The world's climate has always varied naturally but compelling evidence from around the world indicates that a new kind of climate change is now under way foreshadowing drastic impacts on people, economies and ecosystems. Levels of carbon dioxide and other
“greenhouse gases” in the atmosphere have risen steeply during the industrial era owing to human activities like fossil fuel use and deforestation, spurred on by economic and population growth. Like a blanket round the planet, greenhouse gases trap heat energy in the Earth's lower atmosphere. If levels rise too high, the resulting overall rise in air temperatures – global warming – is liable to disrupt natural patterns of climate.
In its Fourth Assessment Report, the Intergovernmental Panel on Climate Change (IPCC) concluded that the evidence that climate change is already occurring is unequivocal and is due in large part to human activity. The IPCC says the world faces an average temperature rise of around 3°C this century if greenhouse gas emissions continue to rise at their current pace and are allowed to double from their pre-industrial level. The impacts of this climate change, particularly temperature increases, are already being witnessed on natural and human systems around the world and are very likely to increase.
People in some areas may benefit from climate change, but many more will struggle to cope.
Developing countries will suffer more than others, as their lack of resources makes them especially vulnerable to adversity or emergencies on any major scale. Yet on a per person basis, people in developing countries contribute only a small proportion of greenhouse gas emissions.
The particular needs of developing countries in adapting to climate change are of critical importance. In many key ways, the problem of climate change is interlinked with development: economic growth is essential for developing countries to improve the health, economic livelihood and quality of life of their citizens. Economic growth is also essential to increase the capacity of developing countries to adapt to the negative impacts of climate change. But historically, increased economic development and the corresponding increase in energy use have also led to increased emissions of greenhouse gases. The challenge of addressing climate change is to break the link between economic development and greenhouse gas emissions. In this way, climate change is fundamentally a sustainable development issue.
WHAT IS CLIMATE CHANGE?
Climate includes patterns of temperature, precipitation, humidity, wind and seasons.
"Climate change" affects more than just a change in the weather - it refers to seasonal
UN Framework Convention on Climate Change changes over a long period of time. These climate patterns play a fundamental role in shaping natural ecosystems, and the human economies and cultures that depend on them.
Because so many systems are tied to climate, a change in climate can affect many related aspects of where and how people, plants and animals live, such as food production, availability and use of water, and health risks.
For example, a change in the usual timing of rains or temperatures can affect when plants bloom and set fruit, when insects hatch or when streams are their fullest. This can affect historically synchronized pollination of crops, food for migrating birds, spawning of fish, water supplies for drinking and irrigation, forest health, and more.
Some short-term climate variation is normal, but longer-term trends now indicate a changing climate. A year or two of an extreme change in temperature or other condition doesn’t mean a climate change trend has been "erased.”
CLIMATE CHANGE AND GLOBAL WARMING
Climate Change and Global Warming are not exactly, but they’re closely related, and some people use the terms interchangeably. Global warming causes climates to change. "Global warming" refers to rising global temperatures, while “climate change” includes other more specific kinds of changes, too. Warmer global temperatures in the atmosphere and oceans leads to climate changes affecting rainfall patterns, storms and droughts, growing seasons, humidity, and sea level.
Also, while “global warming” is planet-wide, “climate change” can refer to changes at the global, continental, regional and local levels. Even though a warming trend is global, different areas around the world will experience different specific changes in their climates, which will have unique impacts on their local plants, animals and people. A few areas might even get cooler rather than warmer.
CLIMATE CHANGE IMPACTS
All across the world, people are taking action because climate change has serious impacts, locally and globally. For example, in 2007, scientists from the International Panel on Climate Change (IPCC) predicted that warming oceans and melting glaciers due to global warming and climate change could cause sea levels to rise 7-23 inches by the year 2100. Worldwide, densely populated coastal communities and infrastructure that supports them would be affected (such as city buildings and homes, roads, ports and wastewater treatment plants).
Some would be flooded or more vulnerable to storm damage. In flat terrain, the shoreline could move many miles inland.
Other effects are also serious. In some places, floods and/or drought could become more frequent and more severe. Even seemingly less dramatic local changes in temperature,
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precipitation and soil moisture could severely impact many things important to human life and all life around us, including:
i. natural ecosystems;
ii. agriculture and food supplies;
iii. human health;
iv. forestry;
v. water resources and availability;
vi. energy use; and vii. transportation
Many people are concerned that we are losing time to make a difference. Climate change and its effects may be irreversible. Life could become very difficult for some populations - plant, animal and human. Species, cultures, resources and many lives could be lost.
IS CLIMATE CHANGE REALLY HAPPENING?
Yes. In February 2007, the International Panel on Climate Change (IPCC) reported to the United Nations that the Earth’s climate system is undoubtedly getting warmer.
The graph below shows the global annual temperature change since 1880. Even with variation over the years, the general trend is clearly upward. Some cooler temperatures in recent years have prompted people to ask if there is now a global cooling trend, but as the graph shows, even several years of cooling do not mean a long-term warming trend is over.
