what is the effect of forests on human life and climate?

Answer 1

People had long speculated that the climate might be altered where forests were cut down, marshes drained or land irrigated. Scientists were skeptical. During the first half of the 20th century, they studied climate as a system of mechanical physics and mineral chemistry, churning along heedless of the planet's thin film of living organisms. Then around 1960, evidence of a rise in carbon dioxide showed that at least one species could indeed alter global climate — humanity. As scientists looked more deeply into how carbon moved in and out of the atmosphere, they discovered many ways that other organisms could also exert powerful influences. Forests in particular were deeply involved in the carbon cycle, and from the 1970s onward, scientists argued over just what deforestation might mean for climate. By the 1980s, it was certain that all the planet's ecosystems were major players in the climate changes that would determine their own future.

"In our century the biosphere has acquired an entirely new meaning; it is being revealed as a planetary phenomenon of cosmic character." — W.I. Vernadsky

George Woodwell, a botanist who had recently joined the Marine Biology Laboratory at Woods Hole to direct their Ecosystems Center, went still further with calculations he had begun independently of Bolin. Woodwell believed that deforestation and agriculture were putting into the air as much CO2 as the total from burning fossil fuel, or maybe even twice as much. His message was that the attack on forests must be stopped, not just for the sake of preserving nature but also to avoid disrupting the climate.

Broecker and other geochemists thought Woodwell was making ridiculous extrapolations from scanty data. Defending their own calculations, the geochemists insisted that the oceans could not possibly be taking up so much carbon. "The subject dominated the Dahlem conference," Woodwell recalled, "stimulating much discussion."The arguments spilled over into general social questions of environmentalism and regulation. People's beliefs about the sources of CO2 were becoming connected to their beliefs about what actions (if any) governments should take..


Researchers tried to resolve the problem scientifically, attacking it from many directions. In meetings, workshops, and publications the experts met and wrangled, sometimes bitterly but always politely. As occasionally happens in scientific debates, opinions divided largely along disciplinary lines: oceanographers plus geochemists versus biologists. The physical scientists like Broecker pointed out that they could reliably calibrate their models of the oceans with data on how the waters took up radioactive materials (fallout from nuclear weapon tests was especially useful). Woodwell's biology was manifestly trickier. His opponents argued that nobody really knew what was happening to the plants of the Amazon and Siberia. When he invoked field studies carried out in this or that patch of trees, his opponents brought up more ambiguous studies, or just said that studies of a few hectares here and there could scarcely be extrapolated to all the world's forests.


The Carbon Dioxide Greenhouse Effect

In the 19th century, scientists realized that gases in the atmosphere cause a "greenhouse effect" which affects the planet's temperature. These scientists were interested chiefly in the possibility that a lower level of carbon dioxide gas might explain the ice ages of the distant past. At the turn of the century, Svante Arrhenius calculated that emissions from human industry might someday bring a global warming. Other scientists dismissed his idea as faulty. In 1939, G.S. Callendar argued that the level of both carbon dioxide and temperature had been rising, but most scientists found his arguments implausible. It was almost by chance that a few researchers in the 1950s discovered that global warming truly was possible. In the early 1960s, C.D. Keeling measured the level of carbon dioxide in the atmosphere: it was rising fast. Researchers began to take an interest, struggling to understand how the level of carbon dioxide had changed in the past, and how the level was influenced by chemical and biological forces. They found that the gas plays a crucial role in climate change, so that the rising level could gravely affect our future.

Level of CO2 in the atmosphere, 1958-2004 :

After 1988
During the 1990s, further ice core measurements indicated that during past glacial periods, temperature changes had preceded CO2 changes by a few centuries. Was it necessary to give up the simple hypothesis that had attracted scientists ever since Tyndall in the 19th century — that changes in CO2 were a simple and direct cause of ice ages? Some scientists doubted that the time lag could be measured so precisely, and pointed to data suggesting that the level of the gas had changed ahead of temperature after all.(54) There were many ways the gas level could interact with climate. Perhaps variations of temperature and weather patterns had caused land vegetation to release extra CO2 or take it up... perhaps the oceans were involved through massive changes in their circulation or ice cover... or through changes in their CO2-absorbing plankton, which would bloom or decline insofar as they were fertilized by minerals, which reached them from dusty winds, rivers, and ocean upwelling, all of which could change with the climate... or perhaps there were still more complicated and obscure effects.

