Climate Change: Turning Up The Heat

Introduction

There is mounting evidence to suggest that the climate of the world is changing. Most people agree that we are experiencing climate change, defined as any long term trend or shift in the average value for any climatic element, but both experts and the public alike disagree about what is causing it. Is it a natural process, or are humans causing or amplifying it? Some argue that the effects of climate change are already being felt and will prove problematic, if not disastrous, for living organisms and their habitats. Others say that climate change will right itself in time. In this study, I will examine the evidence for the existence of climate change, its causes and its effects.

The ‘Greenhouse’ Effect

The sun is the driving force behind weather systems and climate and its radiation makes life on Earth possible. The Earth receives energy from the sun in the form of visible and ultraviolet light. About 50% of this is absorbed by the surface of the Earth and clouds and things like snow reflect 30% of the sun’s radiation.The Earth’s surface radiates energy in the infrared range. The ‘greenhouse’ effect works by the absorption of most of this infrared radiation by ‘greenhouse’ gases in the atmosphere. These gases also radiate energy in the form of infrared both upwards into space and downwards towards the Earth’s surface, warming the Earth. The ‘greenhouse’ effect is not only natural, but vital. Without it the Earth’s surface would be about 33 degrees Celsius colder and life as we know it would not be possible.

However, some argue that human activities such as the burning of fossil fuels have led to more ‘greenhouse’ gases in the atmosphere and this is making the planet warmer than it should be. This is known as the ‘enhanced greenhouse effect’. The enhanced ‘greenhouse’ effect generates positive feedback by increasing the amount of water evaporating and condensing to form clouds, which trap more heat. Deforestation contributes to the enhanced ‘greenhouse’ effect because trees and other plant materials use carbon dioxide in photosynthesis, the waste product of which is oxygen, so, naturally, there will be less photosynthesis in the atmosphere if there are less plants and therefore more carbon dioxide.

Evidence: Is Climate Change Natural or are We to Blame?

The global temperature has risen since the mid-nineteenth century, the time when industry turned away from traditional primary industries like agriculture towards more heavy secondary industry which lead to the rise of factory production. Evidence from the past shows that our planet’s climate has changed a number of times in its lifetime. There have been several ‘ice ages’ and historical evidence such as paintings and dairies showing warmer and colder periods (a good example is the very cold winter in Britain in the 1600’s, which froze the river Thames over). Some experts argue that the activities of man have made these fluctuations happen more frequently and that the changes that the global climate is experiencing will have disastrous effects for the planet. Some say the problem is natural and, in time, will return to normal. A few say climate change is not happening and accuse the government of sensationalizing the problem as an excuse to raise taxes! Both sides present their own evidence:

Evidence for Climate Change as a Man-Made Process

Due to ice at the poles melting at an alarming rate, because of higher global temperatures, sea levels have risen 1.8 mm a year between 1963-2003 and some argue that this rate is increasing. Deeper areas of oceans are warming and this also causes the expansion of the water, leading to even higher sea levels. This could prove disastrous for low-lying countries such as Holland, the Maldives and areas of Asia such as Bangladesh, which already has severe floods.

According to a study [4] by scientists at the University of Bristol for presentation at Copenhagen in March 2009, the acidity of the world’s oceans due to the increased levels of dissolved carbon dioxide is of “great concern”. They compared the current acidification rate with a great prehistoric release of greenhouse gases, which is known to have killed many marine species. They predicted serious consequences for marine calcifiers- creatures such as shellfish that form chalky shells, especially in areas around the poles. The pH of oceans has fallen by 0.1 arbitrary units since the Industrial Revolution, suggesting that a change in human activity has brought about the change in pH levels. In addition, figures show that 11 of the world’s hottest years were 1995 through to 2006. Many of the world’s valley glaciers are over 50% smaller than in 1850.

According to Marine and Atmospheric Research scientist, Dr Penny Whetton in a report for the IPCC (a group of about 2,500 scientists from around the world), “atmospheric concentrations of the main greenhouse gases, carbon dioxide and methane far exceed concentrations over the previous 650,000 years, primarily due to combustion of fossil fuels, agriculture and land-use changes”. She also says “Increases in the amount of precipitation are very likely in high latitudes, while decreases are likely in most subtropical land regions, including southern Australia.” [6]. This may lead to flooding in the Northern Hemisphere and drought in the Southern Hemisphere.

Studies show that the quantities of several ‘greenhouse’ gases have increased by 25% since 1750 (the beginning of the Industrial Revolution) and since the 1980’s, 75% of carbon dioxide emissions have come from burning fossil fuels, supporting the argument that warming of the Earth is due, at least in part, to humans.

Evidence for Climate Change as a Natural Process

Changing climate patterns is nothing new. There have been several glacial periods known as ‘ice ages’, followed by interglacial periods which are warmer. Pollen samples in sediments that have been carbon-dated show that there were once tundra plants in the south of the UK and that these were gradually replaced by forest plants, showing a colder period followed by a warmer one. Further evidence for glaciation in Britain is the presence of isostatic rebound (after ice from glaciation melts, the land is relieved of a great weight, so the land tilts to become level again) much like a set of scales.