The land-ocean temperature index combines data on air temperatures over land with data on sea surface temperatures. (“Mean” is the midpoint between the highest and lowest.) The
UN Framework Convention on Climate Change Although specific, individual events cannot be directly linked to global warming, the IPCC has noted many indications of climate change around the world:
i. Retreating mountain glaciers on all continents;
ii. Thinning ice caps in the Arctic and Antarctic;
iii. Rising sea level – about 6-7 inches in the 20th century;
iv. More frequent heavy precipitation events (rainstorms, floods or snowstorms) in many areas; and
v. More intense and longer droughts over wider areas, especially in the tropics and subtropics
CAUSES FOR CLIMATE CHANGE AND GLOBAL WARMING
This question has been debated a lot, because climate change can be “due to natural variability or as a result of human activity” (IPCC 2007) and because the climate system is very complex.
There is new and stronger evidence that most of the warming over the last 50 years is due to human activities. Ice cores taken from deep in ancient ice of Antarctica show that carbon dioxide levels are higher now than at any time in the past 650,000 years. More carbon dioxide in the atmosphere means warming temperatures. In its 2007 report to the United Nations, the IPCC concluded that it is more than 90 percent likely that the accelerated warming of the past 50-60 years is due to human contributions.
These contributions include increased levels of “heat-trapping” gases (greenhouse gases) such as carbon dioxide in the Earth’s atmosphere. One of the biggest ways people contribute to greenhouse gases is by burning fossil fuels. We use coal, oil, and natural gas to generate electricity, heat our homes, power our factories, and run our cars.
Changing land use patterns contribute, too. Trees and other plants use carbon dioxide and give off oxygen. When trees are cut down for development, agriculture, and other purposes, they’re no longer available to take carbon dioxide out of the air, and actually release carbon dioxide as they decay or burn.
As the levels of carbon dioxide and other greenhouse gases increase, more heat is “trapped”
and global temperatures rise. This causes significant changes in the timing and length of the seasons as well as the amount and frequency of precipitation.
GREENHOUSE GASES AND THE GREENHOUSE EFFECT
The greenhouse effect occurs as a result of greenhouse gases trapping the sun’s heat and keeping it close to the earth. Anyone who has parked a closed car in the sun for a few hours on a summer day has experienced something like the greenhouse effect. The “greenhouse effect” refers to how gases in the earth’s atmosphere naturally keep the earth warm - similar to how a greenhouse keeps plants warm, hence the name. The earth’s natural greenhouse
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effect keeps it about 60 degrees warmer than it would be otherwise. This enables us to live comfortably on earth.
Figure 1. The greenhouse effect
Although many “greenhouse gases” occur naturally, human activities have increased their levels and added new ones. Greenhouse gases of concern include carbon dioxide, methane, nitrous oxide, and fluorinated gases. Scientists say that increased levels of these gases are contributing to climate change. Water vapor is the most abundant greenhouse gas, but human activity isn’t considered a direct cause of changes in its concentration. However, a warming atmosphere can trigger changes in water vapor levels. Some examples of activities that contribute to greenhouse gas levels:
i. Burning fossil fuels – oil, gasoline, gas and coal;
ii. Industrial processes and mining;
iii. Landfills, septic and sewer systems;
iv. Agricultural practices, including fertilizer and manure management; and v. Land use practices, including deforestation.
WEATHER VS CLIMATE
Weather can change from hour-to-hour, day-to-day, and season-to-season. It may rain for an hour and then become sunny and clear. Weather is what we hear about on the television news every night. It includes wind, temperature, humidity, atmospheric pressure, cloudiness, sunshine and precipitation.
Climate is the average weather for a particular region over a long time period. Climate describes the total of all weather occurring over a long period of years in a given place. This includes average weather conditions, regular weather seasons (winter, spring, summer, and fall), and special weather events (like tornadoes and floods). Climate tells us what it's usually
UN Framework Convention on Climate Change A simple way of remembering the difference is that 'climate' is what you expect (cool, wet winters) and 'weather' is what you get (a foggy morning with afternoon sunshine).
HOW IS CLIMATE CHANGE DIFFERENT FROM OZONE
Climate change, caused by global warming, is a different problem than the ozone hole.
The ozone hole is a thinning of the stratosphere's ozone layer, which is roughly 9 to 31 miles above the earth's surface. The depletion of this ozone layer is due to man-made chemicals like chlorofluorocarbons (CFCs). A thinner ozone layer lets more harmful ultraviolet (UV) radiation reach the earth's surface. This problem is now slowly improving since countries around the world agreed to stop manufacturing and using CFCs, an international agreement called the Montreal Protocol.
Global warming, on the other hand, is the increase in the earth's average temperature due to the buildup of carbon dioxide and other greenhouse gases in the atmosphere from human activities. Global warming is causing climate change. The 1997 Kyoto Protocol was the initial effort to curb greenhouse gas production.