The vast plume of contamination from factories, fires, cars and deforestation contains some particles that reflect sunlight away from the earth, cutting its ability to heat the earth.

“One of the impacts of this atmospheric brown cloud has been to mask the true nature of global warming on our planet,” United Nations Environment Programme head Achim Steiner said at the launch in Beijing of a new report on the phenomenon.

The amount of sunlight reaching earth through the murk has fallen by up to a quarter in the worst-affected areas and if the brown cloud disperses, global temperatures could rise by up to 2 degrees Celsius.

But the overall effect of slowing climate change is not the silver lining to a dark cloud that it appears to be.

The choking soup of pollutants may hold temperatures down overall, but the mix of particles means it is also speeding up warming in some of the most vulnerable areas and exacerbating the most devastating impacts of higher temperature.

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The complex impact of the cloud, which tends to cool areas near the surface of the earth and warm the air higher up, is believed to be causing a shortening of the monsoon season in India while increasing flooding there and in southern China.

Soot from the cloud is also deposited on glaciers, which are at the centre of environmentalists’ and politicians’ concerns because they feed Asia’s key rivers and provide drinking water for billions who live along them.

Scientists are still studying the impact on crops, but possible problems include falling harvests because of less energy for photosynthesis and higher ozone concentrations.

There may also be damage from acidic and toxic particles in the cloud that land on plants, and wider changes to weather patterns may dry up or flood fields.

“The emergence of the atmospheric brown cloud problem is expected to further aggravate the recent dramatic escalation of food prices and the consequent challenge for survival among the world’s most vulnerable populations,” the report said.

One consolation, however, is that if the world stopped emitting the particles that form the cloud, it could be expected to vanish in weeks, unlike many longer-lasting greenhouse gasses.

The ingredients that make up the cloud are little different from the smog that cloaks many of the world’s large cities, particularly in developing nations.

Global warming affects all people on Earth
Climate Change 2007: Impacts, Adaptation and Vulnerability [pdf] the report of Working Group II of the United Nations’ Intergovernmental Panel on Climate Change (IPCC), which took six years to assemble and draws from the 2500 survey Scientists more than 130 countries also makes clear that while the poor around the world will suffer most from the effects of global warming, no person on Earth will escape the consequences. The effects of global warming will be felt in all regions and all levels of society.

“It is the poorest of the poor in the world – and this includes poor people even in prosperous societies – which are the most serious consequences”, said Rajendra K Pachauri, the chairman of the expert group and an action by India. “Persons are poor are least equipped to be able to adapt to the impacts of climate change and thus in some sense, this is a global responsibility, in my opinion. “

The summary report on the effects of global warming, is part of two of the four part of the IPCC report to be released in stages during the year 2007. The first part, released in February 2007, confirmed with 90 percent certainty that global warming is unstoppable and now the man responsible for a significant proportion of greenhouse gases trapping heat that caused global temperatures to increase dramatically after mid 20th century.

We need urgent action to reduce global warming
Rising global temperatures could bring some temporary benefits, according to the report, and especially to increase food production because of rain and longer growing seasons in the mid-high latitudes and least number of deaths linked to cold. But these scientists expect short-term benefits to be offset by an increase in droughts, floods, water shortages and hunger in other areas, and more deaths and disease around the world.

“It is now clear that we are jointly responsible for warming the past 50 years, and this is already causing adverse changes in our planet,” said Catherine Pearce, climate campaigner for Friends of the Earth International. “Unless we act now to reduce emissions, is much worse to come, condemning millions in the poorest regions of the world for the loss of lives, livelihoods and homes. Climate change is no longer simply an environmental issue. This is a Excluding humanitarian disaster, which ultimately threaten global security and survival. “

Conclusions of the report include:

* Projected climate change are likely to affect millions of people who are already vulnerable. Heat waves, floods, storms, droughts, fires and will result in increased deaths, diseases and other damage. Global warming is also expected to lead to more deaths due to malnutrition, diseases that cause diarrhea, cardiovascular disease associated with high concentrations of ground-level ozone, and a wide distribution of diseases transmitted by insects, rodents etc.

* Millions more people are projected to be at risk of flooding due to rising sea levels, especially in densely populated and low, settlements, which already face other challenges, such as hurricanes and tropical storms.

* About 20-30 percent of plant and animal species assessed so far are likely to be at greater risk of extinction if increases in global average temperature exceed 1.5-2.5 degrees Celsius. The global average temperature has already risen 0.74 degrees Celsius above pre-industrial levels.

* During the past century, water supplies stored in glaciers and snow cover are projected to decline, reducing water availability in regions supplied by meltwater from major mountain ranges, where more than a sixth of the world’s population now lives. For example, glacial retreat in the Himalayas will disrupt water supplies downstream, which will affect billions of people across India, China, Nepal and Butão.

* In 2020, 75-250 million people in Africa are exposed to scarcity of water due to climate change.

* During the same period, the income of African rain-fed agriculture in some countries could be reduced by 50 percent.

* Latin America faces a substantial risk of loss of biodiversity by mid-century, as the increase in temperature and soil moisture decreases associated leads to a gradual replacement of tropical forest into savanna in parts of the Amazon region.

* People who live in small islands, such as those found in the Caribbean and the Pacific, are particularly vulnerable to rising sea levels, extreme weather, and deterioration of coastal conditions associated with global warming. Climate change is expected to reduce water resources in many small islands and adversely affect the livelihood of island communities, crippling fisheries, tourism and other key components of island economies.

The global average air temperature near the Earth’s surface rose 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the last 100 years. The Intergovernmental Panel on Climate Change (IPCC) concludes, “most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations via the greenhouse effect. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward. The range of values results from the use of differing scenarios of future greenhouse gas emissions as well as models with differing climate sensitivity. An increase in global temperatures is expected to cause the sea level to rise, increase the intensity of extreme weather events, and change the amount and pattern of precipitation. Other effects of global warming include changes in agricultural yields, glacier retreat, species extinctions and increases in the ranges of disease vectors.

Most national governments have signed and ratified the Kyoto Protocol, aimed at reducing greenhouse gas emissions.

The term “global warming” is a specific example of the broader term climate change, which can also refer to global cooling. The United Nations Framework Convention on Climate Change (UNFCCC) uses the term “climate change” for human-caused change, and “climate variability” for other changes.

Earth’s climate changes in response to external forcing, including variations in its orbit around the sun (orbital forcing), volcanic eruptions, and atmospheric greenhouse gas concentrations. The detailed causes of the recent warming remain an active field of research, but the scientific consensus identifies elevated levels of greenhouse gases due to human activity as the main influence. In contrast to the scientific consensus that recent warming is mainly attributable to elevated levels of greenhouse gases, other hypotheses have been suggested to explain the observed increase in mean global temperature. Climate commitment studies indicate that even if greenhouse gases were stabilized at 2000 levels, a further warming of about 0.5 °C (0.9 °F) would still occur.

Greenhouse process is the process by which absorption and emission of infrared radiation by atmospheric gases warms a planet’s atmosphere and surface.

Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F), without which Earth would be uninhabitable. Some other naturally occurring gases contribute very small fractions of the greenhouse effect; one of these, nitrous oxide (N₂O), is increasing in concentration owing to human activity such as agriculture. The atmospheric concentrations of CO₂ and methane have increased by 31% and 149% respectively above pre-industrial levels since 1750. Future CO₂ levels are expected to rise due to ongoing burning of fossil fuels and land-use change. Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100, if coal, tar sands or methane clathrates are extensively used.