climate scientists estimate this percentage is even higher.
The slowdown is being caused by the melting of the Greenland ice sheet. University of Washington atmospheric scientists have estimated that up to half of the recent warming in Greenland and surrounding areas may be due to climate variations that originate in the tropical Pacific but at least half the warming remains attributable to global warming caused by rising carbon dioxide emissions.
As the freshwater from the Greenland ice sheet pours into the Atlantic, it is lighter and colder than heavier, salty water that typically occupies that area. It therefore tends to sit on top of the water column, accumulating over the years and interfering with the formation and sinking of dense, cold and salt-enriched waters. It is the sinking motion of North Atlantic bottom water that powers the Gulf Stream current by pulling warmer, less dense water northward from the tropics. This influx of cold water chokes off the northward flowing Gulf Stream, slowing it down, and affecting ocean circulation downstream as well.
A rapid slowdown in this current would boost sea level rise rates along the highly populated Mid-Atlantic and Northeast coasts of the U.S. It could also bring much cooler conditions than is currently the norm to parts of northern Europe.
This slow down is happening decades ahead of previous predictions and may drive significant changes to climate model projections for the future.
The Gulf Stream is one part of a vast global undersea infrastructure known as the thermohaline circulation, also referred to as the “Global Conveyor Belt.” This circulation, which extends from pole to pole and throughout every ocean, is powered by density differences in ocean waters in different areas of the world. If you disturb any part of this circulation, the entire thing is likely to be disrupted.
We can only guess at the consequences.
Acid rain is precipitation that has high levels of sulphuric and nitric acids and human activity causes most of it. Burning fossil fuels release sulphur dioxide and nitrogen oxide that react with atmospheric gases and the resulting acid rain can harm both plants and animals.
To prevent acid rain we must reduce emissions and curb the burning of fossil fuels, which means finding alternative fuel sources.