Levels of carbon dioxide, trapped in ice cores in Greenland show fluctuation between 180ppm to 280ppm, showing that large increases in carbon dioxide levels have been quite natural and harmless in the past. However, this evidence for climate change as a natural process may be disproved because current carbon dioxide levels are much higher, 383ppm than ever previously recorded. In the last thousand years, there have been less extreme warm and cool periods .

Some experts argue that climate change is part of a natural cycle of warming and cooling that has occurred every 1,500 years for a million years. Authors Dennis Avery and Fred Singer compiled observations from over 500 scientists in their book ‘Unstoppable Global Warming’ and they found historical evidence for the natural cycle including Roman wine production in Britain and portrayals of a warmer climate in museum paintings from medieval Britain as well as the ‘ice ages’. They argue that wildlife has adapted well and sea levels have not risen significantly.

Some supporters of this view argue that because there have been more volcanic eruptions recently, that may contribute to the high levels of carbon dioxide. However, such events are comparatively rare and when Mt. Pintabo in the Philippines erupted, global temperature actually fell slightly due to the pyroclastic material blocking out the sun.

Milankovitch Cycles [1]

Milutin Milankovi? was a Serbian engineer and mathematician who theorized that changes in the Earth’s orbit, Precession (a change in the orientation of the rotation axis of a rotating body) and axial tilt brought about changes in the Earth’s climate such as ‘ice age’ cycles. When the Earth’s orbit takes it further away from the sun its climate will, logically, be colder than when it is closer to the sun. Milankovitch cycles have resulted in fluctuations in climate in the past and some use this as evidence that climate change is not caused by human activities. However, the orbital conditions in recent years do not explain an increase in global temperature.

The Arctic: A Case Study [7]

The Arctic is a good example of and area affected by climate change and some experts say that it will be a good indicator of what is to come for the rest of the world. Average temperatures in the Arctic are rising twice as fast as in the rest of the world and the ice is starting to thin and crack. For example the Ward Hunt Ice Shelf, which has been in existence for 3,000 years started rupturing in 2000. The ice is shrinking at an alarming rate (9% per decade, according to NASA photographs) and some experts predict that Arctic summers could become ice-free by 2050! According to the WWF, Greenland’s ice sheet holds enough water to raise sea levels by 7 meters [8]. This change can have a number of impacts on the Arctic region, its wildlife and its people, as well as worldwide impacts:

The higher melting rate will obviously lead to more sea water. Dark water will absorb more radiation from the sun than light snow and ice, so the Earth will be hotter and this causes more ice to melt. This is known as the Positive Ice Albedo Feedback. This may affect climate around the world.

The tree line will move further north, which will change the ecosystem.

Fish are highly sensitive creatures and a small change in their environmental conditions can prove fatal to them. This will have a knock-on effect with their predators such as seals and polar bears.

The indigenous people of Arctic areas, the Inuit, will also be affected by changes in fish stocks and the local ecosystem as theirs is a traditional lifestyle where they hunt local animals. Therefore climate change will have a negative impact on their natural way of life.

At present, forest fires in Arctic Russia burn almost 10 million hectares each year. Climate change is predicted to increase this. A warmer climate would increase numbers of the Spruce Bark Beetle, that chewed up 3.4 million acres of Alaskan Forest from 1993-2003.

According to a computer model by the NASA Goddard Institute of Space Studies, Kansas State in the USA would be 4 Celsius degrees warmer in the summer without Arctic ice. Warmer winters would mean less winter wheat and warmer summers would rob the soil of 10% of its moisture.

Rising sea levels may lead to salt contamination of freshwater and salinisation of soil, especially around coastal regions. This would cause problems for small islands that depend upon cash crops for survival and economic development and also for agriculture on the coast of the continent of Africa [8]

Some people have argued that there are some economic benefits of global warming in the Arctic. Due to melting ice, previously inaccessible shipping routes for trade may be opened and there is evidence of the presence of large amounts of oil under the ice, which is currently impossible to get to. However, most people think the environmental and socioeconomic costs far outweigh the economic benefits.

Conclusion: Should We Worry?

I believe that we should be concerned about climate change. While there is undisputed evidence that there have been climate changes in the past, which had natural causes and, evidently, corrected themselves, there is just as much evidence that today’s situation was caused by man. Climate change has begun to reach a point at which it is having a negative impact, not only on meteorology and ecosystems, but on a human scale. Industrialised countries and cultures are causing a negative effect elsewhere in the world and both politicians and their people should make an effort to change socioeconomic practices in order to lower their impacts on our environment. I think that the effects of climate change can be lessened and that it is our responsibility to our planet to make sure that climate change is not allowed to continue at its present rate.

Sources:

Wikipedia, the free online encyclopaedia [1]
AS Geography for Edexel (Digby, Hurst Chapman, King, Owen) by Oxford Publishing [2]
dailymail.co.uk [3]
guardian.co.uk [4]
bbc.co.uk [5]
sciencealert.com.au [6]
cru.uea.ac.uk (Pintabo/global temperature graph).
nrdc.org [7]
Geographic Magazine, November 2009 Issue [8]