A key point stood out. In the network of feedbacks that made up the climate system, CO2 was a main driving force. This did not prove by itself that the greenhouse effect was responsible for the warming seen in the 20th century. And it did not say how much warming the rise of CO2 might bring in the future. What was now beyond doubt was that the greenhouse effect had to be taken very seriously indeed. Joining the chorus were analyses of ancient climates, using geological data entirely independent of the computer models. They found a "climate sensitivity"— the response of temperature to a rise in the CO2 level — in the same range as computer models were predicting for future greenhouse warming. The authors concluded that continued emissions would produce a temperature rise of several degrees during the coming century, "a warming unprecedented in the past million years, and... much faster than previously experienced by natural ecosystems..."

By 2005, scientists could compare sophisticated computer estimates of the greenhouse effect with measurements that showed warming in most of the world's ocean basins (it was the oceans that absorbed most of any additional heat energy). The calculations pinned down an imbalance — the Earth was now taking in from sunlight nearly a watt per square meter more than it was radiating back into space, averaged over the planet's entire surface. That was enough energy to cause truly serious effects if it continued. James Hansen, leader of one of the studies, called it the final "smoking gun" proof of greenhouse effect warming.

The likely consequences were explored in many studies, ranging from complex computer models to surveys of how temperatures had actually changed along with gas levels in the past. All agreed that the rising level of CO2 in the atmosphere was causing global warming — probably a rise of several degrees by the late 21st century. The consequences would be severe, perhaps catastrophic, in many parts of the world

Impacts:
The consequences of such a warming were predictable. A variety of different computer models agreed with one another, and also agreed with studies of eras in the distant geological past that had been warmer than the present climate. Indeed many of the predicted changes already seemed to be underway. Here are the likely consequences of warming by a few degrees Celsius — that is, what scientists expect if humanity manages to restrain its emissions within the next few decades, so that greenhouse gases do not rise beyond twice the level maintained for the past few million years.
* Most places will continue to get warmer, especially at night and winter. Heat waves will probably continue to get worse, killing vulnerable people.

* Sea levels will continue to rise for centuries. (The last time the planet had been so warm, the level had been roughly 5 meters higher, submerging coastlines where many millions of people now live.) Although the rise is gradual, storm surges will cause emergencies.

* Weather patterns will keep changing, probably toward an intensified water cycle with stronger storms, floods and droughts. Generally speaking, regions already dry are expected to get drier, and wet regions wetter. In flood-prone regions, whether wet or dry, stronger storms are liable to bring worse flooding. Ice fields and winter snowpack will shrink, jeopardizing water supply systems in some regions. There is evidence that all these things have already begun to happen.

Agricultural systems and ecosystems will be stressed, although some will temporarily benefit. Uncounted valuable species are at risk of extinction, especially in the Arctic, mountain areas, and coral reefs. Tropical diseases will probably spread to warmed regions. Increased CO2 levels will also affect biological systems independent of climate change. Some crops will be fertilized, as will some invasive weeds. The oceans are becoming more acidic, which endangers coral and much other important marine life

The greatest uncertainty now no longer lies in how to calculate the effects of the greenhouse gases and aerosols that humanity pours into the atmosphere. The greatest unknown for the coming century is how much of this pollution we would decide to emit.

Answer 2

To know the global effect you will have to know the micro effect. Example take a very sunny day, an outfield, and a cluster of trees (patch) on that field.
Stand in the sun for 10 minutes, and then get under that cluster of tree.
Now you are protected from the heat, the ultra violet rays of the Sun. You feel cooler, breathe better (because of Oxygen emissions). cut out all the trees and come back to the same spon the next day, and you will be cursing the hell out of the guy who chopped of the trees.

Answer 3

to comprehend the international result you will ought to comprehend the micro result. occasion take an particularly sunny day, an outfield, and a cluster of timber (patch) on that container. Stand in the sunlight for 10 minutes, and then get decrease than that cluster of tree. Now you're risk-free against the warmth, the extremely violet rays of the sunlight. you experience cooler, breathe better (because of the fact of Oxygen emissions). shrink out each and all of the timber and are available back to a similar spon day after on the instant, and you would be cursing the hell out of the guy who chopped of the timber.

Answer 4

forests provide recycling - and change our carbon dioxide that we breathe out into oxygen that we breathe back in